Fluorescence immunoassay for HBsAg using a thermal phase separating polymer

A novel fluorescence immunoassay for HBsAg was developed by using polyNisopropylacrylamide(PNIP) as an immunoreaction carrier. In sandwich immunoassay, after two steps immunoreaction, PNIP precipitates out of water above a critical temperature of 31 , enabling a polymerbound immune complex to be separated from the solution. The calibration graph for HBsAg was linear over the range of 05100 g/mL with a detection limit of \{10 ng/mL\}. This method combines some advantages of both homogeneous and heterogeneous immunoassays, and has been applied to determining the HBsAg in human blood serum with satisfactory results.