title: Investigation of dual-layer membrane cloaking method by surface plasmon resonance for direct chronoamperometric immunoassay of serum sample.
abstract: A "dual-layer membrane cloaking" (DLMC) method was developed to construct disposable electrochemical immunosensor for direct determination of serum sample. Mouse IgG (MIgG) molecules were firstly immobilized on a substrate. After the formation of a didodecyldimethylammonium bromide (DDAB) membrane on the MIgG modified substrate, an additional bovine serum albumin (BSA) thin layer was formed to build a BSA/DDAB dual-layer membrane (DLM). When alkaline phosphatase conjugated anti-mouse IgG antibodies (anti-MIgG-ALP) in human serum were incubated on the substrate, anti-MIgG-ALP was recognized specifically by the immobilized MIgG while all nonspecifically adsorbed proteins were selectively removed together with BSA/DDAB DLM by 5% Triton X-100 (v/v) before final measurements. The BSA/DDAB DLM was characterized and optimized by surface plasmon resonance (SPR) technique, and further employed in a disposable immunoassay based on an ITO chip. Under optimal conditions, MIgG in human serum was directly detected in the range of 2.0-18.0 ng mL(-1) without dilution or separation. A limit of detection as low as 0.922 ng mL(-1) (6.15 pM) was obtained. The proposed DLMC method can efficiently prevent the penetration of matrix proteins through single cloaking membrane and completely eliminate nonspecific adsorption. It has great potential in providing a versatile way for direct determination of serum sample with ultra-sensitivity.
authors.affiliation: School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, PR China. daizong@mail.sysu.edu.cn
authors.forename: Zong
authors.initials: Z
authors.lastname: Dai
authors.forename: Yan
authors.initials: Y
authors.lastname: Yang
authors.forename: Hai
authors.initials: H
authors.lastname: Wu
authors.forename: Xiao-Yong
authors.initials: XY
authors.lastname: Zou
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D055664:Electrochemical Techniques / Q000379:methods*; D007118:Immunoassay / Q000379:methods*; D007074:Immunoglobulin G / Q000097:blood*; D051379:Mice; D017830:Octoxynol / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D015203:Reproducibility of Results; D012710:Serum Albumin, Bovine / Q000737:chemistry; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D007074:Immunoglobulin G; D000644:Quaternary Ammonium Compounds; C046112:didodecyldimethylammonium; D012710:Serum Albumin, Bovine; D017830:Octoxynol