Skin wounds not only cause physical pain for patients but also are an economic burden for society. It is necessary to seek out an efficient approach to promote skin repair. Hydrogels are considered effective wound dressings. They possess many unique properties like biocompatibility, biodegradability, high water uptake and retention etc., so that they are promising candidate materials for wound healing. Chitosan is a polymeric biomaterial obtained by the deacetylation of chitin. With the properties of easy acquisition, antibacterial and hemostatic activity, and the ability to promote skin regeneration, hydrogel-like functional wound dressings (represented by chitosan and its derivatives) have received extensive attentions for their effectiveness and mechanisms in promoting skin wound repair. In this review, we extensively discussed the mechanisms with which chitosan-based functional materials promote hemostasis, anti-inflammation, proliferation of granulation in wound repair. We also provided the latest information about the applications of such materials in wound treatment. In addition, we summarized the methods to enhance the advantages and maintain the intrinsic nature of chitosan via incorporating other chemical components, active biomolecules and other substances into the hydrogels.

Medical device contamination caused by microbial pathogens such as bacteria and fungi has posed a severe threat to the patients’ health in hospitals. Due to the increasing resistance of pathogens to antibiotics, the efficacy of traditional antibiotics treatment is gradually decreasing for the infection treatment. Therefore, it is urgent to develop new antibacterial drugs to meet clinical or civilian needs. Antibacterial polymers have attracted the interests of researchers due to their unique bactericidal mechanism and excellent antibacterial effect. This article reviews the mechanism and advantages of antimicrobial polymers and the consideration for their translation. Their applications and advances in medical device surface coating were also reviewed. The information will provide a valuable reference to design and develop antibacterial devices that are resistant to pathogenic infections.

Carbapenem‐resistant Gram‐negative bacteria (GNB) are heading the list of pathogens for which antibiotics are the most critically needed. Many antibiotics are either unable to penetrate the outer‐membrane or are excluded by efflux mechanisms. Here, we report a cationic block β‐peptide (PAS8‐b‐PDM12) that reverses intrinsic antibiotic resistance in GNB by two distinct mechanisms of action. PAS8‐b‐PDM12 does not only compromise the integrity of the bacterial outer‐membrane, it also deactivates efflux pump systems by dissipating the transmembrane electrochemical potential. As a result, PAS8‐b‐PDM12 sensitizes carbapenem‐ and colistin‐resistant GNB to multiple antibiotics in vitro and in vivo. The β‐peptide allows the perfect alternation of cationic versus hydrophobic side chains, representing a significant improvement over previous antimicrobial α‐peptides sensitizing agents. Together, our results indicate that it is technically possible for a single adjuvant to reverse innate antibiotic resistance in all pathogenic GNB of the ESKAPE group, including those resistant to last resort antibiotics.

Carbapenem-resistant Gram-negative bacteria (GNB) are heading the list of pathogens for whicha ntibiotics are the most critically needed. Many antibiotics are either unable to penetrate the outer-membrane or are excluded by efflux mechanisms.Here,wereport acationic block b-peptide (PAS8-b-PDM12) that reverses intrinsic antibiotic resistance in GNB by two distinct mechanisms of action. PAS8-b-PDM12 does not only compromise the integrity of the bacterial outermembrane,italso deactivates efflux pump systems by dissipating the transmembrane electrochemical potential. As ar esult, PAS8-b-PDM12 sensitizes carbapenem-and colistin-resistant GNB to multiple antibiotics in vitro and in vivo.The b-peptide allows the perfect alternation of cationic versus hydrophobic side chains,r epresenting as ignificant improvement over previous antimicrobial a-peptides sensitizing agents.T ogether, our results indicate that it is technically possible for as ingle adjuvant to reverse innate antibiotic resistance in all pathogenic GNB of the ESKAPE group,i ncluding those resistant to last resort antibiotics. Singapore 637551 (Singapore) Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under https://doi.

Polymer grafting has been a powerful tool in the surface modification of biomaterials. Traditional solventbased grafting, however, often requires laborious procedures taken under harsh conditions, which seriously hinders its practical applications. Here, we report a facile solvent-free graft-from method that is able to achieve a superior surface functionality as compared to most reported results from traditional solvent-based grafting. The grafting was proceeded by conformally coating a cross-linked polyvinylpyrrolidone (PVP) prime layer in the vacuum, immediately followed by in situ grafting of PVP homopolymer chains from the propagating sites on the coating surface. The resultant coating exhibited enriched surface pyrrolidone content compared to the single-layer cross-linked counterpart and a water contact angle of 22°, lower than most reported PVP-grafted surfaces. Medical catheters grafted with PVP achieved a more than 99.9% bacterial antifouling enhancement compared to the pristine catheter, and significantly improved biocompatibility during a 4 week in vivo test in mice. The achieved surface functionality is attributed to the synergistic effect from the functional groups distributed both on the grafted chains and on the cross-linked primer. The effectiveness and simplicity of the vapor grafting method thus suggest a promising surface modification route for biomaterials and beyond.

A series of hydrogels containing guanidine-based polymers using a poloxamer as the matrix were prepared to provide novel wound dressings with antibacterial and repairing-promotion properties for skin wounds. Herein, we developed a series of antibacterial hydrogels, the cationic guanidine-based polymer polyhexamethylene guanidine hydrochloride (PHMG) with poloxamer aqueous solution (12%, w/w) simplified as PHMGP, chitosan (CS)-cross-linked PHMG (referred to as PHMC) with poloxamer aqueous solution simplified as PHMCP, and hyaluronic acid (HA)-modified PHMG (referred to as PHMH) with poloxamer aqueous solution simplified as PHMHP, for enhancing full-thickness skin wound healing. The characterizations, antimicrobial activity, cytotoxicity, and in vivo full-thickness woundhealing capability of these hydrogels were analyzed and evaluated. The results show that though PHMGP possesses great bactericide properties, its cytotoxicity is too strong to support skin regeneration. However, after modified with CS or HA, PHMCP and PHMHP showed good biocompatibility and antimicrobial properties against Gram-positive and Gram-negative bacteria that are commonly present in injured skin. Both PHMCP and PHMHP hydrogels exhibited upgraded wound-healing efficiency in fullthickness skin defects, characterized by a shorter wound closure time, faster re-regeneration, and the earlier formation of skin appendages, compared with those of control or pure poloxamer treatments. Their biological mechanism was detected. Both PHMCP and PHMHP can regulate the related biofactors during the skin repair process such as interleukin-1β (IL-1β), interleukin-6 (IL-6), transforming growth factor beta-1(TGF-β1), alpha-smooth muscle actin (α-SMA), and vascular endothelial growth factor, to promote wound healing with less serious scarring. In short, hydrogels with excellent capabilities to inhibit microorganism infection and promote wound healing were developed, which will shed light on designing and producing wound dressings with promising applications in future.

Nanotechnology using biodegradable polymer carriers with good biocompatibility and bioabsorbability has been studied and applied extensively in drug delivery systems and biomedical engineering. In this work, the triblocked oligomer poly(L-lactide)-bpoly(ethylene glycol)-b-poly(L-lactide) (PLEL) with the molecular weight of 2.08 KDa was first synthesized. Its chemistry was characterized by hydrogen nuclear magnetic resonance (1 H-NMR) spectrum and Fourier transform infrared (FTIR) spectroscopy. Subsequently, the nanoparticles (NPs) of PLEL and pranoprofen (PF)-loaded PLEL were prepared with the average particle size of (151.7 ± 5.87) nm using the method of emulsion solvent evaporation. The formula and drug releasing profile were characterized by a transmission electron microscope (TEM), dynamic light scattering (DLS), and ultraviolet spectrophotometer (US). In vitro cytotoxicity assays and in vivo ophthalmic tests were performed to measure the safety and efficacy of the formulations. The results showed that PF NPs relieved the cytotoxicity of pure PF and eliminated ophthalmic irritation. The drug encapsulated in the nanoparticles displayed long-lasting release and good anti-inflammation efficiency in animal eyes. Therefore, we concluded that the present formula (PF NPs) could provide sustained drug release with good treatment effect on eye inflammation, and is promising for its use in ophthalmology in the future.

Diabetic wounds remain one of the most prevalent hard-to-heal wounds in the clinic. The causative factors impeding the wound healing process include not only the elevated oxidative stress and bacterial...