Abstract
A colorimetric immunoassay has been reported for prostate-specific antigen (PSA) detection with CuO nanoparticles (CuO NPs) as signal labels. The method is based on Cu2+-catalyzed oxidation of ascorbic acid (AA) by O2 to depress the formation of colored gold nanoparticles (AuNPs). Specifically, HAuCl4 can be reduced by AA to produce AuNPs in situ. In the presence of target, CuO NPs-labeled antibodies were captured via the sandwich-type immunoreaction. After dissolving CuO nanoparticles with acid, the released Cu2+ catalyzed the oxidation of AA by O2, thus depressing the generation of AuNPs. To demonstrate the accuracy of the colorimetric assay, the released Cu2+ was further determined by a fluorescence probe. The colorimetric immunoassay shows a linear relationship for PSA detection in the range of 0.1~10 ng/mL. The detection limit of 0.05 ng/mL is comparable to that obtained by other CuO NPs-based methods. The high throughput, simplicity, and sensitivity of the proposed colorimetric immunoassay exhibited good applicability for assays of serum samples.
Highlights
Biosensors have been developed for detection of various analytes in the fields of clinical diagnostics, food industry, pharmaceutical chemistry, and environmental science
In view of the high extinction coefficient of AuNPs, we developed an immunosensor by monitoring the generation of AuNPs, which is mediated by the Cu2+ -catalytic oxidation of ascorbic acid (AA)
The secondary anti-PSA was labeled with CuO nanoparticles (CuO NPs) (Ab2-CuO NPs)
Summary
Biosensors have been developed for detection of various analytes in the fields of clinical diagnostics, food industry, pharmaceutical chemistry, and environmental science. As to the recognition elements, antibodies are the most commonly used biorecognition molecules in construction of biosensors many efforts have being made to replace antibodies with alternative recognition molecules [1,2,3]. Immunoassays are still the most widespread analytical methods for the selective and sensitive detection of targets. Represents the most popular technique of immunoassays in many fields. There still remain some disadvantages about classical ELISA assays, including the complicated and time-consuming implementation procedure, the use of enzyme-labeled, fluorescent or chemiluminescent antibodies, and the bulky measurement instrument. Numerous attempts have being made to improve the conventional immunosensing concepts [4]
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