RCIPL
Repositório Institucional do Politécnico de Lisboa
Entradas recentes
Exploring alginate/zinc oxide-based 3D-printed structures for application as customizable wound dressings
Publication . Cardoso, Sara; Martin, Victor; Leal, Catarina; Monge, Nuno; Colaço, Bruno; Gomes, Pedro; Bettencourt, Ana F.; Ribeiro, Isabel A.C.
Chronic wounds represent a significant global healthcare burden due to the limited effectiveness of current therapeutic strategies. To address this critical need, we developed 3D-printed regenerative wound dressings that can be customized with antimicrobial drugs tailored to individual patient requirements. A novel semisolid extrusion ink combining the biocompatibility and printing properties of alginate (Alg) with the regenerative properties of zinc oxide (ZnO) and hydroxypropyl cellulose (HPC) was produced. Two types of dressings were successfully printed by varying the concentrations of ZnO and HPC: ZnO:HPC at 11:10 and 20:20 % (w/v). Both inks presented an adequate rheological shear-thinning behavior, resulting in wound dressings with a stable matrix structure. Moreover, to grant antimicrobial and antibiofilm activity, an octenidine (OCT)-hydrogel was loaded into the dressing’s macropores. The unloaded dressings with ZnO at 20 % (w/v) and all the OCT-loaded dressings presented antibiofilm activity, showing a biofilm reduction of ~ 75 % against S. aureus. In vitro cellular assays indicated that the unloaded dressings provided regenerative potential by showing wound closure approximately completed in 48 h, highlighting the regenerative potential of the Alg:ZnO:HPC ink. These dressings exhibited in vitro and in vivo cytocompatibility, along with regenerative potential evidenced by collagen deposition and rapid wound closure. OCT-loaded matrices retained the regenerative potential and biocompatibility of the unloaded dressings, supporting their suitability as a platform for advanced wound management.
Using plasma-mediated covalent functionalization of rhamnolipids on polydimethylsiloxane towards the antimicrobial improvement of catheter surfaces
Publication . Dardouri, Maïssa; Bettencourt, Ana; Martin, Victor; Carvalho, Filomena A.; Santos, Catarina
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.
Improving chitosan hydrogels printability: a comprehensive study on printing scaffolds for customized drug delivery
Publication . 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.
3D-printed biosurfactant-chitosan antibacterial coating for the prevention of silicone-based associated infections
Publication . 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.
Hierarchical twist: chirality across scales in cellulose cholesterics
Publication . Monge, N.; Pinto, L. F. V.; Ferreira, E.; Almeida, P. L.; Figueirinhas, J. L.; Carvalho, A. L.; Sebastião, P. J.; Godinho, M. H.
One of the unresolved aspects of cellulose-based liquid crystalline phases is their chirality. Although cellulose is intrinsically chiral, both left-handed (LH) and right-handed (RH) chiral nematic phases are reported in cellulose derivatives under different conditions. The origin of these discrepancies—and whether LH and RH twisted structures coexist within a single material—has remained unclear. Here, the first direct evidence of hierarchical LH and RH twisted structures coexisting in a solvent-free, thermotropic cellulose derivative at room temperature is provided. Free-standing cholesteric films exhibit distinct LH and RH twisted domains, whose pitches respond oppositely to uniaxial mechanical strain: the LH pitch increases, while the RH pitch decreases with increasing strain. This contrasting response results from the coexistence of intertwined LH and RH twisted structures, whose optical axes are oriented differently relative to the strain direction. Notably, after stretching beyond their elastic limit, the films spontaneously recover their original shape within minutes. During this recovery, circular dichroism (CD) measurements reveal an increase in RH pitch and a decrease in LH pitch, evidencing reversible, strain-responsive behavior. Multiscale structural characterization confirms the hierarchical chiral organization and its mechanoresponsive nature, providing new insights into the origin of chirality in cellulose-based liquid crystalline materials.