Effect of Glycosaminoglycans on Cryptosporidium Oocyst Attachment and Excystation.

Cryptosporidium causes severe gastrointestinal disease resulting from the ingestion of oocysts, followed by oocyst excystation in the small intestine and the release of infective sporozoites. An understudied strategy for Cryptosporidium inactivation is purposeful oocyst excystation, as sporozoites do not survive long in the environment. This study showed that C. parvum oocyst excystation was induced by direct contact with various glycosaminoglycans (GAGs), including heparin (Hep), chondroitin sulfate A (CSA), and hyaluronan (HA), assembled on polydopamine (PD)-functionalized surfaces. PD surfaces elicited 97.9 ± 3.6% oocyst attachment, with some of the attached oocysts partially (7.3 ± 1.3%) or fully (4.0 ± 0.6%) excysted after 4 days. The PD-GAG surfaces (GAG concentration = 2 mg/mL) elicited similarly high attachment (>97%) and higher oocyst excystation efficiencies after 4 days. The PD-Hep surfaces elicited the highest number of attached excysted oocysts (11.8 ± 0.63% partially excysted; 11.9 ± 0.49% fully excysted), and the PD-HA surfaces elicited the lowest (8.8 ± 2.1% partially excysted; 7.8 ± 1.2% fully excysted). Surface characterization revealed that the addition of GAGs to the PD surface changed both the surface roughness as well as the surface wettability. Treatment of oocysts with an enzyme that degraded the surface glycocalyx markedly reduced excystation (to <2%) of the oocysts attached to the PD and PD-GAG surfaces. These findings suggest that GAGs provide an important local signal for the excystation of C. parvum oocysts and that certain surface-expressed oocyst receptors are necessary for efficient excystation. These oocyst-receptor relationships may be useful in the design of functionalized surfaces for the purposeful inactivation of oocysts in the environment or in water treatment systems. IMPORTANCE Polydopamine surfaces functionalized with glycosaminoglycans were shown to facilitate the attachment and excystation of Cryptosporidium parvum oocysts. Our findings suggest that a surface-expressed receptor on the oocyst wall plays a key role in excystation, with glycosaminoglycans serving as ligands that trigger the initiation of the process. Future technologies and treatment strategies designed to promote premature excystation of oocysts will minimize the ingestion of sporozoites that initiate infection. Therefore, the results from this study have important implications for the protection of public health from waterborne cryptosporidiosis and may serve as a foundation for engineered surfaces designed to remove oocysts from surface waters or inactivate oocysts in water treatment systems.

Development of cell-imprinted polymer surfaces for Cryptosporidium capture and detection.

Cryptosporidium parvum is waterborne parasite that can cause potentially life-threatening gastrointestinal disease and is resistant to conventional water treatment processes, including chlorine disinfection. The current Environmental Protection Agency-approved method for oocyst detection and quantification is expensive, limiting the ability of water utilities to monitor complex watersheds thoroughly to understand the fate and transport of C. parvum oocysts. In this work, whole cell imprinting was used to create selective and sensitive surfaces for the capture of C. parvum oocysts in water. Cell-imprinted Polydimethylsiloxane (PDMS) was manufactured using a modified stamping approach, and sensitivity and selectivity were analyzed using different water chemistries and different surrogate biological and non-biological particles. The overall binding affinity was determined to be less than that of highly specific antibodies, but on par with standard antibodies and immune-enabled technologies. These initial results demonstrate the potential for developing devices using cell-imprinting for use in waterborne pathogen analysis.

Antibacterial properties of electrospun Ti3C2T z (MXene)/chitosan nanofibers.

Electrospun natural polymeric bandages are highly desirable due to their low-cost, biodegradability, non-toxicity and antimicrobial properties. Functionalization of these nanofibrous mats with two-dimensional nanomaterials is an attractive strategy to enhance the antibacterial effects. Herein, we demonstrate an electrospinning process to produce encapsulated delaminated Ti3C2T z (MXene) flakes within chitosan nanofibers for passive antibacterial wound dressing applications. In vitro antibacterial studies were performed on crosslinked Ti3C2T z /chitosan composite fibers against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) - demonstrating a 95% and 62% reduction in colony forming units, respectively, following 4 h of treatment with the 0.75 wt% Ti3C2T z - loaded nanofibers. Cytotoxicity studies to determine biocompatibility of the nanofibers indicated the antibacterial MXene/chitosan nanofibers are non-toxic. The incorporation of Ti3C2T z single flakes on fiber morphology was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy equipped with an energy-dispersive detector (TEM-EDS). Our results suggest that the electrospun Ti3C2T z /chitosan nanofibers are a promising candidate material in wound healing applications.