Browsing by Author "Silva, Sara Baptista da"
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- Adenosine-loaded silk fibroin aerogel particles for wound healingPublication . Bernardes, Beatriz G.; Rossa, Valentina; Silva, Sara Baptista da; Magalhães, Rui; Costa, Raquel; García-González, Carlos A.; Oliveira, Ana LeiteThe healing process of an injury comprises a series of steps (haemostasis, inflammation and proliferation/maturation). Exudate from wounds is a natural response to heal. However, an excess production can compromise and delay the inflammatory phase, resulting in chronicity. Novel biocompatible, biodegradable and adaptable dressings are sought to promote tissue regeneration, prevent infection and control inflammation. Aerogels are nanostructured dry materials with high porosity, large surface and low bulk density. Bio-based aerogels, from natural polymer sources, can provide advanced performance for wound healing; also, they can act as carriers for bioactive compounds.[1] Adenosine (ADO) is a nucleoside that is expected to trigger the healing process of chronic wounds, promoting angiogenesis and regeneration.[2] Silk fibroin (SF) aerogels can act as promising carriers of bioactive molecules while supporting cell proliferation. Hereupon, SF aerogels loaded with Adenosine were developed in the form of particles for wound healing applications, using supercritical CO2 technology.
- Antioxidants in the prevention and treatment of diabetic retinopathy – a reviewPublication . Silva, Sara Baptista da; Costa, João Paulo; Pintado, Manuela Estevez; Ferreira, Domingos de Carvalho; Sarmento, BrunoDiabetic retinopathy is a disease resulting from diabetic chronic hyperglycemia characterized by microvascular complications in the retina, where neuronal elements responsible for vision are located. It is the main cause of adult blindness in developed countries. Oxidative stress has been widely regarded as the key factor for the emergence of ocular disease and has been involved in increased vascular permeability, disruption of blood-retinal barrier, apoptotic loss of retinal capillary cells, microvascular abnormalities and retinal neovascularization. Dietary supplementation with antioxidants has been related with inhibition of diabetes-induced abnormalities of retinal metabolism, reduction of apoptosis and partial restoration of pericytes. Moreover, the use of topical antioxidants to treat or delaying oxidative stress-related ocular manifestations is still poorly explored, while current diabetic retinopathy therapy includes invasive methods, like surgery. Ocular antioxidant potential therapy represents a non-invasive, safe and less painful methodology, which slows the natural progress of the disease and improves the effectiveness of treatment without significant systemic toxicity. This review underlines the innovative medicines exploited for ocular conditions, a further insight on ocular delivery, benefiting from the advantages of the eye for drug delivery and, additionally, offering new potential applications of antioxidants for the prevention, treatment and control of diabetic retinopathy.
- Development and validation method for simultaneous quantification of phenolic compounds in natural extracts and nanosystemsPublication . Silva, Sara Baptista da; Oliveira, Ana; Ferreira, Domingos; Sarmento, Bruno; Pintado, ManuelaIntroductionSage and savoury (Salvia sp. and Satureja montana, respectively) are plants used in traditional medicine. The quality control of their herbal formulations is of paramount concern to guarantee the expected biological activity of their anti-oxidant compounds. Objective To establish a simple and effective high-performance liquid chromatographic (HPLC) method to evaluate simultaneously quercetin and rosmarinic acid, in a pure form, in natural extracts (sage and savoury), and encapsulated into chitosan nanoparticles. Methods Chromatography was performed on an RP C-18-column, in a gradient mode with a mobile phase comprising methanol:formic acid:water 92.5:2.5:5 (v/v) at a flow rate of 0.75mL/min and at wavelength of 280nm. Results The method was specific, linear in the range of 0.05-1mg/mL (R-2=1.00), precise at the intraday and interday levels, accurate (recovery rate 90.50.6%), and robust to changes in equipment conditions. Conclusion The method established was effective for quercetin and rosmarinic acid characterisation in natural extracts and in chitosan nanoparticles, allowing the loading capacity determination, the association efficiency as well as the in vitro release. This study shows a new HPLC method validated to simultaneous quantification of rosmarinic acid and quercetin in natural extracts and chitosan nanoparticles. This method is also able for detection and quantification of other phenolic and flavanoid compounds in natural matrix.
- Natural extracts into chitosan nanocarriers for rosmarinic acid drug deliveryPublication . Silva, Sara Baptista da; Amorim, Manuela; Fonte, Pedro; Madureira, Raquel; Ferreira, Domingos; Pintado, Manuela; Sarmento, BrunoContext: Nanotechnology can be applied to deliver and protect antioxidants in order to control the oxidative stress phenomena in several chronic pathologies. Chitosan (CS) nanoparticles are biodegradable carriers that may protect antioxidants with potent biological activity such as rosmarinic acid (RA) in Salvia officinalis (sage) and Satureja montana (savory) extracts for safe and innovative therapies. Objective: Development and characterization of CS nanoparticles as a stable and protective vehicle to deliver RA for medical applications using natural extracts as sage and savory. Materials and methods: Antioxidant-CS based nanoparticles were prepared by ionic gelation with sodium tripolyphosphate (TPP), at pH 5.8 with a mass ratio of 7:1 (CS:TPP), with a theoretical antioxidant-CS loading of 40-50%. The nanoparticles were then characterized by different methods such as photon correlation spectroscopy, laser Doppler anemometry, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR), high-performance liquid chromatographic (HPLC), association efficiency, and antioxidant activity. Results and discussion: Individual and small sizing nanoparticles, around 300 nm, were obtained. SEM confirmed smooth and spherical nanoparticles after freeze-drying. No chemical interactions were found between antioxidants and CS, after encapsulation, by DSC and FTIR. The association efficiency was 51.2% for RA (with 40% loading) and 96.1 and 98.2% for sage and savory nanoparticles, respectively (both with 50% loading). Antioxidant activity values were higher than 0.0348 eq [Asc. Ac.] g/L/g extract and 0.4251 μmol/eq Trolox/g extract. Conclusion: The extracts under study are promising vehicles for RA drug delivery in CS nanocarriers.
- A step forward on micro- and nanotechnology in beverage industryPublication . Silva, Sara Baptista da; Borges, Sandra; Freixo, Ricardo J.; Franco, Maria I.; Ramos, Óscar L.The use of micro- and nanotechnology in the beverage industry had a remarkable growth in the recent years, and is expected to have a major impact on the beverage market in the near future because it may offer many potential benefits for the consumers and manufacturers. The dimensions and physicochemical properties exhibited by materials at micro (10− 6 m) and nano (10− 9 m) scale allow their inclusion in various beverages processes, leading to novel material functionalities and applications, showing great advantages than those at the macroscale. Due to their small size, micro- and nanosystems can enhance solubility, bioavailability, and sensorial properties (e.g., mask unpleasant flavors), as well as prevent undesirable physical and chemical reactions and bioactive compounds degradation. This has led to the development of novel and high-performance systems using bio-based materials for beverage industry in several fields such as encapsulation of bioactive compounds (e.g., lipids, vitamins, peptides, antioxidants, and probiotics), safety (e.g., detection of contaminants and microorganisms), and processing (e.g., improvement of texture, color, flavor, and aroma). The increasing number of publications and patents prove the fast growth of this topic in beverage industry, confirmed by the significant number of companies using micro- and nanotechnology in the development of their products. This chapter will provide an overview of the latest evolutions and expectations of forthcoming developments involving the use of bio-based micro- and nanosystems to improve beverage safety, sensory, and nutritional quality. Examples of commercially available beverages products containing bioactive micro- and nanosystems will be also provided, together with a revision of the main challenges for their industrial use and future trends, the potential health effects and risks for human consumption, and the regulatory and safety issues involved.