UV-induced over time transformation of AgNPs in commercial wound dressings and adverse biological effects on Caenorhabditis elegans

Abstract Silver nanoparticles (AgNPs) are frequently used in commercial products; however, the knowledge on their release, environmental modification, and subsequent toxicity is still limited. In this study, we explored the leaking of AgNPs from an enhanced wound dressing under UV radiation as sterilization after use, and the toxic effects were determined using Caenorhabditis elegans (C. elegans). UV radiation was found to cause a series of over time physicochemical changes on released AgNPs during the exposure: initially the formation of smaller secondary AgNPs (intermediate product), then the merging of Ag particles into structures beyond nanoscale (end product). Tissue-specific distribution and total accumulation of Ag in C. elegans both indicated that full UV treatment enhanced the uptake of AgNPs in the nematodes, which also inclined to release more Ag+. However, the end-product of UV treatment alleviated the neural and reproductive toxicity in C. elegans compared to unexposed particles, while the intermediate product induced more apoptosis in the gonad of the worms. Our data elucidated that UV-induced complex physicochemical changes on released AgNPs are a crucial factor influencing its toxicity, and suggestions are given accordingly in order to reduce possible environmental threats from used wound dressings. The investigation on nano-silver wound dressings revealed that special attentions are needed for key environmental factors in both risk assessment and overall regulation of engineered nanomaterial enhanced products.