title: An Enzyme-Free Signal Amplification Technique for Ultrasensitive Colorimetric Assay of Disease Biomarkers.
abstract: Enzyme-based colorimetric assays have been widely used in research laboratories and clinical diagnosis for decades. Nevertheless, as constrained by the performance of enzymes, their detection sensitivity has not been substantially improved in recent years, which inhibits many critical applications such as early detection of cancers. In this work, we demonstrate an enzyme-free signal amplification technique, based on gold vesicles encapsulated with Pd-Ir nanoparticles as peroxidase mimics, for colorimetric assay of disease biomarkers with significantly enhanced sensitivity. This technique overcomes the intrinsic limitations of enzymes, thanks to the superior catalytic efficiency of peroxidase mimics and the efficient loading and release of these mimics. Using human prostate surface antigen as a model biomarker, we demonstrated that the enzyme-free assay could reach a limit of detection at the femtogram/mL level, which is over 103-fold lower than that of conventional enzyme-based assay when the same antibodies and similar procedure were used.
authors.affiliation: Department of Chemistry, Michigan Technological University , Houghton, Michigan 49931, United States.
authors.forename: Haihang
authors.initials: H
authors.lastname: Ye
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20892, United States.
authors.forename: Kuikun
authors.initials: K
authors.lastname: Yang
authors.affiliation: Condensed Matter Physics & Materials Science Department, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: Jing
authors.initials: J
authors.lastname: Tao
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20892, United States.
authors.forename: Yijing
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20892, United States.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Condensed Matter Physics & Materials Science Department, Brookhaven National Laboratory , Upton, New York 11973, United States.|Department of Chemical Engineering, Michigan Technological University , Houghton, Michigan 49931, United States.
authors.forename: Sanaz
authors.initials: S
authors.lastname: Habibi
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20892, United States.
authors.forename: Zhihong
authors.identifier: 0000-0001-9639-905X
authors.initials: Z
authors.lastname: Nie
authors.affiliation: Department of Chemistry, Michigan Technological University , Houghton, Michigan 49931, United States.
authors.forename: Xiaohu
authors.identifier: 0000-0002-6372-7712
authors.initials: X
authors.lastname: Xia
mesh_terms: D015415:Biomarkers / Q000032:analysis; D003124:Colorimetry / Q000379:methods* / Q000592:standards*; D004797:Enzyme-Linked Immunosorbent Assay; D006046:Gold / Q000737:chemistry; D006801:Humans; D007495:Iridium / Q000737:chemistry; D008297:Male; D053768:Metal Nanoparticles / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D010316:Particle Size; D017430:Prostate-Specific Antigen / Q000032:analysis*; D011471:Prostatic Neoplasms / Q000737:chemistry* / Q000175:diagnosis*
chemical_list: D015415:Biomarkers; D007495:Iridium; D010165:Palladium; D006046:Gold; D017430:Prostate-Specific Antigen
keywords: biomarker; detection; enzyme mimic; gold vesicle; iridium nanoparticles