Abstract
There are two parts of work included in this study. The first part of work deals with the fabrication of immunosensors for the detection of progesterone, based on a liposomal competitive assay. Two different sensing platforms were presented herein for the development of the progesterone sensors, one is nitrocellulose membrane-based immunochromatographic approach with optical density measurement; and the other is screen-printed electrode strip with electrochemical detection. Immobilized anti-progesterone antibody on the detection surface, the progesterone-modified liposome, and the sample progesterone altogether in a competitive manner form a perfect immunosensing platform for the detection of progesterone. With nitrocellulose membrane as the detection surface, the calibration curve for progesterone shows a linear range from 10-6 to 10-11 g/mL with a limit of detection (LOD) of 108 pg/mL. As in the case of electrochemical immunoassay, the calibration curve for progesterone depicts a linear range from 10-4 to 10-13 g/mL with LOD of 0.83 pg/mL. It was reported that the concentration of progesterone is about 0.3~0.97 ng/mL in male blood; and in case of female, 0.15~0.7 ng/mL was found in follicular phase and 2.0~25 ng/mL in luteal phase. Both immunochromatographic and electrochemical method clearly shows high selectivity and sensitivity towards progesterone detection in human blood samples. The second part of work describes the development of an electrochemical immunosensor for Luteinizing hormone based on liposomal sandwich assay. In this study, the anti-Luteinizing hormone antibody was immobilized on the screen printed carbon electrode firstly; follow by the sequential addition of sample Luteinizing hormone and anti-Luteinizing hormone-tagged liposome to form a sandwich immunocomplex. The calibration curve for Luteinizing hormone obtained using this newly developed assay has a linear range 0.1 to 1000 mIU/mL with LOD of 0.23 mIU/mL. It has been reported that the level of Luteinizing hormone is about 1.24~7.8 mIU/mL in males and in case of females, 1.68~15 mIU/mL was observed in follicular phase and 0.61~16.3 mIU/mL in luteal phase; 21.9~56.6 mIU/mL before ovulation. It is clear that the detection limit of our immunosensor falls well under this range. Our ultimate goal is to develop an immunosensor for co-detection of Luteinizing hormone and progesterone; therefore, the possible interference from each other must be investigated. We found that the present design is able to detect Luteinizing hormone in the presence progesterone without occurrence of significant interference, and vice versa. We thus conclude that sensors developed herein offer rapid, simple, and sensitive detection approaches and hold promise for the future of healthcare. Such sensors can be further extended to be point-of-care, in-vitro diagnostic kits for the detection of progesterone and Luteinizing hormone, and become an useful ovulation calculator, helping to pinpoint when one ovulates.