Preparation of temperature-sensitive polymer with regulated phase transition temperature and its application in the fluoroimmunoassay

A novel temperature-sensitive polymer, poly(N-isopropylacrylamide-co-acrylamide) [P(NIP-co-AA)], was synthesized.. Its lower critical solution temperature (LCST) could be regulated by changing the content of acrylamide for different purposes. The P(NIP-co-AA) with phase transition temperature (T-tr) of 37degreesC was used as a separating carrier for the reactants in immunoassay and a sandwich fluorescence immunoassay for rabbit IgG was established. The sensitivity of this method was comparable to that using poly-N-isopropylacrylamide (PNIP) as a carrier. However, owing to the elevation of T-tr of the polymer, the immunoreaction could be carried out at a temperature closer to the physiological environment of organism and the rate of inummoreaction was faster. The linear range of determination was 0 similar to 1000 mug/L and the limit of detection was 10 mug/L. This method has been applied to the determination of the rabbit IgG levels in rabbit serum with satisfactory results.