A multiple mixed TiO₂ mesocrystal junction based PEC-colorimetric immunoassay for specific recognition of lipolysis...

A flexible two-step photoelectrochemical (PEC)-colorimetric immunoassay was proposed for ultrasensitive detection of lipolysis stimulated lipoprotein receptor (LSR) which is found to be closely related to ovarian cancer (OC). In this paper, the Cu nanoclusters (CuNCs) enhanced multiple mixed TiO₂ mesocrystals junction (MMMJ) was fabricated via effective combination of multiple different phases TiO₂ mesocrystals (Anatase and Rutile) layers and used as a sensing platform. The strong interaction between different phases layers caused multiple amplification of signal and introduction of Cu NCs further improve PEC properties and catalytic activity to hydrogen peroxide (H₂O₂) what can catalyze lecuo-methylene blue (lecuo-MB) from colorless to blue. As antibody and target antigen captured onto the MMMJ in turn, both PEC properties and catalytic activities were inhibited, leading to decreased photocurrent responses and multiply vivid color variations in lecuo-MB functionalized colorimetric films. Thus, a versatile dual-modal sensing system was developed just by utilizing enhanced MMMJ as a photoelectrode and lecuo-MB as a color change reporter molecule for PEC and colorimetric monitoring of target. Combing all of these advantages, the designed dual-modal immunoassay considerately reduced false positive or negative results during the measurement, and the unique approach for MMMJ construction may also provide a valuable guidance for designing other mixed phase junctions with superior PEC performance.