Biophysical Society Thematic Meeting - October 25-30, 2015

Polymers and Self Assembly: From Biology to Nanomaterials Poster Session II

9-POS Board 9 Studying the Antifouling Properties of Bacterial S-layers Ana Carolina V. Cintra 1,2 , Alberto M. Cencerrado 1 , Jagoba Iturri 1 , Dietmar Pum 1 , Uwe B. Sleytr 1 , José Luis Toca-Herrera 1 . 1 University of Natural Resources and LIfe Sciences Vienna (BOKU), Vienna, Austria, 2 University of São Paulo, Ribeirão Preto, São Paulo, Brazil. The mimicking of (the physico-chemical) properties bacterial surface layers (S-layers), the outermost cell envelope component of prokaryotic organisms, enable infinite possibilities for technological processes and scientific studies. S-layers are composed of single (glyco)protein units acting as building blocks, which re-assemble into crystalline arrays when exposed to different types of supports (i.e. lipid films, polymers, silica). This assembly in a regular arrangement in the case of Lysinibacillus sphaericus (SbpA) is driven by the presence of divalent cations (Ca2+) in the crystallization buffer, which also contributes to its high stability. Among other features, such biomimetic films are characterized by their antifouling activity while forming the crystalline structure. Our study focused on the recrystallization of S-layer from Lysinibacillus sphaericus (SbpA) on hydrophobic silicon surfaces. Subsequently, the formed crystalline films were exposed to different chemical treatments (metal chelator-EDTA and pH variations) in order to disrupt the SbpA crystalline structure, without causing full protein removal. In a second step, the ability of the protein layer to bind different molecules (BSA, polyelectrolytes) was investigated. Quartz crystal microbalance with dissipation (QCM-D) technique was used to monitor the real time variations of mass deposited per unit area along the crystallization, as well as the kinetics of the process. Complementary atomic force microscopy (AFM) measurements allowed for a detailed following of the topographical changes and mechanical properties of the structures formed. Although the stability of the protein crystal was not completely altered by the chemical treatment, the change in its antifouling properties suggests possible a charge rearrangement. This question is currently investigated in our laboratory.

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