A PEG piezoelectric immunoassay for the determination of transferrin in human serum

A new liquid piezoelectric immunoassay, termed as PEG piezoelectric immunoa ssay, has been proposed for the direct determination of transferrin in huma n serum. The method is based on the agglutination of antigen and antibody b y immunoreaction with PEG as a promotor. The response mechanism of the meth od was investigated in detail. It was found that some immune agglutinates w ere adsorbed onto the crystal surface and played an important role in the f requency response of the piezoelectric crystal. The effects of the concentr ation and molecular weight of PEG, the TA dilution and the reaction tempera ture on the response frequency were studied in detail. Under the optimized conditions, the linear detection ranges for transferrin concentration obtai ned by the end-point method and by the initial rate method were 0.24-8.36 a nd 0.16-8.27 mug ml(-1), respectively. The detectable concentration matches the demands of clinical assays. Seven clinical samples were analyzed by th e method, and the analytical results were in satisfactory agreement with th ose given by the rate diffusion turbidimetry. With a simple regeneration, p iezoelectric crystal can be used for more than a hundred times with no decr ease in sensitivity. (C) 2000 Elsevier Science B.V. All rights reserved.