IGF-1 ELISA Assay Kit
The IGF-1 ELISA Assay Kit is For Research Use Only
Size: 1×96 wells
Sensitivity: 0.11 ng/mL
Dynamic Range: 2 – 50 ng/ml
Incubation Time: 1.75 hours
Sample Type: Serum, Plasma
Sample Size: 10 µL
ng/mL = nmol/L x 0.13
nmol/L = ng/mL x 7.65
Product is manufactured by Mediagnost
Insulin-like growth factors (IGF) -I and -II play a pivotal role in regulating the proliferation, differentiation and specific functions of many cell types. IGF-I is identical with Somatomedin C (Sm-C) and has a molecular weight of 7649 daltons. Its major regulators are growth hormone (GH) and nutrition, although its production in specific tissues is affected by a multitude of tropic hormones and other peptide growth factors. In contrast to many other peptide hormones, IGFs are avidly bound to specific binding proteins (IGFBP). The seven classes of IGFBPs which are known at present either bind IGF-I and IGF-II with similar affinities or show a preference for IGF-II.
A major problem of IGF-I measurement results from the interference of IGFBPs in the assay. Direct determinations in untreated serum samples give false values because of the extremely slow dissociation of the IGF-I/IGFBP-3 complexes during the assay incubation. Depending on the ratio IGF-I to IGFBP the following errors may occur (see also Figure below):
Therefore, various techniques were applied to physically separate IGF-I from its binding proteins before measurement, including (a) size exclusion chromatography under acidic conditions, (b) solid-phase extraction and (c) acid-ethanol extraction. These techniques, however, are either inconvenient or time-consuming or give incomplete and not-reproducible recoveries. The most widely used method is the acid-ethanol extraction with a recovery of only 70-80 % of IGFBP-bound IGF-I as a result of co-precipitation. The absolute results of such an extraction are therefore falsely low . The extraction removes the IGFBPs only insufficiently and leads to reduction in sensitivity of the assay due to pre-dilution of the samples by the extraction procedure. Furthermore, the remaining IGFBP may still interfere in the assay. In addition, the acid-ethanol extraction is ineffective in specimens other than serum or plasma (e.g. cell culture media), in which determination of IGF-I is already difficult enough due to the fact that IGFBPs are frequently present at large excess.
To avoid these difficulties, an uncomplicated assay was developed, in which special sample preparation is not required before measurement.