Electrosynthesized poly(1,6-hexanedithiol) as a new immobilization matrix for Au-nanoparticles-enhanced piezoelectric immunosensing

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2007-05, Vol.603 (1), p.96-106
• Main Authors: Fu, Yingchun, Xie, Qingji, Jia, Xue’en, Xu, Xiahong, Meng, Wenhua, Yao, Shouzhuo
• Format: Article
• Language: English
• Subjects: Au nanoparticles; Biological and medical sciences; Biosensors; Biotechnology; Combined electrochemical and piezoelectric impedance measurements; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; Piezoelectric immunosensor of anti-hIgG/hIgG; Poly(1,6-hexanedithiol); Various methods and equipments
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2007.01.016

Electrosynthesized poly(1,6-hexanedithiol) (PHDT) was proposed as a new immobilization matrix for Au-nanoparticles-enhanced piezoelectric immunosensing, with human immunoglobulin G (hIgG)/anti-hIgG as an example. In ethanol containing 0.10 M LiClO 4, the electropolymerization of 1,6-hexanedithiol (HDT) occurred through the oxidation of the –SH groups of HDT and then –S–S– linking at potentials positive of ∼0.7 V vs. SCE, as characterized by the electrochemical quartz crystal microbalance (EQCM). PHDT was prepared potentiostatically at 1.25 V vs. SCE, and Au nanoparticles (AuNPs) were then immobilized on the prepared PHDT films by dip-dry coating. The immobilization amount of AuNPs was investigated vs. the volume of dipped AuNPs solution, and a theoretical discussion is given on the coverage of AuNPs on the PHDT film. Under the optimized experimental conditions, the adsorption amount of anti-hIgG was the greatest on the AuNPs/PHDT/Au electrode, as compared with those at the bare Au and PHDT/Au electrodes. The molar combination ratio of anti-hIgG to hIgG was estimated to be 1:0.493 on the AuNPs/PHDT/Au electrode in a subsequent immunoreaction. Compared with the common immobilization protocol with HDT, namely, AuNPs immobilized directly on an HDT self-assembly (HDT-SA) at an Au electrode (AuNPs/HDT-SA/Au), the AuNPs/PHDT/Au electrode shows better stability and can be constructed more time-effectively, though the adsorption amount of anti-hIgG was comparable with each other. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were utilized for characterizations of and comparison among various surfaces. The electrosynthesized PHDT presented here as a new bio-immobilization matrix is highly recommended for wider applications in biosensing.