Junhui Du,Haibin Liu,Hongshuo Chen,Chuanjin Cui,Wensi Zhang,Xuechao Zhang,Zhang Bin
A competitive electrochemical aptamer biosensor for the selective detection of Pb 2+ was developed in this study. The PAMAM@Au hybrid materials and the bioprobe MB-GNPs-ssDNA were synthesized with chemical methods . Modified electrode with carboxylated graphene oxide was prepared via electrodeposition . PAMAM@Au was immobilized on the modified electrode using the EDC/NHS crosslinker, and aptamer (Apt) was bound to PAMAM@Au hybrid materials using the glutaraldehyde crosslinker. The assembly of MB-GNPs-ssDNA/Apt/PAMAM@Au/GO/SPCE biosensors was achieved through immobilizing bioprobe onto electrodes, based on the theory of aptamer-complementary chain reactions. The fabricated biosensor was characterized through electrochemical experiments, SEM, AFM , TEM, XPS and FTIR . The biosensor's performance was evaluated in a series of Pb 2+ aqueous solutions by differential pulse voltammetry (DPV), and the results demonstrated this biosensor had excellent repeatability, stability, and specificity. The detection range spanned from 0.5 pM/L to 500 nM/L, with a detection limit of 5 fM/L. Consequently, the proposed biosensor can serve as a reliable analytical tool for the sensitive detection of lead ions .
In this work, we report a novel sandwich-type electrochemical aptasensor for sensitive and selective detection of antibiotic kanamycin. This aptasensor was constructed by assembling graphene–polyaniline (GR–PANI) and polyamidoamine dendrimer–Au nanoparticle (PAMAM–Au) nanocomposites on the surfaces of a glass carbon electrode, which as electrode materials exhibited excellent charge-transport property and loading capacity of biomolecules. Followed by the sandwich-type specific identification, kanamycin detection was realized by outputting a redox current from electro-reduction reaction of H2O2 catalyzed by HRP. It was demonstrated that the developed strategy had a wide linear response range from 5 × 10−6 to 4 × 10−2 μg mL−1 and a low detection limit of 4.6 × 10−6 μg mL−1. Additionally, this aptasensor had the advantages in its low cost, high sensitivity, and superb specificity. Thus, it might provide a useful tool for kanamycin determination and related food safety analysis and clinical diagnosis.
Shuyun Meng,Ningning Zhang,Dong Liu,Xiuli Shen,Yuye Li,Fan Jia,Yang Yang,Tianyan You
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.
危险品化学品经营许可证（带存储）