Plasmonically Enhanced Photoelectrochemical Immunoassay Based on Au Nanoparticle-Loaded PAMAM Dendrimers for Cry1Ab Protein Detection

The widespread introduction of Cry1Ab protein in genetically modified crops has aroused considerable concern about the risks on the environment and food safety. Herein, we reported a plasmonic enhanced photoelectrochemical (PEC) immunosensor for the precise determination of the Cry1Ab protein. Its working principle was based on the space confinement-induced surface plasmon resonance to enhance visible-light absorption of photoactive materials. The polyamidoamine (PAMAM) dendrimers were selected as the space-confined template to synthesize gold (Au) nanoparticles, that is, PAMAM–Au, which presented smaller diameter and good dispersive stability. Meanwhile, PAMAM–Au nanocomposites can exhibit significantly enhanced surface electric field intensity according to the finite-difference time-domain analysis. Further, the efficient PEC enhancement of PAMAM–Au was then validated by the highly increased photocurrent in CdSe/PAMAM–Au nanocomposites. The as-fabricated PEC immunosensor provided a wide linear range of over 4 orders of magnitude (0.01–100 ng mL–1), with the detection limit down to 3 pg mL–1 for Cry1Ab analysis. Besides, such an immunosensor was applied to analyze Cry1Ab in corn and wheat samples, and the result was in good agreement with that by the official method, enzyme-linked immunosorbent assay. Our work provides a way to fabricate high-performance sensors for the accurate detection of Cry1Ab in the environment and food products.