Hierarchical PLA/chitosan/AgNPs composites with architecture-dependent antibacterial activity and preliminary ecotoxicological assessment

Biocompatible composites with antibacterial functionality are increasingly sought to reduce plastic dependence and microbial contamination. Here, we report the fabrication of a composite by electrospinning poly(lactic acid) (PLA) nanofibers onto chitosan (CH) films embedded with green-synthesized silver nanoparticles (AgNPs). Physicochemical analyses confirmed integration: FTIR spectra indicated hydrogen bonding between PLA and CH, while XRD patterns revealed decreased crystallinity and amorphous domains. SEM micrographs showed a compact PLA-fiber-coated CH matrix, and the SEIRA effect suggested close proximity between PLA and AgNPs. Thermogravimetric analysis indicated intermediate thermal stability (∼235 °C). Antibacterial activity, assessed by the Bauer–Kirby disk diffusion method against Staphylococcus aureus and Escherichia coli (n = 3), showed that CH films with AgNPs (PCH-AgNPs) achieved the largest inhibition areas (1.767 ± 0.510 mm 2 and 1.760 ± 0.723 mm 2 , respectively), representing an increase of 14–20% over CH films without nanoparticles. PLA-coated composites (PCH-AgNPs/FPLA) exhibited moderate but sustained activity (1.703 ± 0.367 mm 2 for S. aureus and 1.027 ± 0.437 mm 2 for E. coli ), consistent with the FPLA layer modulating total silver availability and antibacterial intensity, as assessed by MP-AES monitoring of total silver diffusion over 30 days. Preliminary ecotoxicological screening using Daphnia sp . and Lactuca sativa showed no treatment-associated increase relative to controls under the single conditions evaluated, without significant inhibition of seed germination (70%), although minor sublethal effects on radicle and hypocotyl elongation were observed, especially in composites without AgNPs. The PCH-AgNPs/FPLA composite combines antibacterial efficacy, thermal stability, and preliminary ecotoxicological compatibility, showing promise for biomedical and environmentally sustainable applications.