New Solid Phases for Estimation of Hormones by Radioimmunoassay Technique

The efforts in this study were initiated to develop and validate new solid phases for estimation of hormones by radioimmunoassay (RIA). The study argued the successful application of different hydroxyapatites (HAP) as new solid phases for estimation of Alpha fetoprotein (AFP), Thyroid Stimulating hormone (TSH) and Luteinizing hormone (LH) in human serum. Hydroxyapatites have different alkali earth elements were successfully prepared by a well-controlled co-precipitation method with stoichiometric ratio value 1.67. The synthesized barium and calcium hydroxyapatites were characterized using XRD and FTIR and data clarified the preparation of pure structures of both BaHAP and CaHAP with no evidence on presence of other additional phases. The prepared solid phases were applied in various radioimmunoassay systems for separation of bound and free antigens of AFP, TSH and LH hormones. The preparation of radiolabeled tracer for these antigens was carried out using chloramine-T as oxidizing agent. The influence of different parameters on the activation and coupling of the used apatite particles with the polyclonal antibodies was systematically investigated and the optimum conditions were determined. The assay was reproducible, specific and sensitive enough for regular estimation of the studied hormones. The intra-and inter-assay variation were satisfactory and also the recovery and dilution tests indicated an accurate calibration. The reliability of these apatite particles had been validated by comparing the results that obtained by using commercial kits. The results finally authenticates that hydroxyapatite particles would have a great potential to address the emerging challenge of accurate quantitation in laboratory medical application.