Measurement of Bovine Somatotropin (bST) and Insulin-like Growth Factor-1 (IGF-1) in Bovine Milk Using an Electrochemiluminescent Assay

Abstract

Bovine somatotropin (bST) and insulin-like growth factor-1 (IGF-1) are peptide hormones that are involved in the regulation of milk production in dairy cows. Because these hormones are present at extremely low concentration in fresh and processed bovine milk, a highly sensitive and specific electrochemiluminescent immunoassay (ECLIA) has been developed to better estimate the concentration of these hormones in milk. The assay employs an imager, a capture antibody bound to a carbon electrode, and a detection antibody coupled to a ruthenium label. In the presence of tripropylamine and an electric pulse, ruthenium generates light proportional to the amount of antigen bound, and the light is captured as signal by a charge-coupled device (CCD) camera. Using bovine milk as the starting matrix, 99.69% of bST and 104.79% of IGF-1 were recoverable. The limit of detection (LOD) was <5 pg/mL for bST and <1 pg/mL for IGF-1. The limit of quantification (LOQ) was <14 pg/mL for bST in milk and <2 pg/mL of IGF-1. The assay is highly specific and shows <0.2% cross-reactivity with other peptide hormones found in bovine milk such as insulin and IGF-2. These data indicate this new, ECLIA is highly sensitive and specific for estimating the concentration of bST or IGF-1 in milk.

Nano-islands integrated evanescence-based lab-on-a-chip on silica-on-silicon and polydimethylsiloxane hybrid platform for detection of recombinant growth hormone

“…The concentration of bST in milk is reported to be of the order of 1-10 ng/ml. 46 The rbST may be found in the milk of the cattle treated with rbST, and concentration of rbST present in the milk may be of the order of hundreds of ng/ml, 47 depending on the quantity of the rbST used for the production of milk. Hence the proposed device is suitable for the detection of rbST in milk.…”

The Promise and Challenges of Determining Recombinant Bovine Growth Hormone in Milk

“…However, rbGH detection in milk present several challenges, mainly related to the sensitivity required for its detection. Indeed, while physiological concentration of rbGH in blood is reported to range from 1 to 10 ng/mL [29,30], it is expected to fluctuate around 1 ng/mL in milk [31]. In addition, rbGH kinetic of elimination in blood suggests that the hormone is detectable only between 4 h and four days after treatment in cow serum [32].…”

“…Extracting and purifying a specific protein like rbGH from such a complex environment requires an accurate knowledge of these components in order to define the appropriate physical-chemical conditions and parameters for a suitable and effective protocol. Based on the physico-chemical properties of rbGH described above (Mw, pI) and considering the very low levels of concentration expected in milk (1-2 mg/mL) [31,37], the main components that should be a problem for the efficient analysis of these residues in milk are detailed below.…”

An immunoenzymatic assay to measure insulin-like growth factor 1 (IGF-1) in buffalo milk with an IGF binding protein blocking pre-treatment of the sample

“…Recently, a new ELISA-based method was developed to measure IGF-1 in milk (McGrath et al, 2008) with a superb performance in terms of sensitivity. Nevertheless, pre-treatment of the samples needed time up to 72 h and the assay required a particular detection system (a charge-coupled device camera), which is much more expensive than the common plate readers, and thus not affordable in all laboratories.…”