Biotin- and Glycoprotein-Coated Microspheres: Potential Surrogates for Studying Filtration of Cryptosporidium parvum in Porous Media

Abstract

Cryptosporidium parvum is a waterborne pathogen, yet no suitable surrogate has been established for quantifying its filtration removal in porous media. Carboxyl polystyrene microspheres with size, density, and shape similar to C. parvum were coated with biotin (free and containing amine, NH(2)) and glycoprotein. These biomolecules have isoelectric points similar to C. parvum (pH ≈ 2), and glycoprotein is a major type of surface protein that oocysts possess. Zeta potential (ζ) and filtration removal of particles in sand of two different grain sizes were examined. Compared to unmodified microspheres, modified microspheres achieved a superior match to the oocysts in ζ, concentration, mass recovery, and collision coefficient. They showed the same log reduction in concentration as oocysts, whereas results from unmodified microspheres deviated by 1 order of magnitude. Of the three types of modified microspheres, glycoprotein-coated microspheres best resembled oocyst concentration, despite having ζ similar to NH(2)-biotin-coated microspheres, suggesting that surface protein also played an important role in particle attachment on solid surfaces. With further validation in environmental conditions, the surrogates developed here could be a cost-effective new tool for assessing oocyst filtration in porous media, for example, to evaluate the performance of sand filters in water and wastewater treatment, water recycling through riverbank filtration, and aquifer recharge.

Biotin- and Glycoprotein-Coated Microspheres as Surrogates for Studying Filtration Removal of Cryptosporidium parvum in a Granular Limestone Aquifer Medium

“…C. parvum oocysts are spherical or oval and 3.9 to 5.9 m in diameter (27) and have an isoelectric point pH of 2.0 to 3.3 (19,28,29). Two strains of oocysts were used in the experiments.…”

“…Although CPMs can mimic the size, buoyant density, and spherical shape of the oocysts, unmodified CPMs are significantly more negatively charged than oocysts (15,19). In addition, unlike …”

“…Although CPMs can mimic the size, buoyant density, and spherical shape of the oocysts, unmodified CPMs are significantly more negatively charged than oocysts (15,19). In addition, unlike oocysts, unmodified CPMs lack a macromolecular structure, which makes them poor surrogates for C. parvum (20,21).…”

“…A recent study by Pang et al (19) demonstrated that glycoprotein-and biotin-coated CPMs are superior to unmodified CPMs in predicting filtration removal of noninactivated C. parvum oocysts, showing the same log 10 reduction in concentration. These biomolecules have a surface charge similar to that of C. parvum with an isoelectric point pH of Ϸ2 (19), and glycoprotein is the major type of protein that C. parvum produces on its cell surface (22). However, only transport in alluvial sand medium was validated in their study, and it is unknown whether these modified CPMs are also useful in predicting C. parvum filtration in other aquifer media with different chemical properties.…”

Tunable Resistive Pulse Sensing: Potential Applications in Nanomedicine

“…TRPS has also been applied for characterisation of bacteria in dairy products such as probiotics [77] and in environmental science [78][79]. In the study of Chung and co-workers [78], they used TRPS to measure the size distribution and surface charge of Francisella tularensis in their investigation of biofilm formation whereas Pang and colleagues [79] carried out comparative analysis of the size distribution and surface charge of biotin and glycoprotein coated microspheres to that of Cryptosporidium parvum oocytes in a bid to develop surrogate markers to quantify removal of the oocytes in porous media.…”