Novel Porphyrinic Covalent Organic Polymer with Polarity-Switchable Dual Wavelength for Accurate and Sensitive Photoelectrochemical Sensing

Herein, we synthesized a novel porphyrinic covalent organic polymer (TPAPP-PTCA PCOP) for constructing a polarity-switchable dual-wavelength photoelectrochemical (PEC) biosensor with ferrocene (Fc) and hydrogen peroxide (H2O2) as regulator and amplifier simultaneously. Interestingly, this new PCOP possessed both n-type and p-type semiconductor characteristics, which thus enabled the appearance of a dual-polarity photocurrent at two different excitation wavelengths. Furthermore, Fc and H2O2 could readily switch the photocurrent of PCOP to the cathode and anode stemming from its efficient electron collection and donation function, respectively. Based on these, a PCOP-based PEC biosensor skillfully integrating dual wavelengths with reliable accuracy and polarity switch with high sensitivity was instituted. As a result, the developed PEC biosensor exhibited a low detection limit down to 0.089 pg mL(-1) for the most powerful natural carcinogen aflatoxin M1 (AFM1) assay. Impressively, the target exhibited a completely opposite photocurrent difference to the interfering substances, and the linear correlation coefficient of the assay was improved compared to single-wavelength detection. The PEC sensing platform not only provided a basis for exploring multicharacteristic photoactive material but also innovatively developed the detection mode of the PEC biosensor.

Automated summary

In this study, a novel porphyrinic covalent organic polymer (TPAPP-PTCA PCOP) was synthesized to construct a polarity-switchable dual-wavelength photoelectrochemical (PEC) biosensor. The PCOP exhibited both n-type and p-type semiconductor characteristics, allowing for the generation of dual-polarity photocurrent at two different excitation wavelengths. The photocurrent of the PCOP could be switched to the cathode and anode by ferrocene and hydrogen peroxide, respectively. A PCOP-based PEC biosensor integrating dual wavelengths, reliable accuracy, and polarity switch with high sensitivity was developed, achieving a low detection limit for aflatoxin M1.