Design of a yeast-based bio-interface on an optical fiber SPR platform toward drug adsorption monitoring.

Yeast biomass, Saccharomyces cerevisiae, has been widely studied for removing heavy metals and organic pollutants, including pharmaceuticals. However, conventional batch methods provide limited insight into time-resolved adsorption and interfacial molecular interactions. We developed an optical fiber-based surface plasmon resonance (SPR) sensor incorporating a yeast-derived bio-interface. A film formation monitoring method based on transmitted light absorbance during electroless Ni plating enabled reproducible fabrication of gold nanofilms. Yeast cells were uniformly immobilized via a spray-based method to construct the bio-interface. Using this sensor, real-time adsorption of pharmaceuticals onto yeast cells was evaluated: Doxorubicin showed a concentration-dependent SPR response, whereas ampicillin showed no significant change in SPR response. The optical fiber configuration allows for direct immersion into environmental waters for in situ measurements, providing a platform for dynamic analysis of microorganism-pollutant interactions and advancing water treatment and environmental monitoring technologies.