An enzyme-assisted photoelectrochemical (PEC) biosensor was established for quantification of exosomes based on the in situ synthesis of Ti3C2 MXene/CdS composites with magnetic separation technology and hybridization chain reaction (HCR).

We report the proof-of-concept of molecularly imprinted polymer (MIP) functionalized Bi2S3/Ti3C2TX MXene nanocomposites for photoelectrochemical (PEC)/electrochemical (EC) dual-mode sensing of chlorogenic acid (CGA). Specifically, the in-situ growth of the Bi2S3/Ti3C2TX MXene served as a transducer substrate for molecularly imprinted polymers such as PEC and EC signal generators, due to its high surface area, suitable bandwidth and abundant active sites. In addition, the chitosan as a binder was encapsulated into MIP by means of phase inversion on a fluorine-doped tin dioxide (FTO) electrode. In the determination of CGA as an analytical model, the dual-mode sensor based on MIP functionalized Bi2S3/Ti3C2TX MXene nanocomposites had good selectivity, excellent stability and acceptable reproducibility, which displayed a linear concentration range from 0.0282 μM to 2824 μM for the PEC signal and 0.1412 μM to 22.59 μM for the EC signal with a low detection limit of 2.4 nM and 43.1 nM, respectively. Importantly, two dual-response mode with different transduction mechanisms could mutually conform to dramatically raise the reliability and accuracy of detection compared to single-mode detection. This work is a breakthrough for the design of dual-mode sensors and will provide a reasonable basis for the construction of dual-mode sensor platforms.

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