Busila, M, Tabacaru A, Mussat V, Vasile BS, Neasu IA, Pinheiro T, Roma-Rodrigues C, Baptista PV, Fernandes AR, Matos AP, Marques F.
2020.
Size-Dependent Biological Activities of Fluorescent Organosilane-Modified Zinc Oxide Nanoparticles, 2020. J Biomed Nanotechnol. 16(2):137-152.
AbstractSurface modification of zinc oxide nanoparticles (ZnO NPs) is a strategy to tune their biocompatibility. Herein we report on the synthesis of a series of fluorescent ZnO NPs modified with 2-10% (3-glycidyloxypropyl)trimethoxysilane (GPTMS) to investigate the fluorescence properties and to explore their applications in microbiology and biomedicine. The obtained ZnO NPs were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR). Size reduction occurred from ca. 13 nm in unmodified ZnO to 3-4 nm in silane-modified samples and fluorescence spectra showed size-dependent variation of the photoemission bands' intensity. The antibacterial and cytotoxic activities were investigated on Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria, and in ovarian (A2780) and prostate (PC3) cancer cells by tetrazolium/formazan-based methods. The antibacterial effect was higher for E. coli than S. aureus, while the cytotoxic activity was similar for both cancer cells and varied with the particle size. Cell death by apoptosis, and/or necrosis versus autophagy, were explored by flow cytometry using an Annexin V based-method and transmission electron microscopy (TEM). The main mechanism of ZnO NPs toxicity may involve the generation of reactive oxygen species (ROS) and the induction of apoptosis or autophagy. This work revealed the potential utility of GPTMS-modified ZnO NPs in the treatment of bacterial infection and cancer.
Alves-Barroco, C, Rivas-Garcia L, Fernandes AR, Baptista PV.
2020.
Tackling Multidrug Resistance in Streptococci - From Novel Biotherapeutic Strategies to Nanomedicines, 2020. Front Microbiol. 11:579916.
AbstractThe pyogenic streptococci group includes pathogenic species for humans and other animals and has been associated with enduring morbidity and high mortality. The main reason for the treatment failure of streptococcal infections is the increased resistance to antibiotics. In recent years, infectious diseases caused by pyogenic streptococci resistant to multiple antibiotics have been raising with a significant impact to public health and veterinary industry. The rise of antibiotic-resistant streptococci has been associated to diverse mechanisms, such as efflux pumps and modifications of the antimicrobial target. Among streptococci, antibiotic resistance emerges from previously sensitive populations as result of horizontal gene transfer or chromosomal point mutations due to excessive use of antimicrobials. Streptococci strains are also recognized as biofilm producers. The increased resistance of biofilms to antibiotics among streptococci promote persistent infection, which comprise circa 80% of microbial infections in humans. Therefore, to overcome drug resistance, new strategies, including new antibacterial and antibiofilm agents, have been studied. Interestingly, the use of systems based on nanoparticles have been applied to tackle infection and reduce the emergence of drug resistance. Herein, we present a synopsis of mechanisms associated to drug resistance in (pyogenic) streptococci and discuss some innovative strategies as alternative to conventional antibiotics, such as bacteriocins, bacteriophage, and phage lysins, and metal nanoparticles. We shall provide focused discussion on the advantages and limitations of agents considering application, efficacy and safety in the context of impact to the host and evolution of bacterial resistance.
Alves Ferreira, D, L MMDRS, A FR, Martins M.
2020.
A Tale of Two Ends: Repurposing Metallic Compounds from Anti-Tumour Agents to Effective Antibacterial Activity, 2020. Antibiotics (Basel). 9(6)
AbstractThe rise in antibiotic resistance coupled with the gap in the discovery of active molecules has driven the need for more effective antimicrobials while focusing the attention into the repurpose of already existing drugs. Here, we evaluated the potential antibacterial activity of one cobalt and two zinc metallic compounds previously reported as having anticancer properties. Compounds were tested against a range of Gram-positive and -negative bacteria. The determination of the minimum inhibitory and bactericidal concentrations (MIC/MBC) of the drugs were used to assess their potential antibacterial activity and their effect on bacterial growth. Motility assays were conducted by exposing the bacteria to sub-MIC of each of the compounds. The effect of sub-MIC of the compounds on the membrane permeability was measured by ethidium bromide (EtBr) accumulation assay. Cell viability assays were performed in human cells. Compound TS262 was the most active against the range of bacteria tested. No effect was observed on the motility or accumulation of EtBr for any of the bacteria tested. Cell viability assays demonstrated that the compounds showed a decrease in cell viability at the MIC. These results are promising, and further studies on these compounds can lead to the development of new effective antimicrobials.
Oliveira, AR, Mota C, Mourato C, Domingos RM, Santos MFA, Gesto D, Guigliarelli B, Santos-Silva T, Romão MJ, Pereira IAC.
2020.
Towards the mechanistic understanding of enzymatic CO2 reduction, 2020. ACS CatalysisACS Catalysis. : American Chemical Society
AbstractReducing CO2 is a challenging chemical transformation that biology solves easily, with high efficiency and specificity. In particular, formate dehydrogenases are of great interest since they reduce CO2 to formate, a valuable chemical fuel and hydrogen storage compound. The metal-dependent formate dehydrogenases of prokaryotes can show high activity for CO2 reduction. Here, we report an expression system to produce recombinant W/Sec-FdhAB from Desulfovibrio vulgaris Hildenborough fully loaded with cofactors, its cata-lytic characterization and crystal structures in oxidised and reduced states. The enzyme has very high activi-ty for CO2 reduction and displays remarkable oxygen stability. The crystal structure of the formate-reduced enzyme shows Sec still coordinating the tungsten, supporting a mechanism of stable metal coordination during catalysis. Comparison of the oxidised and reduced structures shows significant changes close to the active site. The DvFdhAB is an excellent model for studying catalytic CO2 reduction and probing the mecha-nism of this conversion.Reducing CO2 is a challenging chemical transformation that biology solves easily, with high efficiency and specificity. In particular, formate dehydrogenases are of great interest since they reduce CO2 to formate, a valuable chemical fuel and hydrogen storage compound. The metal-dependent formate dehydrogenases of prokaryotes can show high activity for CO2 reduction. Here, we report an expression system to produce recombinant W/Sec-FdhAB from Desulfovibrio vulgaris Hildenborough fully loaded with cofactors, its cata-lytic characterization and crystal structures in oxidised and reduced states. The enzyme has very high activi-ty for CO2 reduction and displays remarkable oxygen stability. The crystal structure of the formate-reduced enzyme shows Sec still coordinating the tungsten, supporting a mechanism of stable metal coordination during catalysis. Comparison of the oxidised and reduced structures shows significant changes close to the active site. The DvFdhAB is an excellent model for studying catalytic CO2 reduction and probing the mecha-nism of this conversion.
Das, K, Datta A, Frontera A, Wen YS, Roma-Rodrigues C, Raposo LR, Fernandes AR, Hung CH.
2020.
Zn(II) and Co(II) derivatives anchored with scorpionate precursor: Antiproliferative evaluation in human cancer cell lines, 2020. J Inorg Biochem. 202:110881.
AbstractA 'scorpionate' type precursor [bdtbpza=bis(3,5-di-t-butylpyrazol-1-yl)acetate] has been employed to synthesize two mononuclear Zn(II) and Co(II) derivatives, namely [Zn(bdtbpza)2 (H2O)2].2.5CH3OH.2[(CH3)3C-C3H2N2-C(CH3)3] (1) and [Co(bdtbpza)2(CH3OH)4] (2) in good yield. Single crystal X-ray diffraction analysis reveals that in 1, the Zn(II) atom is tetrahedrally surrounded by a pair of Oacetate atoms of two bis(pyrazol-1-yl)acetate units and two water molecules; while in 2, the Co(II) atom shows an octahedral environment coordinating a pair of Oacetate atoms of two bis(pyrazol-1-yl)acetate units along with four methanol molecules. The EPR spectra of 2 recorded at 77 and 298K confirmed the tetragonal symmetry of the high spin Co(II). The DFT (Density functional theory) computation is in good agreement with the geometry proposed for compounds 1 and 2. Both the compounds display a high antiproliferative activity against HCT116 (colorectal carcinoma) and A2780 (ovarian carcinoma) cell lines compared to human normal dermal fibroblasts. In the case of A2780 cells, compounds 1 and 2 exhibit IC50 values that are similar to those described for cisplatin, a widely used chemotherapeutic drug. Exposure of A2780 cells to the IC50 concentration of each compound led to an increase of the number of apoptotic and autophagic cells. In the case of compound 1, the accumulation of intracellular ROS (Reactive oxygen species) is responsible for triggering A2780 cell death.
Lima, N, Baptista AC, Faustino BMM, Taborda S, Marques A, Ferreira I.
2020.
Carbon threads sweat-based supercapacitors for electronic textiles. Scientific Reports. 10:7703.
AbstractFlexible and stretchable energy-storage batteries and supercapacitors suitable for wearable electronics are at the forefront of the emerging field of intelligent textiles. In this context, the work here presented reports on the development of a symmetrical wire-based supercapacitor able to use the wearer’s sweat as the electrolyte. The inner and outer electrodes consists of a carbon-based thread functionalized with a conductive polymer (polypyrrole) which improves the electrochemical performances of the supercapacitor. The inner electrode is coated with electrospun cellulose acetate fibres, as the separator, and the outer electrode is twisted around it. The electrochemical performances of carbon-based supercapacitors were analyzed using a simulated sweat solution and displayed a specific capacitance of 2.3 F.g−1, an energy of 386.5 mWh.kg−1 and a power density of 46.4 kW.kg−1. Moreover, cycle stability and bendability studies were performed. Such energy conversion device has exhibited a stable electrochemical performance under mechanical deformation, over than 1000 cycles, which make it attractive for wearable electronics. Finally, four devices were tested by combining two supercapacitors in series with two in parallel demonstrating the ability to power a LED.
Adeoye, O, Conceição J, Serra PA, da Silva AB, Duarte N, Guedes RC, Corvo MC, Aguiar-Ricardo A, Jicsinszky L, Casimiro T, Cabral-Marques H.
2020.
Cyclodextrin solubilization and complexation of antiretroviral drug lopinavir: In silico prediction; Effects of derivatization, molar ratio and preparation method. Carbohydrate Polymers. 227:115287.: Elsevier
AbstractLopinavir (LPV) is currently used in combination with ritonavir for the clinical management of HIV infections due to its limited oral bioavailability. Herein, we report the application of an in silico method to study cyclodextrin (CyD) host-guest molecular interaction with LPV for the rational selection of the best CyD for developing a CyD based LPV delivery system. The predicted CyD, a (2-hydroxy)propyl-gamma derivative with high degree of substitution (HP17-γ-CyD) was synthesized and comparatively evaluated with γ-CyD and the commercially available HP-γ-CyD. All complexes were prepared by supercritical assisted spray drying (SASD) and co-evaporation (CoEva) at molar ratios (1:1 and 1:2); and afterwards fully characterized. Results indicate a higher LPV amorphization and solubilization ability of HP17-γ-CyD. The SASD processing technology also enhanced LPV solubilization and release from complexes. The application of in silico methodologies is a feasible approach for the rational and/or deductive development of CyD drug delivery systems.
Strohmeier, P, Honnet C, Perner-Wilson H, Teyssier M, Fruchard B, Baptista AC, Steimle J.
2020.
Demo of PolySense: How to Make Electrically Functional Textiles. CHI Conference on Human Factors in Computing Systems. :1-4.
AbstractWe demonstrate a simple and accessible method for enhancing textiles with custom piezo-resistive properties. Based on in-situ polymerization, our method offers seamless integration at the material level, preserving a textile's haptic and mechanical properties. We demonstrate how to enhance a wide set of fabrics and yarns using only readily available tools. During each demo session, conference attendees may bring textile samples which will be polymerized in a shared batch. Attendees may keep these samples. While the polymerization is happening, attendees can inspect pre-made samples and explore how these might be integrated in functional circuits. Examples objects created using polymerization include rapid manufacturing of on-body interfaces, tie-dyed motion-capture clothing, and zippers that act as potentiometers.
dos Santos, LM, Bernard FL, Polesso BB, Pinto IS, Frankenberg CC, Corvo MC, Almeida PL, Cabrita E, Menezes S, Einloft S.
2020.
Designing silica xerogels containing RTIL for CO2 capture and CO2/CH4 separation: Influence of ILs anion, cation and cation side alkyl chain length and ramification. Journal of Environmental Management. 268:110340.
AbstractCO2 separation from natural gas is considered to be a crucial strategy to mitigate global warming problems, meet product specification, pipeline specs and other application specific requirements. Silica xerogels (SX) are considered to be potential materials for CO2 capture due to their high specific surface area. Thus, a series of silica xerogels functionalized with imidazolium, phosphonium, ammonium and pyridinium-based room-temperature ionic liquids (RTILs) were synthesized. The synthesized silica xerogels were characterized by NMR, helium pycnometry, DTA-TG, BET, SEM and TEM. CO2 sorption, reusability and CO2/CH4 selectivity were assessed by the pressure-decay technique. Silica xerogels containing IL demonstrated advantages compared to RTILs used as separation solvents in CO2 capture processes including higher CO2 sorption capacity and faster sorption/desorption. Using fluorinated anion for functionalization of silica xerogels leads to a higher affinity for CO2 over CH4. The best performance was obtained by SX- [bmim] [TF2N] (223.4 mg CO2/g mg/g at 298.15 K and 20 bar). Moreover, SX- [bmim] [TF2N] showed higher CO2 sorption capacity as compared to other reported sorbents. CO2 sorption and CO2/CH4 selectivity results were submitted to an analysis of variance and the means compared using Tukey's test (5%).