Real-time microgravimetric quantification of Cryptosporidium parvum in the presence of potential interferents

The quartz crystal microbalance with dissipation monitoring (QCM-D) is used to develop a biosensor for detection of viable Cryptosporidium parvum (C. parvum) in water matrices of varying complexity. In a clean environment, a good log–log linear response is obtained for detection of C. parvum in aqueous suspensions with oocyst concentrations from 3 × 105 to 1 × 107 oocysts/mL. C. parvum detection is slightly affected by the presence of dissolved organic acids, likely due to steric stabilization and/or masking of the antibodies/antigens by adsorbed molecules. Colloidal contaminants generally have a greater influence as biosensor interferents, whereby the presence of model latex microspheres, Enterococcus faecalis, or Escherichia coli, led to decreases in biosensor response of up to 64%, 40%, and 20%, respectively.