Percorrer por autor "Monge, Nuno"
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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.
- Adaptation of liquid crystal textures. a contribution to textile design and to the sustainability of the traditional Arraiolos tapestry industryPublication . Monge, Nuno; Areias, M.; Ribeiro, A.C.The textures of liquid crystals, observed in polarized microscopy, show in general an extraordinary beauty depending on the phase and surface conditions. In this work, we present some textures obtained with different phases of liquid crystals and we propose to manipulate this images in different ways to be used as a design tool to create new decorative motives for the textile industry and also for the Arraiolos tapestry. At the end of this work, we present the result obtained from the combination of liquid crystal textures with the art of a painter.
- Cellulose nanocrystals: mind the microgap in iridescent Cellulose Nanocrystal FilmsPublication . Fernandes, Susete N.; Almeida, Pedro L.; Monge, Nuno; Aguirre, Luis E.; Reis, Dennys; de Oliveira, Cristiano L. P.; Neto, António M. F.; Pieranski, Pawel; Godinho, Maria H.Solid films prepared from cellulose nanocrystals (CNCs) present remarkable optical properties: iridescence,[1] selective reflection of left circularly polarized (LCP) light, and transmission of right circularly polarized (RCP) light.[2] The same phenomenon has been observed in certain insect cuticles, for example in the Plusiotis batesi as well as in the Plusiotis optima, where only LCP light is selectively reflected by the cholesteric structure forming the outer exocuticle.[3] In cellulosic films, the adopted left-handed chiral structure is attributed to the self-assembly of nanorods from chiral cellulose.[4] The value of the wavelength of the reflected structure (λ) depends upon the pitch (P) and the average refraction index (n) of the material according to the de Vries expression:
- Cellulosic liquid crystals for films and fibersPublication . Canejo, J. P.; Monge, Nuno; Echeverria, C.; Fernandes, S. N.; Godinho, M. H.Cellulose, the most abundant natural polymer on earth, is used in numerous applications in our day-to-day life. However, the discovery that cellulose-based systems could lead to the formation of liquid crystalline phases only dates to the 1970s. Compared with all known applications of cellulose, the liquid crystalline behavior has been less considered. Associated with this are the low solubility of cellulose and the existence of a chiral nematic precursor solution and its processing under the action of a shear field, which is used to produce fibers and films. In this review, we first conduct a short review of the main features of cellulosic liquid crystalline phases including the main textures observed by polarizing optical microscopy and the cholesteric phase characteristics of thermotropic and lyotropic systems observed for cellulose and cellulose derivatives. Then, we focus on the rheological properties of liquid crystalline solutions and special attention is given to the formation of striations developed during shear and the formation of the band texture, which appears during the relaxation process. Among the different techniques used, special emphasis is given to the results obtained by coupling rheology with optical microscopy (Rheo-optics) and nuclear magnetic resonance (Rheo-NMR) techniques. Some examples described in the literature, related to the use of cellulose and cellulose derivatives liquid crystals to the production of structural color scaffolds, stimuli-responsive films and fibers, are addressed. In these systems, the initial cholesteric phase determines the unique properties exhibited by the films and the fibers produced from cellulosic liquid crystalline systems.
- Design, control, and testing of a multifunctional soft robotic GripperPublication . Correia, Ana; Charters De Azevedo, Tiago; Leite, Afonso; Campos, Francisco M.; Monge, Nuno; Rocha, André; Mendes, Mário J. G. C.This paper proposes a multifunctional soft robotic gripper for a Dobot robot to handle sensitive products. The gripper is based on pneumatic network (PneuNet) bending actuators. In this study, two different models of PneuNet actuators have been studied, designed, simulated, experimentally tested, and validated using two different techniques (3D printing and molding) and three different materials: FilaFlex 60A (3D-printed), Elastosil M4601, and Dragonskin Fast 10 silicones (with molds). A new soft gripper design for the Dobot robot is presented, and a new design/production approach with molds is proposed to obtain the gripper’s PneuNet multifunctional actuators. It also describes a new control approach that is used to control the PneuNet actuators and gripper function, using compressed air generated by a small compressor/air pump, a pressure sensor, a mini valve, etc., and executing on a low-cost controller board—Arduino UNO. This paper presents the main simulation and experimental results of this research study.
- Exploring alginate/zinc oxide-based 3D-printed structures for application as customizable wound dressingsPublication . 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.
- 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.
- Hierarchical twist: chirality across scales in cellulose cholestericsPublication . Monge, Nuno; 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.
- Medidas para poupança de água – abordagens concretas implementadas no ISEL através do projeto de sustentabilidade MySafeWaterPublication . Matos, Manuel; Monge, Nuno; Gonçalves Cavaco Mendes, Mário José; Sousa, Ana Catarina; Silva, Hugo; Costa, Alexandra; Barreiros, Ana MariaO Projeto MySafeWater pretendeu fomentar o uso eficiente da água através de ações concretas para uma melhor gestão dos recursos hídricos numa escola do Ensino Superior, prevenindo a produção de resíduos, diminuído a pegada ecológica. Tendo por base os objetivos, este projeto assentou em três grandes eixos de atuação que serão descritos em detalhe na comunicação a apresentar e resumidamente descritos de seguida.
- Mind the microgap in iridescent cellulose nanocrystal filmsPublication . Fernandes, Susete; Almeida, Pedro L.; Monge, Nuno; Aguirre, Luís E.; Reis, Dennys; Oliveira, Cristiano; Neto, António M. F.; Pieranski, Pawel; Godinho, Maria Helena