[31]. Taking an account the advantages and methods used for nanoparticles, many researchers have prepared modified AuNPs surfaces by the direct covalent linking of the Ab to the nanoparticles and assembling them onto the electrode surface [32]. Xu et al. developed a gold nanorods (GNRs)-Ab conjugate in which the antibody was covalently attached to GNRs with a special spatial conformation through amide (CO-NH) bonds to produce specific sensing probes for the sensitive detection of ��-fetoprotein (AFP) [33].Therefore, here we coupled anti-carbofuran Ab covalently to AuNPs with glutathione as a spacer arm. The presence of carboxyl group at the terminal end of glutathione on the AuNPs surface allowed further modification of the surface using covalent coupling reactions.

The immobilization of Ab on AuNPs was carried out through a stable covalent link between the carboxyl group on the carbon-terminal of the Ab and glutathione capped AuNPs and this process was effected by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and 1,6-diaminohexane (DAH). This kind of approach provided a stable Ab immobilization with free hapten binding sites for further immunoreaction without affecting the structure and function of the Ab. The AuNPs also are good for the immobilization of the Ab onto the electrode and preventing them from dissolving back into the bulk solution.As mentioned above, we introduce a MWCNTs, GS-PEI-Au nanocomposites and AuNPs-antibody conjugate-modified amperometric immunosensor for the detection of carbofuran.

The aim of this work was to develop a fast, simple, inexpensive, stable and highly sensitive immunosensor for carbofuran detection. The experimental conditions related to the performance of the fabricated immunosensor (the thickness of the GS-PEI-Au layer, the pH of the supporting electrolyte, immunoassay temperature and incubation time) were investigated in detail.2.?Experimental2.1. MaterialsAnti-carbofuran monoclonal antibody, carbofuran, bovine serum albumin (BSA, 96�C99%), and EDC were all purchased from Sigma (Beijing, China). HAuCl4 was from Shanghai Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China). GS were obtained from Nanoon Co., Ltd. (Beijing, China). MWCNTs were purchased from Xfnano Co. Ltd. (Nanjing, China). PEI (Mn = 600) were purchased from Shanghai Crystal Pure Reagent Co. Ltd. (Shanghai, China).

Carbofuran was a standard grade product and other reagents were of analytical grade and distilled water was used throughout the experiments. Entinostat Anti-carbofuran monoclonal antibody was dissolved with 0.01 M phosphate buffer solution (PBS, pH 7.4) processed by high-pressure sterilization and stored at 4 ��C. 0.1 M 2-(N-Morpholino)ethanesulfonic acid buffer (MES, pH 5.0) was filtered to remove impurities and bacteria before use. A PBS (0.1 M, pH 7.0) containing 5 mM [Fe(CN)6]3?/4? (1:1) and 0.1 M KCl was used as the detection solution.2.2.