RESUMO
Self-assembly of natural polymers constitute a powerful route for the development of functional materials. In particular, layer-by-layer (LBL) assembly constitutes a versatile technique for the nanostructuration of biobased polymers into multilayer films. Gelatin has gained much attention for its abundance, biodegradability, and excellent gel-forming properties. However, gelatin gels melt at low temperature, thus limiting its practical application. With respect to the above considerations, here, we explored the potential application of gelatin gels as a matrix for protein delivery at physiological temperature. A model protein, bovine serum albumin (BSA), was encapsulated within gelatin gels and then coated with a different number of bilayers of alginate and chitosan (10, 25, 50) in order to modify the diffusion barrier. The coated gel samples were analyzed by means of Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) and confocal Raman spectroscopy, and it was found that the multilayer coatings onto polymer film were interpenetrated to some extent within the gelatin. The obtained results inferred that the coating of gelatin gels with polysaccharide multilayer film increased the thermal stability of gelatin gels and modulated the BSA release. Finally, the influence of a number of bilayers onto the drug release mechanism was determined. The Ritger-Peppas model was found to be the most accurate to describe the diffusion mechanism.
RESUMO
Introducción: la hemovigilancia es una herramienta para mejorar la calidad de la transfusión sanguínea, centrándose principalmente en la seguridad del paciente. Objetivo: identificar y conocer las características y la frecuencia de las reacciones adversas a la transfusión y desarrollar un sistema de hemovigilancia aplicable en nuestro hospital. Material y método: se realizó un estudio de tipo observacional, descriptivo, longitudinal y prospectivo, realizándose el seguimiento de todos los pacientes transfundidos con hemocomponentes en un Hospital Universitario durante 12 meses en un período de dos años (2014-2015). Se registraron las reacciones adversas a la transfusión, los incidentes y los casi incidentes. Resultados: se registraron en total 58 reacciones adversas a la transfusión, correspondiendo a una tasa de 8,3‰ hemocomponentes transfundidos. Conclusiones: el análisis detallado de las reacciones adversas reveló posibilidades de mejoramiento de los procedimientos y permitió la implementación de medidas correctivas y preventivas. El sistema de hemovigilancia utilizado es simple en su estructura y fácilmente aplicable.
Abstract Introduction: hemovigilance is a tool used to improve the quality of blood transfusion, and it mainly focuses on patients’ safety. Objective: to identify and learn about the characteristics and frequency of transfusion related negative effects and to devise a hemovigilance system to be applied in our hospital. Method: we conducted an observational, descriptive, longitudinal and prospective study, and all patients who received hemocomponents at the university hospital in a two year period (2014-2015) were followed up during 12 months. All reactions related to transfusion, adverse incidents and near misses were recorded. Results: 58 transfusion related adverse reactions were recorded, what represented 8,3‰ of the transfused hemocomponents. Conclusion: the detailed analysis of adverse reactions showed procedures to improve results may be adopted and allowed for the implementation of corrective and preventive measures. The hemovigilance system used is simple in terms of its structure and easy to apply.
Resumo Introdução: a hemovigilância é uma ferramenta para melhorar a qualidade da transfusão sanguínea e busca principalmente a segurança do paciente. Objetivo: identificar e conhecer as características e a frequência das reações adversas à transfusão e desenvolver um sistema de hemovigilância aplicável no nosso hospital. Material e método: foi realizado um estudo observacional, descritivo, longitudinal e prospectivo, com o seguimento de todos os pacientes transfundidos com hemocomponentes no Hospital Universitário durante 12 meses em um período de dois anos (2014-2015). As reações adversas à transfusão, os incidentes e os quase incidentes foram registrados. Resultados: foram registradas 58 reações adversas à transfusão, correspondendo a uma taxa de 8,3‰ hemocomponentes transfundidos. Conclusões: a análise detalhada das reações adversas mostrou possibilidades para o aperfeiçoamento dos procedimentos e permitiu implementar medidas corretivas e preventivas. O sistema de hemovigilância utilizado tem uma estrutura simples e é de fácil aplicação.
Assuntos
Segurança do Sangue , Transfusão de SangueRESUMO
Bacterial cellulose (BC) films modified by the in situ method with the addition of alginate (Alg) during the microbial cultivation of Gluconacetobacter hansenii under static conditions increased the loading of doxorubicin by at least three times. Biophysical analysis of BC-Alg films by scanning electron microscopy, thermogravimetry, X-ray diffraction and FTIR showed a highly homogeneous interpenetrated network scaffold without changes in the BC crystalline structure but with an increased amorphous phase. The main molecular interactions determined by FTIR between both biopolymers clearly suggest high compatibility. These results indicate that alginate plays a key role in the biophysical properties of the hybrid BC matrix. BC-Alg scaffold analysis by nitrogen adsorption isotherms revealed by the Brunauer-Emmett-Teller (BET) method an increase in surface area of about 84% and in pore volume of more than 200%. The Barrett-Joyner-Halenda (BJH) model also showed an increase of about 25% in the pore size compared to the BC film. Loading BC-Alg scaffolds with different amounts of doxorubicin decreased the cell viability of HT-29 human colorectal adenocarcinoma cell line compared to the free Dox from around 95-53% after 24h and from 63% to 37% after 48 h. Dox kinetic release from the BC-Alg nanocomposite displayed hyperbolic curves related to the different amounts of drug payload and was stable for at least 14 days. The results of the BC-Alg nanocomposites show a promissory potential for anticancer therapies of solid tumors.
Assuntos
Alginatos/química , Celulose/química , Doxorrubicina/farmacologia , Gluconacetobacter/química , Antibióticos Antineoplásicos/química , Antibióticos Antineoplásicos/farmacocinética , Antibióticos Antineoplásicos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Celulose/metabolismo , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Doxorrubicina/química , Doxorrubicina/farmacocinética , Liberação Controlada de Fármacos , Ácido Glucurônico/química , Células HT29 , Ácidos Hexurônicos/química , Humanos , Microscopia Eletrônica de Varredura , Nanocompostos/química , Nanocompostos/ultraestrutura , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Alicerces Teciduais/química , Difração de Raios XRESUMO
Polyvinyl alcohol (PVA)/cellulose nanowhisker (CNW) nanocomposite hydrogels to be used for wound dressing were obtained by freezing-thawing technique and characterized by means of morphological, physical, thermal, mechanical, barrier and antimicrobial properties. First, cellulose nanowhiskers were obtained by the acid hydrolysis of commercial crystalline microcellulose (MCC) and characterized by its size, shape, morphological, structural and thermal properties. Then, PVA/CNW nanocomposites with several CNW contents (0, 1, 3, 5 and 7wt.%) were obtained. Morphological, thermal, chemical and physical characterization of the PVA/CNW nanocomposite hydrogels was carried out. It was found that the addition of CNW to the hydrogel allows controlling the pore morphology of the samples. On the other hand, the transparency of the samples was maintained, the thermal stability was increased, the mechanical properties were improved and the water vapor transmission rate was in the range of wound dressing applications after CNW incorporation inside the PVA hydrogel matrix. The evaluation of microbial penetration showed that the prepared hydrogels can be considered as a good barrier against different microorganisms. All obtained results indicate that the PVA/CNW materials are promising to be used as wound dressing.