Effects of sterilization on nanogel-based universal coatings: An essential step for clinical translation

Implant associated infections are a serious threat to the well-being of patients, which can be mitigated by taking effective disinfection/sterilization (D/S) methods into account. Nanogels (nGel) are stimuli sensitive polymeric hydrogel particles, which have provided numerous innovative applications in the biomedical field to enhance antifouling, antibacterial properties, or drug delivery, or they can be employed as imaging modalities or can be applied as a coating on biomaterials (implants). Prior to translating their application towards clinical use, nGelbased coated implant materials must undergo an intermediary, pre-requisite process of cleaning, disinfection, and sterilization, in sequence. The interplay among the three crucial pillars- the implant material, the nGel coating (with specific function), and the applied D/S processes influence the fate (success or failure) of medical implant in the host body. In this study, we investigated a previously developed NIPAM-co-APMA core shell nGel coating on various clinically-relevant polymeric and inorganic implant materials and tested them on a diverse range of D/S techniques to assess the retention of the coating quality and antifouling function. The stability and integrity of the nGel coating was analyzed by performing Atomic Force Microscopy and the retention of the antifouling function of the nGel-coating after sterilization was studied by Colony forming units against S. aureus RN4220. Among all the materials that were coated, polymeric materials- polypropylene and polyetheretherketone exhibited exceptional coating stability, post-sterilization while also demonstrating a considerable reduction in bacterial attachment with respect to their 'uncoated, sterilized' and 'coated, non-sterilized' controls. Although often overlooked, sterilization is an indispensable part of clinical translation, therefore research in this domain is of utmost importance when considering clinical translatability.