Development of a biosensor immunoassay for the quantification of alphas1-casein in milk.
An immunoassay to quantify alphas1-casein (alphas1-CN) in milk using an optical biosensor, based on surface plasmon resonance (SPR) measurement, has been developed. The assay consists of a two-step sandwich strategy, with two anti-alphas1-CN antibodies directed against each extremity of the molecule. This strategy permits only intact alphas1-CN to be quantified and not its degradation products. The calibration curve was obtained using a reference milk powder with a known alphas1-CN concentration. Analysis time per sample was less than ten minutes. The antibody-coated surface could be used for more than 150 determinations. Detection limit was established at 0.87 microg/ml and the intra- and inter-assay variation coefficients were 2.86 and 5.31%, respectively. The method was applied to raw milk to quantify intact alphas1-CN, with no pretreatment of the sample. An initial analysis of 48 milk samples permitted alphas1-CN concentrations ranging from 8.8 to 12.06 mg/ml to be obtained.
Muller-Renaud
Stéphanie
S
INRA, Unité de Recherches en Technologie et Analyses Laitière, Place du Champ de Foire, F-39800 POLIGNY, France.
Dupont
Didier
D
Dulieu
Philippe
P
D000818:Animals; D000911:Antibodies, Monoclonal; D015374:Biosensing Techniques; D002138:Calibration; D002364:Caseins / Q000032:analysis* / Q000276:immunology; D002417:Cattle; D007118:Immunoassay / Q000379:methods; D008892:Milk / Q000737:chemistry*; D012680:Sensitivity and Specificity
D000911:Antibodies, Monoclonal; D002364:Caseins