title: A signal-off sandwich photoelectrochemical immunosensor using TiO2 coupled with CdS as the photoactive matrix and copper (II) ion as inhibitor.
abstract: In this work, a novel sandwich photoelectrochemical (PEC) biosensor was developed based on a signal-off strategy using TiO2 coupled with CdS quantum dots (QDs) as the photoactive matrix and copper (II) ion (Cu(2+)) as inhibitor. TiO2/CdS modified indium tin oxide (ITO) electrode was employed for primary antibody (Ab1) immobilization and the subsequent sandwich-type antibody-antigen (Ab-Ag) affinity interactions. Flower-like copper oxide (CuO) was used as labels of secondary antibody (Ab2) and immobilized on the modified electrode via specific affinity interactions between Ab2 and Ag. Cu(2+) was released by dissolving CuO with HCl, and then reacted with CdS to form CuxS (x=1, 2), which would create new energy levels for electron-hole recombination and resulted in a decrease of the photocurrent. CuO, as the labels of Ab2, was first applied in PEC biosensor based on the signal-off strategy of the Cu(2+) for CdS. Greatly enhanced sensitivity was achieved through the coupling of CdS QDs with TiO2. Besides, the introduction of polythiophene (PT-Cl) on the surface of TiO2 made the PEC signal more stable. Under 405nm irradiation at 0.1V, the PEC biosensor for H-IgG determination exhibited a linear range from 0.1pgmL(-1) to 100ngmL(-1) with a low detection limit of 0.03pgmL(-1). The proposed biosensor showed high sensitivity, stability and selectivity, which opens up a new promising signal-off PEC platform for future bioassay.
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Yixin
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Rongxia
authors.initials: R
authors.lastname: Li
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Picheng
authors.initials: P
authors.lastname: Gao
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Hongmin
authors.initials: H
authors.lastname: Ma
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Jiaojiao
authors.initials: J
authors.lastname: Yang
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China.
authors.forename: Bin
authors.initials: B
authors.lastname: Du
authors.affiliation: Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China. Electronic address: sdjndxwq@163.com.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wei
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D002413:Cations, Divalent / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007074:Immunoglobulin G / Q000032:analysis*; D057230:Limit of Detection; D011108:Polymers / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry*; D013876:Thiophenes / Q000737:chemistry; D014025:Titanium / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D002413:Cations, Divalent; D007074:Immunoglobulin G; D011108:Polymers; D013440:Sulfides; D013876:Thiophenes; C034939:cadmium sulfide; C009495:titanium dioxide; C066730:polythiophene; D003300:Copper; D014025:Titanium; C030973:cupric oxide
keywords: Cu(2+) inhibitor; Photoelectrochemical biosensor; Sandwich; Signal-off strategy