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- O projeto MySafeWater no ISELPublication . Barreiros, Ana Maria; Silva, Hugo; Matos, Manuel; Gonçalves Cavaco Mendes, Mário José; Monge, Nuno; Sousa, Ana Catarina; Costa, AlexandraO projeto MySafeWater pretendeu promover os objetivos nacionais e europeus, em matéria de Ambiente, no que se refere essencialmente à promoção do “consumo da água da torneira como forma ambientalmente sustentável de consumo, prevenindo a produção de resíduos e diminuindo a pegada ecológica”, através da informação e da conscientização do papel dos cidadãos na promoção do desenvolvimento sustentável em aspetos como a qualidade da água para consumo humano, abrangendo a participação ativa do público e pela sensibilização ambiental e a participação passiva do público.
- A sustainable synthesis of asymmetric phenazines and phenoxazinones mediated by CotA-LaccasePublication . Sousa, Ana Catarina; Oliveira, Maria Conceição; Martins, Lígia O.; Robalo, Maria PaulaAn efficient and sustainable one-step procedure for the synthesis of new asymmetric phenazines and phenoxazinones from commercially available ortho-substituted diamines and ortho-substituted hydroxyamines is reported. In this study we have expanded the substrate scope of CotA-laccase-catalyzed aerobic oxidations through the use of aromatic amines presenting variable functional groups, including N-substitution, contributing to the rational synthesis of different heterocyclic scaffolds. The transformations proceed smoothly through a cascade of oxidative reactions to the benzoquinonediimine intermediates followed by nucleophilic addition, intramolecular cyclization and aromatization, all performed in mild conditions.
- Silver(I) coordination polymers immobilized into biopolymer films for antimicrobial applicationsPublication . Fernandes, Tiago; Costa, Inês F. M.; Jorge, Paula; Sousa, Ana Catarina; André, Vânia; Cerca, N.; Kirillov, Alexander M.This study describes a template-mediated self-assembly synthesis, full characterization, and structural features of two new silver-based bioactive coordination polymers (CPs) and their immobilization into acrylated epoxidized soybean oil (ESOA) biopolymer films for antimicrobial applications. The 3D silver(I) CPs [Ag-4(mu(8)-H(2)pma)(2)](n)center dot 4nH(2)O (1) and [Ag-5(mu(6)-H(0.5)tma)(2)(H2O)(4)] (n)center dot 2nH(2)O (2) were generated from AgNO3 and pyromellitic (H(4)pma) or trimesic (H(3)tma) acid, also using N,N'-dimethylethanolamine (Hdmea) as a template. Both 1 and 2 feature the intricate 3D layer-pillared structures driven by distinct polycarboxylate blocks. Topological analysis revealed binodal nets with the flu and tcj/hc topology in 1 and 2, respectively. These CPs were used for fabricating new hybrid materials, namely, by doping the [ESOA](n) biopolymer films with very low amounts of 1 and 2 (0.05, 0.1, and 0.5%). Their antimicrobial activity and ability to impair bacterial biofilm formation were investigated in detail against both Gram-positive (Staphylococcus epidermidis and Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacteria. Both silver(I) CPs and derived biopolymer films showed activity against all the tested bacteria in a concentration-dependent manner. Compound 1 exhibited a more pronounced activity, especially in preventing biofilm growth, with mean bacterial load reductions ranging from 3.7 to 4.3 log against the four bacteria (99.99% bacterial eradication). The present work thus opens up antibiofilm applications of CP-doped biopolymers, providing new perspectives and very promising results for the design of functional biomaterials.
- Hybrid silver(I)-doped soybean oil and potato starch biopolymer films to combat bacterial biofilmsPublication . Fernandes, Tiago; Costa, Inês F. M.; Jorge, Paulo; Sousa, Ana Catarina; Andre, Vania; Cabral, Rafaela G.; Cerca, N.; Kirillov, Alexander M.This study describes the preparation, characterization, and antimicrobial properties of novel hybrid biopolymer materials doped with bioactive silver(I) coordination polymers (bioCPs). Two new bioCPs, [Ag2(μ6-hfa)]n (1) and [Ag2(μ4-nda)(H2O)2]n (2), were assembled from Ag2O and homophthalic (H2hfa) or 2,6-naphthalenedicarboxylic (H2nda) acids as unexplored building blocks. Their structures feature 2D metal–organic and supramolecular networks with 3,6L64 or sql topology. Both compounds act as active antimicrobial agents for producing bioCP-doped biopolymer films based on epoxidized soybean oil acrylate (SBO) or potato starch (PS) as model biopolymer materials with a different rate of degradability and silver release. BioCPs and their hybrid biopolymer films (1@[SBO]n, 2@[SBO]n, 1@[PS]n, and 2@[PS]n) with a very low loading of coordination polymer (0.05–0.5 wt %) show remarkable antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis (Gram-positive) and Escherichia coli and Pseudomonas aeruginosa (Gram-negative) bacteria. Biopolymer films also effectively impair the formation of bacterial biofilms, allowing total biofilm inhibition in several cases. By reporting on new bioCPs and biopolymer films obtained from renewable biofeedstocks (soybean oil and PS), this study blends highly important research directions and widens a limited antimicrobial application of bioCPs and derived functional materials. This research thus opens up the perspectives for designing hybrid biopolymer films with outstanding bioactivity against bacterial biofilms.
- Laccases: versatile biocatalysts for the synthesis of heterocyclic coresPublication . Sousa, Ana Catarina; Martins, Lígia O.; Robalo, M. PaulaLaccases are multicopper oxidases that have shown a great potential in various biotechnological and green chemistry processes mainly due to their high relative non-specific oxidation of phenols, arylamines and some inorganic metals, and their high redox potentials that can span from 500 to 800 mV vs. SHE. Other advantages of laccases include the use of readily available oxygen as a second substrate, the formation of water as a side-product and no requirement for cofactors. Importantly, addition of low-molecular-weight redox mediators that act as electron shuttles, promoting the oxidation of complex bulky substrates and/or of higher redox potential than the enzymes themselves, can further expand their substrate scope, in the so-called laccase-mediated systems (LMS). Laccase bioprocesses can be designed for efficiency at both acidic and basic conditions since it is known that fungal and bacterial laccases exhibit distinct optimal pH values for the similar phenolic and aromatic amines. This review covers studies on the synthesis of five- and six-membered ring heterocyclic cores, such as benzimidazoles, benzofurans, benzothiazoles, quinazoline and quinazolinone, phenazine, phenoxazine, phenoxazinone and phenothiazine derivatives. The enzymes used and the reaction protocols are briefly outlined, and the mechanistic pathways described.
- On the performance and recyclability of a green composite based on AESO resinPublication . Seabra, Cláudio P.; Sousa, Ana Catarina; Bragança, Ivo; Silva, Carlos; Robalo, M. Paula; Loja, Amélia; Martins, PauloThe aims and objectives of this paper are two-fold: first to investigate the production of a green composite manufactured with renewable materials (i.e., jute fabric as reinforcement, acrylate epoxidase soybean oil (AESO) as matrix and sisal particles (SP) as filler), by the wet layup method; second, to propose a recycling procedure to recover the individual materials and reuse them in the production of a second-life composite. In the first part, di_erent combinations of SP (0, 5 and 10 wt%) and hardener (2, 5 and 10 wt%) were mixed with AESO resin, poured into a mould, cured and submitted to mechanical and physicochemical characterizations to identify the best conditions for the composite production. Virgin green composites with 10 wt% SP, 5 wt% hardener and 5 layers of jute fabric, capable of assuring 91 HA of hardness and 10.6 MPa of tensile strength, were fabricated. The second part describes the recycling process of the composites with acetone, an organic solvente recommended by the safety, health and environmental criteria, to breakdown the resin matrix and recover the jute fabric reinforcement and resin particles, which were then reused to fabricate a second-life composite. Although the hardness values of the second-life composite were smaller (4%) and the tensile strength varied with composition, the absorption of water was considerably reduced (in the range of 22 to 51%). This last result mitigates one of the green composite’s limitations and fosters circular economy by assuring the applications of the second-life composite in the field of transportations, packing and furniture, among others.
- Towards the rational biosynthesis of substituted phenazines and phenoxazinones by laccasesPublication . Sousa, Ana Catarina; Conceição Oliveira, M.; Martins, Lígia O.; Robalo, Maria PaulaLaccases are multi-copper oxidases that oxidise a wide range of substrates including phenol and aniline derivatives, which could be further involved in coupling reactions leading to the formation of dimeric and trimeric structures. This paper describes the enzyme-mediated dimerisation of several ortho and meta, para-disubstituted aromatic amines into phenazine ("head-to-tail" dimers) and phenoxazinone chromophores. The redox properties of substituted aromatic amines were studied by cyclic voltammetry and the kinetic constants of CotA and Trametes versicolor laccases were measured for selected aromatic amines. The structure of novel enzymatically synthesised phenazine and phenoxazinone dyes using CotA laccase was assessed by NMR and MS. Overall our data show that this enzymatic green process is an efficient alternative to the classic chemical oxidation of aromatic amines and phenols, with an impact on the broad field of applications of these heterocyclic compounds.
- Biocatalytic synthesis of 1,2-naphtoquinones derivatives mediated by CotA-laccasePublication . Sousa, Ana Catarina; Santos, Iolanda; Martins, Lígia O.; Robalo, Maria PaulaCatalysis is one of the cornerstones of our present economy and society and the formation of value-added products is many times directly dependent on catalytic technologies. Nowadays, there is a growing need for development of green strategies involving clean organic reactions, which do not use harmful organic solvents and toxic reagents. Amongst the many options available for a synthetic organic chemist, biocatalysis has emerged as one approach with an excellent potential. Enzyme-catalyzed reactions offer a number of advantages compared to the traditional chemistry-catalyzed reactions and biocatalytic methods impart a “greener” character to the synthesis. Laccases (EC1.10.3.2, p-diphenol:dioxygen oxidoreductases) are multicopper oxidoreductive enzymes which have proven to be versatile and highly/efficient biocatalyst for the synthesis of different value-added chemicals and pharmaceuticals.1 A large number of 1,2-naphthoquinones derivatives have been reported to show antitumor activities by inhibit on of multiple enzymes.2 In addition to their anticancer properties, the naphthoquinone framework has significance in the development of new substances with promising biological activities in other diseases like neurodegenerative and viral diseases.3 The formation of naphthoquinone frameworks is quit-well documented and reported methods include various approaches using organic solvents and different chemical oxidants.4 In this context it is still a challenge to explore alternative and more sustainable synthetic routes for these compounds. As a part of our going research program for exploring the catalytic properties of CotA-laccase, a bacterial laccase isolated from the Bacillus subtilis, we describe in the present communication a practical and simple oxidative CotA-laccase mediated eco-friendly method to obtain 1,2-naphthoquinones derivatives using mild aqueous conditions and O2 as oxidant. All compounds were isolated in good yields and fully characterized by FTIR, NMR and ESI techniques.
- Synthesis of azobenzene dyes mediated by cotA laccasePublication . Sousa, Ana Catarina; Baptista, Sara R.; Martins, Lígia O.; Robalo, Maria PaulaAn eco-friendly protocol for the synthesis of azobenzene dyes by oxidative coupling of primary aromatic amines is reported. As efficient biocatalytic systems, CotA laccase and CotA laccase/ABTS (2,2’-azinobis(3-ethylbenzo-thiazoline-6-sulfonic acid)) enablethe oxidation of various substituted anilines, in aqueous medium, ambient atmosphere and under mild reaction conditions of pH and temperature. A series of azobenzene dyes were prepared in good to excellent yields in an one-potreaction. Amechanistic proposal for the formation of the azoderivatives is presented. Our strategy offers an alternative approach for the direct synthesis of azobenzene dyes, avoiding the harsh conditions generally required formost of the traditional synthetic methods.
- An enzymatic route to a benzocarbazole framework using bacterial CotA laccasePublication . Sousa, Ana Catarina; Piedade, Maria de Fátima M. M.; Martins, Lígia O.; Robalo, Maria PaulaThe CotA laccase-catalysed oxidation of the meta, para-disubstituted arylamine 2,4-diaminophenyldiamine delivers, under mild reaction conditions, a benzocarbazole derivative (1) (74% yield), a key structural motif of a diverse range of applications. This work extends the scope of aromatic frameworks obtained using these enzymes and represents a new efficient and clean method to construct in one step C-C and C-N bonds.