title: Antibody immobilization on to polystyrene substrate--on-chip immunoassay for horse IgG based on fluorescence.
abstract: A simple microfluidic immunoassay card was developed based on polystyrene (PS) substrate for the detection of horse IgG, an inexpensive model analyte using fluorescence microscope. The primary antibody was captured onto the PS based on covalent bonding via a self-assembled monolayer (SAM) of thiol to pattern the surface chemistry on a gold-coated PS. The immunosensor chip layers were fabricated from sheets by CO(2) laser ablation. The functionalized PS surfaces after each step were characterized by contact angle measurement, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). After the antibody-antigen interaction as a sandwich immunoassay with a fluorescein isothiocyanate (FITC)-conjugated secondary antibody, the intensity of fluorescence was measured on-chip to determine the concentration of the target analyte. The present immunosensor chip showed a linear response range for horse IgG between 1 microg/ml and 80 microg/ml (r = 0.971, n = 3). The detection limit was found to be 0.71 microg/ml. The developed microfluidic system can be extended for various applications including medical diagnostics, microarray detection and observing protein-protein interactions.
authors.affiliation: Biomedical Engineering Research Centre, Nanyang Technological University, Singapore, 639553, Singapore. farzana@ntu.edu.sg
authors.forename: Farzana
authors.initials: F
authors.lastname: Darain
authors.forename: Kai Ling
authors.initials: KL
authors.lastname: Gan
authors.forename: Swee Chuan
authors.initials: SC
authors.lastname: Tjin
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized / Q000276:immunology* / Q000378:metabolism; D015374:Biosensing Techniques / Q000295:instrumentation*; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D004867:Equipment Design; D019793:Fluorescein / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D006046:Gold / Q000737:chemistry; D006736:Horses / Q000276:immunology*; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods; D007074:Immunoglobulin G / Q000032:analysis*; D044085:Microfluidics / Q000295:instrumentation / Q000379:methods; D018625:Microscopy, Atomic Force; D018448:Models, Immunological; D011137:Polystyrenes / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods; D013379:Substrate Specificity; D013499:Surface Properties
chemical_list: D055910:Antibodies, Immobilized; D020099:Coated Materials, Biocompatible; D005456:Fluorescent Dyes; D007074:Immunoglobulin G; D011137:Polystyrenes; D006046:Gold; D019793:Fluorescein