Imperial College London

DrRongjunChen

Faculty of EngineeringDepartment of Chemical Engineering

Reader in Biomaterials Engineering
 
 
 
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Contact

 

+44 (0)20 7594 2070rongjun.chen Website

 
 
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Location

 

408ACE ExtensionSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

59 results found

Gu B, Piebalgs A, Huang Y, Roi D, Lobotesis K, Longstaff C, Hughes AD, Chen R, Thom SA, Xu XYet al., 2019, Computational simulations of thrombolysis in acute stroke: Effect of clot size and location on recanalisation, Medical Engineering & Physics, Vol: 73, Pages: 9-17, ISSN: 1350-4533

Acute ischaemic stroke can be treated by intravenous thrombolysis whereby tissue plasminogen activator (tPA) is infused to dissolve clots that block blood supply to the brain. In this study, we aim to examine the influence of clot location and size on lysis pattern and recanalisation by using a recently developed computational modelling framework for thrombolysis under physiological flow conditions. An image-based patient-specific model is reconstructed which consists of the internal carotid bifurcation with the A1 segment of anterior cerebral arteries and M1 segment of middle cerebral arteries, and the M1 bifurcation containing the M2 segments. By varying the clot size and location, 7 scenarios are simulated mimicking thrombolysis of M1 and M2 occlusions. Our results show that initial breakthrough always occurs along the inner curvature of the occluded cerebral artery, due to prolonged tPA residence time in the recirculation zone. For a given occlusion site, lysis completion time appears to increase almost quadratically with the initial clot volume; whereas for a given clot volume, the simulated M2 occlusions take up to 30% longer for complete lysis compared to the corresponding M1 occlusions.

Journal article

Chen S, Ren J, Chen R, 2019, Cryopreservation and Desiccation Preservation of Cells, Comprehensive Biotechnology, Editors: Moo-Young, Elsevier: Pergamon, Publisher: Pergamon, Pages: 157-166, ISBN: 9780444640468

Cell preservation technology is required to retain cell viability and functionality during storage. It is of critical importance for the development of biobanks and the delivery of emerging cell-based therapies including blood transfusion, immunotherapy, reparative and regenerative medicine, and fertility preservation. Cryopreservation at ultralow temperature is currently the main way of long-term cell storage. Preservation of cells in dried state at room temperature is an attractive strategy to overcome the limitations of refrigeration and enable easy transportation. Although achievements have been made in preservation of human, animal and bacteria cells, there is still much space for improving their survival rate and functionality. Cell injuries may easily occur during freezing and drying steps, especially for mammalian cells which are more delicate and freezing/desiccation sensitive. This article reviews the mechanisms of cell damage, describes the challenges for cell preservation, and presents the technologies and protectants used in this rapidly growing field.

Book chapter

Huang Y, Yu L, Ren J, Gu B, Longstaff C, Hughes AD, Thom SA, Xu XY, Chen Ret al., 2019, An activated-platelet-sensitive nanocarrier enables targeted delivery of tissue plasminogen activator for effective thrombolytic therapy, Journal of Controlled Release, Vol: 300, Pages: 1-12, ISSN: 0168-3659

It remains a major challenge to develop a selective and effective fibrinolytic system for thrombolysis with minimal undesirable side effects. Herein, we report a multifunctional liposomal system (164.6 ± 5.3 nm in diameter) which can address this challenge through targeted delivery and controlled release of tissue plasminogen activator (tPA) at the thrombus site. The tPA-loaded liposomes were PEGylated to improve their stability, and surface coated with a conformationally-constrained, cyclic arginine-glycine-aspartic acid (cRGD) to enable highly selective binding to activated platelets. The in vitro drug release profiles at 37 °C showed that over 90% of tPA was released through liposomal membrane destabilization involving membrane fusion upon incubation with activated platelets within 1 h, whereas passive release of the encapsulated tPA in pH 7.4 PBS buffer was 10% after 6 h. The release of tPA could be readily manipulated by changing the concentration of activated platelets. The presence of activated platelets enabled the tPA-loaded, cRGD-coated, PEGylated liposomes to induce efficient fibrin clot lysis in a fibrin-agar plate model and the encapsulated tPA retained 97.4 ± 1.7% of fibrinolytic activity as compared with that of native tPA. Furthermore, almost complete blood clot lysis was achieved in 75 min, showing considerably higher and quicker thrombolytic activity compared to the tPA-loaded liposomes without cRGD labelling. These results suggest that the nano-sized, activated-platelet-sensitive, multifunctional liposomes could facilitate selective delivery and effective release of tPA at the site of thrombus, thus achieving efficient clot dissolution whilst minimising undesirable side effects.

Journal article

He M, Huang L, Hou X, Zhong C, Bachir ZA, Lan M, Chen R, Gao Fet al., 2019, Efficient ovalbumin delivery using a novel multifunctional micellar platform for targeted melanoma immunotherapy, International Journal of Pharmaceutics, Vol: 560, Pages: 1-10, ISSN: 0378-5173

Cancer immunotherapy is considered to be one of the alternatives to traditional chemotherapy. It's known that foreign antigen, such as ovalbumin (OVA), can label tumor cells, leading to neoantigen recognition by cytotoxic T lymphocytes. Herein, a novel multifunctional micelle coated with PEGylated hyaluronic acid (HA) was prepared through self-assembly and electrostatic interaction. The OVA-loaded micelle with uniform size (132.1 ± 0.2 nm in diameter) exhibited favorable stability and sustained release profiles. The HA-coated micelle could target CD44-overexpressed cells and enhance the cellular uptake of OVA by 11.9 fold compared to free OVA. In vitro studies revealed that the cationic polymer, polyethyleneimine, could facilitate endosomal escape of OVA to label a tumor cell. After treatment with the OVA-loaded micelle, tumor growth in mice was significantly inhibited by 70% compared to the group treated with free OVA. All these results suggest the potential application of the immunotherapeutic micellar platform for melanoma treatment.

Journal article

Gu B, Piebalgs A, Huang Y, Longstaff C, Hughes A, Chen R, Thom S, Xu Xet al., 2019, Mathematical modelling of intravenous thrombolysis in acute ischaemic stroke: Effects of dose regimens on levels of fibrinolytic proteins and clot lysis time, Pharmaceutics, Vol: 11, ISSN: 1999-4923

Thrombolytic therapy is one of the medical procedures in the treatment of acute ischaemic stroke (AIS), whereby the tissue plasminogen activator (tPA) is intravenously administered to dissolve the obstructive blood clot. The treatment of AIS by thrombolysis can sometimes be ineffective and it can cause serious complications, such as intracranial haemorrhage (ICH). In this study, we propose an efficient mathematical modelling approach that can be used to evaluate the therapeutic efficacy and safety of thrombolysis in various clinically relevant scenarios. Our model combines the pharmacokinetics and pharmacodynamics of tPA with local clot lysis dynamics. By varying the drug dose, bolus-infusion delay time, and bolus-infusion ratio, with the FDA approved dosing protocol serving as a reference, we have used the model to simulate 13 dose regimens. Simulation results are compared for temporal concentrations of fibrinolytic proteins in plasma and the time that is taken to achieve recanalisation. Our results show that high infusion rates can cause the rapid degradation of plasma fibrinogen, indicative of increased risk for ICH, but they do not necessarily lead to fast recanalisation. In addition, a bolus-infusion delay results in an immediate drop in plasma tPA concentration, which prolongs the time to achieve recanalisation. Therefore, an optimal administration regimen should be sought by keeping the tPA level sufficiently high throughout the treatment and maximising the lysis rate while also limiting the degradation of fibrinogen in systemic plasma. This can be achieved through model-based optimisation in the future.

Journal article

Dong R, Liu R, Gaffney PRJ, Schaepertoens M, Marchetti P, Williams CM, Chen R, Livingston AGet al., 2019, Author Correction: Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving, Nature Chemistry, Vol: 11, Pages: 184-184, ISSN: 1755-4330

Correction to: Nature Chemistry https://doi.org/10.1038/s41557-018-0169-6, published online 3 December 2018.

Journal article

Tascini AS, Noro MG, Seddon JM, Chen R, Bresme Fet al., 2019, Mechanisms of lipid extraction from skin lipid bilayers by sebum triglycerides, Physical Chemistry Chemical Physics, Vol: 21, Pages: 1471-1477, ISSN: 1463-9076

The skin surface, our first barrier against the external environment, is covered by the sebum oil, a lipid film composed of sebaceous and epidermal lipids, which is important in the regulation of the hydration level of our skin. Here, we investigate the pathways leading to the transfer of epidermal lipids from the skin lipid bilayer to the sebum. We show that the sebum triglycerides, a major component of sebum, interact strongly with the epidermal lipids and extract them from the bilayer. Using microsecond time scale molecular dynamics simulations, we identify and quantify the free energy associated with the skin lipid extraction process.

Journal article

Wang S, Attah R, Li J, Chen Y, Chen Ret al., 2018, A pH-responsive amphiphilic hydrogel based on pseudopeptides and poly(ethylene glycol) for oral delivery of hydrophobic drugs, ACS Biomaterials Science and Engineering, Vol: 4, Pages: 4236-4243, ISSN: 2373-9878

Oral administration is a noninvasive and convenient drug delivery route most preferred by patients. However, poor stability in the gastrointestinal tract and low bioavailability of hydrophobic drugs has greatly limited their oral administration. To address this problem, we report a pH-responsive, amphiphilic hydrogel drug carrier based on a pseudopeptide poly(l-lysine isophthalamide) (PLP) and poly(ethylene glycol) (PEG). The hydrogels were prepared by a simple N-(3-(dimethylamino)propyl)-N′-ethyl carbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) coupling reaction, and the cross-linking was confirmed by infrared spectroscopy and differential scanning calorimetry analyses. Because of the pH-responsive conformational alteration of PLP, the hydrogels were relatively hydrophobic and collapsed at acidic pH, but became hydrophilic and swollen at neutral pH. The amphiphilicity enabled the hydrogels to well retain and protect hydrophobic model drugs in the simulated gastric fluid, but efficiently release them in the simulated intestinal fluid. These results suggested that the pH-responsive amphiphilic hydrogels are promising candidates for oral delivery of hydrophobic drugs.

Journal article

Dong R, Liu R, Gaffney P, Schaepertoens M, Marchetti P, Williams C, Chen R, Livingston Aet al., 2018, Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving, Nature Chemistry, Vol: 11, Pages: 136-145, ISSN: 1755-4330

Synthetic chemists have devoted tremendous effort towards the production of precision synthetic polymers with defined sequences and specific functions. However, the creation of a general technology that enables precise control over monomer sequence, with efficient isolation of the target polymers, is highly challenging. Here, we report a robust strategy for the production of sequence-defined synthetic polymers through a combination of liquid-phase synthesis and selective molecular sieving. The polymer is assembled in solution with real-time monitoring to ensure couplings proceed to completion, on a three-armed star-shaped macromolecule to maximize efficiency during the molecular sieving process. This approach is applied to the construction of sequence-defined polyethers, with side-arms at precisely defined locations that can undergo site-selective modification after polymerization. Using this versatile strategy, we have introduced structural and functional diversity into sequence-defined polyethers, unlocking their potential for real-life applications in nanotechnology, healthcare and information storage.

Journal article

Wang S, Ha Y, Huang X, Chin B, Sim W, Chen Ret al., 2018, A new strategy for intestinal drug delivery via pH-responsive and membrane-active nanogels, ACS Applied Materials and Interfaces, Vol: 10, Pages: 36622-36627, ISSN: 1944-8244

Oral administration of hydrophobic and poorly intestinal epithelium-permeable drugs is a significant challenge. Herein, we report a new strategy to overcome this problem by using novel, pH-responsive, and membrane-active nanogels as drug carriers. Prepared by simple physical cross-linking of amphiphilic pseudopeptidic polymers with pH-controlled membrane-activity, the size and hydrophobicity–hydrophilicity balance of the nanogels could be well-tuned. Furthermore, the amphiphilic nanogels could release hydrophobic payloads and destabilize cell membranes at duodenum and jejunum pH 5.0–6.0, which suggests their great potential for intestinal drug delivery.

Journal article

Bachir ZA, Huang Y, He M, Huang L, Hou X, Chen R, Gao Fet al., 2018, Effects of PEG surface density and chain length on the pharmacokinetics and biodistribution of methotrexate-loaded chitosan nanoparticles, INTERNATIONAL JOURNAL OF NANOMEDICINE, Vol: 13, Pages: 5657-5671, ISSN: 1178-2013

Background: One of the most important aspects of drug delivery is extended nanoparticle (NP) residence time in vivo. Herein, we report a series of methotrexate (MTX)-loaded chitosan (CS) NPs coated with differently sized methoxy polyethylene glycol (mPEG) at different mPEG surface densities.Materials and methods: MTX was incorporated into NPs (112.8–171.2 nm in diameter) prepared from the resulting mPEG-g-CS. The NPs had a zeta potential of +7.4–35.0 mV and MTX loading efficiency of 17.1%–18.4%. MTX/mPEG-g-CS NPs showed an initial burst release of MTX followed by a sustained-release profile in PBS at pH 7.4.Results: The in vitro cellular uptake study showed that MTX accumulation in J774A.1 macrophage cells decreased with increasing the mPEG surface density or the mPEG molecular weight. The pharmacokinetic study on Sprague Dawley rats revealed an increase in AUC0–72 h (area under the plasma drug concentration–time curve over a period of 72 hours) with increasing the mPEG surface density or the mPEG molecular weight and a linear correlation between the mPEG surface density and AUC0–72 h.Conclusion: The biodistribution study on Institute of Cancer Research (ICR) mice revealed that MTX/mPEG-g-CS NPs significantly enhanced blood circulation time in the body and decreased accumulation in liver, spleen, and lung. These results suggest the potential of the mPEG-g-CS NPs as a promising candidate for drug delivery.

Journal article

Dong R, Chen R, Livingston A, 2018, Iterative synthesis of sequence-defined, multifunctional, biocompatible PEGs for biomedical applications, 256th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nanoscience, Nanotechnology and Beyond, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Tascini AS, Noro MG, Chen R, Seddon JM, Bresme Fet al., 2018, Understanding the interactions between sebum triglycerides and water: a molecular dynamics simulation study., Physical Chemistry Chemical Physics, Vol: 20, Pages: 1848-1860, ISSN: 1463-9076

In recent years, sebum oil has been found to play a key role in the regulation of the hydration of the outermost layer of the skin, the stratum corneum. Understanding how a major component of the sebum oil, the triglyceride tri-cis-6-hexadecenoin (TG), interacts with water is an important step in gaining insight into the water regulation function of the sebum oil. Here we use molecular dynamics simulations to investigate the structural and interfacial properties of TG in bulk and at the air and water interface. Our model performs very well in reproducing experimental results, such as density, surface tensions and surface pressure area isotherms. We show that triglyceride molecules in the liquid phase assemble together, through the glycerol group, forming a single percolating network. TG-air interfaces orient the lipids with the interface enriched with the hydrophobic tails and the glycerol groups buried inside. When in contact with water, the TG molecules at the interface orient the glycerol group towards the water phase and adopt a characteristic trident conformation. Water is shown to penetrate the TG layer thanks to the interaction with the oxygen atoms of the TG molecules, which acts as a pathway for water diffusion. The activation energy for the passage of water is found to be ≈9.5kBT at 310 K, showing that the layer is permeable to water diffusion.

Journal article

Kluzek M, Tyler AII, Wang S, Chen R, Marques CM, Thalmann F, Seddon JM, Schmutz Met al., 2017, Influence of a pH-sensitive polymer on the structure of monoolein cubosomes., Soft Matter, Vol: 13, Pages: 7571-7577

Cubosomes consist in submicron size particles of lipid bicontinuous cubic phases stabilized by surfactant polymers. They provide an appealing road towards the practical use of lipid cubic phases for pharmaceutical and cosmetic applications, and efforts are currently being made to control the encapsulation and release properties of these colloidal objects. We overcome in this work the lack of sensitivity of monoolein cubosomes to pH conditions by using a pH sensitive polymer designed to strongly interact with the lipid structure at low pH. Our cryo-transmission electron microscope (cryo-TEM) and small-angle X-ray scattering (SAXS) results show that in the presence of the polymer the cubic phase structure is preserved at neutral pH, albeit with a larger cell size. At pH 5.5, in the presence of the polymer, the nanostructure of the cubosome particles is significantly altered, providing a pathway to design pH-responsive cubosomes for applications in drug delivery.

Journal article

Dong R, Chen R, Livingston A, 2017, Liquid-phase iterative synthesis with OSN: A flexible and scalable platform for precision synthetic macromolecules, 254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Wang S, Chen R, 2017, pH-Responsive, Lysine-Based, Hyperbranched Polymers Mimicking Endosomolytic Cell-Penetrating Peptides for Efficient Intracellular Delivery, Chemistry of Materials, Vol: 29, Pages: 5806-5815, ISSN: 0897-4756

The insufficient delivery of biomacromolecular therapeutic agents into the cytoplasm of mammalian cells remains a major barrier to their pharmaceutical applications. Cell-penetrating peptides (CPPs) are considered as potential carriers for cytoplasmic delivery of macromolecular drugs. However, due to the positive charge of most CPPs, strong nonspecific cell membrane bindings may lead to relatively high toxicity. In this study, we report a series of anionic, CPP-mimicking, lysine-based hyperbranched polymers, which caused complete membrane disruption at late endosomal pH while remaining nonlytic at physiological pH. The pH-responsive conformational alterations and the multivalency effect of the hyperbranched structures were demonstrated to effectively facilitate their interaction with cell membranes, thus leading to significantly enhanced membrane-lytic activity compared with their linear counterpart. The unique structures and pH-responsive cell-penetrating abilities make the novel hyperbranched polymers promising candidates for cytoplasmic delivery of biomacromolecular payloads.

Journal article

Wang W, Guo Y, Tiede C, Chen S, Kopytynski M, Kong Y, Kulak A, Tomlinson D, Chen R, McPherson M, Zhou Det al., 2017, Ultraefficient Cap-Exchange Protocol To Compact Biofunctional Quantum Dots for Sensitive Ratiometric Biosensing and Cell Imaging., ACS Applied Materials & Interfaces, Vol: 9, Pages: 15232-15244, ISSN: 1944-8244

An ultraefficient cap-exchange protocol (UCEP) that can convert hydrophobic quantum dots (QDs) into stable, biocompatible, and aggregation-free water-dispersed ones at a ligand:QD molar ratio (LQMR) as low as 500, some 20-200-fold less than most literature methods, has been developed. The UCEP works conveniently with air-stable lipoic acid (LA)-based ligands by exploiting tris(2-carboxylethyl phosphine)-based rapid in situ reduction. The resulting QDs are compact (hydrodynamic radius, Rh, < 4.5 nm) and bright (retaining > 90% of original fluorescence), resist nonspecific adsorption of proteins, and display good stability in biological buffers even with high salt content (e.g., 2 M NaCl). These advantageous properties make them well suited for cellular imaging and ratiometric biosensing applications. The QDs prepared by UCEP using dihydrolipoic acid (DHLA)-zwitterion ligand can be readily conjugated with octa-histidine (His8)-tagged antibody mimetic proteins (known as Affimers). These QDs allow rapid, ratiometric detection of the Affimer target protein down to 10 pM via a QD-sensitized Förster resonance energy transfer (FRET) readout signal. Moreover, compact biotinylated QDs can be readily prepared by UCEP in a facile, one-step process. The resulting QDs have been further employed for ratiometric detection of protein, exemplified by neutravidin, down to 5 pM, as well as for fluorescence imaging of target cancer cells.

Journal article

Gaffney P, Livingston A, Chen R, Dong Ret al., 2017, Defined Monomer Sequence Polymers, WO/2017/042583

Processes of preparing defined monomer sequence polymers are disclosed, in which a backbone portion of the polymer is first prepared by performing one or more sequential monomeric coupling reactions with intervening membrane diafiltration purification/isolation steps, followed by a step of decorating the backbone portion with one or more side chains at predetermined positions along its length. The process represents an improvement on prior art techniques, which impose limitations on the size of the side chains that may be present. Defined monomer sequence polymers that are obtainable by the processes are also disclosed.

Patent

Chen S, Wang S, Kopytynski M, Bachelet M, Chen Ret al., 2017, Membrane-anchoring, comb-like pseudopeptides for efficient, pH-mediated membrane destabilization and intracellular delivery, ACS Applied Materials & Interfaces, Vol: 9, Pages: 8021-8029, ISSN: 1944-8244

Endosomal release has been identified as a rate-limiting step for intracellular delivery of therapeutic agents, in particular macromolecular drugs. Herein, we report a series of synthetic pH-responsive, membrane-anchoring polymers exhibiting dramatic endosomolytic activity for efficient intracellular delivery. The comb-like pseudopeptidic polymers were synthesized by grafting different amounts of decylamine (NDA), which act as hydrophobic membrane anchors, onto the pendant carboxylic acid groups of a pseudopeptide, poly(l-lysine iso-phthalamide). The effects of the hydrophobic relatively long alkyl side chains on aqueous solution properties, cell membrane destabilization activity, and in-vitro cytotoxicity were investigated. The optimal polymer containing 18 mol % NDA exhibited limited hemolysis at pH 7.4 but induced nearly complete membrane destabilization at endosomal pH within only 20 min. The mechanistic investigation of membrane destabilization suggests the polymer-mediated pore formation. It has been demonstrated that the polymer with hydrophobic side chains displayed a considerable endosomolytic ability to release endocytosed materials into the cytoplasm of various cell lines, which is of critical importance for intracellular drug delivery applications.

Journal article

Chen S, Chen R, 2016, A Virus-Mimicking, Endosomolytic Liposomal System for Efficient, pH-Triggered Intracellular Drug Delivery, ACS Applied Materials and Interfaces, Vol: 8, Pages: 22457-22467, ISSN: 1944-8244

A novel multifunctional liposomal delivery platform has been developed to resemble the structural and functional traits of an influenza virus. Novel pseudopeptides were prepared to mimic the pH-responsive endosomolytic behavior of influenza viral peptides through grafting a hydrophobic amino acid, l-phenylalanine, onto the backbone of a polyamide, poly(l-lysine isophthalamide), at various degrees of substitution. These pseudopeptidic polymers were employed to functionalize the surface of cholesterol-containing liposomes that mimic the viral envelope. By controlling the cholesterol proportion as well as the concentration and amphiphilicity of the pseudopeptides, the entire payload was rapidly released at endosomal pHs, while there was no release at pH 7.4. A pH-triggered, reversible change in liposomal size was observed, and the release mechanism was elucidated. In addition, the virus-mimicking nanostructures efficiently disrupted the erythrocyte membrane at pH 6.5 characteristic of early endosomes, while they showed negligible cytotoxic effects at physiological pH. The efficient intracellular delivery of the widely used anticancer drug doxorubicin (DOX) by the multifunctional liposomes was demonstrated, leading to significantly increased potency against HeLa cancer cells over the DOX-loaded bare liposomes. This novel virus-mimicking liposomal system, with the incorporated synergy of efficient liposomal drug release and efficient endosomal escape, is favorable for efficient intracellular drug delivery.

Journal article

Bachelet M, Chen R, 2016, Self-assembly of PEGylated gold nanoparticles with satellite structures as seeds, Chemical Communications, Vol: 52, Pages: 9542-9545, ISSN: 1364-548X

We report a very simple method for the self-assembly of spherical gold nanoparticles (AuNPs), coated with poly(ethylene glycol) (PEG), through a slow evaporation process at room temperature. Clusters of particles forming satellite structures may act as seeds for the self- assembly in a crystallization-like process. Based on the transmission electron microscopy (TEM) images obtained a mechanism for the self-assembly was suggested.

Journal article

Chen R, Chen S, Wu L, 2016, Modified Peptide, GB1612150.1

Patent

Wang S, Liu X, Villar-Garcia IJ, Chen Ret al., 2016, Amino acid based hydrogels with dual responsiveness for oral drug delivery, Macromolecular Bioscience, Vol: 16, Pages: 1258-1264, ISSN: 1616-5195

This study reports a series of novel amino acid based dual-responsive hydrogels. Prepared by a facile one-pot 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) coupling reaction, the solid content, structure, and mechanical behavior of hydrogels could be easily adjusted by changing the concentrations of the polymers and the crosslinkers. With pH-responsive anionic pseudo-peptides as backbones and disulfide-containing l-cystine dimethyl ester as crosslinkers, these hydrogels are able to collapse and form relatively compact structure at an acidic pH, while swelled and partly dissociated at a neutral pH. Further addition of dithiothreitol (DTT) facilitated complete degradation of hydrogels. The high loading efficiency, rapid but complete triggered-release, and good biocompatibility make these hydrogels promising candidates for oral delivery.

Journal article

Zhang W, Wang F, Wang Y, Wang J, Yu Y, Guo S, Chen R, Zhou Det al., 2016, pH and near-infrared light dual-stimuli responsive drug delivery using DNA-conjugated gold nanorods for effective treatment of multidrug resistant cancer cells., J Control Release, Vol: 232, Pages: 9-19

A thiolated pH-responsive DNA conjugated gold nanorod (GNR) was developed as a multifunctional nanocarrier for targeted, pH-and near infrared (NIR) radiation dual-stimuli triggered drug delivery. It was further passivated by a thiolated poly(ethylene glycol)-biotin to improve its cancer targeting ability by specific binding to cancer cell over-expressed biotin receptors. Doxorubicin (DOX), a widely used clinical anticancer drug, was conveniently loaded into nanocarrier by intercalating inside the double-stranded pH-responsive DNAs on the GNR surface to complete the construction of the multifunctional nanomedicine. The nanomedicine can rapidly and effectively release its DOX payload triggered by an acidic pH environment (pH~5) and/or applying an 808nm NIR laser radiation. Compared to free DOX, the biotin-modified nanomedicine displayed greatly increased cell uptake and significantly reduced drug efflux by model multidrug resistant (MDR) breast cancer cell lines (MCF-7/ADR). The application of NIR radiation further increased the DOX release and facilitated its nuclear accumulation. As a result, this new DNA-GNR based multifunctional nanomedicine exerted greatly increased potency (~67 fold) against the MDR cancer cells over free DOX.

Journal article

Wang Y, Guo Y, Shen Y, Chen R, Wang F, Zhou Det al., 2016, HCl-Retarded Gold Nanorod Growth for Aspect Ratio and Shape Tuning, Journal of Nanoscience and Nanotechnology, Vol: 16, Pages: 1194-1201, ISSN: 1533-4880

Journal article

Wang S, Liu X, Villar-Garcia IJ, Chen Ret al., 2016, Macromol. Biosci. 9/2016, Publisher: Wiley Online Library

Other

Song L, Guo Y, Roebuck D, Chen C, Yang M, Yang Z, sreedharan S, Glover C, Thomas JA, Liu D, Guo S, Chen R, Zhou Det al., 2015, Terminal PEGylated DNA-gold nanoparticle conjugates offering high resistance to nuclease degradation and efficient intracellular delivery of DNA binding agents, ACS Applied Materials & Interfaces, Vol: 7, Pages: 18707-18716, ISSN: 1944-8244

Over the past 10 years, polyvalent DNA-gold nanoparticle (DNA-GNP) conjugate has been demonstrated as an efficient, universal nanocarrier for drug and gene delivery with high uptake by over 50 different types of primary and cancer cell lines. A barrier limiting its in vivo effectiveness is limited resistance to nuclease degradation and non-specific interaction with blood serum contents. Herein we show that terminal PEGylation of the complementary DNA strand hybridized to a polyvalent DNA-GNP conjugate can eliminate non-specific adsorption of serum proteins and greatly increases its resistance against DNase I based degradation. The PEGylated DNA-GNP conjugate still retains high cell uptake property, making it an attractive intracellular delivery nanocarrier for DNA binding reagents. We show it can be used for successful intracellular delivery of doxorubicin, a widely used clinical cancer chemotherapeutic drug. Moreover, it can be used for efficient delivery of some cell-membrane impermeable reagents such as propidium iodide (a DNA intercalating fluorescent dye currently limited to the use of staining dead cells only) and a di-ruthenium complex (a DNA groove binder), for successful staining of live cells.

Journal article

Ye YJ, Wang Y, Lou KY, Chen YZ, Chen R, Gao Fet al., 2015, The preparation, characterization, and pharmacokinetic studies of chitosan nanoparticles loaded with paclitaxel/dimethyl-β-cyclodextrin inclusion complexes., International Journal of Nanomedicine, Vol: 10, Pages: 4309-4319, ISSN: 1178-2013

A novel biocompatible and biodegradable drug-delivery nanoparticle (NP) has been developed to minimize the severe side effects of the poorly water-soluble anticancer drug paclitaxel (PTX) for clinical use. PTX was loaded into the hydrophobic cavity of a hydrophilic cyclodextrin derivative, heptakis (2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD), using an aqueous solution-stirring method followed by lyophilization. The resulting PTX/DM-β-CD inclusion complex dramatically enhanced the solubility of PTX in water and was directly incorporated into chitosan (CS) to form NPs (with a size of 323.9-407.8 nm in diameter) using an ionic gelation method. The formed NPs had a zeta potential of +15.9-23.3 mV and showed high colloidal stability. With the same weight ratio of PTX to CS of 0.7, the loading efficiency of the PTX/DM-β-CD inclusion complex-loaded CS NPs was 30.3-fold higher than that of the PTX-loaded CS NPs. Moreover, it is notable that PTX was released from the DM-β-CD/CS NPs in a sustained-release manner. The pharmacokinetic studies revealed that, compared with reference formulation (Taxol(®)), the PTX/DM-β-CD inclusion complex-loaded CS NPs exhibited a significant increase in AUC0→24h (the area under the plasma drug concentration-time curve over the period of 24 hours) and mean residence time by 2.7-fold and 1.4-fold, respectively. Therefore, the novel drug/DM-β-CD inclusion complex-loaded CS NPs have promising applications for the significantly improved delivery and controlled release of the poorly water-soluble drug PTX or its derivatives, thus possibly leading to enhanced therapeutic efficacy and less severe side effects.

Journal article

Xu Z, Wang B, Zhang S, Chen Ret al., 2015, Design and acoustical performance investigation of sound absorption structure based on plastic micro-capillary films, APPLIED ACOUSTICS, Vol: 89, Pages: 152-158, ISSN: 0003-682X

Journal article

Huang Y, Wang D, Zhu X, Yan D, Chen Ret al., 2015, Synthesis and therapeutic applications of biocompatible or biodegradable hyperbranched polymers, Polymer Chemistry, Vol: 6, Pages: 2794-2812, ISSN: 1759-9962

Biocompatible or biodegradable hyperbranched polymers (HBPs), an important subclass of hyperbranched macromolecules, have recently received an increasing attention due to their unique physical and chemical properties as well as their great advantages in therapeutic applications. This review highlights recent advances and future trends in the preparation and applications of biocompatible or biodegradable HBPs for therapeutic purpose. Various biocompatible or biodegradable hyperbranched structures can be obtained by means of step-growth polycondensation (SGP), self-condensing vinyl polymerization (SCVP), self-condensing ring-opening polymerization (SCROP), and so forth. The properties of biocompatible or biodegradable HBPs can be tailored for a specialized purpose through terminal modification, backbone modification, or hybrid modification. A particular emphasis is then placed on their diagnostic, therapeutic delivery and theranostic applications. Finally, future directions and perspectives in this emerging field are briefly discussed. These developments on synthesis and therapeutic applications of biocompatible or biodegradable HBPs promote the interdisciplinary research spanning polymer materials and biomedical sciences.

Journal article

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