Structual Properties Of Chitosan/Hallosite Nanotubes (HNTs)Composite Biomaterials

Chitosan (CS) is a biodegradable natural polymer, because of its excellent performancesuch as biological functionality and compatibility, blood compatibility, which make it achievesignificant progress in pharmaceutical, food, chemical and many other areas. However, itssoftness and lack of biological reactions also limits the application. Halloysite nanotubes(HNTS), is a natural nanotube particles with a certain aspect ratio, non-toxic, high mechanicalstrength and good biocompatibility. The purpose of this research is to study the structuralproperties of chitosan-HNTs composites, and make it achieve both good biological response andexcellent mechanical properties.This work developed novel chitosan-halloysite nanotubes (HNTs) nanocomposite (NC)scaffolds by combining solution-mixing and freeze-drying techniques. The hydrogen bondingand electrostatic attraction between chitosan and HNTs were con rmed by spectroscopy andmorphology analysis. NC scaffolds exhibited signi cant enhancement in compressive strength,compressive modulus, and thermal stability compared with the pure chitosan scaffold. But theNC scaffolds showed reduced water uptake and increased density by the incorporation of HNTs.All the scaffolds exhibited a highly porous structure. In order to assess cell attachment andviability on the materials, NIH3T3-E1mouse broblasts were cultured on the materials. Resultsshowed that chitosan–HNTs nanocomposites were cytocompatible. All these results suggestedthat chitosan–HNTs NC scaffolds exhibited great potential for applications in tissue engineering.We have developed flexible3D porous chitosan composite sponges via the addition ofHNTs. Morphological observation, mechanical property, porosity, swelling ability, anddegradation behaviour in phosphate buffer of the chitosan-HNTs composite sponges wereinvestigated by various physic-chemical methods. Compared with pure chitosan, the compositesponges show a similar morphology with comparable porosity but significantly enhancedmechanical properties. The elastic modulus, compressive strength, and toughness of thecomposite increase by HNTs simultaneously. The whole blood clotting experiment suggest that HNTs could increase the blood clotting rates of chitosan significantly. Cytocompatibility of thecomposite sponges is confirmed by cell attachment and infiltration of fibroblast and vascularendothelial cells. In vivo evaluation on full-thickness excision wounds in experimentalSprague-Dawley rats reveal that these composite sponges enhance the wound healing and helpfor faster re-epithelialization and collagen deposition. All these data demonstrate the potentialapplications of the chitosan-HNTs composite sponges for burn wounds, chronic wounds, anddiabetic foot ulcers.Chitosan hollow nanocapsules were fabricated via a solid–liquid phase separation technique.Fourier transform infrared spectroscopy and X-ray diffraction spectra showed that the structureof chitosan capsules and raw material preparation were basically the same. FSEM and TEMobservations showed that the capsules were nanoscale opened hollow spherical objects with adiameter of400-600nm. BET method has proved that capsule has a large surface area, is101.907m2/g. MTT assay showed that, when concentration of the capsules was relatively small,it had no effect on cell growth, while as the concentration of the material increases，the growth ofthe cells will have certain toxicity. Finally, the experimental results showed that the capsuleshave a capacity of curcumin, and the drug loaded capsules can achieve a slow release effect inPBS solution. These results show that chitosan hollow nanocapsules we had prepared have greatpotential applications in drug loading fields.