Influence of Lysozyme on the Biomimetic Growth of Silica Tubes in Porous Membranes
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1008-T01-04
Influence of Lysozyme on the Biomimetic Growth of Silica Tubes in Porous Membranes ClÈmentine Gautier1, RÈmi Courson1, Pascal Jean Lopez2, Jacques Livage1, and Thibaud Coradin1 1 CNRS-UPMC, Chimie de la Matiere Condensee, 4 place Jussieu, Paris, 75252, France 2 CNRS-ENS, Molecular Biology of Photosynthetic Organisms, 46 rue d'Ulm, Paris, 75005, France
ABSTRACT Pore channels of poly-carbonate membranes were recently used as biomimetic models to study the effect of confinement on silicate condensation, leading to the formation of silica tubes exhibiting a core-shell structure. In this work, we pre-immobilized lysozyme on the membrane pores, inducing the modification of the tube shell formation process, and variation in core particle size. These data strengthen previous assumptions on the role of interfacial interactions on the growth of the tube shell and indicate that such interactions also influence the core particle formation. Such approach therefore seems suitable to mimic the formation of silica/protein multilayers as found in several biomineralizing organisms. INTRODUCTION Many biomineralization processes occur in spatially-delineated environments, such as vesicles or extra-cellular matrices [1]. Such confined media allow the control of the precursor concentrations, favor precursor interactions with template macromolecules and influence the size and shape of the growing mineral phase [2]. In the frame of bio-silicification, the formation of silica in diatoms was shown to occur in specific vesicles containing macromolecules enriched in amine groups [3,4]. Thus, many studies have been devoted to the elucidation of the mechanism of interaction arising between silica precursors and poly-amines in solution [5,6]. However, the possible influence of confinement on the growth of silica has been only sparingly addressed [7-9]. In this context, pore channels of poly-carbonate membranes were recently used as biomimetic confined media to control sodium silicate condensation, leading to the formation of silica tubes exhibiting a core-shell structure [10]. The influence of confinement was explained in terms of enhancement of interfacial interactions and perturbation of the growing particle diffusion. In a step further, poly-L-lysine (PLL), a widely-studied biomimetic poly-amine, was immobilized on the membrane pores [11]. The presence of PLL induces the modification of the tube shell formation process, and the variation of core particle size, strengthening previous assumptions on the role of confinement on silica growth.
In this work, we have extended this approach by pre-immobilizing lysozyme in the membrane pores. Lysozyme was selected because: (i) it is a small protein bearing an important number of lysine and arginine amino acids and can therefore be considered as a biomimetic polyamine, (ii) its ability to interact with silicates in solution has already been demonstrated [12] and (iii) its conformation and orientation upon adsorption depend both on the nature of the surface and on the initial protein conc
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