title: In Situ Generation of Electron Donor to Assist Signal Amplification on Porphyrin-Sensitized Titanium Dioxide Nanostructures for Ultrasensitive Photoelectrochemical Immunoassay.
abstract: An ultrasensitive photoelectrochemical (PEC) immunoassay protocol for quantitative detection of low-abundant proteins at a low potential was designed by utilizing porphyrin-sensitized titanium dioxide (TiO2) nanostructures. Experimental results demonstrated that the water-soluble 5,10,15,20-tetra(4-sulfophenyl)-21H,23H-porphyrin (TSPP) could be bound onto titanium dioxide via the sulfonic group. TSPP-sensitized TiO2 nanostructures exhibited better photoelectrochemical responses and stability in comparison with TiO2 nanoparticles alone under continuous illumination. Using carcinoembryonic antigen (CEA) as a model analyte, a typical PEC immunosensor by using TSPP-TiO2 as the affinity support of anti-CEA capture antibody (Ab1) to facilitate the improvement of photocurrent response was developed. Bioconjugates of secondary antibody and glucose oxidase with gold nanoparticles (Ab2/GOx-AuNPs) was introduced by an antigen-antibody immunoreaction. AuNP acted as a powerful scaffold to bind with bioactive molecules, while GOx catalyzed glucose to in situ generate hydrogen peroxide (H2O2). The generated H2O2 as a sacrificial electron donor could be oxidized by the photogenerated holes to assist the signal amplification at a low potential under light excitation, thus eliminating interference from other species coexisting in the samples. Under optimal conditions, the PEC immunosensor showed a good linear relationship ranging from 0.02 to 40 ng mL(-1) with a low detection limit of 6 pg mL(-1) CEA. The precision, reproducibility, and specificity were acceptable. In addition, the method accuracy was also evaluated for quantitatively monitoring human serum samples, giving results matching with the referenced CEA ELISA kit.
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Shu
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Zhenli
authors.initials: Z
authors.lastname: Qiu
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Junyang
authors.initials: J
authors.lastname: Zhuang
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Mingdi
authors.initials: M
authors.lastname: Xu
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
mesh_terms: D015374:Biosensing Techniques; D002272:Carcinoembryonic Antigen / Q000737:chemistry / Q000302:isolation & purification*; D004579:Electron Transport; D005949:Glucose Oxidase / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007118:Immunoassay / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry; D014025:Titanium / Q000737:chemistry
chemical_list: D002272:Carcinoembryonic Antigen; D011166:Porphyrins; C009495:titanium dioxide; C016136:tetraphenylporphine sulfonate; D006046:Gold; D006861:Hydrogen Peroxide; D014025:Titanium; D005949:Glucose Oxidase
keywords: carcinoembryonic antigen; hybrid nanostructures; photocurrent; photoelectrochemical immunoassay; porphyrins; titanium dioxide nanostructures