Colorimetric-assisted photoelectrochemical sensing for dual-model detection of sialic acid via oxidation-power mediator integration

Development of sensitive and accurate methods for sialic acid (SA) determination is of great significance in early cancer diagnosis. Here, a colorimetric-assisted Photoelectrochemical (PEC) sensor was constructed for SA detection based on the two pairs of cis-diol groups in SA molecule. With the specific recognition of SA via the two pairs of cis-diol groups, the prepared gold-modified Bi2S3 (Au [email protected]2S3) and metal organic framework ([email protected]) were introduced to the electrode and formed a sandwich structure. Based on the properties of inert electroconductivity and nanozyme of the PCN-224, dual-readout of photocurrent and visualization was achieved with the presence of 3,3′,5,5′-tetramethylbenzidine (TMB). Moreover, to intensify the visualization signal, Ce3+ was employed as the mediator to boost the catalysis capability by transferring energy from PCN-224 surface to the whole system. With the unique SA recognition and the mediation of Ce3+, both the photocurrent and the visualization signals sensitively responded with the SA concentration linearly. The present method showed greatly high sensitivity, selectivity and accuracy for SA detection with a limit of detection of 1.44 µmol/L and a wide linear range of 5–1000 µmol/L. This method provided a new promising platform for SA detection and a potential strategy for design of novel biosensors with dual-model readout.