title: Amphiphile disruption of pathogen attachment at the hematite (α-Fe2O3)-water interface.
abstract: Prior studies have indicated that the subsurface transport of Cryptosporidium parvum oocysts is diminished in sediments containing iron oxides and that inner-sphere complexation of oocyst surficial carboxylate plays a role in the retardation. However, the impacts of natural organic matter (NOM) remain poorly understood. In this study, we used a model anionic surfactant, sodium dodecyl sulfate (SDS), as a surrogate for amphiphilic NOM components to examine the impacts of amphiphilic components on oocyst adhesion mechanisms. We employed in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to determine the effects of SDS on the molecular bonds that mediate interactions between oocyst surficial biomolecules and hematite (α-Fe(2)O(3)) surface functional groups over a wide range of solution pH. The results show that the presence of SDS significantly diminishes Fe-carboxylate complexation, as indicated by progressive decreases in intensity of asymmetric and symmetric stretching vibrations of carboxylate [ν(as)(COO(-)) and ν(s)(COO(-))] with reaction time. In addition, one of the ν(s)(COO(-)) bands shifted from 1370 to 1418 cm(-1) upon SDS introduction, suggesting that SDS also changed the complexation mode. The data indicate that competition from the sulfonate groups (OSO(3)(-)) of SDS at α-Fe(2)O(3) surface sites is a primary mechanism resulting in decreased Fe-carboxylate complexation. Sorptive competition from amphiphilic NOM components may therefore increase the mobility of C. parvum oocysts in the environment through disruption of interfacial pathogen-mineral surface bonds.
authors.affiliation: Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona 85721, United States.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Gao
authors.forename: Jon
authors.initials: J
authors.lastname: Chorover
mesh_terms: D001688:Biological Products / Q000737:chemistry / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D016785:Cryptosporidium parvum / Q000166:cytology* / Q000187:drug effects*; D005290:Ferric Compounds / Q000737:chemistry* / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D033661:Oocysts / Q000166:cytology / Q000187:drug effects; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry / Q000494:pharmacology; D014867:Water / Q000737:chemistry*
chemical_list: D001688:Biological Products; D005290:Ferric Compounds; D014867:Water; C000499:ferric oxide; D012967:Sodium Dodecyl Sulfate