Portable and affordable device for on-site quantitative detection of somatic cells in milk

Antimicrobial resistance in mastitis-associated pathogens has heightened concerns over the safety of raw milk, which transmits pathogens from animals to humans. Elevated somatic cell count (SCC) is widely recognized as a key indicator of microbial quality in milk, often linked to mastitis infections. High SCC alters milk composition, compromises milk quality, and reduces shelf life, rendering it unsuitable for consumption. Current methods for quantitative SSC, such as flow cytometry and microscopy, are effective but impractical for on-site applications. To bridge this gap, we developed QuantM, a portable and affordable device that employs amine-functionalized iron oxide nanoparticles to isolate somatic cells from milk via surfactant-induced aggregation. It quantifies SCC in field conditions within 10 minutes, achieving 94.74% sensitivity, 90.0% specificity, and 94.74% accuracy, with a detection limit of 0.017 million cells/mL compared to flow cytometry. This low-cost solution (<$0.10 per test) promises to enhance milk quality and safeguard public health.