title: An electrochemical immunosensor based on enzyme-encapsulated liposomes and biocatalytic metal deposition.
abstract: A novel electrochemical immunosensor based on double signal amplification of enzyme-encapsulated liposomes and biocatalytic metal deposition was developed for the detection of human prostate specific antigen (PSA). Alkaline phosphatase (ALP)-encapsulated and detection antibody-functionalized liposomes were first prepared and used as the detection reagent. In the sandwich immunoassay, the model analyte PSA was first captured by anti-PSA capture antibody immobilized on the electrode and then sandwiched with the functionalized liposomes. The bound liposomes were then lysed with surfactant to release the encapsulated ALP, which served as secondary signal amplification means. ALP on the electrode surface initiated the hydrolysis of ascorbic acid 2-phosphate (AA-p) to produce ascorbic acid. The latter, in turn, reduced silver ions on the electrode surface, leading to deposition of the metal silver on the electrode surface. Linear sweep voltammetry (LSV) was chosen to detect the amount of the deposited silver. The results showed that the anodic stripping peak current was linearly dependent on the PSA concentration in the range of 0.01-100 ng mL(-1), and a detection limit as low as 0.007 ng mL(-1) can be obtained. Since the cut-off value of human PSA is 4 ng mL(-1), the proposed electrochemical immunosensor would be expected to gain widespread applications for the detection of PSA in clinical diagnosis.
authors.affiliation: State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Bo
authors.initials: B
authors.lastname: Qu
authors.forename: Lei
authors.initials: L
authors.lastname: Guo
authors.forename: Xia
authors.initials: X
authors.lastname: Chu
authors.forename: Dan-Hong
authors.initials: DH
authors.lastname: Wu
authors.forename: Guo-Li
authors.initials: GL
authors.lastname: Shen
authors.forename: Ru-Qin
authors.initials: RQ
authors.lastname: Yu
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D000906:Antibodies / Q000032:analysis / Q000276:immunology; D055162:Biocatalysis; D004563:Electrochemistry; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008081:Liposomes / Q000378:metabolism*; D017430:Prostate-Specific Antigen / Q000032:analysis / Q000276:immunology; D012680:Sensitivity and Specificity; D012834:Silver / Q000737:chemistry*; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D000906:Antibodies; D004800:Enzymes, Immobilized; D008081:Liposomes; D013501:Surface-Active Agents; D012834:Silver; D000469:Alkaline Phosphatase; D017430:Prostate-Specific Antigen