Designing Nanostructured Hybrid Inorganic-biological Materials via the Self-assembly
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Designing Nanostructured Hybrid Inorganic-biological Materials via the Self-assembly Evan Koufos and Meenakshi Dutt Chemical and Biochemical Engineering, Rutgers- The State University of New Jersey, Piscataway, New Jersey 08854, USA ABSTRACT Our objective is to design nanostructured hybrid inorganic-biological materials using the selfassembly of functionalized nanotubes and lipid molecules. In this presentation, we summarize the multiple control parameters which direct the equilibrium morphology of a specific class of nanostructured biomaterials. Individual lipid molecules are composed of a hydrophilic head group and two hydrophobic tails. A bare nanotube encompasses an ABA architecture, with a hydrophobic shaft (B) and two hydrophilic ends (A). We introduce hydrophilic hairs at one end of the tube to enable selective transport through the channel. The dimensions of the nanotube are set to minimize its hydrophobic mismatch with the lipid bilayer. We use a Molecular Dynamicsbased mesoscopic simulation technique called Dissipative Particle Dynamics which simultaneously resolves the structure and dynamics of the nanoscopic building blocks and the hybrid aggregate. The amphiphilic lipids and functionalized nanotubes self-assemble into a stable hybrid vesicle or a bicelle in the presence of a hydrophilic solvent. We demonstrate that the morphology of the hybrid structures is directed by factors such as the temperature, the molecular rigidity of the lipid molecules, and the concentration of the nanotubes. We present material characterization of the equilibrium morphology of the various hybrid nanostructures. A combination of the material characterization and the morphologies of the hybrid aggregates can be used to predict the structure and properties of other hybrid materials. INTRODUCTION Our goal is to design hybrid nanostructured biomaterials for use in controlled release applications such as drug delivery, sensing and imaging. These applications require a material platform that can store active compounds and release them upon demand. Our earlier investigations on hybrid nanostructured biomaterials composed of functionalized nanotubes and amphiphilic lipid molecules demonstrated the formation of hybrid lipid bilayers [1-5.] We demonstrated that the morphology of the hybrid aggregate depended upon the rigidity of the aggregate which was controlled by the concentration of the nanotubes [2] and the molecular chain stiffness of the lipid hydrophobic tails [4.] The aggregate morphology can also be tuned via the composition of the soft material which supports the rigid nanoscopic components. In this paper, we explore the effect of the molecular architecture of the lipid molecules which constitute the bilayer on the mechanical properties of the bilayer. Via the Dissipative Particle Dynamics (DPD) approach [1-6] we will investigate the role of the architecture of amphiphilic lipids on the properties of lipid bilayer membranes. We focus on four lipid architectures with differing molecular geometries arising due to the head grou
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