title: A universal multicolor immunosensor for semiquantitative visual detection of biomarkers with the naked eyes.
abstract: 3, 3', 5, 5'-tetramethylbenzidine (TMB) has been widely used as a chromogenic substrate for colorimetric immunoassays. Normally, the colorless TMB is oxidized into yellow TMB2+(in acidic solution) to indicate the presence of the target molecules. However, this kind of monochromic intensity changes seriously confine the accuracy of visual inspection. Herein, we demonstrate for the first time that TMB2+can quantitatively and efficiently etch gold nanorods (AuNRs). The addition of AuNRs into a solution containing different amount of TMB2+generates vivid color responses as colorful as a rainbow, and the etching process can be finished within 90s. As a result, the exact concentration of TMB2+can be easily distinguished with the naked eyes by the corresponding solution color. Based on this finding, we incorporate AuNRs into the well-developed, commercially available horseradish peroxidase (HRP)-TMB immunoassay system, so that it can be utilized for semiquantitative detection of a broad range of disease biomarkers with the naked eyes (termed 'NEQ-IA'). Carcinoembryonic antigen (CEA) and Prostate specific antigen (PSA) had been chosen as example targets to test the feasibility of the proposed biosensor. The results showed good accordance with the conventional methods. Because no sophisticated apparatus but human eyes are used as the readout, the proposed NEQ-IA could be a good supplementary to current state-of-the-art immunoassay methods for those applications that require the use of portable and affordable devices, for example, for the detection of disease biomarkers at home and in the field.
authors.affiliation: State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China; MOE Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Institute of Nanomedicine and Nanobiosensing, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China; MOE Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Institute of Nanomedicine and Nanobiosensing, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China; MOE Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Institute of Nanomedicine and Nanobiosensing, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China. Electronic address: guolh@fzu.edu.cn.
authors.forename: Longhua
authors.initials: L
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China; MOE Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Institute of Nanomedicine and Nanobiosensing, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China.
authors.forename: Bin
authors.initials: B
authors.lastname: Qiu
authors.affiliation: State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China; MOE Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Institute of Nanomedicine and Nanobiosensing, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China.
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China; MOE Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Institute of Nanomedicine and Nanobiosensing, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China.
authors.forename: Huang-Hao
authors.initials: HH
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China; MOE Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Institute of Nanomedicine and Nanobiosensing, College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116 China. Electronic address: zylin@fzu.edu.cn.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Lin
mesh_terms: D001560:Benzidines / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D002272:Carcinoembryonic Antigen / Q000097:blood*; D003124:Colorimetry / Q000379:methods; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D017430:Prostate-Specific Antigen / Q000097:blood*
chemical_list: D001560:Benzidines; D002272:Carcinoembryonic Antigen; C021758:3,3',5,5'-tetramethylbenzidine; D006046:Gold; D017430:Prostate-Specific Antigen
keywords: Carcinoembryonic antigen; Colorimetric detection; ELISA; Gold nanorods; Immunoassay