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ABSTRACT Magnesium (Mg) is essential for the metabolic reactions of the human body and is known for its biocompatibility, its mechanical and physical properties are similar to human bone, which is why it is considered to have high potential in biomedical applications such as temporary and resorbable implants. Through surface modifications, the high tendency to corrosion of Mg could be controlled, such as biodegradable membranes that prevent the passage of chloride ions present in the human organism. To prepare the membrane, solutions of chitosan modified with gelatin and/or glutaraldehyde are used and by means of the electrospray method applied to protect the Mg. To simulate body fluid conditions a Kokubo saline solution (BFK) was prepared. The study focuses on evaluating the corrosion rate of Mg with a coating made of a chitosan electrosprayed membrane, applying electrochemical measurements of electrochemical impedance spectroscopy and linear polarization resistance. The key additive to improve the behavior of the membranes was observed with the use of gelatin, where the membrane with the best results lowing corrosion rates is the Mg CH+GE+GL system, which it was observed with very good physical integrity in the images of morphological analyzes of the surface after 30 days of exposure.
RESUMEN El magnesio (Mg) es esencial para las reacciones metabólicas del cuerpo humano y es conocido por su biocompatibilidad, sus propiedades mecánicas y físicas son similares a las del hueso humano, por lo que se considera que tiene un alto potencial en aplicaciones biomédicas como implantes temporales y reabsorbibles. Mediante modificaciones superficiales se podría controlar la alta tendencia a la corrosión del Mg, como por ejemplo membranas biodegradables que impidan el paso de iones cloruro presentes en el organismo humano. Para preparar la membrana se utilizan soluciones de quitosano modificado con grenetina y/o glutaraldehído y mediante el método de electrorociado se aplican para proteger el Mg. Para simular las condiciones de los fluidos corporales se preparó una solución salina de Kokubo. El estudio se enfoca en evaluar la velocidad de corrosión del Mg con un recubrimiento hecho de una membrana electrorociada con quitosano, aplicando técnicas electroquímicas de espectroscopia de impedancia electroquímica y resistencia de polarización lineal. El aditivo clave para mejorar el comportamiento de las membranas se observó con el uso de gelatina, donde la membrana con mejores resultados bajando los índices de corrosión es el sistema Mg CH+GR+GL, el cual se observó con muy buena integridad física en las imágenes de análisis morfológicos de la superficie después de 30 días de exposición.
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Objective: To prepare tripterygium glycosides-loaded nanoparticles modified by 50% N-acetylated low molecular weight chitosan (LMWC-TG-NPs) and to investigate their in vitro release behavior. Methods: The LMWC-TG-NPs were prepared by modified self-emulsifying solvent diffusion method; The formulation of TG-NPs was optimized by orthogonal design and the modified condition of LMWC was determined based on the single factor analysis. The in vitro drug release of LMWC-TG-NPs was characterized with PBS (pH 7.4) containing 20% ethanol. Results: The optimized formulation of TG-NPs was as follows: Poloxamer 188 (1.0%), PLA (80 mg), organic phase (12 mL), and acetone-ethanol (2:3) were used to prepare TG-NPs suspension. The LMWC-TG-NPs were prepared by incubating TG-NPs suspension with 10% LMWC solution at the ratio of 1:1. The shape of the prepared LMWC-TG-NPs was spherical. The mean particle size, polydispersity index, entrapment efficiency, and drug loading were (207.6 ± 3.4) nm, 0.078 ± 0.009, (61.83 ± 2.43)%, and (10.70 ± 0.37)% (n=3), respectively. The in vitro release characteristics of LMWC-TG-NPs conform to Higuchi equation in PBS buffer composed of 20% ethanol at pH 7.4. Conclusion: The prepared LMWC-TG-NPs show a sustained-release characteristics with well-distributed particle size as well as high entrapment efficiency and drug loading, which could lay the foundation for the research on kidney targeting and toxicity.
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Objective To prepare the ephedrine chitosan-modified liposomes gels, detect the particle diameter and the entrapment efficiency, and investigate the transdermal diffusion characteristics in vitro. Methods Ephedrine liposomes suspensions were prepared using thin film evaporation and slowly dropped by 0.35% chitosan solution with pH values 5-6 in order to prepare the chitosan-modified liposomes gels. The particle diameter of the modified liposomes was detected by Laser Scattering Particle Size Distribution Analyzer. The entrapment efficiency was determined by reverse dialysis method with HPLC. Using Franz Diffusion Cell to investigate transdermal diffusion characteristics of the modified liposomes gels in vitro. Results The mean particle diameter of the modified liposome prepared was from 1 400 to 1 900 nm. The average entrapment efficiency of the modified liposomes was up to (41 ± 0.94)%. Ephedrine in the modified liposomes could penetrate rat skin. The results of the transdermal diffusion test showed the cumulative penetration amount of the ephedrine chitosan-modified liposomes gels was lower than that in the ephedrine solutions with time variation. Conclusion This preparatiom is prepared with simple technology and stable character. The entrapment efficiency of the ephedrine is higher and the assay method is simple and accurate. The penetrating rate of ephedrine is slow and the drug releasing is stable.