Label-Free Capacitive Biosensor for Detection of Cryptosporidium

George Luka,Mina Hoorfar,Homayoun Najjaran,Thomas Johnson,Soroush Dehghani,Ehsan Samiei

doi:10.3390/s19020258

George Luka, Mina Hoorfar + Show 4 more

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https://doi.org/10.3390/s19020258

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Abstract

Cryptosporidium, an intestinal protozoan pathogen, is one of the leading causes of diarrhea in healthy adults and death in children. Detection of Cryptosporidium oocysts has become a high priority to prevent potential outbreaks. In this paper, a label-free interdigitated-based capacitive biosensor has been introduced for the detection of Cryptosporidium oocysts in water samples. Specific anti-Cryptosporidium monoclonal antibodies (IgG3) were covalently immobilized onto interdigitated gold electrodes as the capture probes, and bovine serum albumin was used to avoid non-specific adsorption. The immobilization of the antibodies was confirmed by measuring the change in the contact angle. The detection was achieved by measuring the relative change in the capacitive/dielectric properties due to the formation of Cryptosporidium-antibody complex. The biosensor has been tested for different concentrations of Cryptosporidium. The results show that the biosensor developed can accurately distinguish different numbers of captured cells and densities on the surface of the biosensor. The number of Cryptosporidium oocysts captured on the electrode surface was confirmed using a fluorescein isothiocyanate (FITC) immunofluorescence assay. The response from the developed biosensor has been mainly dependent on the concentration of Cryptosporidium under optimized conditions. The biosensor showed a linear detection range between 15 and 153 cells/mm2 and a detection limit of 40 cells/mm2. The label-free capacitive biosensor developed has a great potential for detecting Cryptosporidium in environmental water samples. Furthermore, under optimized conditions, this label-free biosensor can be extended for detection of other biomarkers for biomedical and environmental analyses.

Highlights

Drinking water contamination with Cryptosporidium represents a major threat to human health and a significant challenge in delivering safe drinking water [1,2]
This paper presents the development of a multiplex label-free interdigitated capacitive based biosensor for the sensitive detection of different concentrations of Cryptosporidium
Cyclic voltammetry (CV) and contact angle measurement were conducted step by step to confirm the formation of the self-assembled monolayer (SAM) and the immobilization of the antibodies

Summary

Introduction

Drinking water contamination with Cryptosporidium represents a major threat to human health and a significant challenge in delivering safe drinking water [1,2]. The oocyst of Cryptosporidium can survive and remain infective outside the host for up to 16 months, and the parasite has high resistance to the most common disinfectants [1]. Cryptosporidium can cause severe cryptosporidiosis, gastroenteritis in healthy adults and death in children and immuno-compromised individuals, especially patients with. AIDS [3,4]. It is estimated that about 30% to 50% of childhood deaths are caused by Cryptosporidium [5]. Cryptosporidiosis is a significant risk in the water supply for developed countries. In 1993 a massive outbreak of Cryptosporidium in Milwaukee infected

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Conclusion