Microencapsulation of immunoglobulin Y: optimization with response surface morphology and controlled release during simulated gastrointestinal digestion / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Immunoglobulin Y (IgY) is an effective orally administered antibody used to protect against various intestinal pathogens, but which cannot tolerate the acidic gastric environment. In this study, IgY was microencapsulated by alginate (ALG) and coated with chitooligosaccharide (COS). A response surface methodology was used to optimize the formulation, and a simulated gastrointestinal (GI) digestion (SGID) system to evaluate the controlled release of microencapsulated IgY. The microcapsule formulation was optimized as an ALG concentration of 1.56% (15.6 g/L), COS level of 0.61% (6.1 g/L), and IgY/ALG ratio of 62.44% (mass ratio). The microcapsules prepared following this formulation had an encapsulation efficiency of 65.19%, a loading capacity of 33.75%, and an average particle size of 588.75 μm. Under this optimum formulation, the coating of COS provided a less porous and more continuous microstructure by filling the cracks on the surface, and thus the GI release rate of encapsulated IgY was significantly reduced. The release of encapsulated IgY during simulated gastric and intestinal digestion well fitted the zero-order and first-order kinetics functions, respectively. The microcapsule also allowed the IgY to retain 84.37% immune-activity after 4 h simulated GI digestion, significantly higher than that for unprotected IgY (5.33%). This approach could provide an efficient way to preserve IgY and improve its performance in the GI tract.

Desenvolvimento e análise de bandagem de bioestimulação dentino/pulpar (BBio) / Development and analysis of dental/pulpar bio-stimulation bandage ("BBIO")

O desenvolvimento de biomateriais com aplicações na área da saúde mostram-se cada vez mais importantes e a procura por novos polímeros com propriedades bioativas, biodegradabilidade, atoxicidade são o foco das principais pesquisas em diferentes aplicações médicas e odontológicas. Os materiais capeadores pulpares evoluíram rapidamente na ultima década, sendo que são disponibilizadas atualmente diversas alternativas para uso clínico odontológico. Este trabalho teve como objetivo o desenvolvimento de um novo produto bioestimulador e capeador dentino/pulpar que poderá ser base para o desenvolvimento e recobrimento de scaffolds para reparo das diferentes estruturas dentárias. O desenvolvimento das bandagens BBio e os resultados obtidos nos testes das propriedades físico-químicas (absorção de água, perda de massa e pH), bem como as análises biológicas da morfologia celular e viabilidade celular com MTT a BBio apresentaram dados favoráveis e desejáveis para sua aplicação clínica. A propriedade de liberação de cálcio foi bastante promissora, sendo esta uma condição que dará a diferenciação positiva da BBio como um produto bioestimulador pulpar. Com esses dados pode-se concluir que a mesma se encontra dentro dos parâmetros desejados para o produto final e com propriedades semelhantes aos produtos existentes no mercado, de qualidade e aprovados pelas agências reguladoras.(AU)

The development of biomaterials with applications in the health area are increasingly important and the search for new polymers with bioactive properties, biodegradability and toxicity are the focus of the main researches in different medical and dental applications. The pulp capping materials evolved rapidly in the last decade, and several alternatives are now available for clinical dental use. This project aimed to develop a new biostimulating and dentin / pulp capping product that could be the basis for the development and recoating of "scaffolds" for repair of different dental structures. The development of the BBio bandages and the results obtained in the physical-chemical properties tests (water absorption, loss of mass and pH), as well as the biological analyzes of the cellular morphology and cell viability with MTT to BBio presented favorable and desirable data for its clinical application. The calcium release property was quite promising, and this is a condition that will give BBio a positive differentiation as a pulp biostimulator product. With this data it can be concluded that it is within the parameters desired for the final product and with properties similar to the products on the market, of quality and approved by the regulatory agencies.(AU)

A broad pH range and processive chitinase from a metagenome library

Chitinases are hydrolases that degrade chitin, a polymer of N-acetylglucosamine linked β(1-4) present in the exoskeleton of crustaceans, insects, nematodes and fungal cell walls. A metagenome fosmid library from a wastewater-contaminated soil was functionally screened for chitinase activity leading to the isolation and identification of a chitinase gene named metachi18A. The metachi18A gene was subcloned and overexpressed in Escherichia coli BL21 and the MetaChi18A chitinase was purified by affinity chromatography as a 6xHis-tagged fusion protein. The MetaChi18A enzyme is a 92-kDa protein with a conserved active site domain of glycosyl hydrolases family 18. It hydrolyses colloidal chitin with an optimum pH of 5 and temperature of 50°C. Moreover, the enzyme retained at least 80% of its activity in the pH range from 4 to 9 and 98% at 600 mM NaCl. Thin layer chromatography analyses identified chitobiose as the main product of MetaChi18A on chitin polymers as substrate. Kinetic analysis showed inhibition of MetaChi18A activity at high concentrations of colloidal chitin and 4-methylumbelliferyl N,N′-diacetylchitobiose and sigmoid kinetics at low concentrations of colloidal chitin, indicating a possible conformational change to lead the chitin chain from the chitin-binding to the catalytic domain. The observed stability and activity of MetaChi18A over a wide range of conditions suggest that this chitinase, now characterized, may be suitable for application in the industrial processing of chitin.

Characterization and identification of chitinase producing Streptomyces venezuelae P10.

In an attempt to isolate chitinase producers from soil, a streptomycete strain was found potent using natural chitin as the substrate. Chitinolytic activity was tested directly on agar plates, also with crude enzyme. Chitinase assay showed that the isolate could produce 0.8 U/ml of the enzyme. The morphological, cultural, physiological and biochemical characters of the isolate P10 were studied, and identified as Streptomyces venezuelae P10.

Características hidrodinámicas de carboximetilquitina y carboximetilquitosana / Hydrodynamic characteristics of carboxymethylchitin and carboxymethylchitosan

Se estudiaron algunas propiedades físico/químicas de 3 derivados carboximetilados, sintetizados a partir de la quitina que se obtiene en Cuba de los carapachos de langostas. Se analiza el comportamiento hidrodinámico de las soluciones de estas sustancias, comprobándose las características de polielectrólito que presentan y se determinan los valores de la masa molar para cada una de ellas

Metodología para estudios de estabilidad química en formulaciones de quitina / Methodology for chemical stability studies in chitin formulations

Se propuso combinar la gravimetría directa como método cuantitativo con la espectroscopia infrarroja como técnica cualitativa complementaria, con el objetivo de establecer la metodología para el seguimiento de la estabilidad química de la quitina como fármaco en diferentes formas farmacéuticas> suspensión, crema, supositorio. La determinación del contenido de quitina por técnicas gravimétricas se validó en cada caso según los parámetros> linealidad, precisión, exactitud y especificidad. El análisis cuantitativo mostró resultados satisfactorios con respecto al contenido de fármaco en el tiempo en todas las formulaciones evaluadas. Estos resultados fueron corroborados por los espectros infrarrojos, manifestándose que la quitina es el único producto retenido en los filtros y que desde el punto de vista químico no ha sufrido alteraciones transcurridos 2 a de estudio