Browsing by Subject "chitosan"
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Item Additive Fabrication of Polymer-Ceramic Composite for Bone Tissue Engineering(University of Texas at Austin, 2017) Ramesh, S.; Eldakroury, M.; Rivero, I.V.; Frank, M.C.The objective of this study is to manufacture chitosan-based biocomposite 3-D scaffolds through additive fabrication for promoting the regeneration of bone defects. Additive manufacturing has enabled the production of effective scaffolds by overcoming traditional limitations such as suboptimal distribution of cells, and poor control over scaffold architecture. In this study, cryomilled biocomposites comprising of poly (lactic) acid (PLA), chitosan (CS) and tricalcium phosphate (TCP) provided the basis for the generation of hydrogels, which were then utilized for the fabrication of scaffolds with orthogonal (0, 90) geometry. Rheological studies were conducted using a rotational rheometer to identify the ideal hydrogel concentration for the continuous production of scaffolds. The scaffolds were fabricated using a 3-axis computerized numerical control (CNC) which was modified to function as a customized bioplotter. Scanning electron microscopy (SEM) was used to observe the morphology of the bioplotted scaffolds. Finally, a short-term stability (14 days) study was conducted to analyze the in vitro degradation behavior of the scaffolds in phosphate buffer saline (PBS).Item Design and in Vitro Evaluation of a New Nano-Microparticulate System for Enhanced Aqueous-Phase Solubility of Curcumin(2013) Guzman-Villanueva, Diana; El-Sherbiny, Ibrahim M.; Herrera-Ruiz, Dea; Smyth, Hugh D. C.; Guzman-Villanueva, Diana; Smyth, Hugh D. C.Curcumin, a yellow polyphenol derived from the turmeric Curcuma longa, has been associated with a diverse therapeutic potential including anti-inflammatory, antioxidant, antiviral, and anticancer properties. However, the poor aqueous solubility and low bioavailability of curcumin have limited its potential when administrated orally. In this study, curcumin was encapsulated in a series of novel nano-microparticulate systems developed to improve its aqueous solubility and stability. The nano-microparticulate systems are based entirely on biocompatible, biodegradable, and edible polymers including chitosan, alginate, and carrageenan. The particles were synthesized via ionotropic gelation. Encapsulating the curcumin into the hydrogel nanoparticles yielded a homogenous curcumin dispersion in aqueous solution compared to the free form of curcumin. Also, the in vitro release profile showed up to 95% release of curcumin from the developed nano-microparticulate systems after 9 hours in PBS at pH 7.4 when freeze-dried particles were used.Item Reducing turbidity of construction site runoff via coagulation with polyacrylamide and chitosan(Center for Research in Water Resources, University of Texas at Austin, 2012-08) Rounce, David Robert; Lawler, Desmond F.; Barrett, Michael E.The U.S. Environmental Protection Agency is in the process of developing a nationwide standard for turbidity in construction site runoff. It is widely expected that this standard cannot be met with conventional erosion and sediment control measures; consequently, innovative practices for managing sediment on construction sites must be developed. The objective of this research was to develop an understanding of how soil characteristics and polymer properties affect the amount of turbidity reduction that can be achieved through flocculation. The polymers used were PAMs, a proprietary product, and chitosan. The charge density of the PAMs ranged from 0% to 50% and the molecular weights ranged from 0.2 to 14 Mg/mol. A protocol for creating modified synthetic stormwater runoff for soil samples was developed and used on soils from seven construction sites. Particle size distributions were used to compare the modified synthetic stormwater runoff with grab samples of stormwater from one site and showed the synthetic runoff was representative of the actual runoff. Flocculation tests were performed on the synthetic runoffs with PAM and chitosan doses from 0.03 to 10 mg/L. The non-ionic PAM, proprietary product, and chitosan were found to be the most effective at reducing the turbidity of all the synthetic runoff below 200 NTU. The high molecular weight anionic PAMs were effective on only two of the seven synthetic runoff samples. Hardness tests were performed indicating interparticle bridging to be the bonding mechanism of the PAM. Electrophoretic mobility tests were performed on two of the soil suspensions and indicated the bonding mechanism of PAM to be interparticle bridging, and the bonding mechanism of chitosan to be a combination of charge neutralization and interparticle bridging. Tests showed as the charge density of the PAM increased, their effectiveness decreased.