Development of an In Situ Photo-Crosslinking Antimicrobial Collagen Hydrogel for the Treatment of Infected Wounds.

Antimicrobial hydrogels have received considerable attention in the treatment of bacteria-infected wounds. Herein, we develop a neutral, soluble collagen via modification with maleic anhydride, serving as a hydrogel precursor. Maleic anhydride-modified collagen (ColME) could form a gel after exposure to UV light and be loaded with the antimicrobial agents, nisin and levofloxacin, to acquire antimicrobial ability. The ColME hydrogel containing nisin and levofloxacin had good cytocompatibility and effectively killed pathogenic bacterial strains, such as Escherichia coli and Staphylococcus aureus. The antimicrobial ColME hydrogels effectively supported the healing of a full-thickness skin wound infected with S. aureus in a mouse model. Our results demonstrate the potential of antimicrobial hydrogels as effective wound dressings via in situ photogelation for the healing of infected wounds.

A systematic scoping review of reflective writing in medical education.

BACKGROUND: Reflective writing (RW) allows physicians to step back, review their thoughts, goals and actions and recognise how their perspectives, motives and emotions impact their conduct. RW also helps physicians consolidate their learning and boosts their professional and personal development. In the absence of a consistent approach and amidst growing threats to RW's place in medical training, a review of theories of RW in medical education and a review to map regnant practices, programs and assessment methods are proposed. METHODS: A Systematic Evidence-Based Approach guided Systematic Scoping Review (SSR in SEBA) was adopted to guide and structure the two concurrent reviews. Independent searches were carried out on publications featured between 1st January 2000 and 30th June 2022 in PubMed, Embase, PsychINFO, CINAHL, ERIC, ASSIA, Scopus, Google Scholar, OpenGrey, GreyLit and ProQuest. The Split Approach saw the included articles analysed separately using thematic and content analysis. Like pieces of a jigsaw puzzle, the Jigsaw Perspective combined the themes and categories identified from both reviews. The Funnelling Process saw the themes/categories created compared with the tabulated summaries. The final domains which emerged structured the discussion that followed. RESULTS: A total of 33,076 abstracts were reviewed, 1826 full-text articles were appraised and 199 articles were included and analysed. The domains identified were theories and models, current methods, benefits and shortcomings, and recommendations. CONCLUSIONS: This SSR in SEBA suggests that a structured approach to RW shapes the physician's belief system, guides their practice and nurtures their professional identity formation. In advancing a theoretical concept of RW, this SSR in SEBA proffers new insight into the process of RW, and the need for longitudinal, personalised feedback and support.

A self-doping conductive polymer hydrogel that can restore electrical impulse propagation at myocardial infarct to prevent cardiac arrhythmia and preserve ventricular function.

Following myocardial infarction (MI), necrotic cardiomyocytes (CMs) are replaced by fibroblasts and collagen tissue, causing abnormal electrical signal propagation, desynchronizing cardiac contraction, resulting in cardiac arrhythmia. In this work, a conductive polymer, poly-3-amino-4-methoxybenzoic acid (PAMB), is synthesized and grafted onto non-conductive gelatin. The as-synthesized PAMB-G copolymer is self-doped in physiological pH environments, making it an electrically active material in biological tissues. This copolymer is cross-linked by carbodiimide to form an injectable conductive hydrogel (PAMB-G hydrogel). The un-grafted gelatin hydrogel is prepared in a similar manner as a control. Both test hydrogels not only provide an optimal matrix for CM adhesion and growth but also maintain CM morphology and functional proteins. The conductivity of PAMB-G hydrogel is ca. 12 times higher than that of gelatin hydrogel. Microelectrode array analyses reveal that a heart placed on the PAMB-G hydrogel has a higher field potential amplitude than that placed on the gelatin hydrogel and can pass current from one heart to excite another heart at a distance. The injection of PAMB-G hydrogel into the scar zone following an MI in a rat heart improves electrical impulse propagation over that in a heart that has been treated with gelatin hydrogel, and synchronizes heart contraction, leading to preservation of the ventricular function and reduction of cardiac arrhythmia, demonstrating its potential for use in treating MI.

Experimental study on the photodynamic treatment of choroidal neovasculization with nanophthalocyanine photosensitizer.

AIM: To investigate the therapeutic effects of nanophthalocyanine photosensitizers on an experimental rat choroidal neovescularization (CNV) model, as well as to evaluate the cytotoxicity of which on human retinal pigment epithelia (HRPE) and human retinal endothelial cells (HRECs). METHODS: Two types of photosensitizers, G(1)-ZnPc(COOH)(8) and G(1)-ZnPc(COOH)(8)/m respectively, were administrated for photodynamic therapy (PDT) after a successful establishment of CNV model on Brown-Norway (BN) rats via fundus photocoagulation. The therapeutic effects of the two drugs were assessed through optical coherence tomography (OCT), fluorescein fundus angiography (FFA) and transmission electron microscopy (TEM). For cytotoxicity tests, cell counting kit-8 (CCK-8) assays and changes of mitochondrial transmembrane potential (△Ψm) were conducted on HRPE and HRECs after initial uptake of the two drugs. RESULTS: Both photosensitizers demonstrated an improvement of vascular leakage and closure of CNV 1 week after PDT as confirmed by fundus image, OCT, FFA and TEM. Two weeks after PDT, G(1)-ZnPc(COOH)(8)/m showed a better CNV closure effect versus G(1)-ZnPc(COOH)(8) (P<0.05). A significant difference (P<0.01) was found in uptake of the two drugs in HRPE and HRECs, with no difference between the drugs (P>0.05). Both photosensitizers showed cytotoxicity on HRPE, but G(1)-ZnPc(COOH)(8)/m induced a lower cell viability. CONCLUSION: G(1)-ZnPc(COOH)(8)/m mediated PDT is better than G(1)-ZnPc(COOH)(8) in CNV closure and also have the advantage of fast metabolism leading to less side effect.