In vitro evaluation of 5-Fluorouracil release by microspheres based on chitosan / Montmorillonite/ Avaliação in vitro da libertação de 5-Fluorouracil por microesferas à base de quitosano / Montmorilonite

5-fluorouracil (5-FU) is one of the most widely used chemotherapeutic compounds for cancer treatment and its rapid metabolization and non-uniform oral absorption are the limitations for its use as an oral chemotherapy. Therefore, this study was performed to evaluate the influence of a 5-fluorouracil (5-FU) nanocomposite microspheres with different diameters to test on a controlled release system in the gastrointestinal environment. 5-FU was incorporated into the chitosan/montmorillonite nanocomposite microspheres through the intercalation method. The microspheres containing the 5-FU were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical microscopy (OM). In vitro release fractions at different pHs (1.2, 7.4 and 10.0) were investigated by UV-vis spectroscopy. The release profile of 5-FU for the systems studied was adjusted through the Korsmeyer-Peppas kinetic model, and the results suggested that the mechanism of controlled release at pH 7.4 and 10 occurs by diffusion. In addition, the 5-FU microspheres diameter and roughness directly interfere with the release rate and the released fraction, since the F1 / F2 systems showed a difference in the released fraction of 5-FU of 7.97% and for the systems F3 / F4 the difference was 2.86%. The prepared F1, F2, F3 and F4 systems are suitable for delivery of 5-FU to the gastrointestinal environment in a controlled manner

Inexpensive Apparatus for Fabricating Microspheres for 5-Fluorouracil Controlled Release Systems

The aim of this study was to develop an inexpensive apparatus for fabricating microspheres, based on chitosan, for 5-fluorouracil (5-FU) controlled release. Chitosan microspheres were prepared by precipitation method and the effects of manufacturing parameters (injection and airflow rates) on size distribution microspheres were analyzed by optical and scanning electron microscopy. The results show that the manufacturing parameters, injection and airflow rates, determine the microsphere size distribution. By modulating these parameters, it was possible to produce chitosan microspheres as small as 437 ± 44 μm and as large as 993 ± 18 μm. Chitosan microspheres loaded with 5-FU were also produced using the experimental equipment. The obtained microspheres presented 5-FU controlled release, indicating that the microspheres can be used orally, since they are capable of crossing the stomach barrier and of continuing with the process of 5-FU release

Thermomechanical Behavior of High Performance Epoxy/Organoclay Nanocomposites

Nanocomposites of epoxy resin containing bentonite clay were fabricated to evaluate the thermomechanical behavior during heating. The epoxy resin system studied was prepared using bifunctional diglycidyl ether of bisphenol A (DGEBA), crosslinking agent diaminodiphenylsulfone (DDS), and diethylenetriamine (DETA). The purified bentonite organoclay (APOC) was used in all experiments. The formation of nanocomposite was confirmed by X-ray diffraction analysis. Specimens of the fabricated nanocomposites were characterized by dynamic mechanical analysis (DMA). According to the DMA results a significant increase in glass transition temperature and storage modulus was evidenced when 1 phr of clay is added to epoxy resin

Role of Surfactants in the Properties of Poly(Ethylene Terephthalate)/Purified Clay Nanocomposites

Purified clay was modified with different amounts of alkyl ammonium and phosphonium salts and used as filler in the preparation of PET nanocomposites via melt intercalation. The effect of this type of filler on morphology and thermal and mechanical properties of PET nanocomposites was investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile properties, and transmission electron microscopy (TEM). The results showed that the mixture of alkyl ammonium and phosphonium salts favored the production of PET nanocomposites with intercalated and partially exfoliated morphologies with slight improvement in thermal stability. In addition, the incorporation of these organoclays tended to inhibit PET crystallization behavior, which is profitable in the production of transparent bottles

Use of Piranha Solution as An Alternative Route to Promote Bioactivation of PEEK Surface with Low Functionalization Times

This study aimed to achieve bioactivity on the PEEK surface using piranha solution through a lower functionalization time. For this purpose, the functionalization occurred with piranha solution and 98% sulfuric acid in the proportions of 1:2, 1:1, and 2:1 at periods of 30, 60, and 90 s. The samples treated for longer times at higher concentrations registered the characteristic spectroscopy band associated with sulfonation. Additionally, both chemical treatments allowed the opening of the aromatic ring, increasing the number of functional groups available and making the surface more hydrophilic. The piranha solution treatments with higher concentrations and longer times promoted greater heterogeneity in the surface pores, which affected the roughness of untreated PEEK. Furthermore, the treatments induced calcium deposition on the surface during immersion in SBF fluid. In conclusion, the proposed chemical modifications using sulfuric acid SPEEK 90 and, especially, the piranha solution PEEK-PS 2:1-90, were demonstrated to be promising in promoting the rapid bioactivation of PEEK-based implants

JATROPHA MOLLISSIMA EXTRACT WITH CHITOSAN/COLLAGEN SCAFFOLDS AND THEIR BIODEGRADABILITY EVALUATION

Scaffolds are devices with interconnected pores that favor cell interaction and proliferation. They play a significant role in tissue engineering, as they mimic the conditions of tissue production in vivo. The aim of this study was to synthesize scaffolds of chitosan, collagen, and Jatropha mollissima by lyophilization and characterize their chemical/biodegradability and morphological properties. For that, techniques of optical microscopy, infrared spectrometry, biodegradation test, and degree of swelling were performed. A 2% (m/v) chitosan/collagen (1:9) in lactic acid solution was produced. Then, Jatropha mollissima crude extract was added to this solution in different proportions of mass (5, 10, and 15%). Optical microscope images indicated the three-dimensional network formation with interconnected pores and predominantly lamellar shape. Through infrared spectrometry, characteristic bands indicated a physical mixture. Also, the swelling degree of all samples was proportional to the amount of Jatropha mollissima extract with the highest percentage of 1852%. Biodegradation test also revealed a proportional ratio between the amount of sap used and the degraded percentage with the lowest value of around 35% in 28 days. In conclusion, it can be inferred that the scaffolds produced show potential to be used in tissue engineering as dressings

Inexpensive Apparatus for Fabricating Microspheres for 5-Fluorouracil Controlled Release Systems

The aim of this study was to develop an inexpensive apparatus for fabricating microspheres, based on chitosan, for 5-fluorouracil (5-FU) controlled release. Chitosan microspheres were prepared by precipitation method and the effects of manufacturing parameters (injection and airflow rates) on size distribution microspheres were analyzed by optical and scanning electron microscopy. The results show that the manufacturing parameters, injection and airflow rates, determine the microsphere size distribution. By modulating these parameters, it was possible to produce chitosan microspheres as small as 437 ± 44 μm and as large as 993 ± 18 μm. Chitosan microspheres loaded with 5-FU were also produced using the experimental equipment. The obtained microspheres presented 5-FU controlled release, indicating that the microspheres can be used orally, since they are capable of crossing the stomach barrier and of continuing with the process of 5-FU release

Synthesis and Preparation of Chitosan/Clay Microspheres: Effect of Process Parameters and Clay Type

This work aimed to prepare chitosan/clay microspheres, by the precipitation method, for use in drug carrier systems. The influence of the process parameters, particularly two airflows of the drag system (2.5 and 10 L·min−1) on the microspheres physical dimensions and properties, such as microstructure, degree of swelling and porosity were evaluated. The samples were characterized by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Water absorption and porosity tests were also performed. The results showed that the process parameters affected the size of the microspheres. The diameter, volume and surface area of the chitosan/clay microspheres decreased when they were prepared with the higher airflow of the drag system. The microspheres presented a porous microstructure, being the pore size, percentage of porosity and degree of swelling affected not only by the process parameters but also by the type of clay. Hybrids (chitosan/clay) with intercalated morphology were obtained and the hybrid prepared with montmorillonite clay at higher airflows of the drag system presented the greatest interlayer spacing and a more disordered morphology. Thus, it is certain that the chitosan/clay nanocomposite microspheres prepared with montmorillonite (CL clay) at higher airflows of the drag system can have good drug-controlled release properties