Boosting the Biocatalytic Precipitation with Enzyme-Loaded Liposomes: Toward a General Platform for Amplified Photoelectrochemical Immunoassay.

Liposome-assisted photoelectrochemical (PEC) bioanalysis represents one of the latest frontiers in the arena of PEC bioanalysis. This work reports a general enzyme-amplified liposomal PEC bioanalysis protocol via the use of enzyme-loaded liposomes to boost the biocatalytic precipitation (BCP) effect. In the representative system, the horseradish peroxidase (HRP)-loaded liposome (HRPLL) and the Au nanoclusters (NCs)/Au nanoparticles (NPs)/TiO2 nanotubes (NTs) framework (AATF) were used as liposomal label and photoelectrode, respectively. In the detection, the sandwich immunocomplex reaction was accomplished in a 96-well plate to confine the HRPLL label, which was then lysed to release the HRP molecules to initiate the BCP process. Due to the amplified formation of HRP-induced BCP on the AATF scaffold, the photo-current response correlated closely with the immunorecognition process and the analyte could be detected very sensitively. This work features the first integration of enzyme-loaded liposomes and the BCP for sensitive PEC bioanalysis, which to our knowledge has not been reported. With the use of various other enzymes, this work could serve as a general basis for the PEC bioanalysis of numerous other target of interest.