Collagen integrity should be considered on using a sterilizing agent for fish skin grafts. This study
defined the optimal concentration of silver nanoparticles (Ag NPs) for sterilization of fish skin
grafts without disrupting collagen content based on microbiological and histological evaluation.
Strips of tilapia skin (n = 5) were randomly allocated to be immersed in Ag NPs solution at different
concentrations of 25, 50, 100, and 250 μg/mL, respectively, for 5 min. The treated skin strips
underwent bacteriological and histological evaluation. Yeast and fungi were more sensitive to Ag NPs
than bacteria. On increasing the nanoparticles concentration, the total counts of aerobic bacteria
decrease giving 933.3 ± 28.67, 601 ± 27.66, 288 ± 16.8, 15 ± 4.08 (CFU/cm2 ± S.D) at 25, 50, 100, and
250 μg/mL, respectively, comparing with untreated sample (1453.3 ± 57.92). Yeasts and filamentous
fungi also exhibited a similar response, achieving a complete inhibition at 100 and 250 μg/mL. Bacillus
cereus and Escherichia coli were the dominant aerobic bacteria, Candida albicans and Rhodotorula
glutinis were the dominant aerobic yeasts, whereas Aspergillus niger, Aspergillus fumigatus, and
Rhizopus stolonifer were the dominant aerobic fungi. The collagen fibers were loose with a wavey
pattern at 25 μg/mL, wavey and slightly disorganized at 50 μg/mL, highly disorganized at 100 μg/
mL, and compactly arranged and slightly loose at 250 μg/mL. Ag NPs at a concentration of 250 μg/
mL could be considered a reliable and feasible method for the sterilization of fish skin grafts before
application on human skin with an effective antimicrobial effect and less disrupting impact on collagen
content.