Percorrer por autor "Veiga, M."
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- Bacterial nanocellulose membranes loaded with vitamin B-based ionic liquids for dermal care applicationsPublication . Chantereau, G.; Sharma, M.; Abednejad, A.; Vilela, C.; Costa, E. M.; Veiga, M.; Antunes, F.; Pintado, M. M.; Sèbe, G.; Coma, V.; Freire, M. G.; Freire, C. S. R.; Silvestre, A. J. D.The development of innovative bio-based skin care products has received an increase attention in the latter years. In the present work, the synthesis of original active principle ingredients based ionic liquids (ILs) with cholinium cation and vitamins B anions followed by their incorporation in bacterial nanocellulose (BC) membranes for topical applications is reported. Three ILs, namely cholinium nicotinate [Ch][B3], cholinium pantothenate [Ch][B5] and cholinium pyridoxylate [Ch][B6], were synthesized through a metathesis reaction and their structure characterized in detail. Thermal analysis confirmed their denomination as ILs and their high thermal resistance. The solubility of these ILs was higher than their vitamin precursors, especially in the case of [Ch][B3] whose solubility increased 30.6-fold enhancing the bioavailability of this vitamin. The incorporation of ILs in BC led to transparent and homogeneous membranes stable up to 190 °C. ILs acted as plasticizers reducing BC brittleness that facilitated their application on irregular skin regions. Moreover, the re-hydration ability of BC-ILs membranes was improved 2.9 to 4.8-fold in comparison to BC, ensuring adequate hydration for ILs release, while the release of ILs in buffer solutions was more complete and faster than the release of vitamins. Finally, BC-ILs were proven not cytotoxic to skin epithelial cells and thus are suitable materials for skin care applications.
- Chitosan as an effective inhibitor of multidrug resistant Acinetobacter baumanniiPublication . Costa, E. M.; Silva, S.; Vicente, S.; Veiga, M.; Tavaria, F.; Pintado, M. M.Over the last two decades worldwide levels of antibiotic resistance have risen leading to the appearance of multidrug resistant microorganisms. Acinetobacter baumannii is a known skin pathogen which has emerged as a major cause of nosocomial outbreaks due to its capacity to colonize indwelling medical devices and natural antibiotic resistance. With chitosan being an effective antimicrobial agent against antibiotic resistant microorganisms, the aim of this work was to access its potential as an alternative to traditional antimicrobials in the management of A. baumannii growth. What the results showed was that both chitosan MW’s tested were active upon A. baumannii’s planktonic and sessile growth. For planktonic growth MICs and MBCs were obtained at relatively low concentrations (0.5–2 mg/mL) while for sessile growth chitosan proved to be an effective inhibitor of A. baumannii’s adhesion and biofilm formation. Considering these results chitosan shows a high potential for control of A. baumannii infections.
- Chitosan nanoparticles as alternative anti-staphylococci agents: bactericidal, antibiofilm and antiadhesive effectsPublication . Costa, E. M.; Silva, S.; Vicente, S.; Neto, C.; Castro, P. M.; Veiga, M.; Madureira, R.; Tavaria, F.; Pintado, M. M.Chitosan is a biocompatible, bioactive, non-toxic polymer that due to these characteristics has been widely used as a carrier for targeted delivery of bioactive molecules. In recent years, and considering that chitosan has a strong antimicrobial potential, the scientific community's focus has shifted onto the possible antimicrobial activity of chitosan nanoparticles. With this in mind, the aim of this work was to produce low molecular weight chitosan nanoparticles, through the ionic gelation method and characterize their potential biological activity against three staphylococci (MSSA, MRSA and MRSE) in planktonic and sessile environments. The chitosan nanoparticles produced had an average size of 244 ± 12 nm, an average charge of 17.3 ± 1.4 mV and had a MIC of 1.25 mg/mL for all tested microorganisms. Bactericidal activity was only registered for MSSA and MRSA with the time-inhibition curves showing bactericidal activity within 1 h. Assays regarding chitosan nanoparticles' impact upon sessile populations showed that they were effective in preventing MRSE adhesion and highly effective in reducing MRSA and MSSA biofilm formation.
- Impact of an anthocyanin-rich blueberry extract upon Lactobacillus and Bifidobacterium adhesion to Caco-2 and HT29-MTX cell linesPublication . Veiga, M.; Costa, E. M.; Batista, P.; Silva, S.; Pintado, M. M.Introduction: Blueberries have been associated with several potentially beneficial properties including antioxidant and anti-inflammatory activity and, more recently, with the modulation of the intestinal microbiota. Gut microbiota is considered as essential for the normal functioning of the body and the maintenance of health, with the connection between gut microbiota composition of the intestinal microbiota and the overall health and wellbeing having been widely and systematically reported by the scientific community. Previous works have shown that an anthocyanin rich blueberry extract, when in contact with certain bifidobacteria, was capable of inhibiting the adhesion of potential pathogens to a mucin coated surface, which mimicked the intestinal epithelium. As such, this work aimed to assess whether the blueberry extract was capable of modulating the adhesion of different probiotic bacteria to Caco-2 and HT29-MTX cells, which are representative of the intestinal epithelium. The adhesion was analyzed without any extract (control), in the presence of frutooligossacharide (FOS) and the anthocyanin rich blueberry extract. Conclusions: Extract helped modulate probiotic adhesion; Bacterial adhesion was higher in the presence of extract; Higher relative adhesion values obtained for bifidobacteria.