Preparation, characterization and activity evaluation of Spirulina-chitooligosaccharides capable of inhibiting biofilms / 生物工程学报

The biofilms formed by pathogenic microorganisms seriously threaten human health and significantly enhance drug resistance, which urgently call for developing drugs specifically targeting on biofilms. Chitooligosaccharides extracted from shrimp and crab shells are natural alkaline oligosaccharides with excellent antibacterial effects. Nevertheless, their inhibition efficacy on biofilms still needs to be improved. Spirulina (SP) is a microalga with negatively charged surface, and its spiral structure facilitates colonization in the depth of the biofilm. Therefore, the complex of Spirulina and chitooligosaccharides may play a synergistic role in killing pathogens in the depth of biofilm. This research first screened chitooligosaccharides with significant bactericidal effects. Subsequently, Spirulina@Chitooligosaccharides (SP@COS complex was prepared by combining chitooligosaccharides with Spirulina through electrostatic adsorption. The binding of the complex was characterized by zeta potential, z-average size, and fluorescence labeling. Ultraviolet-visible spectroscopy (UV-Vis) showed the encapsulation efficiency and the drug loading efficiency reached up to 90% and 16%, respectively. The prepared SP@COS2 exhibited a profound synergistic inhibition effect on bacterial and fungal biofilms, which was mainly achieved by destroying the cell structure of the biofilm. These results demonstrate the potential of Spirulina-chitooligosaccharides complex as a biofilm inhibitor and provide a new idea for addressing the harm of pathogenic microorganisms.

Effects of chitin and sepia ink hybrid sponge on the healing of burning wound rats and its impact on macrophages in vitro

PURPOSE: To detect whether chitin and sepia ink sponge (CS) can promote wound healing and elevate impact of CS on phagocytosis ability of macrophages. METHODS: Forty-eight rats were assigned to four groups: Normal group (Normal), negative control group (Con), chitin and sepia ink sponge group (CS) and positive control Surgicel Gauze(r) group (SG). Deep second-degree burn model was created in rats. Wound area was recorded by digital imaging and determined using Image J software. Samples were collected and kept at -80oC on 3d, 7d, 14d and 21d for cytokines detecting. Transforming growth factor (TGF)-β1, interleukin (IL)-6, matrix metalloproteinase (MMP)-1, hydroxyproline (Hyp) and macrophage activity reflected by tumor necrosis factor (TNF)-α were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Comparing to Con and SG, scabs in CS group fell off and basically healed on 21 day. TGF-β1, IL-6, MMP-1 and Hyp were significantly increased by CS and SG comparing to Con (p < 0.05), CS had more apparently adjustment on TGF-β1 and MMP-1 compared to SG; results in vitro indicated CS significantly promoted phagocytosis ability of macrophages reflected in TNF-α (p < 0.05). CONCLUSION: CS improved wound healing through exerting significant influences on secretion of kinds of cytokines and activating macrophages.

Evaluation of dermal irritancy potential of Carboxymethyl-chitosan hydrogel and poly-(acrylic acid) chitin hydrogel.

OBJECTIVE: The wound dressing synthesized from carboxymethylchitosan hydrogel (CM) and chitin-(polyacrylic acid) hydrogel (PAA) were examined for their dermal irritation potential response using the Draize test. MATERIAL AND METHOD: Eighteen male Sprague-Dawley rats were divided into three groups (6 rats/each). Rats in group 1 were designed as control, group 2 were treated with CM, and group 3 were treated with PAA. The test materials diameter 1 x 1 cm were topically applied on the skin in group 2 and 3. Two skin sites (1 x 1 cm in size) were located at the back. One site was intact and the other was abraded in such a way the stratum corneum had no bleeding. RESULT: After 24 and 72 hours of wrappings, the materials were removed and the test sites were evaluated in terms of erythema and edema using adopted Draize scoring system. At the end of the experiment, all rats were anesthesized with intravenous thiopental sodium. Blood samples from descending aorta were collected for liver and kidney function test and all organs were weighed. The results of this experiment showed 1) no irritation of both materials in this animal model; 2) no material-related induced liver and kidney dysfunction and 3) organ weights had no significant difference between the groups. CONCLUSION: Both CM and PAA should be considered safe to use in the purpose of wound dressing in further clinical trials.

Estudio cinético de la hidrolisis ácida de quitina: parte I / Kinetic study of acid hydrolysis of chitin: part I

En el presente trabajo se ha estudiado la hidrolisis con ácido clorhídrico de la quitina, obtenida mediante el procedimiento descrito por R. D. Henríques y O. M. Nieto (1976), usando dos concentraciones de ácido: 8 y 10 N, y tres temperaturas: 80, 90 y 100 -C, a distintos tiempos de reacción. Se obtuvo el mejor rendimiento en azúcares reductores, dentro de las condiciones estudiadas, para el ácido 10 N a 100 -C y 180 minutos, y éste fue de 97 %. Se observaron distintas pendientes en un diagrama semilogarítmico, para una misma descomposición de la quitina en una condición dada de reacción lo que correspondió a varias constantes aparentes de primer orden. Para cada una de éstas de obtuvo una energía de activación diferente

Estudio cinético de la hidrólisis ácida de quitina: parte II / Kinetic study of acid hydrolysis of chitin: part II

El objetivo de este trabajo es el estudio de la hidrólisis ácida de la quitina suficientemente pura, lo cual permite comparar los resultados cinéticos en este material con los obtenidos para la quitina producida a escala semiindustrial en nuestro país. Se empleó el ácido clorhídrico en concentraciones 8 y 10 N, y temperaturas de 80, 90 y 100 -C, con tiempos de reacción hasta 180 minutos. Se logró una hidrólisis completa del producto con HCL 10 N y temperatura de 100 -C a los 180 minutos, con rendimientos de azúcares reductores de un 99 %. Los gráficos semilogarítmicos que corresponden a la quitina residual muestran distintas pendientes para una misma condición de reacción, y corresponde a cada una un valor para la constante de velocidad aparente de 1er. orden y variadas energías de activación