Alkaline phosphatase-responsive fluorescent polymer probe coated surface for colorimetric bacteria detection

The present study aimed to develop an enzymatic colorimetric method using a surface-adsorbing biosensor to detect and kill bacteria in a single, simple, and rapid assay. The phosphorylated fluorescent probe 2-hydroxychalcone (HCAP) conjugated with an adhesive cationic polymer was designed (HCAP-PVP), which yielded greenish-yellow emission in aqueous buffer. Upon introduction of Escherichia coli and Staphylococcus aureus, the phosphate group inside the HCAP was cleaved by endogenous alkaline phosphatase (ALP) and the greenish-yellow emission ratiometrically changed to deep-red emission. This biosensor system detected bacteria over a wide range of bacterial densities (10¹–10⁷ colony-forming units/mL) after 60 min, with similar bacterial detection abilities between aqueous- and solid-phase assays. Furthermore, the presence of a quaternary ammonium of dodecane in this system displayed efficient antibacterial activity because of the change in cellular hydrophobic interactions, which enabled this material to act as a dual sensor and killing material. Thus, this system is a novel, rapid, and simple enzymatic sensor with high sensitivity that can be used as a solid-based platform to detect and directly eliminate bacteria.