A sensitive biosensor for determination of pathogenic bacteria using aldehyde dehydrogenase signaling system

Aldehyde dehydrogenase (ALDH) was first developed as an enzymatic signaling system of a biosensor for sensitive point-of-care detection of pathogenic bacteria. ALDH and specific aptamers toSalmonella typhimurium(S. typhimurium), as organic components, were embedded in organic-inorganic nanocomposites as a biosensor signal label, integrating the functions of signal amplification and target recognition. The biosensing mechanism is based on the fact that ALDH can catalyze rapid oxidation of acetaldehyde into acetic acid, resulting in pH change with portable pH meter readout. The altered pH exhibited a linear relationship with the logarithm ofS. typhimuriumfrom 10(2)to 10(8) CFU/mL and detection limit of 46 CFU/mL. Thus, the proposed biosensor has potential application in the diagnosis of pathogenic bacteria.