This study reports on the modification of bacterial cellulose (BC) membranes produced by static fermentation of Komagataeibacter xylinus bacterial strains with graphene oxide-silver nanoparticles (GO-Ag) to yield skin wound dressings with improved antibacterial properties. The GO-Ag sheets were synthesized through chemical reduction with sodium citrate and were utilized to functionalize the BC membranes (BC/GO-Ag). The BC/GO-Ag composites were characterized to determine their surface charge, morphology, exudate absorption, antimicrobial activity, and cytotoxicity by using fibroblast cells. The antimicrobial activity of the wound dressings was assessed against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The results indicate that the BC/GO-Ag dressings can inhibit ∼70% of E. coli cells. Our findings also revealed that the porous BC/GO-Ag antimicrobial dressings can efficiently retain 94% of exudate absorption after exposure to simulated body fluid (SBF) for 24 h. These results suggest that the dressings could absorb excess exudate from the wound during clinical application, maintaining adequate moisture, and promoting the proliferation of epithelial cells. The BC/GO-Ag hybrid materials exhibited excellent mechanical flexibility and low cytotoxicity to fibroblast cells, making excellent wound dressings able to control bacterial infectious processes and promote the fast healing of dermal lesions.

Alginate is a biocompatible polysaccharide matrix used for bioactive dressings with inherent healing properties. Most alginate dressings are produced as single-layer dressings. This study explores the potential of bilayer membranes to modulate drug release and enhance antimicrobial properties. We used alginate and chitosan loaded with simvastatin, an anti-inflammatory drug. One membrane comprised dense layers of both alginate and chitosan, while the other featured a dense alginate upper layer and a porous chitosan lower layer. The current study introduces a new approach in which a bilayer membrane is modeled instead of creating a polymeric blend between alginate and chitosan. The upper layer of the membrane contains only alginate loaded with simvastatin, while the bottom layer contains only chitosan. Another innovation is the study of the use of a porous lower layer of chitosan. Therefore, the association of these polymers in a bilayer and porous membrane gives advanced therapeutic dressings (with anti-inflammatory and antimicrobial properties intrinsic to the membrane) that are more efficient in the healing of complex wounds. Comprehensive characterization encompassed physicochemical, thermal, morphological, and mechanical properties. Microbiological tests were conducted using chitosan extract, and cytotoxicity evaluations were performed on fibroblast and keratinocyte cells. The results showed interlayer adhesion due to ionic interactions between alginate and chitosan surfaces. The drying process influenced the morphological and physicochemical features of the membranes. Simvastatin release profiles demonstrated sustained release over an extended period (approximately 60%–70% of the drug after 96 h). Storage assessments revealed that after six months, the membranes maintained around 98% of the initial simvastatin content. The antimicrobial activity test underscored the bacteriostatic efficacy of the chitosan porous layer, making it well-suited for infected wounds. Cell viability tests confirmed the non-cytotoxic nature of the films, highlighting their promising characteristics for treating diverse skin lesion types.

The concept of combi-lipases is herein explored in the full hydrolysis of babassu oil. The commercially immobilized lipases from Candida antarctica (form B) (Novozym^® 435), Rhizomucor miehei (Lipozyme^® RM-IM), and Thermomyces lanuginosus (Lipozyme^® TL-IM) were evaluated as single and combined biocatalysts by a mixture design with triangular surface. As a result, after evaluating the response desirability profiling for all biocatalysts, the best biocatalyst in the reaction was the combi-lipases composed of 75% of Lipozyme^® RM-IM, 17% of Novozym^® 435, and 8% of Lipozyme^® TL-IM, reaching full hydrolysis (>99%) after 4 h of reaction. Subsequently, such combi-lipases were employed as biocatalysts in the optimization of the reaction in a shorter reaction time (3 h). After optimization by the Taguchi method, full hydrolysis (>99%) was reached under optimized reaction conditions (9 wt.% of biocatalyst content, 1:2 (oil/water), 40 °C, and 180 rpm). Under such conditions, the combi-lipases maintained 70% of their initial activity after 10 reaction cycles. The antimicrobial activity against some of the most common environmental bacteria of the obtained free fatty acids (FFAs) was also evaluated. The FFAs inhibited more than 90% of the growth of S. aureus, E. coli, and P. aeruginosus when using 10 mg FFAs/mL.