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.