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The spread of antimicrobial resistance calls for chronic wound management devices that can engage with the wound exudate and signal infection by prompt visual effects. Here, the manufacture of a two-layer fibrous device with independently-controlled exudate management capability and visual infection responsivity was investigated by sequential free surface electrospinning of poly(methyl methacrylate-co-methacrylic acid) (PMMA-co-MAA) and poly(acrylic acid) (PAA). By selecting wound pH as infection indicator, PMMA-co-MAA fibres were encapsulated with halochromic bromothymol blue (BTB) to trigger colour changes at infection-induced alkaline pH. Likewise, the exudate management capability was integrated via the synthesis of a thermally-crosslinked network in electrospun PAA layer. PMMA-co-MAA fibres revealed high BTB loading efficiency (>80 wt.%) and demonstrated prompt colour change and selective dye release at infected-like media (pH > 7). The synthesis of the thermally-crosslinked PAA network successfully enabled high water uptake (WU = 1291 ± 48 − 2369 ± 34 wt.%) and swelling index (SI = 272 ± 4 − 285 ± 3 a.%), in contrast to electrospun PAA controls. This dual device functionality was lost when the same building blocks were configured in a single-layer mesh of core-shell fibres, whereby significant BTB release (~70 wt.%) was measured even at acidic pH. This study therefore demonstrates how the fibrous configuration can be conveniently manipulated to trigger structure-induced functionalities critical to chronic wound management and monitoring.

Current treatments for osteoporotic fractures primarily target bone-resorbing osteoclasts, but they often fail to address fibrosis—a buildup of fibrous tissue that disrupts bone healing. This fibrosis is frequently triggered by bisphosphonates, which, while effective in reducing bone loss, also activate fibroblasts and impair callus formation. Here we show that an injectable hydrogel bone adhesive composed of magnesium-alendronate metal-organic frameworks (Mg-ALN MOF) embedded in a gelatin/dialdehyde starch network can simultaneously suppress bone resorption and reduce fibrosis. The Mg-ALN MOF adhesive binds firmly to irregular bone surfaces and degrades under acidic osteoporotic conditions, gradually releasing Mg 2+ ions. These ions competitively bind to sclerostin (SOST), thereby interrupting the SOST/TGF-β signaling pathway that promotes fibroblast activation and abnormal collagen deposition. This dual-action mechanism significantly enhances fracture healing, resulting in a 27.8% improvement in flexural strength. Our findings suggest a promising therapeutic strategy that combines mechanical support with targeted regulation of both bone resorption and pathological fibrosis. Excessive fibrosis triggered by bisphosphonates impairs fracture healing in osteoporotic bone. Here, the authors develop an injectable magnesium-alendronate MOF-based hydrogel adhesive and show it prevents fibrosis and enhances bone repair, improving healing strength in an osteoporotic rat model.

Photoinduced network formation is an attractive strategy for designing water-insoluble gelatin fibres as medical device building blocks and for enabling late-stage property customisation. However, mechanically competent, long-lasting filaments are still hard to realise with current photoactive, e.g. methacrylated, gelatin systems due to inherent spinning instability and restricted coagulation capability. To explore this challenge, we present a multiscale approach combining the synthesis of 4-vinylbenzyl chloride (4VBC)-functionalised gelatin (Gel-4VBC) with a voltage-free spinning and UV-curing process so that biopolymer networks in the form of either individual fibres or nonwovens could be successfully manufactured. In comparison with state-of-the-art methacrylated gelatin, the mechanical properties of UV-cured Gel-4VBC fibres were readily modulated by adjustment of coagulation conditions, so that an ultimate tensile strength and strain at break of 25 ± 4–74 ± 3 MPa and 1.7 ± 0.3–8.6 ± 0.5% were measured, respectively. The sequential functionalisation/spinning route proved to be highly scalable, so that one-step spun-laid formation of fibroblast-friendly nonwoven fabrics was successfully demonstrated with wet-spun Gel-4VBC fibres. The presented approach could be exploited to generate a library of gelatin building blocks tuneable from the molecular to the macroscopic level to deliver computer-controlled extrusion of fibres and nonwovens according to defined clinical applications.

This study systematically optimised extrusion-printing parameters for polyhydroxybutyrate (PHB) using a Design of Experiment (DoE) approach to improve printability and construct fidelity. A five-factor DoE was conducted to evaluate the individual and interactive effects of printhead temperature, printing pressure, printing speed, bed temperature, and cartridge heating time on the dimensional accuracy of printed constructs. The resulting regression model enabled the identification of statistically significant main and interaction effects among processing variables. An optimised parameter set (printhead temperature 145 °C, pressure 150 kPa, speed 15 mm s−1, bed temperature 25 °C, and cartridge heating time 120 s) enabled the fabrication of PHB scaffolds with substantially improved shape fidelity, which was experimentally validated using verification prints. These results demonstrate that a DoE-based optimisation strategy provides a robust and efficient route for rationally tuning PHB extrusion-printing conditions, thereby enhancing process reliability for scaffold fabrication in regenerative medicine applications.

Macromol. Mater. Eng. 2023, 308, 2300029 DOI: 10.1002/mame.202300029 The above article, published online on April 18, 2023, in Wiley Online Library (https://onlinelibrary.wiley.com/), has been retracted by agreement between the journal Editor‐in‐Chief, David Huesmann, the authors, and Wiley‐VCH GmbH. The retraction has been agreed on following concerns raised by third parties regarding Figures 8 and 9. Further investigation conducted by the journal concluded that elements of the figures in question were duplicated, affecting the interpretation of the associated data and related results. This issue was acknowledged by the authors, who were unable to access and provide the original data. Thus, this article was retracted based on the consequent uncertainty on parts of its conclusions. R.H. was not available to comment on the missing original data and approve the retraction.

UV‐cured collagen‐based hydrogels hold promise in skeletal muscle regeneration due to their soft elastic properties and porous architecture. However, the complex triple helix conformation of collagen and environmental conditions, i.e., molecular oxygen, pose risks to reaction controllability, wet‐state integrity, and reproducibility. To address this challenge, a photoclick hydrogel platform is presented through an oxygen‐insensitive thiol‐ene reaction between 2‐iminothiolane (2IT)‐functionalized type I collagen and multiarm, nonhomopolymerizable norbornene‐terminated polyethylene glycol (PEG). UV‐induced network formation is demonstrated by oscillatory time sweeps on the reacting thiol‐ene mixture, so that significantly increased storage moduli are measured and adjusted depending on the photoinitiator concentration. Variations in PEG functionality (4‐arm and 8‐arm) and PEG content generate hydrogels with skeletal muscle native stiffness ( E c  = 1.3 ± 0.2‒11.5 ± 0.9 kPa), diffusion‐controlled swelling behavior and erosion‐driven degradability. In vitro, no cytotoxic effect is detected on C2C12 murine myoblasts, while myogenic differentiation is successfully accomplished on hydrogel‐seeded cells in then low serum culture medium. In vivo, 7 d subcutaneous implantation of selected thiol‐ene hydrogel in rats reveal higher cell infiltration, blood vessel formation, and denser tissue interface compared to a clinical gold standard collagen matrix (Mucograft, a trademark of Geistlich Biomaterials). These results, therefore, support the applicability and further development of this hydrogel platform for skeletal muscle regeneration.

Adenovirus vectors offer a platform technology for vaccine development. The value of the platform has been proven during the COVID-19 pandemic. Although good stability at 2–8 °C is an advantage of the platform, non-cold-chain distribution would have substantial advantages, in particular in low-income countries. We have previously reported a novel, potentially less expensive thermostabilisation approach using a combination of simple sugars and glass micro-fibrous matrix, achieving excellent recovery of adenovirus-vectored vaccines after storage at temperatures as high as 45 °C. This matrix is, however, prone to fragmentation and so not suitable for clinical translation. Here, we report an investigation of alternative fibrous matrices which might be suitable for clinical use. A number of commercially-available matrices permitted good protein recovery, quality of sugar glass and moisture content of the dried product but did not achieve the thermostabilisation performance of the original glass fibre matrix. We therefore further investigated physical and chemical characteristics of the glass fibre matrix and its components, finding that the polyvinyl alcohol present in the glass fibre matrix assists vaccine stability. This finding enabled us to identify a potentially biocompatible matrix with encouraging performance. We discuss remaining challenges for transfer of the technology into clinical use, including reliability of process performance.

The original version of this Article contained an error.

Photodynamically active fibres (PAFs) are a novel class of stimulus-sensitive systems capable of triggering antibiotic-free antibacterial effect on-demand when exposed to light. Despite their relevance in infection control, however, the broad clinical applicability of PAFs has not yet been fully realised due to the limited control in fibrous microstructure, cell tolerance and antibacterial activity in the physiologic environment. We addressed this challenge by creating semicrystalline electrospun fibres with varying content of poly[(l-lactide)-co-(glycolide)] (PLGA), poly(ε-caprolactone) (PCL) and methylene blue (MB), whereby the effect of polymer morphology, fibre composition and photosensitiser (PS) uptake on wet state fibre behaviour and functions was studied. The presence of crystalline domains and PS–polymer secondary interactions proved key to accomplishing long-lasting fibrous microstructure, controlled mass loss and controlled MB release profiles (37 °C, pH 7.4, 8 weeks). PAFs with equivalent PLGA:PCL weight ratio successfully promoted attachment and proliferation of L929 cells over a 7-day culture with and without light activation, while triggering up to 2.5 and 4 log reduction in E. coli and S. mutans viability, respectively. These results support the therapeutic applicability of PAFs for frequently encountered bacterial infections, opening up new opportunities in photodynamic fibrous systems with integrated wound healing and infection control capabilities.

Wet spinning is an established fibre manufacturing route to realise collagen fibres with preserved triple helix architecture and cell acceptability for applications in biomedical membranes. However, resulting fibres still need to be chemically modified post-spinning to ensure material integrity in physiological media, with inherent risks of alteration of fibre morphology and with limited opportunities to induce fibrillogenesis following collagen fixation in the crosslinked state. To overcome this challenge, we hypothesised that a photoactive type I collagen precursor bearing either single or multiple monomers could be employed to accomplish hierarchically assembled fibres with improved processability, macroscopic properties and nanoscale organisation via sequential wet spinning and UV-curing. In-house-extracted type I rat tail collagen functionalised with both 4-vinylbenzyl chloride (4VBC) and methacrylate residues generated a full hydrogel network following solubilisation in a photoactive aqueous solution and UV exposure, whereby ~85 wt.% of material was retained following 75-day hydrolytic incubation. Wide-angle X-ray diffraction confirmed the presence of typical collagen patterns, whilst an averaged compression modulus and swelling ratio of more than 290 kPa and 1500 wt.% was recorded in the UV-cured hydrogel networks. Photoactive type I collagen precursors were subsequently wet spun into fibres, displaying the typical dichroic features of collagen and regular fibre morphology. Varying tensile modulus (E = 5 ± 1 − 11 ± 4 MPa) and swelling ratio (SR = 1880 ± 200 − 3350 ± 500 wt.%) were measured following post-spinning UV curing and equilibration with phosphate-buffered saline (PBS). Most importantly, 72-h incubation of the wet spun fibres in PBS successfully induced renaturation of collagen-like fibrils, which were fixed following UV-induced network formation. The whole process proved to be well tolerated by cells, as indicated by a spread-like cell morphology following a 48-h culture of L929 mouse fibroblasts on the extracts of UV-cured fibres.