A dual-wavelength ratiometric photoelectrochemical sensor based on molecularly imprinted polymer via differential strategy

Molecularly imprinted polymers (MIPs)-photoelectrochemical (PEC) strategy usually has only one photoactive material as the photocurrent signal. However, ratiometric technique commonly requires two selective signals, the detecting signal and reference signal. Therefore, ratiometric MIPs-PEC sensor has been rarely reported. This work presents a dual-wavelength ratiometric and differential MIPs-PEC platform with a digital multimeter readout, which designed for highly sensitive and selective detection of 2,4-dichlorophenoxyacetic acid (2,4-D). Gold nanoparticles modified porous silicon (Au NPs/PS) and the target (2,4-D) were employed as the light-active species, which can produce photocurrent at two different wavelengths (560 and 280 nm). Furthermore, the improved differential strategy was explored to enhance the anti-interference capability of sensors, by using the response difference between MIPs and non-imprinted polymers (NIPs) as the analytical signals. Benefiting from the sensitivity of ratiometric differential strategy and selectivity of differential MIPs method, this MIPs-PEC sensor affords a linear range of 1.0x10- 11 to 8.0x10- 8 M for detecting 2,4-D, with a detection limit of 8.9x10- 13 M. As an important extension, this ratiometric differential MIPs-PEC technique could be used as an innovative and versatile approach for detecting other MIPs targets with similar properties, such as atrazine (AT) and triphenyl phosphate (TPhP).