November 2021
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27 Reads
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November 2021
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27 Reads
November 2021
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220 Reads
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7 Citations
The rapidly increasing resistance of bacteria to currently approved antibiotic drugs makes surgical interventions and the treatment of bacterial infections increasingly difficult. In recent years, complementary strategies to classical antibiotic therapy have, therefore, gained importance. One of these strategies is the use of medicinal honey in the treatment of bacterially colonized wounds. One of the several bactericidal effects of honey is based on the in situ generation of hydrogen peroxide through the activity of the enzyme glucose oxidase. The strategy underlying this work is to mimic this antibacterial redox effect of honey in an injectable, biocompatible, and rapidly forming hydrogel. The hydrogel was obtained by thiol-ene click reaction between hyperbranched polyethylene glycol diacrylate (HB PEGDA), synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization, and thiolated hyaluronic acid (HA-SH). After mixing 500 µL HB PEGDA (10%, w/w) and 500 µL HASH (1%, w/w) solutions, hydrogels formed in ∼60 s (HB PEGDA/HA-SH 10.0-1.0), as assessed by the tube inverting test. The HB PEGDA/HA-SH 10.0-1.0 hydrogel (200 µL) was resistant to in vitro dissolution in water for at least 64 days, absorbing up to 130 wt% of water. Varying glucose oxidase (GO) amounts (0-500 U/L) and constant glucose content (2.5 wt%) were loaded into HB PEGDA and HASH solutions, respectively, before hydrogel formation. Then, the release of H 2 O 2 was evaluated through a colorimetric pertitanic acid assay. The GO content of 250 U/L was selected, allowing the formation of 10.8 ± 1.4 mmol H 2 O 2 /L hydrogel in 24 h, under static conditions. The cytocompatibility of HB PEGDA/HA-SH 10.0-1.0 hydrogels loaded with different GO activities (≤ 500 U/L) at a constant glucose amount (2.5 wt %) was investigated by in vitro assays at 24 h with L929 and HaCaT cell lines, according to DIN EN ISO 10993-5. The tests showed cytocompatibility for GO enzyme activity up to 250 U/L for both cell lines. The antibacterial activity of HB PEGDA/HA-SH 10.0-1.0 hydrogels loaded with increasing amounts of GO was demonstrated against various gram-positive bacteria (S. aureus and S. epidermidis), antibiotic-resistant gram-positive bacteria (MRSA and MRSE), gram-negative bacteria (P. aeruginosa, E. coli, and A. baumanii), and antibiotic-resistant gram-negative strains (P. aeruginosa and E. coli) using agar diffusion tests. For all gram-positive
May 2021
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91 Reads
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47 Citations
Biomaterials Science
Chondroitin sulfate (CS), as a popular material for cartilage tissue engineering scaffolds, has been extensively studied and reported for its safety and excellent biocompatibility. However, the rapid degradation of pure CS scaffolds has brought a challenge to regenerate neo-tissue similar to natural articular cartilage effectively. Meanwhile, the poly(ethene glycol) (PEG) -based biopolymer is frequently applied as a structural constituent material because of its remarkable mechanical properties, long-lasting in vivo stability, and hypo-immunity. Here, we report that the combination of CS and hyperbranched multifunctional PEG copolymer (HB-PEG) could synergistically promote cartilage repair. The thiol functionalised CS (CS-SH)/HB-PEG hydrogel scaffolds were fabricated via thiol-ene reaction, which exhibits rapid gelation, excellent mechanical properties and prolonged degradation properties. We found that rat adipose-derived mesenchymal stem cells presented great cell viability and improved chondrogenesis in CS-SH/HB-PEG hydrogels. Moreover, the injectable hydrogel scaffolds reduced stem cell inflammatory response, consistent with the well-documented anti-inflammatory activities of CS.
July 2019
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364 Reads
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90 Citations
Nature Communications
Current therapies for most neurodegenerative disorders are only symptomatic in nature and do not change the course of the disease. Gene therapy plays an important role in disease modifying therapeutic strategies. Herein, we have designed and optimized a series of highly branched poly(β-amino ester)s (HPAEs) containing biodegradable disulfide units in the HPAE backbone (HPAESS) and guanidine moieties (HPAESG) at the extremities. The optimized polymers are used to deliver minicircle DNA to multipotent adipose derived stem cells (ADSCs) and astrocytes, and high transfection efficiency is achieved (77% in human ADSCs and 52% in primary astrocytes) whilst preserving over 90% cell viability. Furthermore, the top-performing candidate mediates high levels of nerve growth factor (NGF) secretion from astrocytes, causing neurite outgrowth from a model neuron cell line. This synergistic gene delivery system provides a viable method for highly efficient non-viral transfection of ADSCs and astrocytes.
December 2018
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309 Reads
Biomedical Science and Engineering
Abstract Book: Drug-Free Antibacterial Technology for Medical Applications - First Cambridge International Conference - December 14th, 2018 - Cambridge, UK
August 2018
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35 Reads
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27 Citations
Macromolecules
It is well known that free radical (co)polymerization of multivinyl monomers (MVMs) leads to insoluble gels even at a low monomer conversion, and the gelation point can be predicted by Flory–Stockmayer theory (F–S theory) based on two assumptions: (1) equal reactivity of all vinyl groups and (2) the absence of intramolecular cyclization. This theory has been experimentally studied and verified with conventional free radical (co)polymerization (FRP) of several MVMs (e.g., divinylbenzene, DVB). However, it is still debatable whether this theory is applicable for the polymerization of MVMs using reversible deactivation radical polymerization (RDRP) approaches, such as atom transfer radical polymerization (ATRP). Herein, Monte Carlo simulations using two statistical models—with cyclization (w.c.) and without cyclization (wo.c., corresponding to F–S theory)—and dynamic lattice liquid (DLL) models were conducted to study ATRP of divinyl monomers. The simulated gel points using w.c. and wo.c. models were compared with those obtained from ATRP experiments, from calculation using F–S theory, and from simulations using DLL models. The molecular weights, dispersity, and extent of intermolecular/intramolecular cross-linking were calculated as a function of double bond and cross-linker conversion. The results demonstrated that the gel points obtained from both w.c. and wo.c. models were lower than the values from DLL models and experiments. This indicates that F–S theory cannot be used to accurately predict the polymerization of divinyl monomers via ATRP. Our study shows that the limitation of F–S theory in predicting ATRP reaction of divinyl monomers is not only due to neglecting intramolecular cyclization but also due to spatial restrictions which can cause the reactivity and accessibility of vinyl groups becoming nonequivalent in ATRP of divinyl monomers.
May 2018
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429 Reads
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9 Citations
Biomedical Science and Engineering
Microbial colonization on biomaterials is the main cause of failure of a successful implantation. In fact, local infections can eventually evolve in severe sepsis that might finally end up in a multi-organ failure and death of the patient. Besides, infection has become one of the toughest problems in the medical world, as microorganisms become more resistant to known drugs. Scientific research has been focussing on exploring new strategies to combat this life-threatening problem. In this review, information was collected about currently used polymeric biomaterials in the medical field and the main bacterial infections associated with their implantation. Furthermore, drug-free strategies to overcome this complication are explored, and the existing methodology required for assessment of the antibacterial activity is also described.
May 2018
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143 Reads
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223 Citations
Acta Biomaterialia
Statement of significance: Diabetic wounds, which are a sever type of diabetes, have become one of the most serious clinical problem. There is a great promise in the delivery of adipose stem cells into wound sites using injectable hydrogels that can improve diabetic wound healing. Due to the biocompatibility of poly(ethylene glycol) diacrylate (PEGDA), we developed an in situ RAFT polymerization approach using anti-alcoholi drug - Disulfiram (DS) as a RAFT agent precursor to achieve hyperbranched PEGDA (HP-PEG). HP-PEG can form an injectable hydrogel by crosslinking with thiolated hyaluronic acid (HA-SH). ADSCs can maintain their regenerative ability and be delivered into the wound sites. Hence, diabetic wound healing process was remarkably promoted, including inhibition of inflammation, enhanced angiogenesis and re-epithelialization. Taken together, the ADSCs-seeded injectable hydrogel may be a promising candidate for diabetic wound treatment.
January 2018
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18 Reads
Macromolecular Chemistry and Physics
Back Cover: By a combination of Cu(0)- and Cu(II)-mediated homopolymerization of multivinyl monomers (MVMs) and thiol-ene click chemistry, amphiphilic multifunctional star polymers with high arm numbers are prepared by using single-chain cyclized/knotted nanoparticle (SCKPs) as the core. Further details can be found in article number 1700473 by Dezhong Zhou,* Guangfu Yin,* and co-workers.
January 2018
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16 Reads
... Meanwhile, if the effect of HAMA-HAP in promoting bone formation is indeed linked to its ability to facilitate cell homing and colonization, future avenues for improvement could involve incorporating other porous materials with cell attachment sites or utilizing hyaluronic acid as a backbone to enhance its affinity for cells through techniques such as hyperbranching to attach more functional groups. 22 ...
November 2021
... PLGA-ACH microparticles act as carriers of melatonin and reduce PNIPAm/HA syneresis Drug delivery system and cartilage tissue engineering [284] CS/hyperbranched PEG Adipose-derived MSCs -Injectable hydrogel with excellent mechanical feature, rapid gelation, and extended degradation profile Cartilage tissue engineering [285] ...
May 2021
Biomaterials Science
... PbAE is an ideal carrier for delivering anticancer drugs because of its distinct characteristics including biocompatibility, low cytotoxicity, pH-responsiveness, and ease of production. [20][21][22] At physiological pH, PbAE is neutrally hydrophobic, but under acidic conditions, it becomes positively charged and hydrophilic when protonated. This allows for chemical functionalization and the ability to adjust its structure. ...
July 2019
Nature Communications
... Several computational studies, including Monte Carlo simulations, have aimed to provide a view of complex polymerisation reactions and cycle formation. [24][25][26][27] Scheme 1 Synthesis of branched polyester by TBRT using ethylene glycol dimethacrylate (EGDMA) as the MVT, and 1-dodecanethiol (DDT) as the telogen. Black dotted bonds show bonds formed during the polymerisation. ...
August 2018
Macromolecules
... This unique property of CMCB could be exploited for long-term bioimaging of tumors. This data are in stark contrast with the synthetic imaging agents that their signals decreased fast as they were rapidly metabolized and eliminated 40 . The results demonstrate the potential of CMCB to serve as an efficient tool for tumor imaging. ...
July 2015
... In situ Anti-infammatory increase re-epithelialization and vasculature [170] Oxidized hyaluronic acid, quaternary ammonium-modifed chitosan, and kalium c-cyclodextrin α-lipoic acid Chemical Chronic Self-healing Antibacterial and antioxidant-enhanced tissue granulation and collagen deposition [171] Aldehyde-modifed hyaluronic acid and carboxyethyl chitosan Chemical Diabetic Self-healing Anti-infammatory increase re-epithelialization, vasculature, collagen deposition, and cell proliferation [172] Oxidized hyaluronic acid and antimicrobial peptide Chemical Chronic Self-healing Antibacterial [173] Diphenylalanine-modifed hyaluronic acid and curcumin Chemical Diabetic/ chronic Self-healing Prolonged release of curcumin [174] Phenylboronate conjugated hyaluronic acid and quaternary modifed chitosan Magnesium Physical Diabetic/ chronic Self-healing Anti-infammatory increase vasculature, collagen deposition, and granulation tissue [175] Tiolate-modifed hyaluronic loaded Silver-lignin nanoparticles Physical Diabetic/ chronic ...
May 2018
Acta Biomaterialia
... habitat in which they can evade the influence of the host's own immune system, largely protect themselves from the effects of applied antibiotics and antifungals, and even develop resistance to these agents (Idrees et al., 2018). ...
May 2018
Biomedical Science and Engineering
... Biodegradable scaffolds are a promising candidate for tissue repair. The degradation rate of a scaffold can have significant implications, as fast degradation can impede tissue restoration, release toxins, and compromise stability, while slow degradation hampers adaptation to healing tissue, causes product accumulation, foreign body reactions, and impedes granulation [12][13][14][15][16]. Among the many degradable material, gelatin, a natural protein derived from collagen, has gained significant interest in the field of tissue engineering due to its excellent biocompatibility, biodegradability, and low immunogenicity [17,18]. ...
January 2018
... Nevertheless, those reported theoretical models are more or less deviated from the exact F-S theory, either taking into account the dimension and spatial coordinates of the reactants or making the reactivity of functional groups unequal. To clarify whether F-S theory is suitable for predicting FRP, and to find out to what extent cyclization participates in FRP of MVMs, thus elucidating the mechanism of FRP of MVMs, Wang et al. [51] recently simulated FRP/FRcP of divinyl monomers ( Figure 4A). The simulation was based on two kinetic models-with cyclization model (w.c.) and without cyclization model (wo.c., corresponding to the F-S theory) via Monte Carlo simulation (following Gillespie's algorithm). ...
December 2017
Science China-Chemistry
... Production of Hydrogel Spheres 2.1.1. Synthesis of AHA Acrylated HA (HA) was synthesized by reacting HA (MW 200 kDa, Lifecore Biomedical, Chaska, MN, USA) with acryloyl chloride and glycidol (TCI) in the presence of triethylamine and N-dimethylformamide (Sigma Aldrich, Saint Louis, MO, USA) for 5 days [40]. Next, the reaction mixture was dialyzed against deionized (DI) water for 120 h, frozen at −80 • C for 24 h, and then lyophilized. ...
December 2017
Chemical Communications