Biophysical Society Thematic Meeting

- 72 -

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

, Jagoba Iturri

, Dietmar Pum

, Uwe B.

Sleytr

, José Luis Toca-Herrera

University of Natural Resources and LIfe Sciences Vienna (BOKU), Vienna, Austria,

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.