RESUMO
The possibility of combining nanotechnology with nanomedicine opens a broad field of research which may truly revolutionize our society. The neural system plays a crucial role in the human body, and most related diseases can dramatically change the quality of life. Thus, the present study reports a novel approach for using neurotransmitters as ligands in the synthesis of surface-modified fluorescent nanocrystals for potential use in cell labeling applications. Briefly, CdS quantum dots (QDs) were prepared using L-glutamic and L-aspartic as surface capping agents via a one-step chemical processing method, which resulted in stable aqueous colloidal systems at room temperature and ambient pressure. UV-visible spectroscopy, photoluminescence spectroscopy (PL), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM) were used to characterize the synthesis and relative stability of peptide-capped CdS nanocrystals. The results demonstrate that both ligands were effective in nucleating and stabilizing CdS quantum dots in colloidal aqueous suspensions, with an estimated dimension below 3.3 nm and with fluorescence activity. Thus, novel nanohybrids were developed based on QDs bioconjugated to surface-active neurotransmitter moieties suitable for investigation as potential biomarkers in cell targeting and signaling applications.
Assuntos
Células/metabolismo , Neurotransmissores/química , Pontos Quânticos/química , Transdução de Sinais , 1,2-Dipalmitoilfosfatidilcolina/química , Adsorção , Ácido Aspártico/química , Compostos de Cádmio/química , Fluorescência , Ácido Glutâmico/química , Humanos , Ligantes , Luz , Membranas , Tamanho da Partícula , Pontos Quânticos/ultraestrutura , Espalhamento de Radiação , Soluções , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Sulfetos/química , Propriedades de Superfície , TermodinâmicaRESUMO
PURPOSE: To compare the intravitreal pharmacokinetic profile of a triamcinolone acetonide formulation containing the preservative benzyl alcohol (TA-BA) versus a preservative-free triamcinolone acetonide formulation (TA-PF), and evaluate potential signs of toxicity to the retina. METHODS: A total of 60 New Zealand male white rabbits, divided into two groups, were studied. In the TA-BA group, 30 rabbits received an intravitreal injection of TA-BA (4 mg/0.1 ml) into the right eye. In the TA-PF group, 30 rabbits received an intravitreal injection of TA-PF (4 mg/0.1 ml) into the right eye. The intravitreal drug levels were determined in 25 animals from each group by high-performance liquid chromatography (HPLC). The potential for toxicity associated with the intravitreal triamcinolone injections was evaluated in five randomly selected animals from each group by electroretinography (ERG) and by light microscopy. RESULTS: Median intravitreal concentrations of TA-BA (µg/ml) were 1903.1, 1213.0, 857.8, 442.0, 248.6 at 3, 7, 14, 21 and 28 days after injection. Intravitreal concentrations of TA-PF (µg/ml) were 1032.9, 570.1, 516.6, 347.9, 102.8 at 3, 7, 14, 21 and 28 days after injection. The median intravitreal triamcinolone concentration was significantly higher in the TA-BA compared to the TA-PF group at 7 days post-injection (p < 0.05). There was no significant difference between the two groups in median triamcinolone concentration at the other time points evaluated. There was no evidence of toxic effects on the retina in either group based on ERG or histological analyses. CONCLUSIONS: Following a single intravitreal injection, the median concentration of triamcinolone acetonide is significantly higher in the TA-BA compared to the TA-PF group at 7 days post-injection. No toxic reactions in the retina were observed in either group.
Assuntos
Degeneração Macular/tratamento farmacológico , Retina/efeitos dos fármacos , Triancinolona Acetonida/farmacocinética , Corpo Vítreo/metabolismo , Animais , Cromatografia Líquida de Alta Pressão , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Eletrorretinografia/efeitos dos fármacos , Injeções Intravítreas , Degeneração Macular/metabolismo , Degeneração Macular/fisiopatologia , Masculino , Coelhos , Retina/metabolismo , Retina/fisiopatologia , Triancinolona Acetonida/administração & dosagem , Corpo Vítreo/efeitos dos fármacosRESUMO
PURPOSE: The transplant of retinal pigment epithelium (RPE) cells on supports may well be an effective therapeutic approach to improve the visual results of patients with age-related macular degeneration. In this study, two biodegradable polyurethanes were investigated as supports for human RPE cells (ARPE-19). METHODS: Polyurethane aqueous dispersions based on poly(caprolactone) and/or poly(ethylene glycol) as soft segments, and isophorone diisocyanate and hydrazine as hard segments were prepared. Polyurethane films were produced by casting the dispersions and allowing them to dry at room temperature for one week. The ARPE-19 cells were seeded onto the polyurethane films and they were investigated as supports for in vitro adhesion, proliferation, and uniform distribution of differentiated ARPE-19 cells. Additionally, the in vivo ocular biocompatibility of the polyurethane films was evaluated. RESULTS: The RPE adhered to and proliferated onto the polyurethane supports, thus establishing cell-PUD surface interactions. Upon confluence, the cells formed an organized monolayer, exhibited a polygonal appearance, and displayed actin filaments which ran along the upper cytoplasm. At 15 days of seeding, the occluding expression was confirmed between adjacent cells, representing the barrier functionality of epithelial cells on polymeric surfaces and the establishment of cell-cell interactions. Results from the in vivo study indicated that polyurethanes exhibited a high degree of short-term intraocular biocompatibility. CONCLUSIONS: Biodegradable polyurethane films display the proper mechanical properties for an easy transscleral-driven subretinal implantation and can be considered as biocompatible supports for a functional ARPE-19 monolayer.
Assuntos
Materiais Biocompatíveis , Proliferação de Células , Células Epiteliais/fisiologia , Poliuretanos/química , Epitélio Pigmentado da Retina/citologia , Engenharia Tecidual/métodos , Alicerces Teciduais , Citoesqueleto de Actina/fisiologia , Animais , Adesão Celular , Diferenciação Celular , Linhagem Celular , Células Epiteliais/transplante , Feminino , Humanos , Hidrazinas/química , Imuno-Histoquímica , Isocianatos/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Poliésteres/química , Polietilenoglicóis/química , Ratos , Ratos Endogâmicos BN , Epitélio Pigmentado da Retina/transplante , Fatores de TempoRESUMO
Chitosan, a biodegradable and biocompatible polysaccharide, is a potentially useful material in various fields. We produced mono and bilayer chitosan films containing dexamethasone as a drug carrier for controlled release. The chitosan drug-loaded films were produced by a casting/solvent evaporation technique using 2 wt% acetic acid solution and distilled water and they were dried at room temperature. These films were characterized by release and swelling studies, DSC and ATR-FTIR. The total profile for water absorption was similar for the types of films developed. ATR-FTIR analysis showed little change in the band position of the O--H and N--H stretching from dexamethasone and chitosan, respectively. DSC analysis from bilayer film indicates that the dexamethasone peak was shifted from 256 to 240 degrees C. These results suggested an interaction between hydroxyl and amino groups of chitosan and hydroxyl groups of dexamethasone. In the drug release studies it was observed 89.6% release from the monolayer film in 8h and 84% from the bilayer film in 4 weeks. These results suggested that the chitosan sheet prepared in this study is a promising delivery carrier for dexamethasone.