Herein, a family of thiourea containing silicone-based photoresins suitable for creating silicone objects with excellent elasticity was developed for use in conventional digital light processing 3D printers. Rapid manufacturing of silicone products is highly desirable for small-volume manufacturing, especially for the application of customer-specific medical devices. However, because of their intrinsic high viscosity and lack of intermolecular interactions, 3D printing with silicone remains an ongoing challenge as suitable resins are not commercially available. To improve the elasticity of 3D-printed silicones, dynamic noncovalent intermolecular interactions between polymer chains were increased through the introduction of thiourea groups. Furthermore, a molecular design strategy was implemented based on utilizing "oligomeric" and "polymeric" PDMS units to adjust the ratio of thiourea segments. The cured silicone elastomer developed here displayed a maximum elongation of up to 1000% under tensile load and excellent cyclic compression durability. Moreover, this approach allowed for the 3D printing of PDMS-based objects with complex microarchitectures, high resolution, excellent surface finishing, and low cytotoxicity. The silicone thiourea resins have potential application in medical devices, wearable devices, and soft robotics.

Active ester polymers are commonly used for fast development of novel polymer libraries, but they require post-polymerization modification, which is not atom-efficient or economical. In order to more efficiently produce 2-hydroxypropyl methacrylamide (HPMAm) libraries, it would be advantageous to perform a direct copolymerization with active ester monomers. In this work, the synthesis of copolymer libraries of pentafluorophenyl methacrylate (PFPMA) and the hydrophilic monomer HPMAm is investigated. Surprisingly, HPMAm induces premature hydrolytic cleavage of PFPMA, which occurs during polymerization and depends on the HPMAm/PFPMA feed ratio. Copolymerization of PFPMA with N-isopropylmethacrylamide and the methacrylate monomers 2-hydroxypropylmethacrylate and N-isopropylmethacrylate reveals that the hydrolytic cleavage is promoted by copolymerization with methacrylamides only. By switching from a thermal- to a light-based initiator and lowering the reaction temperature, premature hydrolytic cleavage of PFPMA is avoided and allows direct copolymerization of HPMAm together with PFPMA to create polymer libraries for biomaterial screening.

Upon exposure to visible light, controlled multiple dose protein release was demonstrated by using a microspherical depot composed of biodegradable poly(ε-caprolactone) (PCL), bovine serum albumin (BSA) or horseradish peroxidase (HRP) as model protein, polymer-coated gold nanoparticles as photothermal component, which can potentially reduce the number of invasive therapeutic injections.

The use of biomacromolecular therapeutics has revolutionized disease treatment, but frequent injections are required owing to their short half-life in vivo. Thus there is a need for a drug delivery system that acts as a reservoir and releases the drug remotely "on demand". Here we demonstrate a simple light-triggered local drug delivery system through photo-thermal interactions of polymer-coated gold nanoparticles (AuNPs) inside an agarose hydrogel as therapeutic depot. Localized temperature increase induced by the visible light exposure caused reversible softening of the hydrogel matrix to release the pre-loaded therapeutics. The release profile can be adjusted by AuNPs and agarose concentrations, light intensity and exposure time. Importantly, the biological activity of the released bevacizumab was highly retained. In this study we demonstrate the potential application of this facile AuNPs/hydrogel system for ocular therapeutics delivery through its versatility to release multiple biologics, compatibility to ocular cells and spatiotemporal control using visible light.

Event Abstract Back to Event Saving vision with light: Photo-modulated ocular drug delivery Johan D. Basuki1*, Xavier D. Mulet1, Chen Hao2*, Hong D. Zhang3, Keith D. Mclean1* and Timothy D. Hughes1* 1 CSIRO, Manufacturing, Australia 2 Wenzhou Medical University, School of Optometry and Ophthalmology and Eye Hospital, China 3 University of Melbourne, Centre for Eye Research Australia, Australia Introduction: Age-related macular degeneration (AMD) is the leading cause of blindness in Australia today[1]. The only way to save vision requires monthly injection to the back of the eye with biomacromolecular anti-angiogenics, such as bevacizumab (Avastin®) and ranibizumab (Lucentis®)[2]. This invasive procedure, with the potential for sight threatening complications, has obvious negative impacts on patient’s quality of life as well as posing a major burden on the global health care system. A drug delivery system that serves as a reservoir to enable sustained release or ‘on-demand’ release of therapeutic protein/antibody would be beneficial, since it will significantly reduce the number of injections into the back of the eye[3]. The release of therapeutic payloads from the drug reservoir can be modulated on demand by light, particularly due to its external spatiotemporal control[4]. Materials/Method: In order to fabricate a photo-responsive drug delivery system a thermo-rensponsive polymer was formulated into a hydrogel containing light sensitive nanoparticles (LSNPs) and therapeutic payloads (Fig. 1). The release of different payloads, ranging from small molecules (doxorubicin, trimacinolone acetonide) to biomacromolecules (lysozyme, bovine serum albumin, and IgG/antibody), can be switched on and off upon exposure to visible light (Fig. 2). This hydrogel can be modified to a dispersion of microparticles or a thermo-reversible polymer solution for ocular injection, while additional surface coating can be applied for long-term sustained release. Results and Discussion: Released lysozyme, bevacizumab, and ranibizumab from this formulation exhibited above 85% biological activities after their exposure to light, in particular bevacizumab due to its binding affinity to human VEGF in the anti-angiogenic AMD therapy (Fig. 3). The microparticulate formulation did not show in vitro toxicity to ocular cells, and was injected subconjunctivally through a 30-gauge needle to the rabbit. In this preliminary animal study the corneal and retinal examinations of the injected eye confirmed the biocompatibility of the formulation. Conclusion: Due to its minimum toxicity and high versatility, this implantable photo-modulated drug delivery system has a potential to improve the treatment of ocular diseases. The release rate of the loaded drug can be tuned on demand by internal (e.g. LSNPs and polymer concentration) and external parameters (e.g. light intensity) for controlled dose. Fengxiang Qie; Randy Suryadinata; Linda Ge; Tianwei Tan; Xiaojuan Hao; Mark GreavesReferences:[1] Hugh R Taylor, Jill E Keeffe, Hien T V Vu, Jie Jin Wang, Elena Rochtchina, M Lynne Pezzullo and Paul Mitchell, "Vision loss in Australia", Medical Journal of Australia, Vol. 182, June 2005[2] Jayakrishna Ambati, John P. Atkinson and Bradley D. Gelfand, "Immunology of age-related macular degeneration", Nature Reviews Immunology, Vol. 13, June 2013[3] Owen A. Anderson, James W.B. Bainbridge and David T. Shima, "Delivery of anti-angiogenic molecular therapies for retinal disease", Drug Discovery Today, Vol. 15, April 2010[4] Salvatore Sortino, "Photoactivated nanomaterials for biomedical release applications", Journal of Materials Chemistry, Vol. 22, Nov. 2012 Keywords: Drug delivery, stimuli-response, Polymeric material, Bioactive molecule Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: General Session Oral Topic: Biomaterials for therapeutic delivery Citation: Basuki JD, Mulet XD, Hao C, Zhang HD, Mclean KD and Hughes TD (2016). Saving vision with light: Photo-modulated ocular drug delivery. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.02105 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. * Correspondence: Dr. Johan D Basuki, CSIRO, Manufacturing, Clayton, Australia, johan.basuki@csiro.au Dr. Chen Hao, Wenzhou Medical University, School of Optometry and Ophthalmology and Eye Hospital, Wenzhou, China, chenhao@mail.eye.ac.cn Dr. Keith D Mclean, CSIRO, Manufacturing, Clayton, Australia, Keith.McLean@csiro.au Dr. Timothy D Hughes, CSIRO, Manufacturing, Clayton, Australia, tim.hughes@csiro.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Johan D Basuki Xavier D Mulet Chen Hao Hong D Zhang Keith D Mclean Timothy D Hughes Google Johan D Basuki Xavier D Mulet Chen Hao Hong D Zhang Keith D Mclean Timothy D Hughes Google Scholar Johan D Basuki Xavier D Mulet Chen Hao Hong D Zhang Keith D Mclean Timothy D Hughes PubMed Johan D Basuki Xavier D Mulet Chen Hao Hong D Zhang Keith D Mclean Timothy D Hughes Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

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, alpha-D-mannose, alpha-D-glucose and beta-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, alpha-D-mannose functionalized IONPs, (IONP@P(OEGA)-b-P(N3Man)), exhibited high r(2) transverse relaxivity when measured in a 9.4 T MRI. A significant change in T-2 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 alpha-D-mannose, in a lung cancer cell line (A549).

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.

A library of magnetic nanoparticles was generated usingin situco-precipitation of ferrous (Fe2+) and ferric (Fe3+) ions from aqueous solutions in the presence of functional block copolymers.

Biofilms are increasingly recognized as playing a major role in human infectious diseases, as they can form on both living tissues and abiotic surfaces, with serious implications for applications that rely on prolonged exposure to the body such as implantable biomedical devices or catheters. Therefore, there is an urgent need to develop improved therapeutics to effectively eradicate unwanted biofilms. Recently, the biological signaling molecule nitric oxide (NO) was identified as a key regulator of dispersal events in biofilms. In this paper, we report a new class of core cross-linked star polymers designed to store and release nitric oxide, in a controlled way, for the dispersion of biofilms. First, core cross-linked star polymers were prepared by reversible addition-fragmentation chain transfer polymerization (RAFT) via an arm first approach. Poly(oligoethylene methoxy acrylate) chains were synthesized by RAFT polymerization, and then chain extended in the presence of 2-vinyl-4,4-dimethyl-5-oxazolone monomer (VDM) with N,N-methylenebis(acrylamide) employed as a cross-linker to yield functional core cross-linked star polymers. Spermine was successfully attached to the star core by reaction with VDM. Finally, the secondary amine groups were reacted with NO gas to yield NO-core cross-linked star polymers. The core cross-linked star polymers were found to release NO in a controlled, slow delivery in bacterial cultures showing great efficacy in preventing both cell attachment and biofilm formation in Pseudomonas aeruginosa over time via a nontoxic mechanism, confining bacterial growth to the suspended liquid.

Gold nanoparticles (size 10 nm) were designed to store and release nitric oxide (NO), by functionalizing their surfaces with functional polymers modified with NO-donor molecules.

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), i.e.,(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.

Superparamagnetic iron oxide nanopartic.les (IONPs) have been studied extensively as negative contrast agents to enhance MRI efficacy. For optimal effective clinical use in T-2/T-2* weighted MRI imaging, the aim is to maximize relaxivity (r(2)) of IONPs, and minimize r(1) 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 nanopartides (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 r(2) / r(1) relaxivity ratios in water. At 9.4 T, the r(2)/r(1) relaxivity values that we attained were about 6-fold higher than the commercial, clinically used, MEd contrast agent Resovist.

Angewandte Chemie International EditionVolume 52, Issue 52 p. 14152-14156 Communication Functional Iron Oxide Magnetic Nanoparticles with Hyperthermia-Induced Drug Release Ability by Using a Combination of Orthogonal Click Reactions† Dr. Thuy T. T. N'Guyen, Dr. Thuy T. T. N'Guyen Institut 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)Search for more papers by this authorHien T. T. Duong, Hien T. T. Duong Australian Centre for Nanomedicine, Sydney (Australia)Search for more papers by this authorJohan Basuki, Johan Basuki Australian Centre for Nanomedicine, Sydney (Australia)Search for more papers by this authorDr. Véronique Montembault, Dr. Véronique Montembault Institut 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)Search for more papers by this authorDr. Sagrario Pascual, Dr. Sagrario Pascual Institut 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)Search for more papers by this authorClément Guibert, Clément Guibert PECSA, UMR 7195, Laboratoire de Physico-Chimie des Electrolytes, Colloïdes et Sciences Analytiques, Paris (France)Search for more papers by this authorDr. Jérôme Fresnais, Dr. Jérôme Fresnais PECSA, UMR 7195, Laboratoire de Physico-Chimie des Electrolytes, Colloïdes et Sciences Analytiques, Paris (France)Search for more papers by this authorAssoc. Prof. Dr. Cyrille Boyer, Assoc. Prof. Dr. Cyrille Boyer Australian Centre for Nanomedicine, Sydney (Australia)Search for more papers by this authorDr. Michael R. Whittaker, Dr. Michael R. Whittaker Monash Institute of Pharmaceutical Sciences, Melbourne (Australia)Search for more papers by this authorProf. Dr. Thomas P. Davis, Prof. Dr. Thomas P. Davis Monash Institute of Pharmaceutical Sciences, Melbourne (Australia)Search for more papers by this authorProf. Dr. Laurent Fontaine, Corresponding Author Prof. Dr. Laurent Fontaine laurent.fontaine@univ-lemans.fr Institut 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)Institut 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)Search for more papers by this author Dr. Thuy T. T. N'Guyen, Dr. Thuy T. T. N'Guyen Institut 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)Search for more papers by this authorHien T. T. Duong, Hien T. T. Duong Australian Centre for Nanomedicine, Sydney (Australia)Search for more papers by this authorJohan Basuki, Johan Basuki Australian Centre for Nanomedicine, Sydney (Australia)Search for more papers by this authorDr. Véronique Montembault, Dr. Véronique Montembault Institut 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)Search for more papers by this authorDr. Sagrario Pascual, Dr. Sagrario Pascual Institut 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)Search for more papers by this authorClément Guibert, Clément Guibert PECSA, UMR 7195, Laboratoire de Physico-Chimie des Electrolytes, Colloïdes et Sciences Analytiques, Paris (France)Search for more papers by this authorDr. Jérôme Fresnais, Dr. Jérôme Fresnais PECSA, UMR 7195, Laboratoire de Physico-Chimie des Electrolytes, Colloïdes et Sciences Analytiques, Paris (France)Search for more papers by this authorAssoc. Prof. Dr. Cyrille Boyer, Assoc. Prof. Dr. Cyrille Boyer Australian Centre for Nanomedicine, Sydney (Australia)Search for more papers by this authorDr. Michael R. Whittaker, Dr. Michael R. Whittaker Monash Institute of Pharmaceutical Sciences, Melbourne (Australia)Search for more papers by this authorProf. Dr. Thomas P. Davis, Prof. Dr. Thomas P. Davis Monash Institute of Pharmaceutical Sciences, Melbourne (Australia)Search for more papers by this authorProf. Dr. Laurent Fontaine, Corresponding Author Prof. Dr. Laurent Fontaine laurent.fontaine@univ-lemans.fr Institut 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)Institut 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)Search for more papers by this author First published: 19 November 2013 https://doi.org/10.1002/anie.201306724Citations: 122 † We thank Dr. S. Piogé and Prof. Dr. F. Goutenoire for TEM analyses, A. Durand and E. Mebold for NMR and MALDI-TOF analyses, A. McMillan and R. Whan for FLIM experiments, and Dr. G. Dujardin for helpful discussions. C.B. is thankful for his APD and Future Fellowship from Australian Research Council (ARC). Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat 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. Citing Literature Supporting Information As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Filename Description anie_201306724_sm_miscellaneous_information.pdf5.8 MB miscellaneous_information Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. Volume52, Issue52December 23, 2013Pages 14152-14156 RelatedInformation

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, beta-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.

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.