UNT Libraries - 2 Matching Results

Search Results

Design, Synthesis and Study of Supramolecular Donor – Acceptor Systems Mimicking Natural Photosynthesis Processes

Description: This dissertation investigates the chemical ingenuity into the development of various photoactive supramolecular donor – acceptor systems to produce clean and carbon free energy for the next generation. The process is inspired by the principles learned from nature’s approach where the solar energy is converted into the chemical energy through the natural photosynthesis process. Owing to the importance and complexity of natural photosynthesis process, we have designed ideal donor-acceptor systems to investigate their light energy harvesting properties. This process involves two major steps: the first step is the absorption of light energy by antenna or donor systems to promote them to an excited electronic state. The second step involves, the transfer of excitation energy to the reaction center, which triggers an electron transfer process within the system. Based on this principle, the research is focused into the development of artificial photosynthesis systems to investigate dynamics of photo induced energy and electron transfer events. The derivatives of Porphyrins, Phthalocyanines, BODIPY, and SubPhthalocyanines etc have been widely used as the primary building blocks for designing photoactive and electroactive ensembles in this area because of their excellent and unique photophysical and photochemical properties. Meanwhile, the fullerene, mainly its readily available version C60 is typicaly used as an electron acceptor component because of its unique redox potential, symmetrical shape and low reorganization energy appropriate for improved charge separation behavior. The primary research motivation of the study is to achieve fast charge separation and slow charge recombination of the system by stabilizing the radical ion pairs which are formed from photo excitation, for maximum utility of solar energy. Besides Fullerene C60, this dissertation has also investigated the potential application of carbon nanomaterials (Carbon nanotubes and graphene) as primary building blocks for the study of the artificial photosynthesis process.
Access: This item is restricted to UNT Community Members. Login required if off-campus.
Date: December 2015
Creator: KC, Chandra Bikram

Self-assembly Polymeric Nanoparticles Composed of Polymers Crosslinked with Transition Metals for Use in Drug Delivery

Description: A major drawback of chemotherapy is the lack of selectively leading to damage in healthy tissue, which results in severe acute side effects to cancer patients. The use of nanoparticles as a drug delivery system has emerged as novel strategy to overcome the barriers of immunogenic response, controlled release of therapeutic, and targeting the toxicity only to cancerous cells. In this study, polymeric nanoparticles composed of transition metals and particles derived from natural biopolymers have been generated via self-assembly. For example, nanoparticles composed of cobalt crosslinked with albumin (Co-alb NPs) via Co-amine coordination chemistry of lysine residue were syntheisized in various sizes. The method to generate Co-alb NPs involves no thermal heat, organic solvent or any surfactants, which is ideal for the production of large amounts in a timely manner. The Co-alb NPs displayed exceptional stability under physiological conditions (pH 7.4) for several days with minor changes in size; however degradation could be triggered by reductant (reduced glutathione (GSH), 10 mM) with complete disappearance of particles in less than 2 hour. Numerous therapeutics that are highly effective toward cancer cells have been developed; however, many cannot be administered to patients due to poor solubility in water and pH dependent properties. We have successfully encapsulated 7-ethyl-10-hydroxycampothecin (SN-38) into Co-alb NPs with encapsulation efficiency as high as 94% and loading capacities greater than 30%. We employed an emulsion-solvent evaporation method to incorporate SN-38 into Co-alb (SN38 Co-Alb NPs). Release of the drug from SN38 Co-Alb NPs was determined for particles incubated in PBS or PBS-GSH. SN38 Co-Alb NPs were exceptionally stable under physiological condition (PBS pH 7.4), but exhibited sustained release of SN-38 over time in the presence of GSH. Uptake and toxicity of the particles were also investigated in a gastric carcinoma cell line (SNU-5) where high degrees of macropinocytic uptake ...
Date: December 2015
Creator: Nguyen, Duong Thuy