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- Raoultella ornithinolytica: an opportunistic pathogen in the oral cavity of chronic kidney disease patientsPublication . Costa, Carolina F. F. A.; Campos, Carla; Merino, Ana; Silva, Nádia; Mesquita, Raquel B. R.; Rangel, António O. S. S.; Sampaio-Maia, Benedita
- BIONANOSCULP: development of chitosan-based coatings as an eco-friendly strategy for conservation of outdoor sculpturesPublication . Silva, Nádia; Castro, Diana; Vieira, Eduarda; Pintado, Manuela; Moreira, Patrícia RaquelUrban outdoor sculptures, which are an immeasurable part of our cultural heritage, are easily vulnerable to chemical and physical alterations due to their exposure to weather elements and air pollution. These alterations are aggravated by the colonization of degrading microorganisms. Nowadays, the products used for biodeterioration control of such cultural objects lack versatility or are toxic to the environment and the human health. In order to find new alternatives based on non-toxic and sustainable materials, the BIONANOSCULP project proposes the development of an antimicrobial protective layer for the preventive conservation of outdoor sculptures. For that, chitosan has been tested as a base biopolymer for the synthesis of protective coatings due to its proven antimicrobial properties. Different concentrations and molecular weights of chitosan, as well as the addition of adjuvants and cross-linking agents were tested to obtain coatings with relevant properties for application on metal and stone sculptures. Antimicrobial activity testing, together with physical and chemical assessments are being performed to characterize and evaluate the suitability of the coatings as protective layers able to slow down the growth of relevant microorganisms. Permeability assays and compatibility of the coatings to stone and metal samples are also being considered in order to analyze their performance on different materials while not causing alterations to the original aesthetics of the sculptures.
- Flow cytometry for the assessment of microbiological contamination of outdoor sculpturesPublication . Silva, Nádia Caetano; Pintado, Manuela; Moreira, Patrícia
- Chitosan nanoparticles for daptomycin delivery in ocular treatment of bacterial endophthalmitisPublication . Silva, Nádia C.; Silva, Sara; Sarmento, Bruno; Pintado, ManuelaContext: Chitosan nanoparticles were prepared to encapsulate daptomycin and proposed as a delivery system of this antibiotic to the eye for the treatment of bacterial endophthalmitis. Objective: The aim of this study was to develop daptomycin-loaded nanoparticles to apply directly to the eye, as a possible non-invasive and less painful alternative for the treatment of endophthalmitis, increasing the effectiveness of treatment and reducing toxicity associated with systemic administration.Materials and methods: Nanoparticles were obtained by ionotropic gelation between chitosan and sodium tripolyphosphate (TPP). Physicochemical and morphological characteristics of nanoparticles were evaluated, as well as determination of antimicrobial efficiency of encapsulated daptomycin and stability of the nanoparticles in the presence of lysozyme and mucin.Results: Loaded nanoparticles presented mean particle sizes around 200 nm, low polydispersity index, and positive zeta potential. Morphological examination by scanning electron microscopy (SEM) confirmed their small size and round-shaped structure. Encapsulation efficiency ranged from 80 to 97%. Total in vitro release of daptomycin was obtained within 4 h. Determination of minimum inhibitory concentrations (MICs) showed that bacteria were still susceptible to daptomycin encapsulated into the nanoparticles. Incubation with lysozyme did not significantly affect the integrity of the nanoparticles, although mucin positively affected their mucoadhesive properties. Discussion and conclusion: The obtained nanoparticles have suitable characteristics for ocular applications, arising as a promising solution for the topical administration of daptomycin to the eye.
- Biotechnology for art conservation: Microbiological characterization of public outdoor sculpturesPublication . Silva, Nádia; Pintado, Manuela; Moreira, Patrícia
- 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.
- BIONANOSCULP, an ongoing project in biotechnology applications for preventive conservation of outdoor sculpturesPublication . Moreira, P R; Silva, N; Pullar, R. C.; Ben-Arfa, B. A. E.; Abreu, J. G.; Henriques, F.; Pintado, M M E; Vieira, EThe objective of this paper is the presentation of the research strategies adopted and results of the ongoing BIONANOSCULP research project that is aiming to develop solutions in the area of sustainable nanomaterials, which are non-invasive and high-performance in their preventive conservation approach. An integrated methodology was designed as a holistic strategy to the characterisation of the microbiota present on the surface of public outdoor sculptures. Gathering objective data in the characterization of the surface microbiota of public outdoor sculptures is important, in order to design strategies for the preventive conservation of these objects that make use of biotechnology innovative coatings. Such is one of the objectives of the project BIONANOSCULP. Methodologies applied include conservation reports, surface sampling methodologies using gels, 3D modeling, SEM, flow cytometry and metagenomics. The project is already significantly contributing to create a bridge between the experts from different areas: the skills of biotechnologists, microbiologists, materials scientists, art historians and conservators-restorers to assess the state of conservation, biodeterioration and biocontamination of a selected number of sculptures, and to design the appropriate materials to pursue preventive conservation through coatings with anti-microbial activities.
- The importance of antimicrobial peptides and their potential for therapeutic use in ophthalmologyPublication . Silva, Nádia C.; Sarmento, Bruno; Pintado, ManuelaThe reduced effectiveness of some of the most important antibiotics owing to increasing resistance of microorganisms as well as the absence of new classes of antimicrobial agents have been concerning researchers and clinicians in recent years. Thus, the development and approval of new compounds for clinical applications is of great importance. Among these compounds, antimicrobial peptides (AMPs) appear to be excellent candidates for the development of novel antimicrobial agents. Some AMPs and antimicrobial proteins have been shown to be active against relevant pathogens in ocular infections as well as in biofilm eradication from contact lenses. Thus, they are considered promising in the prevention and management of ocular diseases. This review summarises the main classes and characteristics of AMPs and antimicrobial proteins, in particular those found in ocular structures and fluids. Some AMPs with activity against ocular pathogens and their potential as therapeutic agents to treat and prevent ocular infections are emphasised.
- Oral lesions associated with removable prosthesis among elderly patient'sPublication . Veiga, Nélio; Herdade, Ana; Diniz, Liliany; Brites, Beatriz; Pinto, Sílvia; Santos, Ana; Antunes, Cláudia; Monteiro, Débora; Rebelo, Gabriela; Silva, Nádia; Coelho, Carina; Correia, AndréDental prosthesis has the main goal of oral rehabilitation of edentulous areas present in the oral cavity. Removable dentures purpose is mainly the oral rehabilitation of edentulous areas. Some secondary purposes for the dental prosthesis include elimination of disease, restoration of the remaining teeth and preservation of the surrounding oral tissues. Due to life expectancy rose, removable dentures wear is frequent nowadays. However, their functional and qualitative limitations can lead to oral lesions. The aim of this study is to present several oral lesions caused by dentures wear and their clinical characteristics among elderly patients. It is based on a literature review, intending to emphasize the importance of proper control and denture adaptation to oral environment. A good manufacturing and hygiene of a denture is of great relevance in order not to compromise the oral mucosa. Removable dentures won’t replace a patient’s normal dentition. Their repeated use can cause denture lesions, leading to mastication inefficiency and patient’s decreasing nutritional capacity. These lesions are more common when there is a poor oral hygiene. Thus, the health professional´s instructions are of great importance as well as removable dentures and patient’s oral health monitoring and periodic assessments.
- Biocontamination assessment and microbiological characterization of outdoor sculptures: “O Guardador do Sol” case studyPublication . Silva, Nádia C.; Pintado, M.M.E; Moreira, Patricia