Tunable release of ions from graphene oxide laminates for sustained antibacterial activity in a biomimetic environment

Silver has long been recognised for its potent antimicrobial properties, but achieving a slow and longer-term delivery of silver ions presents significant challenges. While several attempts have been made to achieve controlled dosages of silver ions, sustaining their release for more than a few days in a biomimetic environment, particularly in the presence of complex proteins, has not been successfully demonstrated. This challenge is underscored by the absence of technology for sustaining antimicrobial activity, especially in the context of orthopaedic implants where long‐term efficacy, extending beyond seven days, is essential. In this study, we have successfully demonstrated the tunable, slow, and
longer-term release of silver ions from the two-dimensional nanocapillaries (1 nm wide) of GO laminates incorporated with Ag ions (Ag-GO) for antimicrobial applications. To closely mimic a physiologically relevant serum-based
environment, we introduce a novel in vitro study model using 100% fetal bovine serum (FBS) as the test medium for microbiology, biocompatibility, and bioactivity studies. To emulate fluid circulation in a physiological environment, we challenge our in vitro studies with serum exchange protocols on different days. Our findings show that the Ag-GO coating can sustainably release silver ions at a minimum dosage of 10 μg/cm²/day, providing an effective and sustained antimicrobial barrier for over ten days.