Publication Date

2011

Document Type

Honors Thesis

Department

Chemistry

Keywords

Fourier transform infrared spectroscopy, Lysine, Alginates, Biofilms-Structure, Molecular structure, Silicon-Structure, Silica-Structure, FTIR, PLL, Secondary structure

Abstract

Bio-film bacteria pose one of the greatest threats to human health in terms of antibiotic-resistant infections. A bio-film is an aggregation of microorganisms encased by a complex matrix of proteins and polysaccharides. While many investigators have sought to destroy the complex matrix, few have studied the molecular mechanisms involved in bio-film adsorption. Therefore, the goal of this research is to elucidate the basic architectural foundation of bio-films via FTIR. FTIR studies have helped elucidate the adsorption mechanisms of PLL. The Amide I region of the FTIR spectra (1600-1700 cm-1) is primarily used for structural information while the Amide II region is often used for hydrogen-deuterium exchange studies. Hydrophilic adsorption is mainly driven by electrostatic interactions. As a result, PLL adopted the more compact β-sheet conformation (1618 and 1681 cm-1) with the addition of ionic strength. PLL adsorption to hydrophobic surfaces is driven by hydrophobic interactions. At pH 11, PLL is neutral and in the Ф±-helix conformation. FTIR studies showed that PLL remained in that conformation as it adsorbed to the surface (1637 cm-1). The PLL film also underwent a dehydration process, which showed a conformational change from the α-helix to the β-sheet to increase intermolecular hydrogen bonds. FTIR studies of alginate and its interactions with polyelectrolytes are few and controversial. Some explanations were inferred from the spectra, mainly that the symmetric and antisymmetric carbonyl bands did not experience shifts in band positions due to the lack of ionic interactions with PLL. Alginate, however, will not be studied via FTIR in the future.

Language

English

Comments

60 p. ill. (some col.) Honors project-Smith College, Northampton, Mass., 2011. Includes bibliographical references (p. 56-60)

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