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

- Using ionic liquid as functional monomer to fabricate dodecahedral gold nanocrystals (AuNCs).
- Transthyretin was self-assembled on an AuNCs/MoS2 interface to fabricate an immunosensing platform.
- Photoelectrochemical sensing of tetrabromobisphenol A was evaluated.
- Tetrabromobisphenol A in spiked lake water was determined accurately.

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 (MoS2) nanosheets to fabricate AuNCs/MoS2 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/MoS2/GCE provides a sensing platform for TBBPA. Its sensing performance towards TBBPA was found significantly improved by the integration of AuNCs onto MoS2 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 [Ri = (i0 − i)/i0] between the photocurrent variation (△i = i0 − i) and the original photocurrent (i0) is linearly related to the logarithm of TBBPA concentration (cTBBPA) from 0.1 nM to 1.0 μM. The linear relationship can be described by the following equation: Ri = 0.09092 log cTBBPA (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.

A photoelectrochemical immunosensor has been developed for tetrabromobisphenol A determination based on the specific reaction between TTR and TBBPA. The enhanced effects of dodecahedral gold nanocrystals on the photocurrent response of MoS2 nanosheets were demonstrated.155