Classius Ferreira da Silva

Design and characterization of chitosan/zeolite composite films — Effect of zeolite type and zeolite dose on the film properties

Chitosan films can be used as wound dressings for the treatment of chronic wounds and severe burns. The antimicrobial properties of these films may be enhanced by the addition of silver. Despite the antimicrobial activity of silver, several studies have reported the cytotoxicity as a factor limiting its biomedical applications. This problem may, however, be circumvented by the provision of sustained release of silver. Silver zeolites can be used as drug delivery platforms to extend the release of silver. The objective of this study was to evaluate the addition of clinoptilolite and A-type zeolites in chitosan films. Sodium zeolites were initially subjected to ion-exchange in a batch reactor. Films were prepared by casting technique using a 2% w/w chitosan solution and two zeolite doses (0.1 or 0.2% w/w). Films were characterized by thermal analysis, color analysis, scanning electron microscopy, X-ray diffraction, and water vapor permeation. The results showed that films present potential for application as dressing. The water vapor permeability is one of the main properties in wound dressings, the best results were obtained for A-type zeolite/chitosan films, which presented a brief reduction of this property in relation to zeolite-free chitosan film. On the other hand, the films containing clinoptilolite showed lower water vapor permeation, which may be also explained by the best distribution of the particles into the polymer which also promoted greater thermal resistance.

Desenvolvimento e caracterização de filmes compósitos de quitosana e zeólitas com prata

Zeolites were subjected to ion exchange or impregnation with silver and added to chitosan films for producing burns dressings. Zeolites were characterized by nuclear magnetic resonance (NMR), total reflection X-ray fluorescence (TXRF), scanning electron microscopy (SEM). The polymer films were analyzed with respect to their mechanical properties, water vapor permeability (WVP), and release of silver. It was observed that the ion exchange did not modify the morphology of the starting zeolite. Clusters of zeolite were observed in the micrographs of the films and they influenced the mechanical properties due to local disruption in the packing of the polymer chains of chitosan. The methodology of ion exchange or impregnation directly influenced the amount of silver present in the zeolite surface and consequently changed the silver release profile in an of simulated exudate fluid. The kinetic models suggested that the release of the silver was not primarily governed by Ficks law of diffusion.

Chitosan as flocculant agent for clarification of stevia extract

Stevia is used as a sweetener due to its low calorific value and its taste, which is very similar to that of sucrose. After extraction from dried leaves, stevia extract is dark in colour, and therefore needs to be whitened to increase acceptance by consumers. In this study we tested chitosan, a cationic polyelectrolyte, as flocculant agent for the whitening of the Stevia extract. Positive charges of chitosan can interact electrostatically with a counter-ion, sodium tripolyphosphate (TPP), and then chitosan precipitates. A factorial design was used to study the whitening process, in which Glycosides Removal, Colour Removal, Turbidity Removal and Soluble Solids Removal were evaluated. The studied factors were Chitosan Mass and pH of the TPP solution. The results showed that chitosan is a good flocculant agent, being able to flocculate both the glycosides and the pigments that make the extract coloured.

The effect of andiroba oil and chitosan concentration on the physical properties of chitosan emulsion film

Chitosan film is used as a dressing to heal burns. The physical and biological properties of the film can be modified by the addition of phytotherapic compounds. This work used the casting -solvent evaporation technique to prepare chitosan film containing andiroba oil (Carapa guianensis) which has anti-inflammatory, antibiotic, and healing properties. The objective of this study was to determine the effect of the concentrations of chitosan and andiroba oil on the physical properties of chitosan films. The emulsion films were evaluated concerning the mechanical properties and fluid handling capacity. Additionally, scanning electron microscopy and thermal analysis were performed. The results showed that the barrier and mechanical properties were affected by the addition of andiroba oil, and these may be modulated as a function of the concentration of oil added to the film. The thermal analysis showed no evidence of chemical interactions between the oil and chitosan.

Clarification of Aqueous Stevia Extract Using Alginate Beads — Evaluation by Factorial Design Methodology

Stevia is used as a sweetener due to its low calorific value and its taste, which is very similar to that of sucrose. Stevia extract is dark in colour and needs to be clarified for better acceptance by consumers. The adsorption processes widely used in clarification do not use organic solvents. Alginate beads have been used as the adsorbent material in the present work. Experiments were carried out in batch mode in which the aqueous stevia extract was mixed with the alginate beads prepared previously by ionotropic gelation. A factorial design was used to study the process of clarification, in which colour removal and the percentage of stevioside adsorbed were evaluated. The studied factors were temperature, pH of the aqueous stevia extract and adsorption time. The results showed that alginate beads are capable of adsorbing both the steviosides and the pigments that give colour to the extract. The experimental design showed that only the pH and contact time were important variables in determining the percentage clarification, in contrast to the other responses which were not affected by the various factors studied. An equation describing the percentage clarification as a function of pH and time is proposed.

Effect of pH on the Clarification of Stevia rebaudiana Bertoni Extract Using Alginate Beads

Stevia rebaudiana Bertoni is plant used for producing a natural sweetener. After extraction from leaves, stevia extract is dark in colour and must be clarified for better acceptance by consumers. Adsorption processes are widely employed in the clarification because they do not use organic solvents. In the present work, the use of alginate beads as an adsorbent was investigated. Experiments were carried out in a batch system in which the aqueous stevia extract was mixed with the alginate beads previously prepared by ionotropic gelation. The effect of pH on the adsorption process was evaluated and the performance of the beads was examined by colorimetric analysis (colour removal, turbidity removal and adsorption of stevia steviol glycosides), as well as by refractive analysis for determining the adsorption of soluble solids. The results showed that the alginate beads were capable of adsorbing both the stevia steviol glycosides and the pigments that colour the extract. The best results were observed at a pH value of 2.0.

Chitosan-based nanocomposites for drug delivery

Abstract Chitosan (CS) is a semi-synthetic biopolymer obtained from chitin that is the second most abundant biopolymer. Many devices produced from CS have been widely used for drug delivery systems and biomaterials. Biocompatibility, biodegradability, nonallergenicity, and antimicrobial activity are advantageous properties of CS; moreover, CS has also exhibited healing properties. Some properties can be potentiated by using the CS to produce CS-based nanocomposites. In this sense, this chapter intends to give some CS nanodevices with different kind of fillers (reinforcements) and their application to the drug delivery systems. Fillers such as nanoparticles, nanolayer, and nanofibrous are discussed.

Applications of nanocomposite materials in the delivery of anticancer drugs

Abstract Cancer is one of the leading causes of death around the world. Conventional cancer treatment is still associated with many side effects which make the treatment difficult to the acceptance by the patients. Nanotechnology came to help the human being to overcome and improve the cancer treatment. In the nanotechnology field, nanocomposite represents a new hope to enhance the cancer treatment, being by the use of nanocomposite in therapeutic or in diagnostic or even theranostic which would be the promising future of the medicine. It is not possible to address to nanocomposite for cancer treatment without mentioning the importance of the nanocomposite for the diagnostic system applications such as computed tomography and magnetic resonance imaging. More efforts should also be directed at scaled-up synthesis, long-term assessment of toxicity and establishment of regulatory protocols for diagnostic, nanotherapeutics, and nanotheranostics systems.

Innovative nanocompounds for cutaneous administration of classical antifungal drugs: a systematic review

Abstract Nanomedicine manipulates materials at atomic, molecular, and supramolecular scale, with at least one dimension within the nanometer range, for biomedical applications. The resulting nanoparticles have been consistently shown beneficial effects for antifungal drugs delivery, overcoming the problems of low bioavailability and high toxicity of these drugs. Due to their unique features, namely the small mean particle size, nanoparticles contribute to the enhanced drug absorption and uptake by the target cells, potentiating the therapeutic drug effect. The topical route is desirable due to the adverse effects arising from oral administration. This review provides a comprehensive analysis of the use of nano compounds for the current treatment of topical fungal infections. A special emphasis is given to the employment of lipid nanoparticles, due to their recognized efficacy, versatility, and biocompatibility, attracting the major attention as novel topical nanocompounds used for the administration of antifungal drugs.

Organic/Zeolites Nanocomposite Membranes

There are different types of fuel cells, but Polymer Electrolyte Membrane (PEM) Fuel Cells are one of the most promising because they are low-temperature fuel cells. The solid polymer electrolyte has to present transport selectivity, besides the ion conductivity; thus in case of using in fuel cells, the membrane must let the hydrogen ions pass easily and block the passage of fuel (methanol or hydrogen) as well as oxidant molecules (oxygen) which have to be kept separated from each other. In addition to these properties, list other important properties that PEMs must show for high performance: low electronic conductivity, low water transport through diffusion and electro-osmosis, oxidative and hydrolytic stability, good mechanical stability in both dry and hydrated states, low cost, and capability for fabrication into membrane electrode assembly (MEA). This chapter is divided into seven sections. The first section presents some statistical data of publications concerning fuel cell, PEM fuel cells (PEMFC) and PEMFC with zeolites. The second section exhibits some concepts about zeolites types, structure, properties and industrials applications. The third section presents the role of the zeolite properties on the performance of the PEMFC. The fourth section describes the main technique used for producing zeolite/polymer nanocomposite membrane for PEMFCs. The two following sections outline the state of the art of using the zeolite for PEMFC applications, being the fifth and sixth sections dedicated to the synthetic and natural polymers, respectively.