ATR-FTIR study of lipopolysaccharides at mineral surfaces

Sanjai J. Parikh, Jon Chorover

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

Lipopolysaccharides (LPS) are ubiquitous in natural aqueous systems because of bacterial cell turnover and lysis. LPS sorption and conformation at the mineral/water interface are strongly influenced by both solution and surface chemistry. In this study, the interaction of LPS with various surfaces (ZnSe, GeO2, α-Fe2O3, α-Al2O3) that vary in surface charge and hydrophobicity was investigated using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The presence of Ca2+ (versus Na+) in LPS solutions resulted in aggregate reorientation and increased sorptive retention. ATR-FTIR spectra of Na-LPS systems are consistent with reduced surface affinity and are similar to those of solution phase LPS. Ca-LPS spectra reveal hydrophobic interactions of the lipid A region at the ZnSe internal reflection element (IRE). However, pH-dependent charge controls Ca-LPS sorption to hydrophilic surfaces (GeO2, α-Fe2O3, and α-Al2O3), where bonding occurs principally via O-antigen functional groups. As a result of accumulation at the solid-liquid interface, spectra of Ca-LPS represent primarily surface-bound LPS. Variable-angle ATR-FTIR spectra of Ca-LPS systems show depth-dependent trends that occur at the spatial scale of LPS aggregates, consistent with the formation of vesicular structures.

Original languageEnglish (US)
Pages (from-to)188-198
Number of pages11
JournalColloids and Surfaces B: Biointerfaces
Volume62
Issue number2
DOIs
StatePublished - Apr 1 2008

Keywords

  • ATR-FTIR spectroscopy
  • Depth profiling
  • Endotoxins
  • LPS

ASJC Scopus subject areas

  • Biotechnology
  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

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