Enzyme-controlled mesoporous nanosensor for the detection of living Saccharomyces cerevisiae

We report herein the construction of an integrated and sensitive enzyme-powered colorimetric nanosensor for the quantification of living Saccharomyces cerevisiae. The nanodevice is provided with a pH-sensitive supramolecular nanovalve in capped benzimidazole-functionalized mesoporous silica nanoparticles with β-cyclodextrin-coated gold nanoparticles containing adatamantane-modified glucose oxidase as bioactive element. The sensing approach relies on the ability of living S. cerevisiae cells to produce invertase, which hydrolyzes sucrose to fructose and glucose. Enzymatic transformation of glucose to gluconic acid on the nanosensor surface results in the opening of the pores and delivery of an encapsulated dye, as a consequence of the local decrease in the pH. The nanosensor allows the detection of the living yeast in the range of 8·102 – 4·108 CFU/mL, exhibiting high selectivity and reproducibility, and retaining full sensing capacity after 2 weeks of storage. The nanodevice has also been successfully validated in wine samples spiked with S. cerevisiae.