Burnett School of Biomedical Sciences, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, FL 32826, USA.
J Biomed Nanotechnol. 2012 Aug;8(4):558-66. doi: 10.1166/jbn.2012.1423.
We report synthesis of a novel core-shell silica based antimicrobial nanoparticles where the silica shell has been engineered to accommodate copper (Cu). Synthesis of the core-shell Cu-silica nanoparticle (C-S CuSiO2NP) involves preparation of base-hydrolyzed Stöber silica "seed" particles first, followed by the acid-catalyzed seeded growth of the Cu-silica shell layer around the core. The Scanning Electron Microscopy (SEM) and the Transmission Electron Microscopy (TEM) measured the seed particle size to be -380 nm and the shell thickness to be -35 nm. The SEM particle characterization confirms formation of highly monodispersed particles with smooth surface morphology. Characterization of particle size distribution in solution by Dynamic Light Scattering (DLS) technique was fairly consistent with the electron microscopy results. Loading of Cu to nanoparticles was confirmed by the SEM-Energy Dispersive X-Ray Spectroscopy (EDS) and Atomic Absorption Spectroscopy (AAS). The Cu loading was estimated to be 0.098 microg of metallic copper per mg of C-S CuSiO2NP material by the AAS technique. Antibacterial efficacy of C-S CuSiO2NP was evaluated against E. coli and B. subtilis using Cu hydroxide ("Insoluble" Cu compound, sub-micron size particles) as positive control and silica "seed" particles (without Cu loading) as negative control. Bacterial growth in solution was measured against different concentrations of C-S CuSiO2NP to determine the Minimum Inhibitory Concentration (MIC) value. The estimated MIC values were 2.4 microg metallic Cu/mL for both E. coli and B. subtilis. Bac-light fluorescence microscopy based assay was used to count relative population of the live and dead bacteria cells. Antibacterial study clearly shows that C-S CuSiO2NP is more effective than insoluble Cu hydroxide particles at equivalent metallic Cu concentration, suggesting improvement of Cu bioavailability (i.e., more soluble Cu) in C-SCuSiO2NP material due to its core-shell design.
我们报告了一种新型核壳结构硅基抗菌纳米粒子的合成方法，其中硅壳经过设计以容纳铜（Cu）。核壳型 Cu-硅纳米粒子（C-S CuSiO2NP）的合成涉及首先制备碱性水解的 Stöber 硅“种子”颗粒，然后在核心周围通过酸催化生长 Cu-硅壳层。扫描电子显微镜（SEM）和透射电子显微镜（TEM）测量种子颗粒的粒径为-380nm，壳层厚度为-35nm。SEM 颗粒特征确认形成了具有光滑表面形态的高度单分散颗粒。通过动态光散射（DLS）技术对溶液中颗粒粒径分布的表征与电子显微镜结果相当一致。通过 SEM-能量色散 X 射线光谱（EDS）和原子吸收光谱（AAS）证实了 Cu 对纳米粒子的负载。通过 AAS 技术，Cu 的负载量估计为每毫克 C-S CuSiO2NP 材料 0.098μg 的金属铜。使用 Cu（OH）2（“不溶性”Cu 化合物，亚微米级颗粒）作为阳性对照，硅“种子”颗粒（未负载 Cu）作为阴性对照，评估了 C-S CuSiO2NP 对大肠杆菌和枯草芽孢杆菌的抗菌功效。通过测量不同浓度的 C-S CuSiO2NP 对溶液中细菌生长的影响，确定最小抑菌浓度（MIC）值。估计的 MIC 值分别为 2.4μg 金属 Cu/mL 大肠杆菌和枯草芽孢杆菌。基于 Bac-light 荧光显微镜的检测用于计数活细菌和死细菌细胞的相对数量。抗菌研究清楚地表明，在等效金属 Cu 浓度下，C-S CuSiO2NP 比不溶性 Cu（OH）2 颗粒更有效，这表明由于其核壳设计，C-SCuSiO2NP 材料中的 Cu 生物利用度（即更可溶的 Cu）得到了提高。
