Ruiz Christhy V, Becerra María E, Giraldo Oscar
Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia- Sede Manizales, Kilometro 9 vía al aeropuerto, La Nubia, 170003 Manizales, Colombia.
Grupo de Investigación en Procesos Químicos, Catalíticos y Biotecnológicos, Universidad Nacional de Colombia-Sede Manizales, Kilometro 9 vía al aeropuerto, La Nubia, 170003 Manizales, Colombia.
Nanomaterials (Basel). 2020 Jan 17;10(1):163. doi: 10.3390/nano10010163.
Caffeic acid (CA) molecules were immobilized in a layered inorganic host matrix based on zinc hydroxide structures with different starting interlayer anions, nitrate, and acetate. The chemical composition, structure, thermal stability, morphology, and surface of the host matrices and hybrid compounds were analyzed by X-ray diffraction (XRD), themogravimetric/differencial thermal analysis (TG/DTA), Fourier transform infrarred spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Additionally, the surface charge of the materials was investigated using zeta potential at pH ~7. The results show an influence of the surface charge on the chemical, interaction, and structure of the resulting hybrid materials as a function of the starting layered structures. An expansion of the basal spacing to 10.20 Å for zinc hydroxide nitrate (ZHN), and a shrinkage to 10.37 Å for zinc hydroxide acetate (ZHA). These results suggest that the CA lies with a tilt angle in the interlayer region of the inorganic host matrix. The immobilization of CA is favored in ZHN, with respect to ZHA, because a single-layered phase was identified. A higher thermal stability at 65 °C was observed for ZHN-CA than for ZHA-CA. The evaluation of the release behavior showed a higher percentage of CA released from ZHN than ZHA, and the release mechanism was described by the Elovich model. The hybrid materials show potential characteristics for use as bioactive delivery systems.
咖啡酸（CA）分子被固定在基于具有不同起始层间阴离子（硝酸盐和乙酸盐）的氢氧化锌结构的层状无机主体基质中。通过X射线衍射（XRD）、热重/差示热分析（TG/DTA）、傅里叶变换红外光谱（FT-IR）、扫描电子显微镜（SEM）和X射线光电子能谱（XPS）对主体基质和杂化化合物的化学成分、结构、热稳定性、形态和表面进行了分析。此外，在pH值约为7时使用zeta电位研究了材料的表面电荷。结果表明，表面电荷对所得杂化材料的化学性质、相互作用和结构有影响，这是起始层状结构的函数。硝酸锌氢氧化物（ZHN）的基面间距扩大到10.20 Å，而乙酸锌氢氧化物（ZHA）的基面间距缩小到10.37 Å。这些结果表明，CA以倾斜角位于无机主体基质的层间区域。相对于ZHA，CA在ZHN中的固定更有利，因为鉴定出了单层相。观察到ZHN-CA在65°C时的热稳定性高于ZHA-CA。释放行为的评估表明，ZHN释放的CA百分比高于ZHA，并且释放机制由Elovich模型描述。这些杂化材料显示出作为生物活性递送系统的潜在特性。
