Pepsin-induced modification of silver nanoparticles in simulated gastric fluid

The behavior of AgNPs in simulated gastric fluids (SGFs) with and without pepsin was studied through time-dependent UV–Vis absorption spectroscopy and transmission electron microscopy. The dissolution at the initial stage and the subsequent particle growth and aggregation were observed in the absence of pepsin in SGF. On the other hand, individual AgNPs were protected via the formation of protein corona when pepsin was introduced into SGF. In addition, the agglomeration of AgNPs continued in SGF with pepsin, and gap narrowing between AgNPs was observed during the agglomeration. Flocculation eventually occurred as a result of continuous agglomeration. In addition, the degree of the agglomeration of AgNPs was found to be determined by the relative quantity of nanoparticles and pepsin. The experimental results indicate that the status of individual NPs and their congregative characteristics should be considered in the evaluation of the safety and toxicity of nanometer-scale materials.