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Projeto de investigação
Laboratory of Separation and Reaction Engineering - Laboratory of Catalysis and Materials
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Immobilization and Characterization of L-Asparaginase over Carbon Xerogels
Publication . Barros, Rita A. M.; Cristóvão, Raquel O.; Carabineiro, Sónia A. C.; Neves, Márcia C.; Freire, Mara G.; Faria, Joaquim L.; Santos-Ebinuma, Valéria C.; Tavares, Ana P. M.; Silva, Cláudia G.; LAQV@REQUIMTE; DQ - Departamento de Química; MDPI - Multidisciplinary Digital Publishing Institute
L-asparaginase (ASNase) is an aminohydrolase currently used in the pharmaceutical and food industries. Enzyme immobilization is an exciting option for both applications, allowing for a more straightforward recovery and increased stability. High surface area and customizable porosity make carbon xerogels (CXs) promising materials for ASNase immobilization. This work describes the influence of contact time, pH, and ASNase concentration on the immobilization yield (IY) and relative recovered activity (RRA) using the Central Composite Design methodology. The most promising results were obtained using CX with an average pore size of 4 nm (CX-4), reaching IY and RRA of 100%. At the optimal conditions (contact time 49 min, pH 6.73, and [ASNase] 0.26 mg·mL−1), the ASNase-CXs biocomposite was characterized and evaluated in terms of kinetic properties and operational, thermal, and pH stabilities. The immobilized ASNase onto CX-4 retained 71% of its original activity after six continuous reaction cycles, showed good thermal stability at 37 °C (RRA of 91% after 90 min), and was able to adapt to both acidic and alkaline environments. Finally, the results indicated a 3.9-fold increase in the immobilized ASNase affinity for the substrate, confirming the potential of CXs as a support for ASNase and as a cost-effective tool for subsequent use in the therapeutic and food sectors.
An Injectable Thermoreversible Hydrogel Loaded with ManNAc for GNE Myopathy
Publication . Violante, Cristiana; Marques-Da-Silva, Dorinda; Videira, Paula Alexandra; Lagoa, Ricardo; DCV - Departamento de Ciências da Vida; UCIBIO - Applied Molecular Biosciences Unit
GNE myopathy (GNEM) is a rare adult-onset disease characterized by atrophy and weakness of skeletal muscles caused by mutations in the GNE gene. There is no approved therapy, but clinical trials with supplementation with N-acetylmannosamine (ManNAc) alleviated the GNEM-associated decrease in sialylation. Nevertheless, oral intake of ManNAc has shown low absorption and high gastrointestinal adverse effects. In this regard, the aim of this work was to explore an alternative delivery route for ManNAc directly targeting the muscle tissues. For this we investigated the thermal responses of Pluronic F-127 gel and its muscle adhesion after subcutaneous injection, and the kinetics of release of gelencapsulated ManNAc in phosphate buffered saline medium. The results obtained show the thermal response of Pluronic F-127 represents a unique opportunity for its injectability and function as a drug delivery system directly acting on the muscle surrounding area and showing gel stability in the target area. Moreover, the continuous delivery of ManNAc from the gel (20% Pluronic F-127) was detected during 3h, at a continuous rate and slower than using a simple ManNAc solution. In conclusion, the data obtained in this work supports the possible use of the Pluronic F-127 thermoreversible hydrogel loaded with ManNAc in GNE myopathy therapy and research.
Improved L-Asparaginase Properties and Reusability by Immobilization onto Functionalized Carbon Xerogels
Publication . Barros, Rita A. M.; Cristóvão, Raquel O.; Carneiro, Inês G.; Barros, Maria A.; Pereira, Matheus M.; Carabineiro, Sónia A. C.; Freire, Mara G.; Faria, Joaquim L.; Santos-Ebinuma, Valéria C.; Tavares, Ana P. M.; Silva, Cláudia G.; LAQV@REQUIMTE; DQ - Departamento de Química; Wiley | Wiley-VCH Verlag
Enzyme immobilization can offer a range of significant advantages, including reusability, and increased selectivity, stability, and activity. In this work, a central composite design (CCD) of experiments and response surface methodology (RSM) were used to study, for the first time, the L-asparaginase (ASNase) immobilization onto functionalized carbon xerogels (CXs). The best results were achieved using CXs obtained by hydrothermal oxidation with nitric acid and subsequent heat treatment in a nitrogen flow at 600 °C (CX−OX-600). Under the optimal conditions (81 min of contact time, pH 6.2 and 0.36 g/L of ASNase), an immobilization yield (IY) of 100 % and relative recovered activity (RRA) of 103 % were achieved. The kinetic parameters obtained also indicate a 1.25-fold increase in the affinity of ASNase towards the substrate after immobilization. Moreover, the immobilized enzyme retained 97 % of its initial activity after 6 consecutive reaction cycles. All these outcomes confirm the promising properties of functionalized CXs as support for ASNase, bringing new insights into the development of an efficient and stable immobilization platform for use in the pharmaceutical industry, food industry, and biosensors.
Removal of Hydrophobic Organic Pollutants and Copper by Alginate-Based and Polycaprolactone Materials
Publication . Marques-da-Silva, Dorinda; Lopes, João M.; Correia, Iris; Silva, João S.; Lagoa, Ricardo; UCIBIO - Applied Molecular Biosciences Unit; MDPI - Multidisciplinary Digital Publishing Institute
Organic pollutants (OPs) and heavy metals are environmental toxicants associated with great concerns. Decontamination processes are urgent for both, and the possibility to achieve their simultaneous removal from polluted waters is highly interesting. Additionally, in many cases, the effect of organic matter in the removal process is overlooked and must be considered. This work aimed to study the potential of alginate-based and polycaprolactone (PCL) materials to remove OPs and copper ions in the absence and presence of organic matter. The OPs investigated were the polycyclic aromatic hydrocarbons anthracene and benzo[a]pyrene, and the pesticide chlorpyrifos, both hydrophobic compounds. Copper (II) ions were used as a model of heavy metals. Alginate-based spheres were prepared by gelation, and PCL microparticles were obtained by oil/water emulsion solvent evaporation. The materials with the highest efficiencies for OP removal from aqueous solutions were those with activated carbon and PCL. Furthermore, the spheres with activated carbon could remove anthracene and copper simultaneously, even in the presence of humic acid. This work points to activated carbon–alginate spheres as a multifunctional adsorbent able to remove different pollutants and to PCL for potential applications in OP decontamination processes.
Triazaphosphaadamantane-functionalized terpyridine metal complexes
Publication . Librando, Ivy L.; Paul, Anup; Mahmoud, Abdallah G.; Gurbanov, Atash V.; Carabineiro, Sónia A. C.; Silva, M. Fátima C. Guedes da; Geraldes, Carlos F. G. C.; Pombeiro, Armando J. L.; LAQV@REQUIMTE; DQ - Departamento de Química; RSC - Royal Society of Chemistry
In accordance with UN's Sustainable Development Goal (UN's SDG) 12 which encompasses the sustainable use of chemical products and a sound circular economy, this work is focused on the synthesis of Co(II), Ni(II) and Mn(II) complexes bearing combined 1,3,5-triaza-7-phosphaadamantane and benzyl terpyridine core moieties (PTA–Bztpy) as ligand, followed by their evaluation as catalysts for the microwave-assisted cyclohexane oxidation using tert-butyl hydroperoxide (TBHP) as oxidant. The most active catalyst, with a manganese metal center, was heterogenized on six different carbon materials. The results disclosed the influence of several reaction parameters, such as catalyst loading, temperature, reaction time and solvent, on the catalytic activity and selectivity of the homogeneous and carbon-supported catalysts. Recyclability of the carbon-supported catalyst allowed facile separations, recovery and reuse for five consecutive cycles.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/50020/2020