Switching photocurrent polarity and mimicking enzyme functions of MIL-53(Fe)@hemin for homogeneous dual-modal ultrasensitive detection of PTP1B

Protein tyrosine phosphatase 1B (PTP1B) as a regulatory enzyme is an important target for the early diagnosis and drug discovery of diabetes, obesity, and cancer. Herein, a homogeneous dual-modal biosensor integrating photoelectrochemical and colorimetric (PEC-CL) strategies was developed in light of the switching photocurrent polarity and mimicking enzyme functions of MIL-53(Fe)@hemin for the sensitive detection of PTP1B activity. Magnetic Fe3O4@Au NPs were synthesized for more sufficient homogeneous biorecognition, and modified with the phosphorylated peptides (p-Peptide), and sequentially connected with MIL-53(Fe)@hemin by the specific coordination of phosphate groups with Fe(III). After PTP1B-mediated specific recognition and dephosphorylation, the separated MIL-53(Fe)@hemin were quickly collected via magnetic separation for further PEC and CL assay. MIL-53(Fe)@hemin not only switched the photocurrent polarity of SnS2 NFs from anode to cathode, but also exhibited excellent peroxidase-like activity for oxidizing 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2. As a signal amplifier, MIL-53(Fe) acted as a nanocarrier to load abundant PEC signal switching factor of hemin, and synergistically enhanced its enzyme-mimic property. Consequently, ultrasensitive PEC biosensing (with linear response range of 0.1 pg mL−1 to 3000 ng mL−1 and detection limit of 0.074 pg mL−1) assisted by visual CL strategy (with linear response range of 10 pg mL−1 to 3000 ng mL−1 and detection limit of 0.24 pg mL−1) for PTP1B activity assay were achieved, which not only provided high sensitivity, but also possessed portability, perceptual intuition and reliability.