Search Results (83)

Photobiomodulation (PBM) is a non-invasive therapeutic strategy that uses red and near-infrared (NIR) light in the 590–950 nm range to modulate the cellular and molecular pathways involved in retinal homeostasis. At the molecular level, PBM acts primarily through photon absorption by cytochrome c oxidase (CcO, complex IV of the mitochondrial electron transport chain), whose four metal centres—two copper (CuA and CuB) and two heme groups (heme a and heme a₃)—absorb light across approximately 600–1000 nm. Photon capture promotes photodissociation of inhibitory nitric oxide (NO) from the binuclear CuB–heme a₃ centre, accelerates electron transfer, restores the proton-motive force and increases ATP synthesis. These primary events trigger a coordinated molecular programme that includes (i) transient mitochondrial reactive oxygen species (ROS) bursts that activate the Nrf2/Keap1/ARE axis and upregulate phase II antioxidant enzymes (HO-1, NQO1, GCLC, SOD2, catalase, GPx); (ii) calcium- and cAMP-dependent secondary signalling that converges on PI3K/Akt, MAPK/ERK, AMPK and mTOR pathways; (iii) suppression of NF-κB-driven cytokine production (TNF-α, IL-1β, IL-6) and of NLRP3 inflammasome activation; (iv) downregulation of the HIF-1α/VEGF axis, particularly at 590 nm; (v) anti-apoptotic remodelling of the Bcl-2/Bax ratio with reduced cytochrome c release and caspase-3/9 activation; and (vi) PGC-1α/TFAM/NRF1-driven mitochondrial biogenesis, alongside restoration of fission/fusion homeostasis (Drp1, Mfn1/2, Opa1) and PINK1/Parkin-mediated mitophagy. Wavelength specificity has a defined molecular basis: 590 nm modulates VEGF signalling and RPE pump activity, 660 nm interacts with the CuB centre and enhances O₂ binding at CcO, and 850 nm is absorbed by CuA and supports electron entry into complex IV. A second molecular axis is the bidirectional crosstalk between PBM and the circadian system: mitochondrial respiration, ATP turnover and CcO activity oscillate over the 24 h cycle under the control of the BMAL1/CLOCK and PER/CRY core machinery, the NAD⁺/SIRT1–SIRT3 axis and REV-ERBα. Preliminary preclinical and human observations suggest that NIR-induced bioenergetic and functional gains may be coupled to this rhythm, with greater benefit reported when light is delivered in the morning window (≈08:00–11:00); this time dependence should be regarded as an emerging hypothesis rather than an established clinical principle. The clinical evidence is unevenly developed across indications. It is most robust for non-exudative age-related macular degeneration, where multiwavelength PBM (590/660/850 nm; Valeda Light Delivery System) has shown disease-modifying potential in randomized controlled trials (LIGHTSITE I–III and the LIGHTSITE IIIB extension), with sustained BCVA gains and reduced incidence of geographic atrophy over 24 months and beyond. Evidence for retinitis pigmentosa, central serous chorioretinopathy and, with red-light monotherapy, childhood myopia is at present limited to small or short-term studies and remains preliminary. This narrative review synthesizes the molecular machinery engaged by PBM, integrates clinical findings across retinal diseases and discusses how chronotherapeutic delivery of light, aligned with the molecular clock, may further optimize therapeutic efficacy. Full article

Polysaccharide-based hydrogels represent promising platforms for the development of bioactive wound dressings due to their biocompatibility, bioadhesive properties, and ability to maintain a moist environment at the wound interface. In this study, polymeric films were developed from natural polysaccharides incorporating olive mill wastewater (OMW) as a natural antibacterial agent. Chitosan (medium molecular weight), sodium alginate, sodium hyaluronate, and xanthan gum were selected to prepare hydrogel formulations either as single polymers or binary mixtures. Hydrogels were prepared by aqueous dispersion under magnetic stirring and subsequently converted into films using a solvent casting method. The resulting films were characterized in terms of rheological behavior, pH, morphology, thickness and water content. The obtained hydrogel films showed good casting ability, producing smooth and homogeneous matrices with adequate deformability and skin adhesion. Furthermore, they demonstrated a suitable capacity to absorb and retain water, mimicking the management of wound exudate. OMW was incorporated into the hydrogel formulations as a source of phenolic compounds with well-known antioxidant and antimicrobial properties. The presence of these bioactive compounds provides the films with potential antibacterial and antibiofilm activity against clinically relevant multidrug-resistant staphylococcal strains. These findings suggest that OMW-loaded polysaccharide hydrogels represent a promising and sustainable strategy for the development of antibacterial films for wound healing applications. Full article

Despite the demand for personalized wound care, integrating diagnostics and therapeutics into a unified platform remains a significant challenge. To address this, we developed a 3D-printed theranostic hydrogel using vat photopolymerization, enabling precise, multifunctional wound management. The hydrogel matrix, composed of poly(acrylamide-co-hydroxyethyl acrylate) and carboxymethyl cellulose, was chemically crosslinked with poly(ethylene glycol) diacrylate. Bromocresol purple was integrated into the photosensitive resin to enhance printing fidelity and serve as a diagnostic indicator, providing a distinct colorimetric shift upon skin infection. For controlled drug delivery, graphene oxide (GO) and levofloxacin were incorporated into the system. The 3D-printed hydrogel demonstrated superior swelling capacity (>600%), ideal for absorbing wound exudate. A semi-quantitative linear colorimetric response was observed across varying pH levels, allowing for clear differentiation between healthy healing skin (pH 4.0–6.0) and infected conditions (pH 7.0 and above). Furthermore, the hydrogel exhibited infection-stimulated therapy, with a cumulative levofloxacin release of 92.63% at pH 8, significantly higher than in acidic conditions. Moreover, the incorporation of GO further optimized the delivery profile by tuning absorption and release rates. Synergizing real-time monitoring and on-demand therapeutic action, this 3D-printed system offers a scalable, robust solution for future-ready, personalized wound management. Full article

This study aimed to manufacture and characterize highly porous dressings based on gellan gum (GG) and sodium alginate (Alg) hydrogels modified with zinc oxide (ZnO) and bacitracin (BAC) intended for infected and exuding wounds. ZnO nanoparticles (ZnO(n)) were 26 ± 4 nm in size according to atomic force microscopy (AFM), while the size of the microparticles (ZnO(m)) was 1.02 ± 0.01 µm according to laser diffraction measurements. Their relative surface areas were 39.16 m²/g and 4.56 m²/g, respectively. Microbiological studies showed that ZnO(n) exhibited antibacterial activity in contact with the Gram+ Staphylococcus aureus; thus, they were selected for embedding in a hydrogel matrix. Four types of composite hydrogel samples were manufactured: GG/Alg, GG/Alg+ZnO, GG/Alg+BAC, and GG/Alg+ZnO+BAC, which were subjected to freeze drying. The water absorption of all materials exceeded 4000%, showing excellent liquid absorbability. Burst release of BAC was found at a level of 90% in the first 2 h. In vitro cytotoxicity studies on L929 fibroblasts did not show a toxic effect of extracts from the GG/Alg and GG/Alg+BAC samples, contrary to samples supplemented with ZnO(n). In microbiological studies, the enhanced antibacterial effect of ZnO(n) and BAC was observed in contact with Staphylococcus aureus and Staphylococcus epidermidis strains. Therefore, GG/Alg+BAC+ZnO is the most promising dressing system for the treatment of infected and exuding wounds. Full article

Additive manufacturing has been adopted in several industries including the medical field to develop new personalised medical implants including tissue engineering scaffolds. Custom patient-specific scaffolds can be additively manufactured to speed up the wound healing process. The aim of this study was to design, fabricate, and evaluate a range of materials and scaffold architectures for 3D-printed wound dressings intended for soft tissue applications, such as skin repair. Multiple biocompatible polymers, including polylactic acid (PLA), polyvinyl alcohol (PVA), butenediol vinyl alcohol copolymer (BVOH), and polycaprolactone (PCL), were fabricated using a material extrusion additive manufacturing technique. Eight scaffolds, five with circular designs (knee meniscus angled (KMA), knee meniscus stacked (KMS), circle dense centre (CDC), circle dense edge (CDE), and circle no gradient (CNG)), and three square scaffolds (square dense centre (SDC), square dense edge (SDE), and square no gradient (SNG), with varying pore widths and gradient distributions) were designed using an open-source custom toolpath generator to enable precise control over scaffold architecture. An in vitro degradation study in phosphate-buffered saline demonstrated that PLA exhibited the greatest material stability, indicating minimal degradation under the tested conditions. In comparison, PVA showed improved performance relative to BVOH, as it was capable of absorbing a greater volume of exudate fluid and remained structurally intact for a longer duration, requiring up to 60 min to fully dissolve. Tensile testing of PLA scaffolds further revealed that designs with increased porosity towards the centre exhibited superior mechanical performance. The strongest scaffold design exhibited a Young’s modulus of 1060.67 ± 16.22 MPa and withstood a maximum tensile stress of 21.89 ± 0.81 MPa before fracture, while maintaining a porosity of approximately 52.37%. This demonstrates a favourable balance between mechanical strength and porosity that mimics key properties of engineered tissues such as the meniscus. Overall, these findings highlight the potential of 3D-printed, patient-specific scaffolds to enhance the effectiveness and customisation of tissue engineering treatments, such as meniscus repair, offering a promising approach for next-generation regenerative applications. Full article

This work investigates the structural, acoustic, and thermo-oxidative degradation behavior of elastomeric composites made from neat EPDM and recycled devulcanized EPDM (EPDMd) blends, both with and without silica (SiO₂). SiO₂ plays a complex role in degradation, possibly acting as a catalyst and also affecting the properties of the materials. Samples were subjected to accelerated degradation at 80 °C for 30 days. The characterization included the mechanical, spectroscopical (FTIR-ATR), thermal (TGA), and morphological (SEM) studies of the samples. Given EPDM’s use in construction as a sound-absorber, its acoustic properties were also analyzed. The determination of the mechanical properties shows that the incorporation of SiO₂ improves the Young’s modulus (YM), maintains the tensile strength (TS) at similar values, and causes a decrease in elongation at break (EB). The content of EPDMd slightly decreases both the TS and the EB and increases the YM. The thermo-oxidative degradation of the studied composites does not affect the TS values, but it increases the YM for the samples with and without SiO₂ for EPDMd contents higher than 40 phr, and decreases the EB for samples with and without SiO₂ for all EPDMd contents. The FTIR-ATR, TGA, and SEM results show that the addition of SiO₂ catalyzes the thermo-oxidative degradation process, while the EPDMd inhibits structural degradation. Migration of the ZnSt₂ included in the formulations to the surface is common in these elastomers. In this case, EPDMd forms microaggregates, which retain the exudation of ZnSt₂ crystals, especially in the non-degraded samples. The degraded samples present irregular structures, with microcavities, cracks, and occlusions, which increase the acoustic absorption mainly at frequencies below 1500 Hz. Full article

Over the past years, with the growing interest in sustainable biomaterials, marine collagen has been emerging as an interesting alternative to bovine collagen. It is more easily absorbed by the body and has higher bioavailability. In this study, collagen was extracted from Dicentrarchus labrax (sea bass) skin, a fishery by-product, thus valorizing waste streams while reducing environmental impact. To overcome the intrinsic weak mechanical of collagen, it was combined with chitosan to produce composite scaffolds for skin tissue engineering. The incorporation of collagen proved crucial for scaffold performance: (i) it promoted the formation of an open-pore architecture, favorable for cell infiltration and proliferation; (ii) it enhanced swelling behavior suitable for exudate absorption and maintenance of a moist wound environment; (iii) by tuning the chitosan/collagen ratio, it enabled us to control the degradation rate; (iv) it conferred antioxidant properties; and (iv) by adjusting collagen/chitosan concentrations, it allowed fine-tuning of mechanical properties, ensuring sufficient strength to resist stresses encountered during wound healing. In vitro assays demonstrated that the scaffolds were non-cytotoxic and effectively supported mouse adipose tissue fibroblasts’ adhesion and proliferation. Finally, all formulations exhibited marked bactericidal activity against the human pathogen Staphylococcus aureus and the methicillin-resistant Staphylococcus aureus, with a Log reduction greater than 3 (a reduction of at least 99.9% in bacterial growth) compared to the control. Collectively, these findings highlight collagen not only as a sustainable resource but also as a functional component that drives the structural, physicochemical, biological, and antimicrobial performance of chitosan/collagen scaffolds for skin tissue engineering. Full article

Acne vulgaris is a chronic disease that occurs in the pilosebaceous units and ranks eighth in the global prevalence of all diseases. In its severe forms such as pustules, cysts, and nodules, acne can lead to permanent scarring and post-inflammatory hyperpigmentation, which are often difficult to reverse in the short term and significantly affect patients’ psychological well-being and social interactions. Although a variety of pharmacological treatments are available, including retinoids, antibiotics, anti-androgens, benzoyl peroxide, and corticosteroids, the high recurrence rate and limited efficacy in scar prevention highlight the urgent need for innovative therapeutic strategies. Electrospinning technology has recently gained attention for fabricating nanofibrous patches with high porosity, biocompatibility, and biodegradability. These patches can offer antibacterial activity, absorb exudates, and provide mechanical protection, making them promising platforms for acne wound care. This review first outlines the pathophysiology of acne and the biological mechanisms underlying scar formation. We then present an overview of electrospinning techniques, commonly used polymers, and recent advancements in the field. Finally, we explore the potential of electrospun nanofibers loaded with mesenchymal stem cells or exosomes as next-generation therapeutic systems aimed at promoting scarless acne healing. Full article

The application of conductive polymers in wound dressings presents great potential for accelerated wound healing since their high electrical conductivity and biocompatibility facilitate the delivery of external electrical stimuli to cells and tissues, promoting cell differentiation and proliferation. Electrospinning is a very straightforward method for the preparation of polymeric wound dressings capable of mimicking the extracellular matrix of skin, promoting hemostasis, absorbing wound exudate, allowing atmospheric oxygen permeation and maintaining an appropriately moist environment. In this work, in situ chemically polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) was achieved through hyaluronic acid-doping. The synthesized PEDOT was used for the production of conductive and biodegradable chitosan (CS)/gelatin (GEL)/PEDOT electrospun meshes. Additionally, the randomly aligned meshes were crosslinked with a 1,4-butanediol diglycidyl ether and their physicochemical and mechanical properties were investigated. The results show that the incorporation of a conductive polymer led to an increase in conductivity of the solution, density and fiber diameter that influenced porosity, water uptake, and dissolvability and biodegradability of the meshes, while maintaining appropriate water vapor permeation values. Due to their intrinsic similarity to the extracellular matrix and cell-binding sequences, CS/GEL/PEDOT electrospun nanofibrous meshes show potential as conductive nanofibrous structures for electrostimulated wound dressings in skin tissue engineering applications. Full article

Infection control and bleeding management in deep wounds remain urgent and unmet clinical challenges that demand innovative, multifunctional, and sustainable solutions. Unlike previously reported sodium alginate and silk fibroin-based gel formulations, the present work introduces a dual-functional system combining antimicrobial and haemostatic activity in the form of conformable aerogel beads. This dual-functional formulation is designed to absorb exudate, promote clotting, and provide localized antimicrobial action, all essential for accelerating wound repair in high-risk scenarios within a single biocompatible system. Aerogel beads were obtained by supercritical drying of a silk fibroin–sodium alginate blend, resulting in highly porous, spherical structures measuring 3–4 mm in diameter. The formulations demonstrated efficient ciprofloxacin encapsulation (42.75–49.05%) and sustained drug release for up to 12 h. Fluid absorption reached up to four times their weight in simulated wound fluid and was accompanied by significantly enhanced blood clotting, outperforming a commercial haemostatic dressing. These findings highlight the potential of silk-based aerogel beads as a multifunctional wound healing platform that combines localized antimicrobial delivery, efficient fluid and exudate management, biodegradability, and superior haemostatic performance in a single formulation. This work also shows for the first time how the prilling encapsulation technique with supercritical drying is able to successfully produce silk fibroin and sodium alginate composite aerogel beads. Full article

An ancient repertoire of ultraviolet (UV)-absorbing pigments which survive today in the phylogenetically oldest extant photosynthetic organisms, the cyanobacteria, point to a direction in evolutionary adaptation of the pigments and their associated biota; from largely UV-C absorbing pigments in the Archean to pigments covering ever more of the longer wavelength UV and visible regions in the Phanerozoic. Since photoprotection is not dependent on absorption, such a scenario could imply selection of photon dissipation rather than photoprotection over the evolutionary history of life, consistent with the thermodynamic dissipation theory of the origin and evolution of life which suggests that the most important hallmark of biological evolution has been the covering of Earth’s surface with organic pigment molecules and water to absorb and dissipate ever more completely the prevailing surface solar spectrum. In this article we compare a set of photophysical, photochemical, biosynthetic, and other inherent properties of the two dominant classes of cyanobacterial UV-absorbing pigments, the mycosporine-like amino acids (MAAs) and scytonemins. We show that the many anomalies and paradoxes related to these biological pigments, for example, their exudation into the environment, spectral coverage of the entire high-energy part of surface solar spectrum, their little or null photoprotective effect, their origination at UV-C wavelengths and then spreading to cover the prevailing Earth surface solar spectrum, can be better understood once photodissipation, and not photosynthesis or photoprotection, is considered as being the important variable optimized by nature. Full article

Background/Objectives: Foam dressings are designed for their ability to manage exudate and are selected to optimize wound repair. Various foam dressings are available, ranging from basic polyurethane to more sophisticated options, incorporating active components to combat infections or foster healing. This study investigates the requirements for the most suitable foam dressing through a combination of field research, laboratory testing, and clinical evaluation. Methods: We tested 17 foam dressings commonly used by wound care professionals while attending an international conference. An effective foam dressing should absorb wound fluid for several days, as wound care professionals value absorption and retention capacity, often favoring less frequent changing dressings, preferably twice a week or even weekly. Results: The foam dressings tested can absorb the expected amount of exudate typically produced by different wound types. There is some variability in retention capacity and product prices, resulting in differences in cost-effectiveness among products. In addition, some dressings are enriched with active ingredients that can accelerate healing through their antimicrobial and anti-inflammatory properties, such as foam dressings infused with silver or honey. A honey-based foam dressing was evaluated in a clinical survey involving eight wound care specialists, and four clinical cases with varying wound pathologies were discussed in more detail to highlight its key properties. Conclusions: Ideally, a foam dressing should have adequate absorption and retention capacities, effectively resolve and prevent infections, protect against external trauma, ensure optimal patient comfort without damaging newly formed granulation tissue, accelerate wound healing processes, and reduce wound care time (e.g., remaining in place for 7 days). Together, these factors make honey- or silver-loaded foam dressings more cost-effective than plain dressings due to their antimicrobial activities and ability to nourish tissues. Full article

Background: The skin acts as a barrier against external threats, and moisture is crucial for effective wound healing, as it promotes epithelial cell migration. Thus, a high water content supports wound healing by maintaining moisture, absorbing exudate, and forming a protective barrier. Here, we created three different micro-patterned hydrogels and tested them on rat skin wounds. Materials and Methods: Three different micro-patterned (waves, lines, and checks) hydrogel patches were created using three-dimensional polymer networks. On SD rat skin, wounds were created by making incisions, and the hydrogel patches were applied. The rats were divided into three experimental groups based on the hydrogel micro-patterns. Rats without hydrogel (vehicle) and those with flat hydrogel (no shape) were considered as controls. The wound closure rate (WCR) was calculated, and the expression of Col1A protein was measured by western blot. Results: After 7 days, the WCR was significantly higher in the groups treated with micro-patterned hydrogel patches compared to the vehicle and no-shape groups. Specifically, the WCR was highest in the checks micro-patterned hydrogel group compared to the waves and lines micro-patterned hydrogel groups. Furthermore, Col1A protein expression was evaluated at days 7 and 14, revealing a significant increase in expression after 14 days in the checks micro-patterned hydrogel group compared to the waves and lines micro-patterned hydrogel groups. Conclusions: The checks micro-patterned hydrogel patches demonstrated superior wound healing efficacy, as indicated by a higher WCR and increased Col1A protein expression after 14 days. These findings highlight the importance of hydrogel pattern design in improving wound healing suggesting that optimized micro-patterns can enhance therapeutic outcomes in skin wound management. Full article

In this study, a hydrogel material based on porcine gelatin and sodium alginate was synthesized for use as a dressing for chronic wound treatment. The hydrogels were covalently cross-linked using polyethylene glycol diglycidyl ether (PEGDE 500), and the interaction between the components was confirmed via FTIR. The properties of the resulting hydrogels were examined, including gel-fraction volume, swelling degree in different media, mechanical properties, pore size, cytotoxicity, and the ability to absorb and release analgesics (lidocaine, novocaine, sodium diclofenac). The hydrogel’s resistance to enzymatic action by protease was enhanced both through chemical cross-linking and physical interactions between gelatin and alginate. The absorption capacity of the hydrogels, reaching 90 g per dm² of the hydrogel dressing, indicates their potential for absorbing wound exudates. It was demonstrated that the antiseptic (chlorhexidine) contained in the structured gelatin–alginate hydrogels can be released into an infected substrate, resulting in a significant inhibition of pathogenic microorganisms (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Aspergillus niger). These results clearly demonstrate that the obtained hydrogel materials can serve as non-traumatic dressings for the treatment of chronic and/or infected wounds. Full article

Background/Objectives: Hydrocolloid dressings are commonly used in the treatment of chronic wounds by forming a gel-like protective layer upon the dispersion of water, absorbing exudate, and creating a moist environment that promotes healing. However, the use of hydrocolloids has expanded outside of wound care, and this review summarizes the evidence for their use within dermatology. Methods: To perform this narrative review, several databases were searched for manuscripts that described the use of hydrocolloid dressings within dermatology. Results: The hydrophilic and colloidal dispersion properties of hydrocolloid dressings facilitate the formation of an absorptive, hydrating, and protective layer. In addition, the viscous layer supports innate immunity by activating immune cells such as granulocytes and monocytes, making them effective in wound care. Hydrocolloid dressings appear to be an effective treatment in acute wounds, with the potential of reduced healing time and easier application compared to traditional dressings. The majority of the related research suggests that hydrocolloid dressings and standard dressings have similar efficacy in healing pressure ulcers, and the prevention of hypertrophic and keloid scars. Early reports suggest that hydrocolloid dressings have a role in the treatment of facial dermatitis and acne vulgaris. Conclusions: Hydrocolloid dressings have been studied most extensively for chronic wounds and then for use in acute wounds. There have been a few studies on their use for treating acne, facial atopic dermatitis, and hypertrophic scarring. While more clinical studies are needed, there appears to be early evidence of hydrocolloid dressing use within dermatology. Full article