title: Binding kinetics of biomolecule interaction at ultralow concentrations based on gold nanoparticle enhancement.
abstract: Measuring the kinetic constants of protein-protein interactions at ultralow concentrations becomes critical in characterizing biospecific affinity, and exploring the feasibility of clinical diagnosis with respect to detection sensitivity, efficiency and accuracy. In this study, we propose a method that can calculate the binding constants of protein-protein interactions in sandwich assays at ultralow concentrations at the pg/mL level, using a localized surface plasmon coupled fluorescence fiber-optic biosensor (LSPCF-FOB). We discuss a two-compartment model to achieve reaction-limited kinetics under the stagnant conditions of the reaction chamber. The association rate constant, dissociation rate constant, and the equilibrium dissociation constant, that is, k(a), k(d), K(D), respectively, of the kinetics of binding between total prostate-specific antigen (t-PSA) and anti-t-PSA at concentrations from 0.1 pg/mL to 1 ng/mL, were measured either in PBS or in human serum. This is the first time that k(a), k(d), and K(D) have been measured at such a low concentration range in a complex sample such as human serum.
authors.affiliation: Department of Optics and Photonics, National Central University, Taoyuan, Taiwan.
authors.forename: Li-Chen
authors.initials: LC
authors.lastname: Su
authors.forename: Ying-Feng
authors.initials: YF
authors.lastname: Chang
authors.forename: Chien
authors.initials: C
authors.lastname: Chou
authors.forename: Ja-an Annie
authors.initials: JA
authors.lastname: Ho
authors.forename: Ying-Chang
authors.initials: YC
authors.lastname: Li
authors.forename: Li-Dek
authors.initials: LD
authors.lastname: Chou
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Lee
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized / Q000276:immunology; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002417:Cattle; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007700:Kinetics; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D051379:Mice; D055100:Optical Fibers; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D013379:Substrate Specificity
chemical_list: D055910:Antibodies, Immobilized; D007074:Immunoglobulin G; D006046:Gold