title: Aptamer-Au NPs conjugates-accumulated methylene blue for the sensitive electrochemical immunoassay of protein.
abstract: In this paper, we combine the advantages of aptamer, nanomaterial and antibody to design an electrochemical sandwich immunoassay for the ultrasensitive detection of human immunoglobulin E (IgE) by using methylene blue (MB) as electrochemical indicator. The sandwich structure is fabricated by using goat anti-human IgE as capturing probe. Aptamer-Au nanoparticles (NPs) conjugates are used both as a sandwich amplification element as well as an accumulation reagent of MB. Once the aptamer-Au NPs conjugates specifically bind to electrode surface, MB molecules are accumulated on its surface by the specific interaction of MB with G base of aptamer-Au NPs conjugates. Therefore, with the increase of human IgE concentration, more aptamer-Au-NPs conjugates are bound, and thus, more MB molecules are accumulated. A good linear relationship is obtained for the detection of human IgE over a range of 1-10,000 ng/ml with a lowest detection limit of 0.52 ng/ml. In addition, by using BSA, human IgA and human IgM as contrast, the excellent specificity of this sensing system for the detection of human IgE is also demonstrated.
authors.affiliation: Department of Chemical Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA.
authors.forename: Jianlong
authors.initials: J
authors.lastname: Wang
authors.forename: Ahsan
authors.initials: A
authors.lastname: Munir
authors.forename: Zhonghong
authors.initials: Z
authors.lastname: Li
authors.forename: H Susan
authors.initials: HS
authors.lastname: Zhou
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D052157:Aptamers, Nucleotide / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D015374:Biosensing Techniques / Q000379:methods*; D002417:Cattle; D004563:Electrochemistry; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007073:Immunoglobulin E / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D008751:Methylene Blue / Q000737:chemistry*
chemical_list: D000906:Antibodies; D052157:Aptamers, Nucleotide; D007073:Immunoglobulin E; D006046:Gold; D008751:Methylene Blue