Browsing by Author "Machado, Paulo Filipe Brito"
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- Desenho e produção de novos veículos para entrega de fármacosPublication . Machado, Paulo Filipe Brito; Correia, Ilídio Joaquim Sobreira; Silva, Ana Sofia Matias daNanotechnology is a science that conjugates several disciplines from engineering to chemistry, physics and biology at a molecular level. One of the areas of research with particular focus over the last few years is nanomedicine. It is expected that several improvements in medical care, from diagnosis to treatment, will occur, in the near future, due to the application of nanotechnology to medicine. Several biological and chemical compounds are being applied for the production of drug delivery systems at the nanoscale. These biocompatible systems have some interesting properties that make them capable of performing a targeted delivery of drugs and other materials. Lipossomes, solid lipid nanoparticles, dendrimers, nanoemulsions, polymeric nanoparticles and inorganic nanoparticles like carbon nanotubes, magnetic and ceramic nanoparticles are examples of drug delivery systems. Mesoporous silica nanoparticles are ceramic particles with good structural and biological properties that can be easily functionalized, allowing the bond of other compounds, like for instance gold. The objective of the present work was to produce mesoporous silica nanoparticles, to functionalize their surface and also to bond gold nanoparticles to form a core/shell nanosystem. The produced nanoparticles were characterized by Scanning Electron Microscopy, Fourier Transform Infrared spectroscopy and X-Ray Diffraction. Moreover, the loading and release profiles of the nanoparticles were also characterized using ibuprofen as model drug. In vitro studies were performed to evaluate the internalization and cytotoxicity of the produced nanocarriers. The results herein presented, suggest that the produce nanosytem are suitable for future drug delivery applications.
- Design of oligoaziridine-PEG coatings for efficient nanogold cellular biotaggingPublication . Silva, A. Sofia; Bonifácio, Vasco; Raje, Vivek; Branco, Paula S.; Machado, Paulo Filipe Brito; Correia, Ilídio Joaquim Sobreira; Ricardo, Ana AguiarGold nanoparticles (AuNPs) are the most investigated nanomaterials for theragnosis applications. In a research field where live cell assays, as well as the tracking of nanomaterials into a cell's environment, are of extremely importance, water-soluble AuNPs have been intensively studied to overcome the toxic effects exerted by coatings. Unfortunately, AuNPs fluorescent tagging often fails due to self-quenching and a careful design must be carried out to maintain optoelectronic properties and biocompatibility. In this work, the synthesis of fluorescent gold nanoprobes, able to enter the cell's environment (biotags) and target the cell nucleus, was designed and the particles tracked by confocal laser scanning microscopy. The coating of AuNPs with maleimide poly(ethylene glycol) and fluorescent oligoaziridine biocompatible oligomers, resulted in robust, optically active biotags that open novel insights into cancer theragnosis.
- Preparation of end-capped pH-sensitive mesoporous silica nanocarriers for on-demand drug deliveryPublication . Moreira, André; Gaspar, Vítor Manuel Abreu; Costa, Elisabete C.; Diogo, Duarte Miguel de Melo; Machado, Paulo Filipe Brito; Paquete, Catarina; Correia, Ilídio Joaquim SobreiraNanocarriers with a pH responsive behavior are receiving an ever growing attention due to their potential for promoting on-demand drug release and thus increase the therapeutic effectiveness of anti-tumoral pharmaceutics. However, the majority of these systems require costly, time-consuming and complex chemical modifications of materials or drugs to synthesize nanoparticles with pH triggered release. Herein, the development of dual drug loaded pH-responsive mesoporous silica nanoparticles (MSNs) with a calcium carbonate-based coating is presented as an effective alternative. This innovative approach allowed the loading of a non-steroidal anti-inflammatory drug (Ibuprofen) and Doxorubicin, with high efficiency. The resulting dual drug loaded MSNs have spherical morphology and a mean size of 171 nm. Our results indicate that under acidic conditions the coating disassembles and the drugs are rapidly released, whereas at physiologic pH the release is slower and gradually increases with time. Furthermore, an improved cytotoxic effect was obtained for Doxorubicin–Ibuprofen MSNs coated with CaCO3 in comparison with non-coated particles. The cytotoxic effect of dual loaded carbonate coated particles, was similar to that of Doxorubicin + Ibuprofen free drug administration at 72 h, even with the delivery of a significantly lower amount of drug by MSNs-CaCO3. These results suggest that the carbonate coating of MSNs is a promising approach to create a pH-sensitive template for a delivery system with application in cancer therapy.