Browsing by Subject "Chitosan"
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Item Development and evaluation of an imidazole-modified chitosan for nucleic acid and contrast agent delivery(2009-05) Ghosn, Bilal; Roy, KrishnenduOver the past several decades, gene therapy technologies have been developed for a diverse number of applications ranging from DNA-based vaccines to gene silencing with RNAi. While all are powerful tools, a common limitation for these technologies is the need for effective and safe delivery to target sites within the body. Such delivery vectors are necessary for retention of bioactivity and stability, while also providing a method of cellular and tissue uptake and distribution, which may require endosomal escape. Although, viral and lipid-based technologies have shown promise as nucleic acid delivery vectors, both have inherent issues such as cytoxicity, oncogenicity, and immunogenicity. Thus, the development of polymer-based non-viral vectors has been an area of great focus over the past decade. While many polymeric vectors have been developed for plasmid DNA (pDNA) delivery, very few have shown effective delivery of short interfering RNA (siRNA), a powerful tool for gene silencing via the RNA interference mechanism. Furthermore, very few prospective delivery vectors have shown versatility for the administration of siRNA through multiple routes of administration. The overall goal of this research was to develop a biocompatible non-viral delivery system for the delivery of plasmid DNA, siRNA, and contrast agents through the modification of the natural biopolymer chitosan. We have synthesized an imidazole modified chitosan (chitosan-IAA) by conjugation of imidazole acetic acid to chitosan. Extensive evaluation and characterization of the modified polymer demonstrates enhanced solubility and buffering capacity within the physiological and endosomal pHs, thus providing enhanced endosomal escape by exploiting the "proton sponge" effect. We have demonstrated effective in vitro gene expression and gene silencing with chitosan-IAA mediated delivery of pDNA and siRNA, respectively. Furthermore, we have demonstrated in vivo gene silencing by delivery of siRNA through both intranasal and intravenous routes of delivery with chitosan-IAA/siRNA nanocomplexes. We have also demonstrated delivery of contrast agents up to 45 nm in size through mucosal tissue following treatment with chitosan and no contrast agent modification in both human and animal tissue. In conclusion, we have successfully developed a versatile and highly effective delivery vector for both nucleic acids and contrast agents.Item Preparation and Characterization of Chitosan-Alginate Nanoparticles for Trans-Cinnamaldehyde Entrapment(2014-11-04) Loquercio, Andre STrans-cinnamaldehyde incorporated chitosan and alginate nanoparticles were synthesized using the ionic gelation and polyelectrolyte complexation technique. Alginate, chitosan, calcium chloride, and trans-cinnamaldehyde at predetermined concentrations were complexed electrostatically to optimize size and loading efficiency (i.e. preliminary study). A final extrapolated methodology using optimized processing parameters (e.g. stirring, homogenization, and equilibration time; droplet size) was developed and utilized for controlled release, morphological, thermal, antioxidant, and antimicrobial studies. The best working alginate to chitosan mass ratio was determined to be 1.5:1 at a pH dispersion of 4.7. Particle size (166.26 nm) and encapsulation efficiency (73.24%) were further optimized at this mass ratio using an alginate:calcium chloride mass ratio of 4.8:1, alginate:trans-cinnamaldhyde mass ratio of 37.5:1, 18 gauge syringe needle, stirring times of 90 minutes, 15 minutes of homogenization, and equilibration time of 24 hours. Optimized nanoparticles showed increased shelf life (6 weeks) and translucency in solution. Release tests showed trans-cinnamaldehyde release from loaded nanoparticles best followed the bioexponential model; a burst release function (32.5% cumulative release) followed by a sustained release function (62.31% final cumulative release). Differential scanning calorimetry confirmed inclusion of oil into nanoparticles by indirectly comparing thermal stability of free trans-cinnamaldehyde with loaded trans-cinnamaldehyde in the inclusion complex. Nanoparticles resembled a spherical shell and core type arrangement (i.e. spherical, distinct, and regular) and were in the size range of 10-100 nm. The final radical scavenging effect of loaded particles in apple juice was 62% and trans-cinnamaldehyde was just as available to react in free form as it was in inclusion complexes. Minimum inhibitory concentration values (MIC) for trans-cinnamaldehyde loaded nanoparticles was 7,031.25 ?g/ml for Escherichia coli O157:H7 and 14,062.5 ?g/ml for Listeria monocytogenes. The concentration of trans-cinnamaldehyde in the inclusion complexes corresponded to a MIC of approximately 730 and 1,4062 ?g/ml of free trans-cinnamaldehyde for E. coli O157:H7 and L. monocytogenes, respectively. Results indicated that L. monocytogenes was more tolerant to the inhibition by trans-cinnamaldehyde inclusion complex in comparison to E. coli O157:H7. Overall, results suggest that the application of antimicrobial polymeric nanoparticles optimized for essential oil loading in food systems may be effective at inhibiting specific pathogens.Item Reducing turbidity of construction site runoff via coagulation with polyacrylamide and chitosan(2012-05) 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.