Publications 2013

Australian Centre for NanoMedicine Publications 2013

Polymer Chemistry DOI: 10.1039/C3PY01676E

The precise molecular location of gadolinium atoms has a significant influence on the efficacy of nanoparticulate MRI positive contrast agents

Yang Li1, Sophie Laurent2, Lars Esser4,5, Luce Vander Elst2, Robert N Muller2,3, Andrew B Lowe4*, Cyrille Boyer1,4*, Thomas P Davis5,6*.

Graphical abstract: The precise molecular location of gadolinium atoms has a significant influence on the efficacy of nanoparticulate MRI positive contrast agents 

In this work, we studied the influence of the structure of macromolecular ligands on the relaxivity of gadolinium contrast agents constructed as nanoparticle systems. Macromolecular ligands were assembled as single-molecule nanoparticles in the form of either discrete core cross-linked star polymers or hyperbranched polymers. 1-(5-Amino-3-aza-2-oxypentyl)-4,7,10-tris(tert-butoxycarbonylmethyl)-1,4,7,10-tetraaza-cyclododecane (DO3A–tBu–NH2) chelate was incorporated into different parts (arms, cores, and end-groups) of the polymeric structures using activated ester/amine nucleophilic substitutions, deprotected and complexed with Gd3+. The relaxivity properties of the ligated Gd3+ agents were then studied to evaluate the effect of macromolecular architecture and Gd3+ placement on their behavior as discrete nanoparticle magnetic resonance imaging (MRI) contrast agents. The precise placement of Gd3+ in the polymeric structures (and therefore in the nanoparticles) proved to be critical in optimizing the performance of the nanoparticles as MRI contrast agents. The relaxivity was measured to vary from 11 to 22 mM_1 s_1, 2–5 times higher than that of a commercial DOTA–Gd contrast agent when using a magnetic field strength of 0.47 T. The relaxivity of these nanoparticles was examined at different magnetic fields from 0.47 T to 9.4 T. Finally, the residence time of the coordinated water (sM) and the rotational correlation time of the final molecule (sR) were evaluated for these different nanostructures and correlated with the polymeric architecture.

1Australian Centre for Nanomedicine, School of Chemical Engineering, The University of New South Wales, Sydney NSW 2052 Australia 2NMR and Molecular Imaging Laboratory, Department of General, Organic and Biomedical Chemistry, University of Mons, 7000 Mons Belgium 3CMMI - Center of Microscopy and Molecular Imaging, Rue Adrienne Bolland 8 B-6041 Gosselies Belgium 4Centre for Advanced Macromolecular Design, School of Chemical Engineering, University of New South Wales, Sydney NSW 2052 Australia 5Monash Institute of Pharmaceutical Sciences, Monash University, Parkville VIC 3052 Australia 6Department of Chemistry, University of Warwick, Coventry UK CV4 7AL

 

Langmuir (DOI: 10.1021/la403669v)

Light-Induced Organic Monolayer Modification of Iodinated Carbon Electrodes

Callie Fairman, Muthukumar Chockalingam, Guozhen Liu, Alexander H Soeriyadi†‡, J Justin Gooding*†‡

 Abstract Image

We report the modification of carbon electrodes formed from pyrolyzed photoresist films (PPF) via plasma iodination followed by the organic monolayer modification of these surfaces. The iodinated surfaces were characterized using cyclic voltammetry, atomic force microscopy, and X-ray photoelectron spectroscopy to enable the optimization of the iodination while preserving the stability and smoothness of the carbon surface. Subsequently, the C–I surface was further modified with molecules that possess an alkene or alkyne at one end through light activation with low energy (visible range λ 514 nm). The versatility of the modification reaction of the C–I surfaces is shown by reactions with undecylenic acid, 1,8-nonadiyne, and S-undec-10-enyl-2,2,2-trifluoroethanethioate (C11-S-TFA). Modification with 1,8-nonadiyne allows further modification via “click” chemistry with azido-terminated oligo(ethylene oxide) molecules demonstrated briefly to alter the hydrophilicity of the surface after attachment of ethylene oxide moieties. Furthermore, patterning of C11-S-TFA was demonstrated using a simple photolithography technique. Deprotection of the C11-S-TFA gave a free thiol allowed patterning of gold nanoparticles on the surface as verified using scanning electron microscopy (SEM). These results demonstrate that plasma iodination to form C–I is a versatile, simple, and modular approach to functionalize the carbon surface.

School of Chemistry, University of New South Wales, Sydney NSW 2052 Australia Australian Centre for NanoMedicine, University of New South Wales, Sydney NSW 2052 Australia

   

Frontiers in Plant Science (doi: 10.3389/fpls.2013.00503)

Imaging lipid domains in cell membranes: the advent of super-resolution fluorescence microscopy

Dylan M Owen1 and Katharina Gaus2*

 

 www.frontiersin.org

The lipid bilayer of model membranes, liposomes reconstituted from cell lipids, and plasma membrane vesicles and spheres can separate into two distinct liquid phases to yield lipid domains with liquid-ordered and liquid-disordered properties. These observations are the basis of the lipid raft hypothesis that postulates the existence of cholesterol-enriched ordered-phase lipid domains in cell membranes that could regulate protein mobility, localization and interaction. Here we review the evidence that nano-scaled lipid complexes and meso-scaled lipid domains exist in cell membranes and how new fluorescence microscopy techniques that overcome the diffraction limit provide new insights into lipid organization in cell membranes.

1Department of Physics and Randall Division of Cell and Molecular Biophysics, King’s College London, London UK 2Centre for Vascular Research and Australian Centre for Nanomedicine, University of New South Wales, Sydney NSW Australia

  

Macromolecular Rapid Communication DOI: 10.1002/marc.201300730

Simultaneous Polymerization-Induced Self-Assembly (PISA) and Guest Molecule Encapsulation

Bunyamin Karagoz1,2, Cyrille Boyer1,*, Thomas P Davis3,4,*

Thumbnail image of graphical abstract 

Nanoparticles with various morphologies such as micelles, worm-like/rod-like and spherical vesicles are made using a polymerization-induced self-assembly (PISA) approach via a one-pot RAFT dispersion polymerization. On polymerization/self-assembly, we report a concurrent highly efficient loading of guest molecules within the nanoparticle structures. Different nanoparticle morphologies, such as spherical micelles, worm-like, rod-like, and spherical vesicles, are achieved by gradually increasing the number-average degree of polymerization (DPn) of the PST block via increasing polymerization times (in a poor solvent) as determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. In parallel, a guest molecule (Nile Red) is encapsulated during the polymerization without disturbing the morphology or the polymerization kinetics.

1B Karagoz, C Boyer Centre for Advanced Macromolecular Design and Australian Centre for NanoMedicine, School of Chemical Engineering, University of New South Wales, Sydney NSW 2052 Australia  2B Karagoz Istanbul Technical University Department of Chemistry, Maslak 34469 Istanbul Turkey 3T P Davis Monash Institute of Pharmaceutical Sciences , Monash University Parkville VIC 3052 Australia

  

Angewandt Chemie DOI: 10.1002/anie.201306724

Functional Iron Oxide Magnetic Nanoparticles with Hyperthermia-Induced Drug Release Ability by Using a Combination of Orthogonal Click Reactions

Thuy T T N'Guyen1, Hien T T Duong2, Johan Basuki2, Véronique Montembault1, Sagrario Pascual1, Clément Guibert4, Jérôme Fresnais4, Cyrille Boyer2, Michael R Whittaker3, Thomas P Davis3, Dr Laurent Fontaine1

 
 Thumbnail image of graphical abstract

Click and drug: A combination of orthogonal click reactions is employed for the preparation of functional iron oxide nanoparticles (IONPs) that show unprecedented hyperthermia-induced drug release through a magnetically stimulated retro-Diels–Alder (rDA) process. Magnetic stimulation induces sufficient local energy in close proximity to the cycloadduct to initiate the rDA process

1Institut des Molécules et des Matériaux du Mans, UMR 6283—Equipe Méthodologie et Synthèse des Polymères, CNRS—Université du Maine, Avenue Olivier Messiaen 72085 Le Mans Cedex France 2Australian Centre for Nanomedicine, Sydney Australia 3Monash Institute of Pharmaceutical Sciences, Melbourne Australia 4PECSA, UMR 7195, Laboratoire de Physico-Chimie des Electrolytes, Colloïdes et Sciences Analytiques Paris France

 

Proceedings of the National Academy of Sciences of USA (doi: 10.1073/pnas.1314209111)

Dynamic control of β1 integrin adhesion by the plexinD1-sema3E axis

Young I Choia,b,1, Jonathan S Duke-Cohana,b,1, Wei Chenc,d,e, Baoyu Liuc,d,e, Jérémie Rossyf,g, Thibault Tabarinf,g, Lining Juc,d,e, Jingang Guia,b, Katharina Gausf,g, Cheng Zhuc,d,e, and Ellis L Reinherza,b,2

Fig. 1. 

Cell-expressed integrins mediate adhesion with other cells and with extracellular matrix and are essential for embryonic development and for controlling leukocyte migration in later life. Integrin adhesion depends on conformational change leading to activation, although it remains unknown exactly how integrins alter their conformational state and adhesion in response to guidance cues. We show that the guidance molecule plexinD1 controls clustering of integrins in patches on the cell membrane and that the activation state of individual integrins in these patches can be switched off by binding of sema3E to plexinD1. Disruption of this pathway causes abnormal thymocyte adhesion regulation and migration during development, leading to autoimmune phenomena.

aLaboratory of Immunobiology and Department of Medical Oncology, Dana-Farber Cancer Institute and bDepartment of Medicine, Harvard Medical School, Boston MA 02115; cCoulter Department of Biomedical Engineering, dWoodruff School of Mechanical Engineering, and eInstitute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332 and fCentre for Vascular Research and gAustralian Centre for Nanomedicine, University of New South Wales, Sydney NSW 2052 Australia

  

Langmuir (DOI: 10.1021/la4037919)

Molecularly Engineered Surfaces for Cell Biology: From Static to Dynamic Surfaces

J Justin Gooding*†‡ Stephen G Parker†‡ Yong Lu†‡, Katharina Gaus†§

 
 Abstract Image

Surfaces with a well-defined presentation of ligands for receptors on the cell membrane can serve as models of the extracellular matrix for studying cell adhesion or as model cell surfaces for exploring cell-cell contacts. Because such surfaces can provide exquisite control over, for example, the density of these ligands or when the ligands are presented to the cell, they provide a very precise strategy for understanding the mechanisms by which cells respond to external adhesive cues. In the present feature article, we present an overview of the basic biology of cell adhesion before discussing surfaces that have a static presentation of immobile ligands. We outline the biological information that such surfaces have given us, before progressing to recently developed switchable surfaces and surfaces that mimic the lipid bilayer, having adhesive ligands that can move around the membrane and be remodeled by the cell. Finally, the feature article closes with some of the biological information that these new types of surfaces could provide.

The Australian Centre for NanoMedicine, School of Chemistry, and §Centre for Vascular Research, University of New South Wales, Sydney 2052 Australia

  

Chemical Science Doi: 10.1039/C3SC52838C

Magnetic nanoparticles with diblock glycopolymer shells give lectin concentration-dependent MRI signals and selective cell uptake

Johan Basuki, Lars Esser, Hien Duong, Qiang Zhang, Paul Wilson, Michael R Whittaker, David Haddleton, Cyrille Boyer, Thomas P Davis

Graphical abstract: Magnetic nanoparticles with diblock glycopolymer shells give lectin concentration-dependent MRI signals and selective cell uptake 

Multivalent glycopolymers exhibit a strong affinity for specific lectin proteins depending on their specific carbohydrate functionality. In this work, we report a facile one-pot synthesis of diblock PEG-glycopolymers using a combination of Cu(0) mediated living radical polymerization and click chemistry to attach three different carbohydrates, α-D-mannose, α-D-glucose and β-D-glucose, to iron oxide nanoparticle (IONP) surfaces. The resultant IONP@P(OEGA)-b-P(sugar) nanoparticles were then extensively characterized using a wide range of analytical techniques, including ATR-FTIR, XPS and TEM. Interestingly, α-D-mannose functionalized IONPs, (IONP@P(OEGA)-b-P(N3Man)), exhibited high r2 transverse relaxivity when measured in a 9.4 T MRI. A significant change in T2 relaxation was observed following binding to the lectin concanavalin A (Con A), with a response proportional to the lectin concentration. The results reported herein indicate that the specific binding of lectin to nanoparticle surfaces can be quantitatively detected using MRI, showing significant promise for future diagnostic applications. Additionally we found a significant improvement in cell uptake for IONPs functionalized with α-D-mannose, in a lung cancer cell line (A549).                                                                    

aAustralian Centre for NanoMedicine, School of Chemical Engineering, University of New South Wales, 2052 Sydney Australia bCentre for Advanced Macromolecular Design, University of New South Wales 2052 Sydney Australia cDepartment of Chemistry, University of Warwick, Coventry ULCV4 7AL UK  dMonash Institute of Pharmaceutical Sciences, Monash University, Parkville VIC 3052 Australia

  

ACS NANO DOI: 10.1021/nn404407g

Using Fluorescence Lifetime Imaging Microscopy to Monitor Theranostic Nanoparticle Uptake and Intracellular Doxorubicin Release

Johan S Basuki, Hien TT Duong, Alexander Macmillan§, Rafael B Erlich†‡, Lars Esser, Mia C Akerfeldt, Renee Megan Whan§, Maria Kavallaris†‡, Cyrille Boyer, Thomas P Davis

 

 Abstract Image

We describe the synthesis of iron oxide nanoparticles (IONPs) with excellent colloidal stability in both water and serum, imparted by carefully designed grafted polymer shells. The polymer shells were built with attached aldehyde functionality to enable the reversible attachment of doxorubicin (DOX) via imine bonds, providing a controlled release mechanism for DOX in acidic environments. The IONPs were shown to be readily taken up by cell lines (MCF-7 breast cancer cells and H1299 lung cancer cells), and intracellular release of DOX was proven using in vitro fluorescence lifetime imaging microscopy (FLIM) measurements. Using the fluorescence lifetime difference exhibited by native DOX (1 ns) compared to conjugated DOX (4.6 ns), the intracellular release of conjugated DOX was in situ monitored in H1299 and was estimated using phasor plot representation, showing a clear increase of native DOX with time. The results obtained from FLIM were corroborated using confocal microscopy, clearly showing DOX accumulation in the nuclei. The IONPs were also assessed as MRI negative contrast agents. We observed a significant change in the transverse relaxivity properties of the IONPs, going from 220 to 390 mM–1 s–1, in the presence or absence of conjugated DOX. This dependence of MRI signal on IONP-DOX/water interactions may be exploited in future theranostic applications. The in vitro studies were then extended to monitor cell uptake of the DOX loaded IONPs (IONP@P(HBA)-b-P(OEGA) + DOX) into two 3D multicellular tumor spheroids (MCS) grown from two independent cell lines (MCF-7 and H1299) using multiphoton excitation microscopy.                                       

Australian Centre for NanoMedicine, University of New South Wales, Sydney 2052 Australia Children Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales, PO Box 81 Randwick Sydney NSW 2031 Australia §Biomedical Imaging Facility, University of New South Wales, Sydney NSW 2052 Australia; Monash Institute of Pharmaceutical Sciences, Monash University, Parkville Melbourne VIC 3052 Australia

  

Polymer Chemistry DOI: 10.1039/C3PY01306E

Polymerization-Induced Self-Assembly (PISA) – control over the morphology of nanoparticles for drug delivery applications

Bunyamin Karagoza, Lars Esserbcd, Hien T Duongb, Johan S Basukib, Cyrille Boyer*b, Thomas P Davis*bcd

 

 polymerchemistry2

In this paper, we describe the synthesis of asymmetric functional POEGMA-b-P(ST-co-VBA) copolymers in methanol, yielding in one-pot polymerization a range of nanoparticle morphologies, including spherical micelles, worm-like, rod-like micelles and vesicles. The presence of the aldehyde group was then exploited to form crosslinks or to conjugate chemotherapy compounds, such as doxorubicin, via pH-breakable bonds (Schiff base or imine) directly to the preformed nanoparticles. The influence of the nanoparticle morphologies on the MCF-7 breast cancer cell line uptake was investigated using flow cytometry and confocal microscopy. Finally, the IC50 of DOX, following nanoparticle delivery, was studied showing significant influence of the nanoparticle carrier morphology on therapeutic efficacy for breast cancer.

aIstanbul Technical University, Department of Chemistry, Maslak 34469 Istanbul Turkey bAustralian Centre for NanoMedicine, University of New South Wales, Sydney NSW 2052 Australia cMonash Institute of Pharmaceutical Sciences (MIPS), Monash University, VIC 3052 Australia dDepartment of Chemistry, University of Warwick, Coventry CV47AL UK

 

  
BOOK: ISBN: 978-1-62948-228-6. Recent Advances in Drug Delivery Research

ACN and the Children's Cancer Institute Australia produced Chapter 7. Polyphenol Conjugate: Synthesis and Potential Biomedical Applications

O Vittorio, G Cirillo, S Hampel, F Iemma and M Kavallaris, Children’s Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales, Sydney Australia and others)

 book

Book Description: It has been over 100 years since Dr. Paul Ehrlich referred to an ideal therapeutic agent able to target and treat only a highly specific site in an organism in 1906: the so-called “magic bullet”. The birth of new technologies, such as nanostructures, combined with the improved knowledge on the physiology and the biochemistry at the basis of human behavior have opened completely new trails in medicine, making the research over drug delivery one of the most vital fields of science. This book presents a timely and informative summary of the current progress in a variety of subject areas, including medicine, chemistry, and biology. This book is written by experts in the field and serves as an indispensable reference to advanced researchers. The last advances in drug delivery, including nanoparticles, conjugated polyphenol, enhanced permeability and retention effect and also chimeric nanosystems, are addressed and provided by extensive and recent literature. (Imprint: Nova Biomedical)

  

ACS Macro Letters DOI: 10.1021/mz4004375

Selective Postmodification of Copolymer Backbones Bearing Different Activated Esters with Disparate Reactivities

Yang Li, Hien TT Duong, Mathew W Jones, Johan S Basuki, Jinming Hu§, Cyrille Boyer*†‡, Thomas P Davis

 

 acsletters2013

In this communication, we report an easy method for introducing functional groups into polymer structures by successively reacting two different activated ester functionalities (pentafluorophenyl (PFP) ester and azlactone (AZ)) with different functional amine compounds. By exploiting the difference in reactivity of the two activated esters (PFP and AZ) toward different amino compounds, we demonstrate, for the first time, a selective modification of the different activated ester groups, thereby introducing functional groups to the polymer backbone in a controlled manner. Statistical and block copolymers of vinyl dimethyl azlactone (VDM) and pentafluorophenyl acrylate (PFPA), ie (p(VDM-stat-PFPA)) and (p(VDM-block-PFPA)), were prepared using reversible addition–fragmentation transfer (RAFT) polymerization and subsequently modified using a library of amino compounds, yielding macromolecules with bespoke functionality. In additional work, the functional macromolecules were self-assembled into nanoparticles.

Australian Centre for Nanomedicine, School of Chemical Engineering, University of New South Wales, Sydney NSW 2052 Australia Centre for Advanced Macromolecular Design, School of Chemical Engineering, University of New South Wales Sydney NSW 2052 Australia §Monash Institute of Pharmaceutical Sciences, Monash University Melbourne VIC 3052 Australia; Department of Chemistry, University of Warwick Coventry CV47AL UK

  

Biomaterial Science DOI 10.1039/C3BM60148J

Stimuli-responsive functionalized mesoporous silica nanoparticles for drug release in response to various biological stimuli

Xin Chenab, Xiaoyu Chengab, Alexander H Soeriyadiab, Sharon M Sagnellaad, Xun Luab, Jason A Scottc, Stuart B Lowea, Maria Kavallarisad, J Justin Gooding*ab

 Graphical abstract: Stimuli-responsive functionalized mesoporous silica nanoparticles for drug release in response to various biological stimuli

A silica-based mesoporous nanosphere (MSN) controlled-release drug delivery system has been synthesized and characterized. The system uses L-cysteine derivatized gold nanoparticles (AuNPs), bound to the MSNs using Cu2+ as a bridging ion. The AuNPs serve as removable caps that hinder the release of drug molecules inside the amino functionalized MSN mesoporous framework. The modified MSNs themselves exhibit negligible cytotoxicity to living cells, as revealed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The drug delivery system requires one of two biological stimuli to trigger drug release. These stimuli are either: low pH (pH 4 mM). The feasibility of biologically controlled release was demonstrated through the stimuli-induced removal of the AuNP caps over the MSN releasing the anticancer drug doxorubicin. We envisage that this MSN system could play a significant role in developing new generations of controlled-release delivery vehicles.

aAustralian Centre for Nanomedicine, University of New South Wales, Sydney NSW 2052 Australia. bSchool of Chemistry, University of New South Wales, Sydney NSW 2052 Australia; cSchool of Chemical Engineering, University of New South Wales, Sydney NSW 2052 Australia dChildren’s Cancer Institute Australia, Lowy Cancer Research Centre, UNSW Australia, Sydney NSW 2052 Australia

  

Journal of Materials Chemistry B DOI: 10.0139/C3TB21090A

Size-dependent Nanographene Oxide as a Platform for Efficient Carboplatin Release

Sami Makharzaa, Giuseppe Cirilloa,b Alicja Bachmatiukc,d,e Orazio Vittoriof,g Rafael Gregorio Mendesa,Steffen Oswalda, Silke Hampela, Mark H Rümmelic,d*

 

 Graphical abstract: Size-dependent nanographene oxide as a platform for efficient carboplatin release

Nanographene oxide (NGO) with well-defined sizes, were produced from graphite via chemical exfoliation and separated into three different size distributions (300 nm, 200 nm, and 100 nm) using intense sonication and sucrose density gradient centrifugation. Prior to Carboplatin (CP) loading, the NGO was functionalized with zero generation Polyamidoamide (PAMAM) which renders an improved dispersibility and stability of the nanocarrier platform in physiological media. Cell viability tests were conducted for pristine NGO samples with average widths of 200 nm and 300 nm show a cytotoxic effect for HeLa cancer cells and mesenchymal stem cells at low (50 µg/ml) and high (100 µg/ml) concentrations, while the pristine NGO sample with an average width of 100 nm revealed no significant cytotoxicity at 50 µg/ml, and only recorded 10% level at 100 µg/ml. After functionalization with PAMAM, the carrier was found to be able to deliver Carboplatin to the cancer cells, by enhancing the drug anticancer efficiency. Moreover, the Carboplatin loaded NGO carrier shows no significant effect on the viability of mesenchymal stem cells (hMSCs) even at high concentration (100 µg/ml).

aIFW Dresden, D-01171 Dresden Germany; bDepartment of Pharmacy, Health and Nutritional Sciences, University of Calabria, I-87036 Arcavacata di Rende (CS) Italy; cIBS Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Daejon 305-701 Republic of Korea; dDepartment of Energy Science, Department of Physics, Sungkyunkwan University, Suwon 440-746 Republic of Korea; eCentre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Sklodowskiej 34, Zabrze 41-819 Poland; fChildren’s Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales NSW Australia; gAustralian Centre for NanoMedicine, University of New South Wales NSW Australia

  

Macromolecules DOI: 10.1021/ma401171d

Polymer-Grafted, Nonfouling, Magnetic Nanoparticles Designed to Selectively Store and Release Molecules via Ionic Interactions

Johan Sebastian Basuki, Hien T T Duong, Alexander Macmillan, Renee Whan, Cyrille Boyer*†, Thomas P Davis

 

Abstract Image 

Surface functionalization of superparamagnetic iron oxide nanoparticles (IONPs) was achieved by exploiting a grafting “onto” approach simultaneously with an in situ modification of the graft block copolymer. Terminal phosphonic-acid-bearing block copolymers composed of pendant-activated ester moieties, that is, poly(pentafluorophenyl acrylate) (P(PFPA)) and poly(oligoethylene glycol acrylate) (P(OEGA)), were synthesized and assembled on IONP surfaces. The assembly was performed in the presence of different primary amines to introduce different functionality to the grafted chains, followed by subsequent thiol–ene Michael additions with acrylates or maleimides to decorate the IONP surface. The aim of this “double”-click chemistry on the polymer-coated nanoparticles was to generate a library of IONPs consisting of an internal layer of functionalized polyacrylamides and an outer shell of antifouling P(OEGA) decorated with fluorescent ligands. The resultant multifunctionalized IONPs were characterized using ATR-FTIR, XPS and TGA, proving the presence of modified polymers on the IONP surfaces. The functionalized nanoparticles proved to be stable in both water and phosphate buffer containing bovine serum albumin. Zeta potentials of the functionalized nanoparticles could be tuned by the judicious choice of functional groups introduced by the primary amines, for example, spermine, 3-(dimethylamino)-1-propylamine, l-lysine, l-histidine, l-arginine, β-alanine, and taurine. Depending on the pH of IONP dispersions, the charge induced by functional groups within the polymer shell was used to encapsulate ionic dyes (methyl blue and rhodamine 6G in cationic and anionic layers, respectively), serving as models for drug loading via ionic complexation. The attachment of fluorophore through thiol–ene Michael addition was demonstrated by conjugating fluorescein-O-acrylate, as monitored by fluorescence spectroscopy. Cytotoxicity studies revealed that multifunctionalized IONPs were nontoxic to normal human lung fibroblast cell lines. Fluorescence lifetime imaging microscopy was employed to demonstrate the complexation and release of rhodamine 6G dye from l-lysine-functionalized IONPs.

Australian Centre for NanoMedicine, School of Chemical Engineering and Biomedical Imaging Facility, Mark Wainwright Analytical Centre, University of New South Wales 2052 Sydney Australia §Monash Institute of Pharmaceutical Sciences, Monash University, Parkville VIC 3052 Australia

 

Macromolecules DOI: 10.1021/ma401250f

Grafting of P(OEGA) Onto Magnetic Nanoparticles Using Cu(0) Mediated Polymerization: Comparing Grafting “from” and “to” Approaches in the Search for the Optimal Material Design of Nanoparticle MRI Contrast Agents

Johan S Basuki, Lars Esser§, Per B Zetterlund, Michael R Whittaker§*, Cyrille Boyer†‡*, Thomas P Davis§*

 macromoleculesaug13

Superparamagnetic iron oxide nanoparticles (IONPs) have been studied extensively as negative contrast agents to enhance MRI efficacy. For optimal effective clinical use in T2/T2* weighted MRI imaging, the aim is to maximize relaxivity (r2) of IONPs, and minimize r1 relaxivity. A prerequisite for successful clinical use of magnetic nanoparticles is colloidal stability in biologically relevant media; biocompatible polymers with antifouling properties such as poly(ethylene glycol) (PEG) can be coated on the surface of IONPs, to improve stability and to impart longer blood circulation times. Our research aim was to optimize IONPs for use as contrast agents by achieving high grafting density and therefore colloidal stability, while retaining the magnetic properties of the IONP core. To attain the optimal material design the chemical functionalities and chain length of the polymeric layer must be precisely controlled. In this paper we describe the synthesis of poly(oligoethylene glycol acrylate) (P(OEGA)) functionalized magnetic iron oxide nanoparticles (IONP) made using a grafting “from” approach. Cu(0)-mediated living radical polymerization (LRP) was used to grow polymer chains of predetermined length from the surface of prefunctionalized IONPs. The polymers chain were further extended via an iterative addition of the same (or another) monomer with high efficiency demonstrating the retention of polymer chain end functionality. IONPs with different lengths of the P(OEGA) layer were also synthesized using a grafting “to” approach as a comparison study. Colloidal stabilities and MRI relaxivites of functionalized IONPs were investigated in both water and fetal calf serum (FCS). The grafting “from” approach proved to be superior to the grafting “to” approach as we were able to produce polymer coated IONPs with much higher r2/ r1 relaxivity ratios in water. At 9.4 T, the r2/r1 relaxivity values that we attained were about 6-fold higher than the commercial, clinically used, MRI contrast agent Resovist

Australian Centre for NanoMedicine, School of Chemical Engineering and Centre for Advanced Macromolecular Design, University of New South Wales, 2052, Sydney, Australia § Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia

 

The Federation of European Biochemical Societies (DOI: 10.1111/febs.12427)

Do signalling endosomes play a role in Tcell activation?

Carola Benzing, Jérémie Rossy, Katharina Gaus*

FEBS Journal 

Signalling endosomes represent a general mechanism for modulating and compartmentalizing cell signalling, which is achieved by delineating specific spatial environments and connecting the plasma membrane with intracellular events. The molecular composition of vesicles, together with their targeting mechanisms and endocytic routes, contributes to the outcome of signalling pathways that are initiated either at the plasma membrane or within endosomes themselves. In T cell signalling, it is now accepted that the spatial distribution of signalling proteins is central to T cell activation not only at the immunological synapse, but also in endosomes travelling to and from the plasma membrane. In addition, there is a global rearrangement of the endosome machinery upon T cell activation, and emerging experimental evidence suggests that vesicles in T cells contain key T cell signalling proteins. We review the various mechanisms by which endosomes contribute to signalling pathways and consider whether signalling endosomes play a role in T cell signalling.

Centre for Vascular Research and Australian Centre for Nanomedicine, University of New South Wales Sydney Australia

 

ACS Medical Chemistry Letters, DOI: 10.1021/ml400082b

Effectively Delivering a Unique Hsp90 Inhibitor Using Star Polymers

Seong Jong Kim,Deborah M Ramsey,Cyrille Boyer, Thomas P Davis,Shelli R McAlpine

 

 acsjuly25

We report the synthesis of a novel heat shock protein 90 (hsp90) inhibitor conjugated to a star polymer. Using reversible addition-fragmentation chain-transfer (RAFT) polymerization, we prepared star polymers comprising PEG attached to a predesigned functional core. The stars were cross-linked using disulfide linkers, and a tagged version of our hsp90 inhibitor was conjugated to the polymer core to generate nanoparticles (14 nm). Dynamic light scattering showed that the nanoparticles were stable in cell growth media for 5 days, and high-performance liquid chromatography (HPLC) analysis of compound-release at 3 different pH values showed that release was pH dependent. Cell cytotoxicity studies and confocal microscopy verify that our hsp90 inhibitor was delivered to cells using this nanoparticle delivery system. Further, delivery of our hsp90 inhibitor using star polymer induces apoptosis by a caspase 3-dependent pathway. These studies show that we can deliver our hsp90 inhibitor effectively using star polymers and induce apoptosis by the same pathway as the parent compound.

Department of Chemistry, University of New South Wales Sydney NSW 2052 Australia Australian Centre for Nanomedicine, University of New South Wales Sydney NSW 2052 Australia

 

ChemPhysChem 2013, 14, 2183-2189

Protein Resistance of Surfaces Modified with Oligo(Ethylene Glycol) Aryl Diazonium Derivatives

Callie Fairman, Joshua Z Ginges, Stuart B Lowe, J Justin Gooding*[a]

 stuart2013

Anti-fouling surfaces are of great importance for reducing background interference in biosensor signals. Oligo(ethylene glycol) (OEG) moieties are commonly used to confer protein resistance on gold, silicon and carbon surfaces. Herein, we report the modification of surfaces using electrochemical deposition of OEG aryl diazonium salts. Using electrochemical and contact angle measurements, the ligand packing density is found to be loose, which supports the findings of the fluorescent protein labelling that aryl diazonium OEGs confer resistance to nonspecific adsorption of proteins albeit lower than alkane thiol-terminated OEGs. In addition to protein resistance, aryl diazonium attachment chemistry results in stable modification. In common with OEG species on gold electrodes, OEGs with distal hydroxyl moieties do confer superior protein resistance to those with a distal methoxy group. This is especially the case for longer derivatives where superior coiling of the OEG chains is possible.

[a]C Fairman, JZ Ginges, SB Lowe, JJ Gooding School of Chemistry University of New South Wales Sydney NSW 2052 Australia

 

Applied Materials and Interfaces, DOI 10.1021/am40060121

Photolithographic Strategy for Patterning Preformed, Chemically Modified, Porous Silicon Photonic Crystal Using Click Chemistry

Ying Zhu,Bakul Gupta,Bin Guan,Simone Ciampi,Peter J Reece,J Justin Gooding*

 appliedmaterialsinterfacesgraphic

Porous silicon (PSi) is an ideal platform for label-free biosensing, and the development of porous silicon patterning will open a pathway to the development of highly parallel PSi biochips for detecting multiple analytes. The optical response of PSi photonic crystal is determined by the changes in the effective bulk refractive index resulting from reactions/events occurring within the internal pore space. Therefore, introducing precise chemical functionalities in the pores of PSi is essential to ensure device selectivity. Here we describe the fabrication of PSi patterns that possess discrete chemical functionalities that are restricted to precise locations. The key difference to previous patterning protocols for PSi is that the entire porous material is first modified with a self-assembled monolayer of a α,ω-diyne adsorbate prior to patterning using a microfabricated titanium mask. The distal alkyne moieties in the monolayer are then amenable to further selective modification by the archetypal “click” reaction, the copper catalyzed alkyne–azide cycloaddition (CuAAC), using the titanium mask as a resist. This type of patterning is suitable for further immobilization of biological recognition elements, and presents a new platform for highly parallel PSi biosensor for multiple detections.

School of Chemistry and the Australian Centre for NanoMedicine and School of Physics, University of New South Wales Sydney 2052 Australia

 

Biophysical Journal. (DOI: 10.1016/j.bpj.2013.05.063)

Quantitative Analysis of Three-Dimensional Fluorescence Localization Microscopy Data

Dylan M Owen,David J Williamson, LiesBoelen, Astrid Magenau, Jérémie Rossy, Katharina Gaus

 

 Full-size image (35 K)

Identifying the three-dimensional molecular organization of subcellular organelles in intact cells has been challenging to date. Here we present an analysis approach for three-dimensional localization microscopy that can not only identify subcellular objects below the diffraction limit but also quantify their shape and volume. This approach is particularly useful to map the topography of the plasma membrane and measure protein distribution within an undulating membrane.                      

Centre for Vascular Research and Australian Centre for Nanomedicine, University of New South Wales Sydney Australia Department of Medicine, Imperial College London, London United Kingdom

 

Journal of Materials Chemistry B, DOI: 10.1039/b000000x

Cancer phototherapy in living cells by multiphoton release of doxorubicin from gold nanospheres

Valerio Voliani*, ab, Giovanni Signorec, Orazio Vittoriobde, Paolo Faracib, Stefano Luinb, Julia Peréz-Prietoa, Fabio Beltramb†

 

 Graphical abstract: Cancer phototherapy in living cells by multiphoton release of doxorubicin from gold nanospheres

Doxorubicin is a widely used but toxic cancer chemotherapeutic agent. In order to localize its therapeutic action and minimize side effects, it was covalently conjugated to peptide-encapsulated gold nanospheres by click-chemistry and then photo-released in a controlled fashion by a multiphoton process. Selective treatment of a chosen region in a 2D layer of U2Os cancer cells is shown by driving photorelease with 561 nm irradiation at μW power. These results show promising directions for the development of practical applications based on nanocarriers that can ensure drug delivery with high spatial and temporal control.

aUniversidad de Valencia, Instituto de Ciencia Molecular, ICMol, Catedrático Jose Beltrán, 2,46980 Paterna Valencia Spain bNEST- Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12 56127 Pisa ItalycCenter for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12 56127 Pisa Italy dChildren's Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales, Randwick NSW Australia eAustralian Centre for Nanomedicine, University of New South Wales, Randwick NSW Australia

 

European Journal of Pharmaceutical Sciences (Volume49, Issue 3, 14 June 2013, Pages 359–365)

Quercetin nanocomposite as novel anticancer therapeutic: Improved efficiency and reduced toxicity

Giuseppe Cirilloab, Orazio Vittoriocde, Silke Hampelb, Francesca Iemmaa, Paolo Parchif, Marco Cecchinic, Francesco Puocia, Nevio Piccia

 

 1-s2 0-s0928098713001358-fx1

A three-functional nanocomposite was prepared by radical polymerization of methacrylic acid around carbon nanotubes in the presence of Quercetin as biologically active molecule and proposed as new anticancer therapeutic. The so-obtained hybrid material was characterized by FT-IR, Raman, SEM, TEM analyses, while the functionalization degree of 2.33mg of Quercetin per g of composite was assessed by Folin–Ciocalteu test. Antioxidant test (DPPH and ABTS) showed that the covalent coupling did not interfere with the antioxidant properties of the flavonoid, while the anticancer activity was greatly enhanced with a recorded IC50 value much lower than free Quercetin. Cell viability tests on healthy cells demonstrated no-toxicity of the conjugate

aDepartment of Pharmacy, Health and Nutrition Sciences, University of Calabria, I-87036 Arcavacata di Rende (CS) Italy bLeibniz Institute for Solid State and Materials Research Dresden, PF 270116 D-01171 Dresden Germany cNEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12 I-56126 Pisa Italy dChildren’s Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales NSW Australia eAustralian Centre for Nanomedicine, University of New South Wales NSW Australia f1st Orthopedic Division University of Pisa, Via Paradisa 2 I-56124 Pisa Italy

 

Current Opinion in Immunology (DOI: 10.1016/j.coi.2013.04.002)

Super-resolution microscopy of the immunological synapse

Jérémie Rossy1, 2, 4, Sophie V Pageon1, 2, 4,Daniel M Davis3, , Katharina Gaus1, 2

 

Deciphering the spatial organisation of signalling proteins is the key to understanding the mechanisms underlying immune cell activation. Every advance in imaging technology has led to major breakthroughs in unravelling how receptor and signalling proteins are distributed within the plasma membrane and how membrane signalling is integrated with endosomes and vesicular trafficking. Recently, super-resolution fluorescence microscopy has been applied to immunological synapses, gaining new insights into the nanoscale organisation of signalling processes. Here, we review the advantages and potential of super-resolution microscopy for elucidating the regulation of many aspects of immune signalling.

1Centre for Vascular Research, University of New South Wales Sydney Australia 2Australian Centre for Nanomedicine, University of New South Wales Sydney Australia 3 Manchester Collaborative Centre for Inflammation Research, Manchester UK

 

Nature Immunology (DOI: 10.1038/ni.2609)

AMP7 controls T cell activation by regulating the recruitment and phosphorylation of vesicular Lat at TCR-activation sites

Paola Larghi, David J Williamson, Jean-Marie Carpier, Stéphanie Dogniaux, Karine Chemin, Armelle Bohineust, Lydia Danglot, Katharina Gaus, Thierry Galli, Claire Hivroz

 

 VAMP7 controls the recruitment of Lat to TCR-activation sites.

The mechanisms by which Lat (a key adaptor in the T cell antigen receptor (TCR) signaling pathway) and the TCR come together after TCR triggering are not well understood. We investigate here the role of SNARE proteins, which are part of protein complexes involved in the docking, priming and fusion of vesicles with opposing membranes, in this process. Here we found, by silencing approaches and genetically modified mice, that the vesicular SNARE VAMP7 was required for the recruitment of Lat-containing vesicles to TCR-activation sites. Our results indicated that this did not involve fusion of Lat-containing vesicles with the plasma membrane. VAMP7, which localized together with Lat on the subsynaptic vesicles, controlled the phosphorylation of Lat, formation of the TCR-Lat-signaling complex and, ultimately, activation of T cells. Our findings suggest that the transport and docking of Lat-containing vesicles with target membranes containing TCRs regulates TCR-induced signaling.

1Institut National de la Santé et de la Recherche Médicale, Unité 932, Immunité et Cancer, Paris, France: Paola Larghi, Jean-Marie Carpier, Stéphanie Dogniaux, Karine Chemin, Armelle Bohineust & Claire Hivroz. 2Centre for Vascular Research and Australian Centre for Nanomedicine, University of New South Wales, Sydney, Australia: David J Williamson & Katharina Gaus. 3Institut Jacques Monod, Unité Mixte de Recherche 7592, Centre National de la Recherche Scientifique, Université Paris Diderot, Sorbonne Paris Cité, Paris, France: Lydia Danglot & Thierry Galli. 4Institut Curie, Centre de Recherche, Pavillon Pasteur, Paris, France. Paola Larghi, Jean-Marie Carpier, Stéphanie Dogniaux, Karine Chemin, Armelle Bohineust & Claire Hivroz. 5Institut National de la Santé et de la Recherche Médicale Equipe de Recherche Labelisée U950, Membrane Traffic in Neuronal and Epithelial Morphogenesis, Paris, France: Lydia Danglot & Thierry Galli

 

Analyst 2013,138, 3593-3615 (DOI: 10.1039/c3an00081h)

Functionalised porous silicon as a biosensor: emphasis on monitoring cells in vivo and in vitro

Bakul Gupta,a Ying Zhu, a Bin Guan,a Peter J Reece,b J Justin Goodinga

 (top) Scheme depicting structural cross-sections and (bottom) observed shifts in the reflectance spectrum for three typical PSi photonic structures used in sensing applications; (a) single layer, (b) microcavity and (c) rugate filter. The single layer is a uniform thin film of several micrometres and produces multiple interference fringes in the visible and near infrared spectral regions. The microcavity is based on a Fabry–Perot resonator with two dielectric mirrors surrounding a cavity layer. The mirrors or composed of alternating layers of high and low porosity PSi of quarter wavelength thickness. The resulting reflectivity spectrum has a characteristic broad high reflectivity band with a dip in the centre corresponding to the resonant cavity mode. Rugate filters consist of films with a sinusoidal refractive index modulation; when the refractive index variation is small a sharp peak is observed above the background of the thin film interference fringes. This type of spectral feature can equally be achieved using Bragg reflectors with a small refractive index between the layers. In all cases a redshift in the spectral features is observed when a material is deposited on the internal wall of the mesoporous scaffold and is the type of shift associated with an affinity based biorecognition interface. The advantage of using a more complex photonic structures is that the cavity resonance (b) and high reflectivity band (c) can be significantly narrower then the equivalent thin films interference fringes and is clearly observed above other spectral features.

Porous silicon photonics is the ideal platform for high sensitivity, high selectivity monitoring of biological molecules in a complex fluidic environment. The potential of this technology was identified almost 15 years ago, however, it has taken considerable advances in porous silicon surface chemistry, photonics, and micro-fabrication to create truly effective devices that can provide new insights into the behaviour of biological systems. In this review we provide a critical assessment of the development of porous silicon optical biosensors from the early demonstrations of affinity based sensing to the current trends in monitoring single cell activity and perspectives in the use of photonic microparticles for biomedical applications.

1School of Chemistry and Australian Centre for NanoMedicine, University of New South Wales, Sydney NSW 2052 Australia 2AgaMatrix Inc 7C Raymond Avenue, Salem NH 03079 USA

 

Physical Chemistry Chemical Physics 2013,15, 9879-9890 DOI: 10.1039/c3cp50355k

The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes

Simone Ciampia, Michael Jamesb, Moinul H Choudhurya, Nadim A Darwisha, J Justin Goodinga

 Graphical abstract: The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes

In this paper we explore a multi-step synthetic strategy toward fabrication of monolayer-modified Si(100) electrodes that can be electrochemically switched. The synthetic scheme is modular and benefits from an established intramolecular lactonization scheme of benzoquinone analogs. A redox-tagged pendant group can be released from the surface such as to allow for in situ monitoring of the switch process. We show that this model system can be used to elucidate chemical and structural events for a surface dynamic system that is rapidly gaining popularity. The influence of polarization times, overpotentials and semiconductor doping type on the kinetic of the switch event is also investigated. In both basic and acidic aqueous electrolytes the release of suitable redox-active markers is found to require unexpectedly large cathodic overpotentials. The release event is accompanied by minor oxidation of the electrode surface and the switched constructs can be regenerated by chemical means with no appreciable deterioration of surface quality.

aSchool of Chemistry and the Australian Centre for NanoMedicine, University of New South Wales, Sydney NSW 2052 Australia; b Bragg Institute, Australian Nuclear Science and Technology Organisation Locked Bag 2001 Kirrawee DC 2232 Australia

 

Electroanalysis 2013, 25 No. 6, 1461-1471 DOI:10.1002/elan.201200667

Gly-Gly-His Immobilized On Monolayer Modified Back-Side Contact Miniaturized Sensors for Complexation of Copper Ions

Urszula E. Wawrzyniak1,*, Patrycja Ciosek1,2, Michal Zaborowski3, Guozhen Liu2,4, J Justin Gooding2

thumbnail image 

Miniaturized planar back-side contact transducers (BSC) with chemically modified gold surface have been utilized as electrochemical sensors. The electrodes have been functionalized by sequential immobilization of aryl diazonium salts or alkanethiols and short peptide Gly-Gly-His. The applicability of gold substrates modified with aryl diazonium salts in voltammetric detection of copper(II) ions in aqueous solutions has been studied. The combination of two fundamental elements of the solid-state electrode, ie back-side contact (BSC) gold sensor and self-assembled monolayers, allowed one to obtain reliable miniaturized copper(II) ion sensors. It can have important future applications in environmental sensing or in implantable biodevices.

aDepartment of Microbioanalytics, Faculty of Chemistry, Warsaw Univeristy of Technology, Noakowskiego 3 00-664 Warsaw Poland bSchool of Chemistry and Australian Centre for NanoMedicine, University of New South Wales, Sydney NSW 2052 Australia cInstitute of Electron Technology, A1 Lotnikow 32/46, 02-668 Warsaw Poland; dKey Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 43007 PR China

 

Molecular Pharmaceutics DOI: 10.1021/mp400049e

Effective Delivery of siRNA into Cancer Cells and Tumors Using Well-Defined Biodegradable Cationic Star Polymers

Cyrille Boyer‡, Joann Teo†‡, Phoebe Phillips§, Rafael B Erlich†‡, Sharon Sagnella†‡, George Sharbeen§, Tanya Dwarte†, Hien T T Duong‡, David Goldstein§, Thomas P Davis*†‡, Maria Kavallaris*†‡, Joshua McCarroll*†‡

 

 Abstract Image

Cancer is one of the most common causes of death worldwide. Two types of cancer that have high mortality rates are pancreatic and lung cancer. Despite improvements in treatment strategies, resistance to chemotherapy and the presence of metastases are common. Therefore, novel therapies which target and silence genes involved in regulating these processes are required. Short-interfering RNA (siRNA) holds great promise as a therapeutic to silence disease-causing genes. However, siRNA requires a delivery vehicle to enter the cell to allow it to silence its target gene. Herein, we report on the design and synthesis of cationic star polymers as novel delivery vehicles for siRNA to silence genes in pancreatic and lung cancer cells. Dimethylaminoethyl methacrylate (DMAEMA) was polymerized via reversible addition–fragmentation transfer polymerization (RAFT) and then chain extended in the presence of both cross-linkers N,N-bis(acryloyl)cistamine and DMAEMA, yielding biodegradable well-defined star polymers. The star polymers were characterized by transmission electron microscopy, dynamic light scattering, ζ potential, and gel permeation chromatography. Importantly, the star polymers were able to self-assemble with siRNA and form small uniform nanoparticle complexes. Moreover, the ratios of star polymer required to complex siRNA were nontoxic in both pancreatic and lung cancer cells. Treatment with star polymer–siRNA complexes resulted in uptake of siRNA into both cell lines and a significant decrease in target gene mRNA and protein levels. In addition, delivery of clinically relevant amounts of siRNA complexed to the star polymer were able to silence target gene expression by 50% in an in vivo tumor setting. Collectively, these results provide the first evidence of well-defined small cationic star polymers to deliver active siRNA to both pancreatic and lung cancer cells and may be a valuable tool to inhibit key genes involved in promoting chemotherapy drug resistance and metastases.

Tumour Biology and Targeting Program, Children’s Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales NSW Australia Australian Centre for Nanomedicine, School of Chemical Engineering, University of New South Wales NSW Australia §Pancreatic Cancer Translational Research Group, School of Medical Sciences, University of New South Wales NSW Australia

 

Langmuir. 2013 Apr 16;29(15):4772-81. doi: 10.1021/la400358e. Epub2013 Apr 5

Using supramolecular binding motifs to provide precise control over the ratio and distribution of species in multiple component films grafted on surfaces: demonstration using electrochemical assembly from aryl diazonium salts

Gui AL, Yau HM, Thomas DS, Chockalingam M, Harper JB, Gooding JJ

 la-2013-00358e 0006

Supramolecular interactions between two surface modification species are explored to control the ratio and distribution of these species on the resultant surface. A binary mixture of aryl diazonium salts bearing oppositely charged para-substituents (either -SO3(-) or -N(+)(Me)3), which also reduce at different potentials, has been examined on glassy carbon surfaces using cyclic voltammetry and X-ray photoelectron spectroscopy (XPS). Striking features were observed: (1) the two aryl diazonium salts in the mixed solution undergo reductive adsorption at the same potential which is distinctively less negative than the potential required for the reduction of either of the two aryl diazonium salts alone; (2) the surface ratio of the two phenyl derivatives is consistently 1:1 regardless of the ratio of the two aryl diazonium salts in the modification solutions. Homogeneous distribution of the two oppositely charged phenyl species on the modified surface has also been suggested by XPS survey spectra. Diffusion coefficient measurements by DOSY NMR and DFT based computation have indicated the association of the two aryl diazonium species in the solution, which has led to changes in the molecular orbital energies of the two species. This study highlights the potential of using intermolecular interactions to control the assembly of multicomponent thin layers.

School of Chemistry and Australian Centre for NanoMedicine, University of New South Wales, Sydney NSW 2052 Australia

 

Australian Journal of Chemistry 66(6) 613-618 http://dx.doi.org/10.1071/CH13043

Demonstrating the Use of Bisphenol A-functionalised Gold Nanoparticles in Immunoassays

Joshua R PetersonA, Yang LuB, Erwann LuaisAC, Nanju Alice LeeBE, J Justin GoodingADE

 
 

Spherical gold nanoparticles (5-nm diameter) were modified with a small-molecule thiolated bisphenol A (BPA) ligand to achieve an estimated coverage of ~3.3 × 10–10 mol cm–2, or 180 ligands per particle. The modified particles were tested in an enzyme-linked immunosorbent assay (ELISA) format to measure functionality and were shown to bind specifically to anti-BPA antibody while resisting the non-specific adsorption of an antibody with no affinity for BPA. It was found that the use of 10% ethanol as a co-solvent was required in the ELISA as aqueous buffers alone resulted in poor binding between anti-BPA antibody and the functionalised nanoparticles. This is likely due to the hydrophobic nature of the BPA ligand limiting its solubility, and therefore its availability for antibody interactions, in purely aqueous environments. To our knowledge, this is the first example of a nanoparticle modified with a small organic molecule being used in an ELISA assay.

ASchool of Chemistry, University of New South Wales, Sydney, NSW 2052 Australia. BSchool of Chemical Engineering, University of New South Wales, Sydney NSW 2052, Australia. CCurrent address: GREMAN, University François Rabelais, Parc de Grandmont, 37200 Tours, France. DAustralian Centre for NanoMedicine, University of New South Wales, Sydney NSW 2052 Australia. ECorresponding authors. Email: justin.gooding@unsw.edu.au, alice.lee@unsw.edu.au

 

Electroanalysis DOI: 10.1002/elan.201200333

An Amperometric Immunosensor Based on a Gold Nanoparticle-Diazonium Salt Modified Sensing Interface for the Detection of HbA1c in Human Blood

Guozhen Liu1, Sridhar G Iyengar2, J Justin Gooding1,*

Electroanalysis 

An amperometric immunosensor for glycosylated hemoglobin (HbA1c) is reported. A glassy carbon electrode is modified with gold nanoparticles (AuNPs) bearing a ferrocene derivative and a glycosylated pentapeptide (GPP) as an epitope to which anti-HbA1c IgG can selectively bind. The rest of the electrode is passivated with an oligo(ethylene oxide) species to give the electrode resistant to nonspecific adsorption of proteins. Complexation of anti-HbA1c IgG with the surface bound epitope resulted in attenuation of the ferrocene electrochemistry. The immunosensor can detect HbA1c in the range of 4.6 %–15.1 % of total hemoglobin in human blood by a competitive inhibition assay.

1School of Chemistry and Australian Centre for NanoMedicine, University of New South Wales, Sydney NSW 2052 Australia 2AgaMatrix Inc 7C Raymond Avenue, Salem NH 03079 USA

 

Journal of Visualized Experiments April 2013 74 e50310 DOI:10.3791/50310

Creating Adhesive and Soluble Gradients for Imaging Cell Migration with Fluorescence Microscopy

Siti Hawa Ngalim1, Astrid Magenau1, Ying Zhu2, Lotte Tønnesen1, Zoe Fairjones1, J Justin Gooding2, Till Böcking1, Katharina Gaus1

 Figure 1

Cells can sense and migrate towards higher concentrations of adhesive cues such as the glycoproteins of the extracellular matrix and soluble cues such as growth factors. Here, we outline a method to create opposing gradients of adhesive and soluble cues in a microfluidic chamber, which is compatible with live cell imaging. A copolymer of poly-L-lysine and polyethylene glycol (PLL-PEG) is employed to passivate glass coverslips and prevent non-specific adsorption of biomolecules and cells. Next, microcontact printing or dip pen lithography are used to create tracks of streptavidin on the passivated surfaces to serve as anchoring points for the biotinylated peptide arginine-glycine-aspartic acid (RGD) as the adhesive cue. A microfluidic device is placed onto the modified surface and used to create the gradient of adhesive cues (100% RGD to 0% RGD) on the streptavidin tracks. Finally, the same microfluidic device is used to create a gradient of a chemoattractant such as fetal bovine serum (FBS), as the soluble cue in the opposite direction of the gradient of adhesive cues.

1Centre for Vascular Research and Australian Centre for Nanomedicine, University of New South Wales, 2School of Chemistry and Australian Centre for Nanomedicine, University of New South Wales

 

RSC Advances DOI: 10.1039/c3ra000102d

Sintered gold nanoparticles as an electrode material for paper-based electrochemical sensors

Devi D Lianaab, Burkhard Ragusea, Lech Wieczoreka, Geoff R Baxtera, Kyloon Chuahb, J Justin Goodingbc, Edith Chow*a

 
Paper-based electrochemical sensor with carbon as the counter electrode, silver/silver chloride as the reference electrode and sintered gold nanoparticles as the working electrode. The working electrodes were constructed by coating the filter paper with a thin layer of nail polish, followed by application of gold nanoparticles and flash sintering of the particles. Two horizontal wax lines on either end of the paper are also present to isolate the electrical connections from solution. (a) Paper-based electrochemical sensor in its unbent form to allow the working electrode to be immersed in solution independently of the counter and reference electrodes. (b) Paper-based electrochemical sensor in its U-shaped form to allow the working, counter and reference electrodes to be all immersed in solution for the electrochemical measurement. (Blue dye was added to the solution for visualisation purposes.)

A simple and economical process for fabricating gold electrodes on paper is presented. Gold nanoparticles stabilised with 4-(dimethylamino)pyridine were applied to nail-polish coated filter paper and made conductive using a camera flash sintering step. To test the ability of the sintered gold nanoparticle film to function as a sensing platform, cysteine was self-assembled on gold and used for the electrochemical determination of copper ions. The cysteine-sintered gold nanoparticle film was able to successfully complex copper ions, with only minor differences in performance compared with a standard cysteine-modified solid-state gold disk electrode. Investigations by Raman spectroscopy revealed the successful removal of the 4-(dimethylamino)pyridine coating during sintering, whereas electrochemical impedance spectroscopy and scanning electron microscopy suggested that differences in the sensing performance could be attributed to the rougher morphology of the sintered gold nanoparticle electrode.

CSIRO Materials Science and Engineering PO Box 218,Lindfield NSW 2070, Australia.  School of Chemistry University of New South Wales Sydney NSW 2052 Australia cAustralian Centre for NanoMedicine University of New South Wales Sydney NSW 2052 Australia

  

Analytical and Bioanalytical Chemistry Vol 405 No11 DOI: 10.1007/s00216-013-6782-8

The impact of antibody/epitope affinity strength on the sensitivity of electrochemical immunosensors for detecting small molecules

SookMei Khor1, 2, Pall Thordarson1, J Justin Gooding1

 

 

A displacement immunoassay involves having a labelled analogue of the analyte (the epitope) already bound to the antibody. The presence of the analyte causes a competition for antibodies, and some of the antibodies dissociates from the epitope so that it can bind with the analyte. Herein, the influence of the affinity of the surface-bound epitope for the antibody on the sensitivity and selectivity of a displacement immunosensor is explored both theoretically and experimentally. An electrochemical immunosensor described previously [1], where the dissociation of antibodies from an electrode surface causes an increase in current from surface-bound ferrocene species, is used for this purpose. As expected, the ease and effectiveness of the bound antibody being displaced is inversely related to the affinity of the antibody to the surface-bound epitope relative to the analyte in solution as expected. However, if the affinity constant is too low, selectivity and/or sensitivity are compromised. Experimental results are qualitatively compared with a simple mass-action model.

1School of Chemistry and Australian Centre for NanoMedicine, University of New South Wales, Sydney NSW 2052 Australia 2AgaMatrix Inc 7C Raymond Avenue, Salem NH 03079 USA

  

Oncogene advance online publication 11 February 2013; doi: 10.1038/onc.2013.11

RNAi-mediated stathmin suppression reduces lung metastasis in an orthotopic neuroblastoma mouse model

F L Byrne1, L Yang1, P A Phillips2, L M Hansford3, J I Fletcher4, C J Ormandy5, J A McCarroll1,6, M Kavallaris1,6

Figure 1 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author 

Metastatic neuroblastoma is an aggressive childhood cancer of neural crest origin. Stathmin, a microtubule destabilizing protein, is highly expressed in neuroblastoma although its functional role in this malignancy has not been addressed. Herein, we investigate stathmin’s contribution to neuroblastoma tumor growth and metastasis. Small interfering RNA (siRNA)-mediated stathmin suppression in two independent neuroblastoma cell lines, BE(2)-C and SH-SY5Y, did not markedly influence cell proliferation, viability or anchorage-independent growth. In contrast, stathmin suppression significantly reduced cell migration and invasion in both the neuroblastoma cell lines. Stathmin suppression altered neuroblastoma cell morphology and this was associated with changes in the cytoskeleton, including increased tubulin polymer levels. Stathmin suppression also modulated phosphorylation of the actin-regulatory proteins, cofilin and myosin light chain (MLC). Treatment of stathmin-suppressed neuroblastoma cells with the ROCKI and ROCKII inhibitor, Y-27632, ablated MLC phosphorylation and returned the level of cofilin phosphorylation and cell invasion back to that of untreated control cells. ROCKII inhibition (H-1152) and siRNA suppression also reduced cofilin phosphorylation in stathmin-suppressed cells, indicating that ROCKII mediates stathmin’s regulation of cofilin phosphorylation. This data demonstrates a link between stathmin and the regulation of cofilin and MLC phosphorylation via ROCK. To examine stathmin’s role in neuroblastoma metastasis, stathmin short hairpin RNA (shRNA)\luciferase-expressing neuroblastoma cells were injected orthotopically into severe combined immunodeficiency-Beige mice, and tumor growth monitored by bioluminescent imaging. Stathmin suppression did not influence neuroblastoma cell engraftment or tumor growth. In contrast, stathmin suppression significantly reduced neuroblastoma lung metastases by 71% (P<0.008) compared with control. This is the first study to confirm a role for stathmin in hematogenous spread using a clinically relevant orthotopic cancer model, and has identified stathmin as an important contributor of cell invasion and metastasis in neuroblastoma.

1Tumour Biology and Targeting Program, Children’s Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales Randwick NSW Australia 2Pancreatic Cancer Translational Research Group, School of Medical Sciences, University of New South Wales Randwick NSW Australia 3Cell Biology Program, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada 4Experimental Therapeutics Program, Children’s Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales Randwick NSW Australia 5Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia 6Australian Centre for Nanomedicine, University of New South Wales Randwick NSW Australia

  

PLoS One (DOI: 10.1371/journal.pone.0052960)

Characterization of a New Series of Fluorescent Probes for Imaging Membrane Order

Joanna M Kwiatek, Dylan M Owen, Ahmed Abu-Siniyeh, Ping Yan, Leslie M Loew, Katharina Gaus

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Visualization and quantification of lipid order is an important tool in membrane biophysics and cell biology, but the availability of environmentally sensitive fluorescent membrane probes is limited. Here, we present the characterization of the novel fluorescent dyes PY3304, PY3174 and PY3184, whose fluorescence properties are sensitive to membrane lipid order. In artificial bilayers, the fluorescence emission spectra are red-shifted between the liquid-ordered and liquid-disordered phases. Using ratiometric imaging we demonstrate that the degree of membrane order can be quantitatively determined in artificial liposomes as well as live cells and intact, live zebrafish embryos. Finally, we show that the fluorescence lifetime of the dyes is also dependent on bilayer order. These probes expand the current palate of lipid order-sensing fluorophores affording greater flexibility in the excitation/emission wavelengths and possibly new opportunities in membrane biology.

Joanna M Kwiatek, Dylan M Owen, Ahmed Abu-Siniyeh, Katharina Gaus: Centre for Vascular Research and Australian Centre for Nanomedicine, University of New South Wales Sydney Australia. Ping Yan, Leslie M. Loew: Center for Cell Analysis and Modelling, University of Connecticut Health Center, Farmington Connecticut United States of America