Comparison of immobilization strategies for Cryptosporidium parvum immunosensors

Cryptosporidium is a waterborne protozoan parasite, which is problematic for the water industry due to widespread environmental presence, low infectious dose and resistance to chlorine disinfection. To replace the existing, slow regulatory monitoring procedure, immunosensors have been proposed. The performance of such sensors is often limited by the antibody immobilization. The aim of this article was to determine the immobilization protocol offering the highest oocyst capture efficiency. Four methods were tested both under static and convective conditions: physisorption, cysteamine–glutaraldehyde linkage, 3-aminopropyl-triethoxysilane functionalization and protein G linkage. The protein G protocol was shown to present the highest recovery rates in both conditions. For the protein G protocol, different antibody concentrations were tested and it was concluded that there is little difference in the recovery rates when the concentration of IgG antibody is higher than 20 µg/mL. Additionally, operation under convective rather than static conditions increased the recovery for every protocol. These results can be useful to inform the design of future biosensor systems, using antibodies as the detection element, for Cryptosporidium.


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