Evando S. Araújo

Hybrid ZnO/TiO2 Loaded in Electrospun Polymeric Fibers as Photocatalyst

Hybrid ZnO/TiO2 nanoparticles were applied as potential photocatalyst agents incorporated into electrospun fibers of enteric block copolymers. The resistance of fibers avoids aggregation and contributes to prolonged action of semiconductor nanoparticles under continuous light irradiation. Such behavior is attributed to the minimal aggregation degree and elevated efficiency of photodegradation of modified nanoparticles in comparison with pristine ones. Hybrid ZnO/TiO2 in nanofibers contributes to the association of different mechanisms such as N-deethylation and cleavage of dye molecules applied in the overall process of photodegradation.

Electrospinning of polymeric fibres: an unconventional view on the influence of surface tension on fibre diameter

The production of regular and bead-free electrospun polymeric fibres requires an adequate combination of different parameters applied in the experimental setup viz. voltage for electrodeposition, viscosity of the solution, density of the polymeric support, the distance between electrodes and the geometry of the spinneret. Determination of the physical balance of forces on the droplet during fibre production was explored and provides relevant theo retical information about the surface tension and radius of polymeric fibres. Based on these predictions, we prepared polymeric electropun fibres of poly (vinyl alcohol), poly (vinyl pyrrolidone) and Eudragit® L100 in order to analyse non-conventional physical properties of experimental systems such as droplet stiffness and their influence on the diameter of resulting fibres.

Phase Inversions in Emulsions Probed by Electrical Impedance Spectroscopy

We report the electrical behavior of emulsions (water/toluene/triton X-100) characterized by double phase inversion induced by temperature. The phase inversions in the continuous media were easily detected from the measurement of slope in the real part of impedance at low frequencies (1Hz < f < 1 MHz) by the use of parameters such as double layer capacitance and charge-transfer resistance (obtained from fitting of data using modified Randles circuit) allowing the detection of an additional phase transition in the limit of low temperature (T < 20°C) since the additional processes such as diffusion can be conveniently characterized.

Electrospun Fibers of Enteric Polymer for Controlled Drug Delivery

The production of electrospun fibers of enteric polymer for controlled delivery of drugs represents a simple and low cost procedure with promising advantages relative to the longer therapeutic window provided by cylindrical geometry in association with intrinsic properties of pH-dependent drug carriers. In this work, we have explored the incorporation of additives (block copolymers of poly(ethylene)-b-poly(ethylene oxide)) into matrix of Eudragit L-100 and the effective action of hybrid composites on delivery of nifedipine, providing improvement in the overall process of controlled release of loaded drug.

Bactericidal Activity of Usnic Acid-Loaded Electrospun Fibers

BACKGROUND Usnic acid has been progressively reported in the literature as one of the most important lichen metabolites characterized by a rich diversity of applications such as antifungal, antimicrobial, antiprotozoal and antiviral agent. Particularly, antimicrobial activity of usnic acid can be improved by encapsulation of active molecules in enteric electrospun fibers, allowing the controlled release of active molecule at specific pH. Few relevant patents to the topic have been reviewed and cited. METHODS Bactericidal activity of usnic acid-loaded electrospun fibers of Eudragit L-100 and polyvinylpyrrolidone was examined against Staphylococcus aureus using inhibition hales methodology. RESULTS The controlled release of active material at high pH is established after 10 minutes of interaction with media and results in reasonable activity against S. aureus, as detected by inhibition hales. CONCLUSION The strong biological activity of usnic acid-loaded electrospun fibers provides a promising application for corresponding material as a bactericidal agent for wound healing treatment.

Characterization and Electrical Response to Humidity of Sintered Polymeric Electrospun Fibers of Vanadium Oxide-(\({\hbox{TiO}}_{{2}} /{\hbox{WO}}_{{3}} \))

Metal oxide composites have attracted much consideration due to their promising applications in humidity sensors in response to the physical and chemical property modifications of the resulting materials. This work focused on the preparation, microstructural characterization and analysis of humidity-dependent electrical properties of undoped and vanadium oxide (V2O5)-doped titanium oxide/tungsten oxide (TiO2/WO3) sintered ceramic films obtained by electrospinning. The electrical properties were investigated by impedance spectroscopy (400 Hz–40 MHz) as a function of relative humidity (RH). The results revealed a typical transition in the transport mechanisms controlled by the appropriated doping level of V2O5, which introduces important advantages to RH detection due to the atomic substitution of titanium by vanadium atoms in highly doped structures. These aspects are directly related to the microstructure modification and structure fabrication procedure.