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533 results on '"Duarte, Ana Rita C."'

138. Chitin/chitosan based aerogels: processing and morphology

Author

Duarte, Ana Rita C., Silva, Simone Santos, Reis, R. L., and Universidade do Minho

Subjects
Chitosan, Aerogels, Chitin
Abstract

Marine origin biopolymers are of great interest due to their chemical and biological diversity. In particular, chitin and chitosan have attracted attention as potential sources of valuable materials with a vast range of properties and characteristics. In fact, the importance of these polymers is found in a high number of publications in the literature, focusing on their preparation methodology, analysis of physicochemical properties and applications. Recent studies have emphasized the processing of chitin and chitosan aerogels using mainly supercritical fluid technology, solâ gel methodology and freeze-drying techniques. In this chapter, we review the processing methodologies used and discuss the different methodologies obtained. We also highlight the possibility of preparing functional aerogels with bioactive properties from these natural origin polymers., FCT-Fuel Cell Technologies Program (REGPOT-CT2012-316331-POLARIS), info:eu-repo/semantics/publishedVersion

Published
2018

142. Natural deep eutectic systems for nature‐inspired cryopreservation of cells.

Author

Hornberger, Kathlyn, Li, Rui, Duarte, Ana Rita C., and Hubel, Allison

Subjects
EUTECTIC reactions, DIFFERENTIAL scanning calorimetry, THERMOPHYSICAL properties, CELL preservation, MORPHOLOGY, CRYOPRESERVATION of cells
Abstract

Natural deep eutectic systems (NADES) are emerging as potential cryoprotective agents (CPA) for cell preservation. In this investigation, we develop an optimized CPA formulation using trehalose‐glycerol NADES (T:G) diluted in Normosol‐R and supplemented with isoleucine. Differential scanning calorimetry (DSC) is used to define the thermophysical properties of NADES‐based solutions, and Raman spectroscopy is used to characterize the effect of NADES on ice formation and hydrogen bonding. Jurkat cells are cryopreserved in each solution, and post‐thaw cell recovery, apoptosis, and growth are quantified. Raman spectra and heat maps show that NADES suppresses both ice formation and dehydration of the nonfrozen region. Supplementing NADES with isoleucine does not affect the solution's thermophysical properties but significantly improves the cells' survival and proliferation post‐thaw. The study indicates that thermophysical properties of CPA solutions alone cannot predict optimal cell survival, suggesting that stabilization of biological structures by CPAs may play a role in successful cryopreservation. [ABSTRACT FROM AUTHOR]

Published
2021
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143. Gelatin-based biodegradable ureteral stents for the treatment of urothelial tumors of the upper urinary tract cancer

Author

Barros, Alexandre António Antunes, Browne, S., Oliveira, C., Lima, Estêvão Augusto Rodrigues de, Duarte, Ana Rita C., Healy, K. E., Reis, R. L., and Universidade do Minho

Subjects
Cancer cells, Science & Technology, Upper urinary tract, Drug-eluting, Stents
Abstract

Upper urinary tract urothelial carcinoma (UTUC) accounts for 5â 10% of urothelial carcinomas and is a disease that has not been widely studied as carcinoma of the bladder. To avoid the problems of conventional therapies, such as the need for frequent drug instillation due to poor drug retention, we developed a biodegradable ureteral stent (BUS) impregnated by supercritical fluid CO2 (scCO2) with the most commonly used anti-cancer drugs, namely paclitaxel, epirubicin, doxorubicin, and gemcitabine. The release kinetics of anti-cancer therapeutics from drug-eluting stents was measured in artificial urine solution (AUS). The in vitro release showed a faster release in the first 72h for the four anti-cancer drugs, after this time a plateau was achieved and finally the stent degraded after 9 days. Regarding the amount of impregnated drugs by scCO2, gemcitabine showed the highest amount of loading (19.57â μg drug /mg polymer: 2% loaded), while the lowest amount was obtained for paclitaxel (0.067â μg drug /mg polymer: 0.01% loaded). A cancer cell line (T24) was exposed to graded concentrations (0.01 to 2000â ng/ml) of each drug for 4 and 72 hours to determine the sensitivities of the cells to each drug (IC50). The direct and indirect contact study of the anti-cancer biodegradable ureteral stents with the T24 and HUVEC cell lines confirmed the anti-tumoral effect of the BUS impregnated with the four anti-cancer drugs tested, reducing by 75% of the viability of the T24 cell line after 72h and demonstrating minimal cytotoxic effect on HUVECs., info:eu-repo/semantics/publishedVersion

Published
2016

144. The role of supercritical fluids in biomaterials processing - Where do we stand?

Author

Duarte, Ana Rita C., Reis, R. L., and Universidade do Minho

Subjects
Biomaterials, Supercritical fluids, Engenharia e Tecnologia::Biotecnologia Industrial, Ciências Médicas::Biotecnologia Médica, Tissue engineering, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries)
Abstract

No abstract was submitted., ENiGMA (FCT); SWIMS (FCT); IF FCT Investigator 2013 IBEROMARE (POCTEP); SPECIAL (FP7); POLARIS (FP7) RL1 -ABMR -NORTE-01-0124-FEDER-000016, info:eu-repo/semantics/publishedVersion

Published
2016

145. Solubility and Permeability Enhancement of active compounds: Therapeutic Deep Eutectic Systems as New Vehicles for Drug Delivery

Author

Duarte, Ana Rita C., Barreiros, Susana, Matias, Ana A., Reis, R. L., Paiva, Alexandre, and Universidade do Minho

Subjects
Science & Technology, Pharmaceutics, Deep Eutectic Solvents, Ciências Médicas::Biotecnologia Médica, Controlled delivery, Ibuprofen
Abstract

Therapeutic deep eutectic systems (THEDES) are here proposed as a new class of pharmaceutical active ingredient (API) whose distinctive characteristic is the fact that they are liquid at room temperature. Eutectic systems have been described in the pharmaceutical sciences as an alternative formulation able to enhance bioavailability of the API. THEDES are constituted by one active agent and a coformer or two active agents, which when combined at a particular molar ratio become liquid at room temperature. In this work, we explore the prepararation of the THEDES menthol-ibuprofen. The solubility and dissolution profile in phosphate buffer solution (pH 7.4) was performed at 37°C and compared with those of the pure API. Furthermore, the in vitro permeability of the liquid THEDES and the API in powder form, was evaluated using a Franz diffusion cell and caco-2 cells as model of human intestinal epithelium. The solubility of the API's when in the THEDES system improved as much as up to 12 fold. Furthermore, for this system the permeability was calculated to be 14â à â 10â 5 cm/s representing a 3 fold increase in comparison with the pure API. The results indicate that both solubilization and permeability were greatly enhanced when the API is complexed in the THEDES liquid form. The results obtained demonstrate the potential of THEDES to overcome the drawbacks of poorly water soluble molecules and increase bioavailability of the APIs and the possibility to develop new delivery systems., info:eu-repo/semantics/publishedVersion

Published
2016

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