Sericin-reinforced polysaccharide composites for potential regenerative and antibacterial applications

In this work, three polysaccharide matrices were prepared with varying chitosan-to-alginate weight ratios (70:30, 50:50, 30:70) and used to develop sericin-reinforced composite biomaterials loaded with ciprofloxacin and silver, either as nanoparticles or silver ions incorporated into nanocrystalline hydroxyapatite (AgHA). To obtain composites, a solid-liquid method was employed in combination with lyophilization. SEM analysis revealed highly porous structures with pore sizes ranging from 50 to 200 μm for silver nanoparticle composites and below 100 μm for AgHA-containing composites. Ciprofloxacin was loaded with high efficiency (95.2 ± 1.1%), while silver loading efficiencies were 29.3 ± 2.6% for nanoparticles and 20.4 ± 1.3% for AgHA. In vitro release studies demonstrated biphasic ciprofloxacin release over 28 days, with initial diffusion-driven release followed by a slower phase (Korsmeyer-Peppas model, n = 0.035-0.070). Silver ions were released similarly, whereas silver nanoparticles exhibited zero-order kinetics in the second phase. Antimicrobial testing revealed significant activity against multidrug-resistant Staphylococcus aureus NCTC9789 and Pseudomonas aeruginosa PAO1161. Cytotoxicity assays confirmed that all composites were non-toxic to BALB/c 3T3 fibroblasts. These results indicate that the developed composites possess dual functionality-serving as temporary bone dressings for wounds and local drug delivery systems-offering sustained antibiotic release and prolonged antimicrobial protection, which may help to prevent infections associated with orthopedic implants.