Controlling Silver Release from Antimicrobial Surface Coatings for Biofouling Control

Silver is used as a biocide for disinfection in the water treatment and supply system of spacecraft. However, its short lifetime result in high operating costs and risk of biofilm development. The innovation of this NASA STTR project relies on the development of novel surface coating chemistries able to extend the lifetime of nanosilver-based antimicrobial coatings, used in water treatment systems of spacecraft, without affecting their anti-biofouling performance. The overarching hypothesis is that silver nanoparticles can be passivated by partial sulfidation, forming Ag/Ag2S core-shell structures with low silver leaching rate but excellent long-term biocidal properties. This project will the optimal physicochemical properties that balance dissolution rate and biocidal activity in nanosilver. Then, we will develop the in situ nucleation and passivation conditions able to generate the desired particle properties on stainless steel and surfaces relevant for spacer water treatment systems. Dissolution rate, biocidal properties, and biofilm development kinetic will be followed over time to demonstrate the long-term performance of the partially sulfidized nanosilver coatings. The results of this project will lead to the development of a passivated surface coating generator technology to be used in spacecraft systems for sustained biofouling control.