Study on the Simultaneously Quantitative Detection for β-Lactoglobulin and Lactoferrin of Cow Milk by Using Protein Chip Technique

Objective To research a protein chip method which can simultaneously quantitative detect beta-Lactoglobulin (beta-L) and Lactoferrin (Lf) at one time. Methods Protein chip printer was used to print both anti-beta-L antibodies and anti-Lf antibodies on each block of protein chip. And then an improved sandwich detection method was applied while the other two detecting antibodies for the two antigens were added in the block after they were mixed. The detection conditions of the quantitative detection for simultaneous measurement of beta-L and Lf with protein chip were optimized and evaluated. Based on these detected conditions, two standard curves of the two proteins were simultaneously established on one protein chip. Finally, the new detection method was evaluated by using the analysis of precision and accuracy. Results By comparison experiment, mouse monoclonal antibodies of the two antigens were chosen as the printing probe. The concentrations of beta-L and Lf probes were 0.5 mg/mL and 0.5 mg/mL, respectively, while the titers of detection antibodies both of beta-L and Lf were 1: 2,000. Intra- and inter-assay variability was between 4.88% and 38.33% for all tests. The regression coefficients of protein chip comparing with ELISA for beta-L and Lf were better than 0.734, and both of the two regression coefficients were statistically significant (r = 0.734, t = 2.644, P = 0.038; and r = 0.774, t = 2.998, P = 0.024). Conclusion A protein chip method of simultaneously quantitative detection for beta-L and Lf has been established and this method is worthy in further application.