Toward immunoassay chips: Facile immobilization of antibodies on cyclic olefin copolymer substrates through
Daekyung Sung1, Dong Ho Shin2, Sangyong Jon3
1Graduate Program of Medical System Engineering (GMSE), School of Life Sciences, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, Republic of Korea.
Abstract:
Our research efforts have focused on the surface modification and the potential as a biochip material of commercially available cyclic olefin copolymer (COC) substrates. For the surface modification of hydrophobic COC substrates we synthesized two types of amphiphilic polymers having three important functions: hydrophobic (dodecyl or benzyl) groups, serving to anchor the COC substrate; a PEG component, which acts as a repellent of non-specific biomolecules; and an NHS ester group for conjugation of biomolecules. Formation of the polymer adlayers on COC surface was confirmed using a contact angle analyzer. The anti-biofouling property of the polymer-coated COC surface was examined by measuring the extent of nonspecific adsorption of immunoglobulin G (IgG), resulting in a very low level of the protein adsorption compared to uncoated COC surfaces (control). In addition, antibodies, used as representative biomolecules for immunoassay, could be selectively immobilized on the polymer-coated COC surface. Sandwich immunoassay using anti-rabbit IgG immobilized COC surface showed linear response to rabbit IgG of model analyte over a range from 1 to 1000 ng/mL with detection limit of 1-10 ng/mL. We also fabricated a Lab-On-a Chip type of COC biochip, which could detect a cardiac marker protein, troponin I (TnI), with detection limit of 10 ng/mL.
