Percorrer por autor "Silva, D. C."
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- Antimicrobial casein/poly(vinyl alcohol) electrospun nanofibers-based dressingsPublication . Nobre, D.; Ekoh, E.; Silva, D. C.; Branco, A. C.; Pais, V.; Almeida, A.; Barroso, H.; Salema-Oom, M.; Fangueiro, R.; Colaço, R.; Galante, R.; Serro, A. P.Diabetes affects millions globally, with a rising prevalence. Chronic wounds are one of its major complications, due to the healing difficulty, highlighting the need for innovative solutions to improve the treatments efficacy. Electrospun nanofiber dressings show promising due to their ECM-like structure, oxygen permeability, and potential for bioactive functionalization. In this study, casein/poly(vinyl alcohol) (CAS/PVA) nanofibers were electrospun with antimicrobial compounds: Octiset®, polyhexanide, and ZnO particles. After crosslinking with glutaraldehyde (GA), the nanofibers mats were characterized regarding their morphology, swelling capacity, enzymatic degradation, drug release behavior, cytotoxicity, hemocompatibility, irritability potential and antimicrobial potential. They demonstrated notable swelling capacity, and therefore potential to absorb exudate and maintain a moist healing environment in the wound. Those containing polyhexanide and Octiset® (CAS/PVA_Poli and CAS/PVA_Octi) showed a significant drug release for over 4–8 h, that prolonged at a slower rate for 24 h, being mainly diffusion-controlled. The crosslinker reduced the amount of drug released and the degradation of the nanofibers but increased their water absorption capacity. CAS/PVA_Poli and CAS/PVA_Octi exhibited the most interesting set of results, as besides being non-cytotoxicity, hemocompatible and non-irritant, presented excellent antimicrobial efficacy and superior performance when compared with the crosslinked samples. They were effective against Staphylococcus aureus, Escherichia coli, and Candida albicans, and in particular against Methicillin Resistant Staphylococcus aureus and Streptococcus pyogenes which are a dangerous threat in diabetic wounds. Overall, their morphological similarity with the extracellular matrix and excellent biological properties, turns them good candidates to be used in dressings for the treatment of diabetic wounds.
- PVA/casein/chitosan-based hydrogels with antioxidant bioactive agents for diabetic wound treatmentPublication . Gonçalves, M.; Branco, A. C.; Silva, V.; Silva, D. C.; Salema-Oom, M.; Coelho, J.; Colaço, R.; Galante, R.; Poeta, P.; Saramago, B.; Serro, A. P.Wound healing is a complex process, especially in chronic conditions such as diabetes mellitus, often hindered by a prolonged inflammatory stage. Modern wound dressings aim to protect wound beds and accelerate the healing process. Hydrogel dressings have raised special interest due to their ability to retain moisture. This work focused on developing innovative wound dressings with antioxidant properties to improve the healing of chronic wounds, namely through the regulation of the oxidative environment in diabetic wounds. A base hydrogel composed of polyvinyl alcohol (PVA)/casein/chitosan was produced by freeze-thawing method. Astaxanthin and ozonized oils were incorporated in the formulation in different amounts. In general, all hydrogels presented adequate physical, chemical and biological properties to be used as dressing materials, but the ozonized oil containing hydrogel BOz12_2 stood out as the most promising one. Its porous and hydrophilic network provided high water retention and an adequate water vapor transmission rate, while maintaining structural integrity with a slow degradation profile and suitable mechanical strength. The material also exhibited moderate mucoadhesion, ensuring sufficient adherence without compromising wound removal. Importantly, it proved to be non-toxic, non-irritant, and hemocompatible, while simultaneously showing strong antioxidant activity and selective antimicrobial efficacy, including inhibition of vancomycin-resistant Enterococcus faecium strains.