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- Potential chitosan-coated alginate nanoparticles for ocular delivery of daptomycinPublication . Costa, J. R.; Silva, N. C.; Sarmento, B.; Pintado, M.Daptomycin may offer an antibacterial alternative for the treatment of endophthalmitis caused by methicillin-resistant Staphylococcus aureus (MRSA) and other potential agents. In the present project, mucoadhesive chitosan-coated alginate (CS-ALG) nanoparticles are proposed as an effective delivery system for daptomycin permeation across ocular epithelia, with potential for the treatment of bacterial endophthalmitis. CS-ALG nanoparticles were prepared by ionotropic pre-gelation of an alginate core followed by chitosan polyelectrolyte complexation, and characterized regarding particle size, polydispersity, and zeta potential. The encapsulation efficiency was determined and antimicrobial activity was also tested after encapsulation of the antibiotic. Also, in vitro ocular permeability of free daptomycin and encapsulation into chitosan and CS-ALG nanoparticles was evaluated using ocular epithelial cell culture models. Formulated daptomycin-loaded CS-ALG nanoparticles were negatively charged, with a size range of 380–420 nm, suitable for ocular application. The encapsulation efficiency was between 79 and 92 %, with decreasing alginate:daptomycin mass ratios. The antibacterial activity of daptomycin against major microorganisms responsible for bacterial endophthalmitis was not affected by encapsulation into nanoparticles. Daptomycin permeability was up to 16 % (chitosan nanoparticles) and 9 % (CS-ALG nanoparticles) through corneal cell monolayer, and 18 % (chitosan nanoparticles) and 12 % (CS-ALG nanoparticles) for retinal cell monolayer after 4 h, demonstrating epithelial retention of the drug compared to free drug. The developed daptomycin-loaded CS-ALG nanoparticles seem to be an interesting and potential system for ocular daptomycin delivery and treatment of bacterial endophthalmitis.
- Polymeric nanoparticles as oral delivery systems for a grape pomace extract towards the improvement of biological activitiesPublication . Costa, Joana R.; Xavier, Miguel; Amado, Isabel R.; Gonçalves, Catarina; Castro, Pedro M.; Tonon, Renata V.; Cabral, Lourdes M.C.; Pastrana, Lorenzo; Pintado, Manuela E.Grape pomace (GP) is a major by-product from the wine industry, known for its bioactive compounds and their impact upon gastrointestinal (GI) health. However, bioaccessibility is often poor due to their degradation during digestion. This work aimed to encapsulate bioactive GP extract (GPE) into chitosan (CS) and alginate (Alg) nanoparticles (NPs) to mitigate degradation in the GI tract. Alg and CS NPs were optimized using a rotatable central composite design and NPs were characterized for their size, polydispersity, zeta potential and total phenolics (TP) association efficiency. The best formulations showed sizes ranging 523–853 nm, polydispersity indexes of 0.11–0.36, zeta potential of −15.0–14.9 mV and TP association efficiencies of 68 and 65%. FTIR confirmed that there was no formation of new chemical groups after association of the polymers with GPE. Both formulations improved the bioaccessibility of different phenolics following in vitro GI digestion, leading to in-creased antioxidant and antimicrobial activities. Moreover, the permeability of bioactive compounds through a Caco-2/HT29-MTX co-culture was reduced, suggesting a higher residence time in the intestine. Cy5.5 was used for tracking the CS NPs, which did not affect the metabolic activity of Caco-2 and HT29-MTX cells. Confocal microscopy images confirmed the adsorption of NPs to the cellular layer and suggested a reduction of the tight junction protein occludin when cells were incubated with Cy5.5-CS in solution. This study suggests that encapsulation of GPE can offer protection against along the GI tract and improve its biological activity with significant impact for oral delivery applications, including functional foods.
- Delivery systems for antimicrobial peptides and proteins: towards optimization of bioavailability and targetingPublication . Costa, Joana R.; Sarmento, Bruno; Silva, Nádia C.; Pintado, ManuelaAntimicrobial peptides (AMPs) and proteins are produced by a wide range of organisms as important elements of their defense mechanisms, forming a large number of antimicrobial compounds that can be used to treat several human infections. The potential for the use of AMPs and antimicrobial proteins in therapeutics is growing, but their application is often limited, due to their poor physical and/or chemical properties. In recent years, several drug delivery systems have been proposed to carry such molecules, in an attempt to overcome the difficulties regarding their properties. However, no review has yet systematized the most relevant information on this subject. Therefore, this review summarizes the work that has been conducted to develop delivery systems for the transport and protection of AMPs and antimicrobial proteins, including their description and potential applications, while highlighting the opportunities for future research in this field.
- Enzymatic production of xylooligosaccharides from Brazilian Syrah grape pomace flour: a green alternative to conventional methods for adding value to agricultural by-productsPublication . Costa, Joana R.; Tonon, Renata V.; Gottschalk, Leda M. F.; Santiago, Manuela C. P. A.; Mellinger-Silva, Caroline; Pastrana, Lorenzo; Pintado, Maria M; Cabral, Lourdes M. C.BACKGROUND: The aim of this work was to determine the most favorable conditions for the production of xylooligosaccharides (XOS) from Brazilian Syrah grape pomace. Chemical processes were performed using a rotatable central composite design, where the concentration of sulfuric acid or concentration of sodium hydroxide and grape pomace flour: solvent mass ratio were the dependent variables. Enzymatic production was also evaluated using xylanase produced by Aspergillus niger 3T5B8 and Viscozyme® enzymatic commercial cocktail. RESULTS: Chemical extraction allowed to recover 21.8 to 74.6% and 5.2 to 96.3% of total XOS for acid and alkaline processes, respectively. Enzymatic production using xylanase extracted up to 88.68 ± 0.12% of total XOS and up to 84.09 ± 2.40% with Viscozyme®. CONCLUSION: The present study demonstrated different feasible methods to produce high added value molecules, the xylooligosaccharides, from Syrah grape pomace flour, valorizing this major by‐product. The use of enzymatic cocktails demonstrated to be an alternative to the conventional methods, allowing to obtain an eco‐friendly and sustainable grape pomace extract.