Conjugated polymer as a signal amplifier for novel silica nanoparticle-based fluoroimmunoassay.
Immunoassays are conventional methods for protein detection, which rely on specific antibody-antigen recognition. Very few strategies have been developed for signal amplification of immunoassays. In this work, we report a conjugated polymer amplified silica nanoparticle (NP)-based immunoassay for IgG detection. After immobilization of the prime antibody on the NP surface, the NPs are used to capture antigen and Cy3 labeled secondary antibody in a sandwich assay format. The presence of target antigen in solution brings the fluorescent Cy3 molecules to the NP surface. Addition of a cationic conjugated polymer further amplifies the fluorescence signal of the dye, which improves the assay sensitivity and selectivity. Within the tested concentration range, a linear response for IgG detection is observed from 0 to 1 microg/mL with a detection limit of approximately 1.1 ng/mL. Due to the pink color of Cy3 molecules, the assay also allows naked eye detection of IgG with a detection limit of 50 ng/mL. The polymer amplified NP assay represents a simple strategy for antigen detection with high sensitivity and selectivity.
Wang
Yanyan
Y
Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore.
Liu
Bin
B
D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology; D015374:Biosensing Techniques / Q000295:instrumentation*; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation*; D007074:Immunoglobulin G / Q000032:analysis* / Q000737:chemistry / Q000276:immunology; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D011108:Polymers / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*
D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D011108:Polymers; D012822:Silicon Dioxide