Estradiol free in Saliva ELISA

>Background:Estradiol (1,3,5(10)-estratriene-3,17β-diol; 17β-estradiol; E21) is a C18 steroid hormone with a molecular weight of 272.4 Dalton. It is the most potent natural estrogen, produced mainly by granulosa cells of the female ovary and the placenta by the aromatization of androstenedione to estrone, followed by conversion of estrone to estradiol by 17β HSD. Estradiol is also synthesized in other tissues including testicles, adrenal gland, fat tissue, liver, breast, and brain. Estradiol promotes cell proliferation and inhibits apoptosis in tumors (6-8). For this reason, estradiol plays important roles in the development of breast cancer especially in premenopausal and postmenopausal women. The plasma and saliva estradiol concentrations are significantly increased in breast cancer patients compared to those in healthy women. In plasma, estradiol is largely bound to SHBG and albumin. Only a fraction of 2.21% is free and biologically active, the percentage remaining constant throughout the menstrual cycle. Estradiol acts primarily as an agonist of the estrogen receptor (ER) subtypes ERα and ERβ, nuclear steroid hormone receptors which trigger the appropriate response at the nuclear level in the target sites. These sites include follicles, uterus, breast, vagina, urethra, hypothalamus, pituitary and to a lesser extent liver and skin. In the female, estradiol acts as a growth hormone for tissue of the reproductive organs. During the menstrual cycle, estradiol secretion follows a cyclic, biphasic pattern with the highest concentration found immediately prior to ovulation. This estradiol peak stimulates the hypothalamic-pituitary axis to secrete the gonadotropins follicle stimulating hormone (FSH) and luteinizing hormone (LH), which are essential for follicular maturation and ovulation. In the luteal phase, estradiol, in conjunction with progesterone, prepares the endometrium for implantation. During pregnancy, estradiol concentration increases due to placental production and high levels are sustained throughout pregnancy. Salivary steroid levels can reflect the circulating level of free steroid rather than total levels in serum, which is explained by the absence of circulating estradiol binding proteins. Therefore, saliva provides an excellent specimen for monitoring estradiol levels across the menstrual cycle or during hormone replacement therapy.

Description:
The Estradiol free in Saliva ELISA is a solid phase enzyme-linked immunosorbent assay based on the principle of competitive binding. The microtiter wells are coated with a polyclonal antibody (rabbit) directed towards antigenic sites of the estradiol molecule. During incubation, estradiol in the added sample competes with the added enzyme conjugate, which is estradiol conjugated to horseradish peroxidase, for binding to the coated antibody. After a washing step to remove all unbound substances, the solid phase is incubated with the substrate solution. The colorimetric reaction is stopped by addition of stop solution, and optical density (OD) of the resulting yellow product is measured. The intensity of color is inversely proportional to the concentration of the analyte in the sample. A standard curve is constructed by plotting OD values against concentrations of standards, and concentrations of unknown samples are determined using this standard curve.

Product features:
The kit contains reagents for 96 determinations;
Microtiter plate consisting of 12x8 (breakapart);
Microtiter plate reader at 450/620 nm;
Limit of detection: 0,716 pg/mL;
IVD