Advances in recent nanoscience technologies have generated a new compilation of biocompatible, fluorescent nanoparticles derived from semiconductor quantum dots (QDs). QDs are extremely small in size and possess very large surface areas, which gives them unique physical properties and applications distinct from those of bulk systems. When exposed to biological fluid, these QDs may become coated with proteins and other biomolecules given their dynamic nature. These protein-QD systems may affect or enhance the changes in protein structure and stability, leading to the destruction of biological function. It is believed that these QDs can act as nucleation centers and subsequently promote protein fibril formation. Protein fibrillation is closely associated with many fatal human diseases, including neurodegenerative diseases and a variety of systemic amyloidoses. This topic of protein-QD interaction brings about many key issues and concerns, especially with respect to the potential risks to human health and the environment. Herein, the behavioral effects of dihydrolipoic acid (DHLA)-capped CdSe/ZnS (core/shell) QDs in hen egg-white lysozyme (HEWL) and human serum albumin (HSA) protein systems were systematically analyzed. This study gives rise to a better understanding of the potentially useful application of these protein-QD systems in nanobiotechnology and nanomedicine as a bioimaging tool and/or as a reference for controlled biological self-assembly processes.

Thesis (M.S.)--Mississippi State University. Department of Chemistry. / Title from title screen. Includes bibliographical references.

The present work is synthesizing novel protein-based superabsorbent hydrogels from albumin protein (AP) and isolated zygomycetes protein (IZP) via modification with an acylating reagent and a bifunctional crosslinker, also investigation on their swelling behaviors under some conditions. The hydrophilic acylating reagent was introduced into albumin and zygomycetes proteins and hydrophylicity of albumin and isolated zygomycetes protein were increased by ethylenediaminetetraacetic dianhydride (EDTAD). Provided protein hydrogels through this method include modification of lysyl residues in the unfolded proteins via adding of one or more hydrophilic carboxyl groups. The reaction was developed with a dialdehyde crosslinking reagent (glutaraldehyde) in order to stabilize the modified protein configuration. The maximum capacity of EDTAD-AP hydrogel swelling was observed 296 g water per g of dry gel, and for EDTAD-IZP hydrogel was 87 g water per g of dry gel.In this study, effect of selected physical and chemical parameters such as protein structure, extent of modification, protein concentration, various pH, ionic strength, gel particle size, temperature as important factors affecting the water uptake behavior of superabsorbent hydrogel were investigated. In addition, the effect of some organic solvents particularly absolute ethanol for increasing the swelling properties was studied. / Uppsatsnivå: D

[pt] Na busca de novos quimioterápicos diferentes dos clássicos derivados de cisplatina, ligantes derivados aroíl-hidrazônicos e complexos de cobre(II) aparecem como compostos promissores. Esta tese relata o desenvolvimento e a síntese de uma nova combinação desses compostos a partir de oito ligantes bases de Schift aroíl-hidrazônicos inéditos e seus Cu2-complexos derivados de sais de perclorato ou acetato 1‒14. Os complexos de cobre(II) obtidos contêm em suas estruturas modelos estruturais de sítios ativos de algumas metaloenzimas. Os compostos foram amplamente caracterizados utilizando várias técnicas espectroscópicas e analíticas. As análises por difração de raios X de quatro ligantes e cinco complexos são descritas em detalhes nessa tese. A estabilidade dos compostos foi estudada em meio celular e sua atividade biológica foi analisada. Os resultados incluem um estudo da interação de dois ligantes derivados de tiofeno (H3L1) ou furano (H3L2) e seus respectivos complexos 1 e 2 (primeiro conjunto de compostos) com uma proteína e DNA do timo de vitelo (calf thymus DNA), com o objetivo de medir a afinidade de ligação à albumina sérica bovina e ao DNA usando as técnicas de absorção de UV/Visível e/ou fluorescência. Adicionalmente, foi visto através de técnicas de espalhamento de luz que a interação entre os compostos e a proteína é reversível. Uma importante contribuição do presente trabalho foi analisar a capacidade de clivagem do DNA plasmidial de dois complexos 1 e 2 usando a técnica de espalhamento de luz dinâmico. Neste trabalho são estudadas as alterações do raio hidrodinâmico do DNA plasmidial causada pelo corte nas hélices resultante da presença dos complexos. Ensaios de citotoxicidades em algumas células cancerígenas, revelaram a alta capacidade dos ligantes (H3L1 and H3L2) e dos complexos (1 e 2) de induzir a morte celular. Ademais, as muitas propriedades biológicas, incluindo a atividade anticancerígena do fragmento isoxazol, motivaram sua inclusão na estrutura dos ligantes H3L3 and H2L4 e complexos 3‒6 (segundo conjunto de compostos). A combinação dessas estruturas pode vir a ser promissora na procura de novos medicamentos contra o câncer. A interação dos derivados dos ligantes isoxazol-aroíl-hidrazônicos com o DNA foi diretamente estudada por espectroscopia na absorbância e fluorescência, usando as propriedades luminescentes apresentadas pelos ligantes. No caso dos complexos, o ensaio de deslocamento de brometo de etídio revelou uma afinidade importante através da intercalação nos ácidos nucleicos da sequência do DNA. Adicionalmente, este trabalho conseguiu demostrar que ligantes e complexos contendo um braço fenólico no lugar de um braço piridínico melhoram a citotoxicidade in vitro em células de câncer de mama epitelial humano, alcançando a faixa nanomolar. A capacidade de metalação e transmetalação dos ligantes binucleares H3L3 e H2L4 e seus complexos de cobre 3‒6 com Fe(II), Fe(III) e Zn(II) provenientes do meio biológico foi verificada como uma estratégia adicional para induzir a morte de células cancerígenas. Além disso, para estudar a interação dos compostos com o sistema biológico e/ou para demostrar a permeabilidade celular dos compostos, os ligantes (H3L5‒H3L7) e complexos (7‒12) foram funcionalizados com fluoróforos potentes como pireno (H3L5) (conjunto três de compostos), benzopiranotiofeno (H3L6) ou borodipirrometeno (H3L7) (conjunto quatro de compostos) associados aos fragmentos hidrazônicos. Estudos de microscopia de fluorescência do ligando H3L7 comprovaram sua presença dentro de células de câncer. Também, análises de co-localização para organelas mostraram a afinidade dos ligantes com a mitocôndria. Finalmente, motivada pelas propriedades biológicas da molécula isoniaziada e seu uso em tratamentos de quimioterapia, esta tese mostra de forma general a síntese, caracterização e citotoxicidade de um novo ligante isoniazídico (H2L8) e seus complexos de perclorato ou acetato de cobre(II) 13 e 14 (conjunto cinco de compostos) visando realizar um pedido de patente. / [en] On the search of new chemotherapeutic agents differing from the classic cisplatin family drugs, aroylhydrazonic derivatives and their copper(II) complexes appear as promising compounds. This thesis reports on the design and syntheses of a novel combination of them through eight new aroylhydrazones and their fourteen perchlorate and/or acetate Cu2-complexes 1‒14. The obtained bioinspired copper(II) complexes constitute structural models for the active sites of some type 3 copper enzymes. The compounds were fully characterized using various spectroscopic and analytical techniques. X-ray diffraction structures for four ligands and five complexes are described in detail. Compounds stability was studied in cellular medium and their biological activity was examined. The results include a large study on the interaction of two thiophene (H3L1) or furan (H3L2) ligand derivatives and their respective μ-hydroxo dicopper complexes 1 and 2 (first set of compounds) respectively, with bovine serum albumin protein and calf thymus DNA using different spectroscopic techniques, which include the binding affinity to BSA and DNA using UV/Visible and/or fluorescence techniques. Additionally, scattering techniques revealed that the interaction between the compounds and BSA induces reversible aggregation of the biomolecules. As an important contribution of the present work, the plasmid DNA cleavage ability of the complexes 1 and 2 was studied by Dynamic Light Scattering. The changes of hydrodynamic radius values of pBR322 plasmid DNA are correlated to the nick induced by the complexes in the helices. Cytotoxic assays on some cancer cells revealed the high ability of H3L1 and H3L2, and complexes 1 and 2 to induce cell death. On the other hand, the many biological properties, including anticancer activity, of the isoxazole molecule, motivated the inclusion of this moiety in two ligands H3L3 and H2L4 and four complexes 3‒6 (second set of compounds). Interaction of these isoxazole-aroylhydrazonic ligand derivatives with DNA was directly studied by absorbance and fluorescence spectroscopy, as a result of the fluorescence properties displayed by the ligands. In the case of the isoxazole-aroylhydrazonic complexes-DNA interaction, the ethidium bromide displacement assay revealed significant affinity by intercalation binding mode of the nucleic acid in the DNA sequence. Additionally, this work successfully demonstrated that ligands and complexes containing a phenol pendant arm instead of a pyridine one improve the in vitro cytotoxicity on human epithelial breast cancer cells, attaining nanomolar range. Metal chelation and transmetallation ability of binucleating ligands H3L3 and H2L4 and their copper complexes 3‒6 with Fe(II), Fe(III) and Zn(II) from the biological medium was verified as an additional cell death induction anticancer strategy. Moreover, to study the interaction of the compounds with the biological system and to demonstrate their cell permeability, ligands (H3L5‒H3L7) and complexes (7‒12) were functionalized in their hydrazone moieties with potent fluorophores, such pyrene (H3L5) (set three of compounds), benzopyranothiophene (H3L6), or boron-dipyrromethene (H3L7) derivatives (set four of compounds). Fluorescence microscopy studies proved the presence of ligand H3L7 inside cancer cells, proving its ability to pass through the cell membrane. Besides, co-localization analysis for organelles showed the affinity of this ligand for the mitochondria. Finally, motived by the wide spectrum of biological properties of the isoniazid molecule and its use in chemotherapy, this thesis reports the syntheses, characterization and cytotoxicity studies on cancer cells of a new isonicotinoyl hydrazone ligand (H2L8) and its perchlorate or acetate copper(II) complexes 13 and 14 (set five of compounds), which are involved in a patent request.