Center for Research and Development of Functional Materials, Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil.
School of Engineering, São Paulo State University (UNESP), Guaratinguetá, SP, Brazil.
Sci Rep. 2022 Feb 28;12(1):3341. doi: 10.1038/s41598-022-07200-9.
This study reports the synthesis of hybrid nanostructures composed of cerium dioxide and microcrystalline cellulose prepared by the microwave-assisted hydrothermal route under distinct temperature and pH values. Their structural, morphological and spectroscopic behaviors were investigated by X-Rays Diffraction, Field Emission Gun Scanning Electron Microscopy, High-Resolution Transmission Electron Microscopy, and Fourier-Transform Infrared, Ultraviolet-Visible, Raman and Positron Annihilation Lifetime spectroscopies to evaluate the presence of structural defects and their correlation with the underlying mechanism regarding the biocide activity of the studied material. The samples showed mean crystallite sizes around 10 nm, characterizing the formation of quantum dots unevenly distributed along the cellulose surface with a certain agglomeration degree. The samples presented the characteristic Ce-O vibration close to 450 cm and a second-order mode around 1050 cm, which is indicative of distribution of localized energetic levels originated from defective species, essential in the scavenging of reactive oxygen species. Positron spectroscopic studies showed first and second lifetime components ranging between 202-223 ps and 360-373 ps, respectively, revealing the presence of two distinct defective oxygen species, in addition to an increment in the concentration of Ce-oxygen vacancy associates as a function of temperature. Therefore, we have successfully synthesized hybrid nanoceria structures with potential multifunctional therapeutic properties to be further evaluated against the COVID-19.
本研究报告了通过微波辅助水热法在不同温度和 pH 值下制备的由二氧化铈和微晶纤维素组成的杂化纳米结构的合成。通过 X 射线衍射、场发射枪扫描电子显微镜、高分辨率透射电子显微镜以及傅里叶变换红外、紫外-可见、拉曼和正电子湮没寿命光谱研究了它们的结构、形态和光谱行为，以评估结构缺陷的存在及其与基础机制的相关性，研究材料的杀菌活性。样品的平均晶粒尺寸约为 10nm，这表明在纤维素表面不均匀分布着一定程度团聚的量子点。样品呈现出接近 450cm 的特征 Ce-O 振动和 1050cm 左右的二阶模式，这表明存在由缺陷物种引起的局部能级分布，这对于清除活性氧物种至关重要。正电子光谱研究表明，第一和第二寿命分量分别在 202-223ps 和 360-373ps 之间，这表明除了温度函数下 Ce-氧空位配合物浓度的增加外，还存在两种不同的缺陷氧物种。因此，我们已经成功合成了具有潜在多功能治疗特性的杂化纳米氧化铈结构，将进一步针对 COVID-19 进行评估。
