Detection of Cryptosporidium parvum in buffer and in complex matrix using PEMC sensors at 5 oocysts mL−1

We show for the first time that a piezoelectric-excited millimeter-sized cantilever (PEMC) sensor can detect five Cryptosporidium parvum oocysts in 25% milk in PBS background in a flow format (1 mL min−1). To improve sensitivity, a secondary antibody (murine IgM) was used to confirm the attachment of oocysts to the sensor. PEMC sensor is a resonant-mode cantilever sensor whose resonant frequency decreases when target analyte binds to its surface. The sensor was functionalized with Protein G, and then immobilized with goat polyclonal IgG anti-C. parvum for oocysts detection. In the dynamic range of 50–10,000 oocysts mL−1 the sensor response is characterized by a semi-log relationship between resonant frequency response and C. parvum oocysts concentration. In 25% milk background, binding kinetics was slower and total sensor response was lower (∼45%) than in water-like buffer.