Electrospun phospholipid polymer substrate for enhanced performance in immunoassay system.

A functional polymer bearing both phosphorylcholine and active ester groups, poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)-co-N-succinimidyloxycarbonyl di(ethylene glycol) methacrylate (PENHS)] (PMBS), provided a highly biomolecule-friendly platform for immunoassays. The nonbiofouling property of the PMBS remarkably reduces the background noise from nonspecific adsorption of proteins in the analyte in an enzyme-linked immunosorbent assay (ELISA), which improves the specificity and signal-to-noise ratio. Electrospinning deposition, a versatile and cost-effective technique, was employed to fabricate nanofibrous PMBS. This nanostructure increased the surface area of the polymer, allowing more antibodies to bind to the polymer interface and enhancing the sensitivity of the biosensing system. The electrospun PMBS fibers were stable and retained their unique morphologies after contact with an aqueous solution for 4.0 h. The ability of PMBS to reduce background noise without blocking by protein-based reagents was verified by comparison with an immunoassay conducted on a polystyrene substrate. The ELISA of human immunoglobulin-G with the electrospun PMBS substrate showed a good sigmoidal relationship with a linear detection range from 1.0 to 100 ng/mL. The detection time was 25% shorter than the conventional assay as the blocking step was omitted. The immobilized primary antibodies exhibited high stability on the electrospun PMBS; 60% and 25% of the residual bioactivity remained after storage in dry conditions for 2 and 4 weeks, respectively. Thus, for further development of biosensors, nanostructured PMBS can improve lifetime of immobilized biomolecules, and also contribute to an enhanced reliability and signal-to-noise ratio of immunoassay.