Liposome-coated mesoporous silica nanoparticles loaded with L-cysteine for photoelectrochemical immunoassay of aflatoxin B1
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The authors describe a photoelectrochemical (PEC) immunoassay for determination of aflatoxin B1 (AFB1) in foodstuff. The competitive immunoreaction is carried out on a microplate coated with a capture antibody against AFB1 using AFB1-bovine serum albumin (BSA)-liposome-coated mesoporous silica nanoparticles (MSN) loaded with L-cysteine as a support. The photocurrent is produced by a photoactive material consisting of cerium-doped Bi2MoO6. Initially, L-cysteine acting as the electron donor is gated in the pores by interaction between mesoporous silica and liposome. Thereafter, AFB1-BSA conjugates are covalently bound to the liposomes. Upon introduction of the analyte (AFB1), the labeled AFB1-BSA complex competes with the analyte for the antibody deposited on the microplate. Accompanying with the immunocomplex, the liposomes on the MSNs are lysed upon addition of Triton X-100. This results in the opening of the pores and in a release of L-cysteine. Free cysteine then induces the electron-hole scavenger of the photoactive nanosheets to increase the photocurrent. The photocurrent (relative to background signal) increases with increasing AFB1 concentration. Under optimum conditions, the photoactive nanosheets display good photoelectrochemical responses, and allow the detection of AFB1 at a concentration as low as 0.1 pg·mL−1 within a linear response in the 0.3 pg·mL−1 to 10 ng·mL−1 concentration range. Accuracy was evaluated by analyzing naturally contaminated and spiked peanut samples by using a commercial AFB1 ELISA kit as the reference, and well-matching results were obtained.
KeywordsPhotoelectrochemical immunoassay Aflatoxin B1 Ce-doped Bi2MoO6 nanosheets Peanut sample
Authors thank the National Natural Science Foundation of China (21475025 & 21675029), and the Program for Changjiang Scholars and Innovative Research Team in University (IRT15R11) for financial assistance.
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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