Detection of bovine mastitis biomarkers in milk by porous silicon optical biosensors

The proposed research specifically addresses the most prevalent health problem in dairy cows, which is a major problem for dairy industry worldwide, by developing a generic integrated biosensing platform for on-site monitoring applications. Bovine mastitis (BM) is one of the most frequent diseases in dairy cattle, having a large effect on farm economics, including increased treatment costs, decreased milk yield and even death. Traditional diagnostic methods check the quality of milk through the detection of mammary gland inflammation, diagnosis of infection and its causative microorganisms. However, all those techniques lack the ability to detect analyses in real-time or outside the laboratory boundaries. Even, the "on-site" California Mastitis Test has low sensitivity and difficulties in results interpretation. Therefore, there is an urgent need for a rapid, non-destructive, accurate, cost effective, simple and portable method to evaluate in real-time new cases of BM, that will be followed by corrective and/or prevention actions, leading to a positive effect on animal health and overall economy of the dairy farms. Herein, we have designed and fabricated an optical biosensing platform, based on porous Silicon (PSi) nanostructures, a Fabry-Pérot thin film, for the detection and quantification of BM predicting biomarkers - Haptoglobin (Hp) and N-acetyl-β-D-glucosaminidase (NAGase). We show specific detection assay by immobilizing Hemoglobin for the detection of Hp and horseradish peroxidase for indirect detection of NAGase, within the PSi nanostructure. The BM predicting biomarkers are monitored in real-time by reflective interferometric Fourier transform spectroscopy. Our studies reveal that the optical nanostructure capable of multitasking i.e., immobilization, size-exclusion separation, rapid and sensitive detection of specific biological targets in “real” milk samples, offering simultaneous real-time detection based on physical characteristics. Thus, the main advantage of the presented biosensing concept is the ability to detect BM predicting biomarkers in milk, using a simple and portable experimental setup.