title: Irregular-shaped platinum nanoparticles as peroxidase mimics for highly efficient colorimetric immunoassay.
abstract: Enzyme-linked immunosorbent assay (ELISA) methods based on natural enzyme-labeled probes have been applied in the immunoassays, but most have some inevitable limitations (e.g. harsh preparation, purification and storage) and are unsuitable for routine use. Herein we synthesized a new class of irregular-shaped platinum nanoparticles (ISPtNP) with a mean length of 7.0 nm and a narrowing width from 2.0 to 5.0 nm along the longitudinal axes, which were utilized as peroxidase-like mimics for the development of colorimetric immunoassays. Compared with bioactive horseradish peroxidase (HRP), the synthesized ISPtNP exhibited a low Km value (~0.12 mM) and a high Kcat value (~2.27×10(4)s(-1)) for 3,3',5,5'-tetramethylbenzidine (TMB) with strong thermal stability and pH tolerance. The catalytic mechanism of the ISPtNP toward TMB/H2O2 was for the first time discussed and deliberated in this work. Based on a sandwich-type assay format, two types of colorimetric immunoassay protocols were designed and developed for the detection of rabbit IgG (RIgG, as a model) by using the synthesized ISPtNP and conventional HRP as the labeling of detection antibodies, respectively. Similar detection limits (LODs) of 2.5 ng mL(-1) vs. 1.0 ng mL(-1) were obtained toward RIgG with the ISPtNP labeling compared to HRP format. Intra- and inter-assay coefficients of variation were less than 13%. Importantly, the ISPtNP-based assay system could be suitable for use in a mass production of miniaturized lab-on-a-chip devices and open new opportunities for protein diagnostics and biosecurity.
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education and Fujian Province), Department of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Zhuangqiang
authors.initials: Z
authors.lastname: Gao
authors.forename: Mingdi
authors.initials: M
authors.lastname: Xu
authors.forename: Li
authors.initials: L
authors.lastname: Hou
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
mesh_terms: D000818:Animals; D040761:Biomimetic Materials / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D003124:Colorimetry; D004797:Enzyme-Linked Immunosorbent Assay; D006735:Horseradish Peroxidase / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007074:Immunoglobulin G / Q000032:analysis*; D056656:Lab-On-A-Chip Devices; D053768:Metal Nanoparticles / Q000737:chemistry*; D008904:Miniaturization; D009195:Peroxidase / Q000378:metabolism; D010984:Platinum / Q000737:chemistry*; D011817:Rabbits
chemical_list: D007074:Immunoglobulin G; D010984:Platinum; D006735:Horseradish Peroxidase; D009195:Peroxidase