Photoelectrochemical immunosensing of tetrabromobisphenol A based on the enhanced effect of dodecahedral gold nanocrystals/MoS2 nanosheets

Dodecahedral gold nanocrystals (AuNCs) were synthesized by using a 1-(10-bromodecyl)-3-methylimidazolium bromide ionic liquid as functional monomer and protectant. AuNCs were self-assembled onto molybdenum disulfite (MoS 2 ) nanosheets to fabricate AuNCs/MoS 2 nanocomposite, which was drop-coated onto a glassy carbon electrode surface to generate an interface for transthyretin (TTR) immobilizing. With a similar chemical structure to thyroxine, tetrabromobisphenol A (TBBPA) was specifically recognized by transthyretin and the TTR/AuNCs/MoS 2 /GCE provides a sensing platform for TBBPA. Its sensing performance towards TBBPA was found significantly improved by the integration of AuNCs onto MoS 2 nanosheets. Three conditions for assay development, such as incubation time, incubation temperature, and pH value, were investigated and found the optimum conditions were 200   s, 35   °C, and pH 7.0 respectively. Under these conditions, the ratio [ R i   =   ( i 0   −   i )/ i 0 ] between the photocurrent variation (△ i   =   i 0   −   i ) and the original photocurrent ( i 0 ) is linearly related to the logarithm of TBBPA concentration ( c TBBPA ) from 0.1   nM to 1.0   μM. The linear relationship can be described by the following equation: R i   =   0.09092 log c TBBPA (M)   +   0.8976 (R   =   0.993). The detection limit is calculated to be 0.045   nM (S/N   =   3). The photoelectrochemical immunosensor was used to accurately determine TBBPA concentration in South-Lake spiked water samples.