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NANOSTRUCTURED and MESOSTRUCTURED BIO-HYBRIDS Rajendra Kumar Kasinath and Laurie Gower ABSTRACT Mesostructured hybrid materials are potentially applicable in several biological analogues especially when they possess hierarchical ordering at several length scales. Here we aim to synthesize one such hybrid system consisting of inorganic calcium phosphate (CaP) nano-particles and chitosan bio-polymer. Upon synthesis: METHODOLOGY Ca(OH) + H PO + chitosan 2 3 4 hybrid susp. Reaction temperature ~100C; acid feed rate 4 ml/min. Chitosan was introduced to the reactants at the point when CaP crystals start to nucleate. Upon completion of the reaction the suspension was sonicated for ½ hr and fixed volumes oven dried at 37C. •an interpenetrating assembly of CaP and chitosan was observed, PO43- ions •two distinct levels of structure were observed when the composite suspension of CaP-chitosan was dried into films:20-30 nm (primarily nano CaP) and at several microns (consisting of CaP and chitosan) and •films were graded from mainly inorganic (CaP) on the bottom surface to organic (chitosan) on the top. (A) Meso-structured films Transfer 25 ml to Petri dish Sealed reactor Oven dry at 37C Magnetic stirrer SEM, TEM, FTIR, XRD. Heater and stirrer plate After solvent extraction RESULTS pH and temperature probe Chitosan solution Effect of chitosan concentration during synthesis 0 g/ml 20 g/ml 40 g/ml (B) 70 g/ml without chitosan 150 g/ml 220 g/ml 70 g/ml chitosan •Composite suspensions (A) were well dispersed. (C) •Dried films were smooth, continuous (B) and adherent. •The degree of nano particulate assembly was optimal at about 40-50 g/ml of chitosan added during synthesis. •CaP nano-particles are believed to be assembled (C) here through electrostatic interactions between Organic-Inorganic meso-structured hybrid film pendent organic chains adsorbed onto the particles. •The cross section of the films showed a remarkable graded organic-inorganic nanostructure. Mainly organic •Further studies are underway to understand the exact mechanism. (Chitosan) XRD/Rietveld analysis and TEM studies •Possible applications include a 2-tiered reservoir for drug delivery, cementum analogue, for avulsed teeth re-insertion, and tissue engineering scaffolds. 25 nm 37 nm Mainly inorganic (nanoHA) Levels of morphological grading TOP 70 g/ml chitosan without chitosan •XRD, FTIR and Rietveld analyses showed that the CaP nanoparticles were hydroxycarbonated apatite or HCA (refined crystallite shapes shown in inset). •Refined shape for the nanoparticles were consistent with TEM studies indicating suppressed growth in the [001] direction. Also SEAD suggested that the particles were assembled on their 001 planes. (004) (002) Chitosan film with porous substructure •Presence of nanoporosity and nanoparticles heightens the possibility for both high drug loading capacity as well as internalization by nano-particle mediated transcytosis. BOTTOM Assembled CaP nano-particles Bioengineering, Montana Tech of the University of Montana Materials Science and Engineering, University of Florida Chitosan-CaP interpenetrating structure with nano-porosity