ProfessorRongjunChen

Watkins KA, Chen R, 2015, pH-responsive, lysine-based hydrogels for the oral delivery of a wide size range of molecules, International Journal of Pharmaceutics, Vol: 478, Pages: 496-503, ISSN: 0378-5173

Hydrogels synthesized from poly(l-lysine isophthalamide) (PLP) crosslinked with l-lysine methyl ester were investigated as drug delivery systems for a wide size range of molecules (0.3-2000 kDa). PLP is an anionic, pseudo-peptidic polymer that is an ideal hydrogel backbone due to its pH-responsiveness and amphiphilicity. Drug loading and release were evaluated for various model drugs: hydrophobic fluorescein (Mw = 332 Da) and hydrophilic fluorescein isothiocyanate-dextran (FITC-Dex Mw = 10 kDa, 150 kDa, 500 kDa, and 2000 kDa). Weight incorporation was high, up to 22.8 ± 3.1%. Release after 24 h in pH 7.4 was in the range from 70.4 ± 1.2% to 91.6 ± 0.8% for all model drugs. In contrast, drug release after 24 h in pH 3.0 was significantly lower, less than 8% for fluorescein, 500 kDa, and 2000 kDa FITC-Dex. Thus, the adaptability of these novel hydrogels to both hydrophobic and hydrophilic molecules, spanning a wide size range, suggests their use as a platform delivery system. This is also the first known hydrogel system for the oral delivery of payloads larger than 70 kDa, which, combined with triggered release in response to pH changes along the gastrointestinal tract, indicates that these hydrogels have promising applications in oral drug delivery.

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• Citations: 34

Wang Y, Wang F, Guo Y, Chen R, Shen Y, Guo A, Liu J, Zhang X, Zhou D, Guo Set al., 2014, Controlled synthesis of monodisperse gold nanorods with different aspect ratios in the presence of aromatic additives, Journal of Nanoparticle Research, ISSN: 1572-896X

This paper reports the synthesis of monodisperse gold nanorods (GNRs) via a simple seeded growth approach in the presence of different aromatic additives, such as 7-bromo-3-hydroxy-2-naphthoic acid (7-BrHNA), 3-hydroxy-2-naphthoic acid (HNA), 5-bromosalicylic acid (5-BrSA), salicylic acid (SA) or phenol (PhOH). Effects of the aromatic additives and hydrochloric acid (HCl) on the structure and optical properties of the synthesized GNRs were investigated. The longitudinal surface plasmon resonance (LSPR) peak wavelength of the resulting GNRs was found to be dependent on the aromatic additive in the following sequence: 5-BrSA (778 nm) > 7-BrHNA (706 nm) > SA (688 nm) > HNA (676 nm) > PhOH (638 nm) without addition of HCl, but this was change to 7-BrHNA (920 nm) > SA (890 nm) > HNA (872 nm) > PhOH (858 nm) > 5-BrSA (816 nm) or 7-BrHNA (1005 nm) > PhOH (995 nm) > SA (990 nm) > HNA (980 nm) > 5-BrSA (815 nm) with the addition of HCl or HNO3. The LSPR peak wavelength increased with concentrations of 7-BrHNA increased without addition of HCl, however, there was a maximum LSPR peak wavelength when HCl was added. The LSPR peak wavelength increased with amount of HCl added. These results presented here thus established a simple approach to synthesize monodisperse GNRs of different LSPR wavelength.

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Xu Z, Xu Z, Cao J, Ruan X, Chen Ret al., 2014, Development and Characterization of a Novel Polymer Microchannel Tube, Polymer-Plastics Technology and Engineering, Vol: 53, Pages: 1442-1449

This paper establishes a novel polymer microchannel tube (MCT) with a channel (0.9-3.0 mm in diameter) in the center surrounded by an array of microchannels (50-300 μm) using extrusion technology. The draw ratio and melt drawing length are demonstrated to significantly affect the cross-sectional parameters of MCT, which is consistent with numerical simulations using Polyflow® and theoretical analysis. It’s found the process parameters negligibly influence the relative proportions between cross-sectional parameters. Based on a simplified drawing model, a prediction function of high reliability (R-square ＞95%) for cross-sectional parameters is set up. The MCTs are formed more uniformly compared with microcapillary films (MCFs) because of the elimination of the sharp boundary effect. Each of the microchannels is formed elliptically as a result of the non-uniform velocity distribution around the injector tip exit. The mechanism that the ambient air is automatically entrained into the microchannels at atmospheric pressure was elucidated.

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Zhang S, Chen R, Malhotra G, Critchley K, Vakurov A, Nelson Aet al., 2014, Electrochemical modelling of QD-phospholipid interactions, Journal of Colloid and Interface Science, Vol: 420, Pages: 9-14

HypothesisThe aggregation of quantum dots (QD) and capping of individual QDs affects their activity towards biomembrane models.ExperimentsElectrochemical methods using a phospholipid layer on mercury (Hg) membrane model have been used to determine the phospholipid monolayer activity of thioglycollic acid (TGA) coated quantum dots (QDs) as an indicator of biomembrane activity. The particles were characterized for size and charge.FindingsThe activity of the QDs towards dioleoyl phosphatidylcholine (DOPC) monolayers is pHdependent, and is most active at pH 8.2 within the pH range 8.2 to 6.5 examined in this work. This pH dependent activity is the result of increased particle aggregation coupled to decreasing surface charge emanating from the TGA carboxylic groups employed to stabilize the QD dispersion in aqueous media. Capping the QDs with CdS/ZnS lowers the particles' activity to phospholipid monolayers.

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Chen R, 2013, Polymers in Drug Delivery: Concepts, Developments and Potential, Drug Delivery Systems: Advanced Technologies Potentially Applicable in Personalised Treatment, Editors: Coelho, Publisher: Springer Netherlands, Pages: 1-34

Targeteddeliveryoftherapeuticagents,includingsmall-moleculedrugs and biopharmaceuticals, to the specific site of action can improve their safety and pharmaceutical efficacy. Controlled-release polymer technologies have played an important role in the advancement of targeted drug delivery research. Modern advances in polymeric drug delivery will depend on rational design of polymers tailored for carrying specific payload and exerting desirable biological functions as a result of a detailed and thorough understanding of biological processes. This chapter provides a unique coverage of the field of polymers in drug delivery. It addresses the foundations of drug delivery in a conceptual context, highlights the extracellular and intracellular barriers to effective polymeric drug delivery, critically reviews the recent developments in different classes of polymeric delivery agents (including polymer-drug conjugates, polymeric micelles, multi-component polyplexes, polymer-modified liposomes, polymersomes, and membrane-disruptive polymers), and discusses their applications for the treatment of various diseases including cancer.

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Khormaee S, Choi Y, Shen MJ, Xu B, Wu H, Griffiths GL, Chen R, Slater NKH, Park JKet al., 2013, Endosomolytic Anionic Polymer for the Cytoplasmic Delivery of siRNAs in Localized In Vivo Applications, ADVANCED FUNCTIONAL MATERIALS, Vol: 23, Pages: 565-574, ISSN: 1616-301X

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• Citations: 32

Song L, Ho VHB, Chen C, Yang Z, Liu D, Chen R, Zhou Det al., 2013, Efficient, pH-Triggered Drug Delivery Using a pH-Responsive DNA-Conjugated Gold Nanoparticle, ADVANCED HEALTHCARE MATERIALS, Vol: 2, Pages: 275-280, ISSN: 2192-2640

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Chen R, 2013, Polymers in Drug Delivery: Concepts, Developments and Potential, ISBN: 9789400760097

Targeted delivery of therapeutic agents, including small-molecule drugs and biopharmaceuticals, to the specific site of action can improve their safety and pharmaceutical efficacy. Controlled-release polymer technologies have played an important role in the advancement of targeted drug delivery research. Modern advances in polymeric drug delivery will depend on rational design of polymers tailored for carrying specific payload and exerting desirable biological functions as a result of a detailed and thorough understanding of biological processes. This chapter provides a unique coverage of the field of polymers in drug delivery. It addresses the foundations of drug delivery in a conceptual context, highlights the extracellular and intracellular barriers to effective polymeric drug delivery, critically reviews the recent developments in different classes of polymeric delivery agents (including polymer-drug conjugates, polymeric micelles, multi-component polyplexes, polymer-modified liposomes, polymersomes, and membrane-disruptive polymers), and discusses their applications for the treatment of various diseases including cancer. © Springer Science+Business Media Dordrecht 2013.

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• Citations: 4

Cao J, Xu Z, Wang B, Chen Ret al., 2012, Influence of injection air pressure on the microcapillary formation within extruded plastic films, JOURNAL OF MATERIALS SCIENCE, Vol: 47, Pages: 8188-8196, ISSN: 0022-2461

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• Citations: 12

Ahire JH, Wang Q, Coxon PR, Malhotra G, Brydson R, Chen R, Chao Yet al., 2012, Highly Luminescent and Nontoxic Amine-Capped Nanoparticles from Porous Silicon: Synthesis and Their Use in Biomedical Imaging, ACS APPLIED MATERIALS & INTERFACES, Vol: 4, Pages: 3285-3292, ISSN: 1944-8244

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• Citations: 93

Slater NKH, Lynch A, Chen R, 2011, Mammalian cell preservation methods, WO/2011/089391

This invention relates to methods for reversibly permeabilising mammalian cells to preservation agents, such as trehalose, using synthetic polymers. Suitable synthetic polymers include lysine iso- phthalamide polymers, in particular lysine iso-phthalamide polymers pendanted with one or more hydrophobic amino acids, such as leucine or phenylalanine. Polymer-mediated permeability allows cells to be loaded with high concentrations of preservation agents prior to preservation, for example cryopreservation or lyopreservation, and this allows an increased proportion of cells to remain viable following preservation.

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Zhang S, Nelson A, Coldrick Z, Chen Ret al., 2011, The Effects of Substituent Grafting on the Interaction of pH-Responsive Polymers with Phospholipid Monolayers, LANGMUIR, Vol: 27, Pages: 8530-8539, ISSN: 0743-7463

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• Citations: 20

Lynch AL, Chen R, Slater NKH, 2011, pH-responsive polymers for trehalose loading and desiccation protection of human red blood cells, BIOMATERIALS, Vol: 32, Pages: 4443-4449, ISSN: 0142-9612

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• Citations: 56

Metanawin T, Tang T, Chen R, Vernon D, Wang Xet al., 2011, Cytotoxicity and photocytotoxicity of structure-defined water-soluble C₆₀/micelle supramolecular nanoparticles, NANOTECHNOLOGY, Vol: 22, ISSN: 0957-4484

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• Citations: 27

Ho VHB, Slater NKH, Chen R, 2011, pH-responsive endosomolytic pseudo-peptides for drug delivery to multicellular spheroids tumour models, BIOMATERIALS, Vol: 32, Pages: 2953-2958, ISSN: 0142-9612

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• Citations: 46

Ho VHB, Barczab A, Chen R, Slater NKHet al., 2010, Magnetic Cell Labeling and Manipulation in Cell Cultures, AIP Conference Proceedings, Vol: 1311, Pages: 363-368

Magnetic cell labeling has numerous applications in cell separation and sorting, tissue engineering and magnetic resonance imaging. Mammalian cells can be magnetically labeled by first biotinylating their cell membrane proteins and then binding streptavidin-coated paramagnetic particles onto the biotinylated proteins. Characterization studies indicated that the extent of cell biotinylation could be controlled by varying the biotinylating reagent concentration. Since the paramagnetic particles have high mass magnetization, the labeled cells were very responsive to magnetic field gradients and they could be targeted and patterned precisely using magnets. Magnetic multicellularspheroids were generated from these labeled cells and the constituent cells were found to be viable. These spheroids could be patterned using magnetic fields in a few seconds. This cell labeling methodology can be adapted to a wide variety of mammalian cell types. The labeled cells can then be manipulated in two dimensional cell culture or as three dimensional magnetic spheroids.

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Lynch AL, Chen R, Dominowski PJ, Shalaev EY, Yancey RJ, Slater NKHet al., 2010, Biopolymer mediated trehalose uptake for enhanced erythrocyte cryosurvival, BIOMATERIALS, Vol: 31, Pages: 6096-6103, ISSN: 0142-9612

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• Citations: 61

Chen R, Folarin N, Ho VHB, McNally D, Darling D, Farzaneh F, Slater NKHet al., 2010, Affinity recovery of lentivirus by diaminopelargonic acid mediated desthiobiotin labelling, JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES, Vol: 878, Pages: 1939-1945, ISSN: 1570-0232

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• Citations: 12

Ho VHB, Mueller KH, Barcza A, Chen R, Slater NKHet al., 2010, Generation and manipulation of magnetic multicellular spheroids, BIOMATERIALS, Vol: 31, Pages: 3095-3102, ISSN: 0142-9612

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• Citations: 66

Khormaee S, Chen R, Park JK, Slater NKHet al., 2010, The Influence of Aromatic Side-Chains on the Aqueous Properties of pH-Sensitive Poly(L-lysine <i>iso</i>-phthalamide) Derivatives, JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION, Vol: 21, Pages: 1573-1588, ISSN: 0920-5063

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• Citations: 9

Ho VHB, Barcza A, Chen R, Mueller KH, Darton NJ, Slater NKHet al., 2009, The precise control of cell labelling with streptavidin paramagnetic particles, BIOMATERIALS, Vol: 30, Pages: 6548-6555, ISSN: 0142-9612

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• Citations: 26

Liechty WB, Chen R, Farzaneh F, Tavassoli M, Slater NKHet al., 2009, Synthetic pH-Responsive Polymers for Protein Transduction, ADVANCED MATERIALS, Vol: 21, Pages: 3910-+, ISSN: 0935-9648

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• Citations: 27

Chen R, Khormaee S, Eccleston ME, Slater NKHet al., 2009, Effect of L-Leucine Graft Content on Aqueous Solution Behavior and Membrane-Lytic Activity of a pH-Responsive Pseudopeptide, BIOMACROMOLECULES, Vol: 10, Pages: 2601-2608, ISSN: 1525-7797

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• Citations: 20

Chen R, Khormaee S, Eccleston ME, Slater NKHet al., 2009, The role of hydrophobic amino acid grafts in the enhancement of membrane-disruptive activity of pH-responsive pseudo-peptides, BIOMATERIALS, Vol: 30, Pages: 1954-1961, ISSN: 0142-9612

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• Citations: 86

Chen R, Eccleston ME, Yue Z, Slater NKHet al., 2009, Synthesis and pH-responsive properties of pseudo-peptides containing hydrophobic amino acid grafts, JOURNAL OF MATERIALS CHEMISTRY, Vol: 19, Pages: 4217-4224, ISSN: 0959-9428

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• Citations: 35

Chen R, Yue Z, Eccleston ME, Slater NKHet al., 2008, Aqueous solution behaviour and membrane disruptive activity of pH-responsive PEGylated pseudo-peptides and their intracellular distribution, BIOMATERIALS, Vol: 29, Pages: 4333-4340, ISSN: 0142-9612

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• Citations: 19

Chen R, Slater NKH, Gatlin LA, Kramer T, Shalaev EYet al., 2008, Comparative rates of freeze-drying for lactose and sucrose solutions as measured by photographic recording, product temperature, and heat flux transducer, PHARMACEUTICAL DEVELOPMENT AND TECHNOLOGY, Vol: 13, Pages: 367-374, ISSN: 1083-7450

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• Citations: 14

Chen RJ, Yue ZL, Eccleston ME, Williams S, Slater NKHet al., 2005, Modulation of cell membrane disruption by pH-responsive pseudo-peptides through grafting with hydrophilic side chains, JOURNAL OF CONTROLLED RELEASE, Vol: 108, Pages: 63-72, ISSN: 0168-3659

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• Citations: 29

Eccleston ME, Williams SL, Yue Z, Chen R, Lee KC, Anikina E, Pawlyn C, Barrand MA, Slater NKHet al., 2005, Design and In-vitro Testing of Effective Poly(l-Lysine Iso-Phthalamide) Based Drug Targeting Systems for Solid Tumours, Food and Bioproducts Processing, Vol: 83, Pages: 141-146

The mode of cell uptake, relative cytotoxicity and efficacy of poly (l-lysine iso-phthalamide)-drug conjugates, PEG-graft poly (l-lysine iso-phthalamide)-drug containing micelles, poly (l-lysine iso-phthalamide) modified drug/protein nanospheres and unmodified protein nanospheres as potential delivery systems have been evaluated using doxorubicin and polymethine fluorophores as model drugs. pH dependent cell membrane lysis has been demonstrated using a haemolysis model and the cytotoxicity of the polymeric system evaluated using standard MTT and LDH activity assays. In-vitro toxicity and cellular targeting data are presented and the potential healthcare impact of such systems is discussed.

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Li CZ, Feng NQ, Li YD, Chen RJet al., 2005, Effects of polyethlene oxide chains on the perfonrmance of polycarboxylate-type water-reducers, CEMENT AND CONCRETE RESEARCH, Vol: 35, Pages: 867-873, ISSN: 0008-8846

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• Citations: 143