Percorrer por autor "Ribeiro, Isabel A. C."
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- 3D-printed biosurfactant-chitosan antibacterial coating for the prevention of silicone-based associated infectionsPublication . Narciso, Francisco; Cardoso, Sara; Monge, Nuno; Lourenço, Madalena; Martin, Victor; Duarte, Noélia; Santos, Catarina; Gomes, Pedro; Bettencourt, Ana; Ribeiro, Isabel A. C.Infections associated with the surfaces of medical devices represent a critical problem due to biofilm formation and the growing resistance towards antibacterial drugs. This is particularly relevant in commonly used invasive devices such as silicone-based ones where a demand for alternative antibiofilm surfaces is increasing. In this work, an antimicrobial chitosan-biosurfactant hydrogel mesh was produced by 3D-printing. The 3D structure was designed to coat polydimethylsiloxane-based medical devices for infection prevention. Additionally, the porous 3D structure allows the incorporation of customized bioactive components. For this purpose, two biosurfactants (surfactin and sophorolipids) were biosynthesized and tested for their antimicrobial activity. In addition, the printing of surfactant-chitosan-based coatings was optimized, and the resulting 3D structures were characterized (i.e., wettability, FTIR-ATR, antimicrobial activity, and biocompatibility). Compared with surfactin, the results showed a better yield and higher antibacterial activity against Gram-positive bacteria for sophorolipids (SLs). Thus, SLs were used to produce chitosan-based 3D-printed coatings. Overall, the SLs-impregnated coatings showed the best antibacterial activity against Staphylococcus aureus planktonic bacteria (61 % of growth inhibition) and antibiofilm activity (2 log units reduction) when compared to control. Furthermore, concerning biocompatibility, the coatings were cytocompatible towards human dermal fibroblasts. Finally, the coating presented a mesh suitable to be filled with a model bioactive compound (i.e., hyaluronic acid), paving the way to be used for customized therapeutics.
- A glance at antimicrobial strategies to prevent catheter-associated medical infectionsPublication . Ricardo, Susana I. C.; Anjos, Inês I. L.; Monge, Nuno; Faustino, Célia M. C.; Ribeiro, Isabel A. C.Urinary and intravascular catheters are two of the most used invasive medical devices; however, microbial colonization of catheter surfaces is responsible for most healthcare-associated infections (HAIs). Several antimicrobial-coated catheters are available, but recurrent antibiotic therapy can decrease their potential activity against resistant bacterial strains. The aim of this Review is to question the actual effectiveness of currently used (coated) catheters and describe the progress and promise of alternative antimicrobial coatings. Different strategies have been reviewed with the common goal of preventing biofilm formation on catheters, including release-based approaches using antibiotics, antiseptics, nitric oxide, 5-fluorouracil, and silver as well as contact-killing approaches employing quaternary ammonium compounds, chitosan, antimicrobial peptides, and enzymes. All of these strategies have given proof of antimicrobial efficacy by modifying the physiology of pathogens or disrupting their structural integrity. The aim for synergistic approaches using multitarget processes and the combination of both antifouling and bactericidal properties holds potential for the near future. Despite intensive research in biofilm preventive strategies, laboratorial studies still present some limitations since experimental conditions usually are not the same and also differ from biological conditions encountered when the catheter is inserted in the human body. Consequently, in most cases, the efficacy data obtained from in vitro studies is not properly reflected in the clinical setting. Thus, further well-designed clinical trials and additional cytotoxicity studies are needed to prove the efficacy and safety of the developed antimicrobial strategies in the prevention of biofilm formation at catheter surfaces.
- Improving chitosan hydrogels printability: a comprehensive study on printing scaffolds for customized drug deliveryPublication . Cardoso, Sara; Narciso, Francisco; Monge,Nuno; Bettencourt, Ana; Ribeiro, Isabel A. C.Chitosan is an interesting polymer to produce hydrogels suitable for the 3D printing of customized drug delivery systems. This study aimed at the achievement of chitosan-based scaffolds suitable for the incorporation of active components in the matrix or loaded into the pores. Several scaffolds were printed using different chitosan-based hydrogels. To understand which parameters would have a greater impact on printability, an optimization study was conducted. The scaffolds with the highest printability were obtained with a chitosan hydrogel at 2.5 wt%, a flow speed of 0.15 mm/s and a layer height of 0.41 mm. To improve the chitosan hydrogel printability, starch was added, and a design of experiments with three factors and two responses was carried out to find out the optimal starch supplementation. It was possible to conclude that the addition of starch (13 wt%) to the chitosan hydrogel improved the structural characteristics of the chitosan-based scaffolds. These scaffolds showed potential to be tested in the future as drug-delivery systems.
- Using plasma-mediated covalent functionalization of rhamnolipids on polydimethylsiloxane towards the antimicrobial improvement of catheter surfacesPublication . Dardouri, Maïssa; Bettencourt, Ana; Martin, Victor; Carvalho, Filomena A.; Santos, Catarina; Monge, Nuno; Santos, Nuno C.; Fernandes, Maria H.; Gomes, Pedro S.; Ribeiro, Isabel A. C.Controlling bacterial biofilm formation on silicone-based bloodstream catheters is of great concern to prevent relatedinfections. Inthis study, rhamnolipids(RLs),glycolipid biosurfactants,specifically a RLs mixture andthepurifieddi-RL (RhaRhaC10:0C10:0) were covalently bonded to silicone with the intention of reaching long-lasting antibiofilm surfaces. RLs mixture and di-RL wereidentified by an UHPLC-MSmethodthat also allowed the confirmation of compound isolation by automated flash chromatography. Silicone surfaces underwent air-plasma treatment, inducing reactive oxygenradicals able to promote theRLs grafting that was confirmed by contactangle,FTIR-ATR andAFMmeasurements. The antibiofilm activity towards different Gram positive strains was evaluated by colony forming units (CFU) count and confocal laser microscopy. In addition, protein adsorption and biocompatibility were also investigated. RLs were successfully grafted onto silicone and RLs mixture and RhaRhaC10C10:0 functionalized specimens reduced the biofilm formation over 2.3 log units against methicillin sensitive Staphylococcus aureus. Additionally, a decrease of 1 log unit was observed against methicillin resistant S. aureus and S. epidermidis. Functionalized samples showed cytocompatibility towards human dermal fibroblasts, hemocompatibility and no vascular irritation potential. The results mentioned above revealed a synergy between the antimicrobial and the anti-adhesive properties of RLs, making these compounds good candidates for the improvement of the medical devices antibiofilm properties.