Poly(N-isopropylacrylamide) microgel-based sensor for progesterone in aqueous samples

Progesterone (P4) is a vital steroid hormone involved in the reproduction cycle and necessary for maintenance of pregnancy in humans and animals. Monitoring P4 concentrations is required in various fields, such as dairy industry, environmental protection, and clinical laboratories. The current available methods for P4 determination are either expensive or time consuming. Therefore, more affordable and easy-to-use sensor technologies for P4 detection are needed. Here, we describe a sensor composed of anti-P4 antibody-modified poly(N-isopropylacrylamide) (pNIPAm) microgels that can be used to construct an optical device (etalon) capable of detecting P4. The binding of P4 and anti-P4 antibodies induces collapse of the pNIPAm microgels in the etalon, resulting in an optical response from the sensor that depends on P4 concentration in solution. Using this developed sensor, a linear detection range of 0.28 to 30 ng/mL P4 could be achieved with a detection limit of 0.28 and 0.25 ng/mL at room temperature and 30 A degrees C, respectively. Moreover, the sensor showed low cross-reactivity with 17 beta-estradiol (E2), demonstrating that the sensor can be used to quantify P4 in the presence of the interference E2.