Point-of-care human milk testing for maternal secretor status

We present an electrochemical impedimetric-based biosensor for monitoring the variation in human milk oligosaccharide (HMO) composition. 2'-Fucosyllactose (2'FL) is an HMO associated with infant growth, cognitive development, and protection from infectious diarrhea, one of the major causes of infant death worldwide. Due to genetic variation, the milk of some women (non-secretors) contains no or very little 2'FL with potential implications for infant health and development. However, there is currently no technology to analyze the presence and concentration of HMOs in human milk at the point-of-care (POC). The lack of such technology represents a major impediment to advancing human milk research and improving maternal-infant health. Towards this unmet need, we report an impedimetric assay for HMOs with an α-1,2 linkage, the most abundant of which is 2'FL. The sensor uses a lectin for affinity, specifically Ulex europaeus agglutinin I (UEA), with electrochemical readout. In spiked studies, the sensor exhibited a high degree of linearity (R² = 0.991) over 0.5 to 3.0 μM with a 330-nM detection limit. The sensor performance was clinically validated using banked human milk samples and correctly identified all secretor vs. non-secretor samples. Furthermore, despite the short 35-min assay time and low sample volume (25 μL), the assay was highly correlated with HPLC measurements. This bedside human milk testing assay enables POC, "sample-to-answer" quantitative HMO measurement, and will be a valuable tool to assess milk composition.