Browsing by Author "Machado, Carla"
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- Development of tailored hydrogels using RAFT polymerization in continuous flow microreactorPublication . Machado, Carla; Oliveira, Tânia; Reitor, Patrícia; Oliveira, Daniela; Freitas, Filipa; Kadhirvel, Porkodi; Dias, Rolando; Costa, Mário RuiThis research is devoted to the development of tools aiding the production of smart hydrogels with tailored molecular architecture and properties. Molecular imprinting, RAFT polymerization and operation in continuous flow microreactor are individually considered and also simultaneously combined in order to try the synthesis of materials with improved performance.
- Molecular imprinting in hydrogels using reversible addition-fragmentation chain transfer polymerization and continuous flow micro-reactorPublication . Kadhirvel, Porkodi; Machado, Carla; Freitas, Ana Filipa Fernandes Lobo; Oliveira, Tânia; Dias, Rolando; Costa, Mário RuiAbstract BACKGROUND Stimuli responsive imprinted hydrogel micro-particles were prepared using reversible addition-fragmentation chain transfer polymerization for targeting genotoxic impurity aminopyridine in aqueous environment using a continuous flow micro-reactor. RESULTS The feasibility of operation with a continuous flow micro-reactor for particles production was demonstrated. A comparative evaluation was carried out between batch and micro-reactor produced imprinted and non-imprinted hydrogels. Experimental results proved that molecular imprints generated by free radical polymerization and controlled radical polymerization showed outstanding performance in adsorption behavior: the q value estimate was about 1000 times higher than the value presented by other researchers. Solid phase extraction results further evidenced the promising imprinting with hydrogels using free radical polymerization and controlled radical polymerization by retaining c. 100% of 3-aminopyridine. The imprinting factor of 4.3 presented in this research appears to be the best value shown so far. CONCLUSION The imprinted materials were successfully prepared both in batch and with a continuous flow micro-reactor. The inclusion of a reversible addition-fragmentation chain transfer agent in controlled radical polymerization was important in optimizing the experimental conditions in the continuous microfluidic approach. Though the reversible addition-fragmentation chain transfer agent was very useful in controlling the reaction kinetics, imprinted micro-particles showed the existence of both non-specific and imprinted sites. It is worth extending this work to demonstrate the impact of reversible addition-fragmentation chain transfer agents in molecular imprinting, considering also operation in a continuous flow micro-reactor to obtain tailored smart hydrogel particles. © 2015 Society of Chemical Industry
- Probabilistic simulation of children exposure to migrants from packaging: photoinitiators from printing inksPublication . Machado, Carla; Fernandes, Conceição; Pereira, Joel; Poças, Maria de FátimaThis paper presents an exercise to simulate exposure of Portuguese consumers to benzophenone, a photoinitiator used in packaging printing inks. The simulation model combines experimental data of benzophenone concentration actually found in packages collected from the market and food consumption and packaging usage data obtained from a database. The model follows a probabilistic approach: the distribution of occurrence data was combines with food consumption data in a probabilistic simulation with the Monte Carlo sampling method. Exposure values found indicate that benzophenone levels of exposure are of no concern healthwise according to the tolerable daily intake defined by EFSA.
- Probabilistic simulation of children exposure to migrants from packaging: photoinitiators from printing inksPublication . Machado, Carla; Fernandes, Conceição; Pereira, Joel; Poças, Maria de FátimaThe present work presents an exercise to simulate exposure of Portuguese consumers to benzophenone, a photoinitiator used in packaging printing inks. The simulation model combined experimental data of benzophenone concentration found in packages collected from market and food consumption and packaging usage data obtained from a database. The model followed a probabilistic approach: the distribution of occurrence data was combined with food consumption data in a probabilistic simulation with the Monte Carlo sampling method. The values found indicate that benzophenone levels of exposure are of no health concern according to the tolerable daily intake defined by EFSA.
- Production of RAFT imprinted smart hydrogel particles in a continuous flow micro-reactorPublication . Machado, Carla; Freitas, Ana Filipa Fernandes Lobo; Kadhirvel, Porkodi; Dias, Rolando; Costa, Mário RuiFeasibility of the production of RAFT imprinted smart hydrogel particles in continuous flow micro-reactor is here showed. Microfluidic continuous operation was combined with RAFT polymerization and molecular imprinting tecniques involving selected template molecules. New strategies for the production of advanced materials with tailored properties are thus developed. Particles syntetized in the continuous flow micro-reactor (set-up scheme depicted in the graphical abstract) were purified and characterized using different techniques, namely batch and continuous drugs adsorption and release processes. Particles were packed in small columns allowing the quick testing of these materials using frontal analysis. Therefore, the usefulness of these particles in biotechnology and biomedicine is likely.