Highly sensitive electrochemical detection of proteins using aptamer-coated gold nanoparticles and surface enzyme reactions.
A novel electrochemical detection methodology is described for the femtomolar detection of proteins which utilizes both DNA aptamer-functionalized nanoparticles and a surface enzymatic reaction. Immunoglobulin E (IgE) was used as a model protein biomarker, which possesses two distinct epitopes for antibody (anti-IgE) and DNA aptamer binding. A surface sandwich assay format was utilized involving the specific adsorption of IgE onto a gold electrode surface that was pre-modified with a monolayer of aptamer-nanoparticle conjugates followed by the specific interaction of alkaline phosphatase (ALP) conjugated anti-IgE. To clearly demonstrate the signal enhancement associated with nanoparticle use, anodic current measurements of the ALP catalyzed oxidation of the enzyme substrate 4-aminophenylphosphate (APP) were also compared with electrode surfaces upon which the aptamer was directly attached. The detection of an unlabelled protein at concentrations as low as 5 fM is a significant improvement compared to conventional electrochemical-based immunoassay approaches and provides a foundation for the practical use and incorporation of nanoparticle-enhanced detection into electrochemical biosensing technologies.
Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National University, 1370 Sankyuk-dong, Buk-gu, Daegu-city, 702-701, Republic of Korea.
Eun Ji
EJ
Nam
Eum Ji
EJ
Kim
Alastair W
AW
Wark
Sangchul
S
Rho
Hyungi
H
Kim
Hye Jin
HJ
Lee
D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry* / Q000378:metabolism; D015374:Biosensing Techniques / Q000379:methods*; D002415:Cats; D004563:Electrochemistry; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis* / Q000378:metabolism; D053768:Metal Nanoparticles / Q000737:chemistry*; D013499:Surface Properties
D052157:Aptamers, Nucleotide; D007073:Immunoglobulin E; D006046:Gold; D000469:Alkaline Phosphatase