Carvalho Silva Renata, Alexandre Muehlmann Luis, Rodrigues Da Silva Jaqueline, de Bentes Azevedo Ricardo, Madeira Lucci Carolina
Institute of Biological Sciences, University of Brasilia - (IB/UnB) 70.910-900, Brasilia/DF, Brazil.
Microsc Res Tech. 2014 Sep;77(9):691-6. doi: 10.1002/jemt.22390. Epub 2014 Jun 12.
Morphometric characterization of nanoparticles is crucial to determine their biological effects and to obtain a formulation pattern. Determining the best technique requires knowledge of the particles being analyzed, the intended application of the particles, and the limitations of the techniques being considered. The aim of this article was to present transmission (TEM) and scanning (SEM) electron microscopy protocols for the analysis of two different nanostructures, namely polymeric nanoemulsion and poly(lactic-co-glycolic acid) (PLGA) nanoparticles, and to compare these results with conventional dynamic light scattering (DLS) measurements. The mean hydrodynamic diameter, the polydispersity index, and zeta potential of the nanostructures of polymeric nanoemulsion were 370.5 ± 0.8 nm, 0.133 ± 0.01, and -36.1 ± 0.15 mV, respectively, and for PLGA nanoparticles were 246.79 ± 5.03 nm, 0.096 ± 0.025, and -4.94 ± 0.86 mV, respectively. TEM analysis of polymeric nanoemulsion revealed a mean diameter of 374 ± 117 nm. SEM analysis showed a mean diameter of 368 ± 69 nm prior to gold coating and 448 ± 70 nm after gold coating. PLGA nanoparticles had a diameter of 131 ± 41.18 nm in TEM and 193 ± 101 nm in SEM. Morphologically, in TEM analysis, the polymeric nanoemulsions were spherical, with variable electron density, very few showing an electron-dense core and others an electron-dense surface. PLGA nanoparticles were round, with an electron-lucent core and electron-dense surface. In SEM, polymeric nanoemulsions were also spherical with a rough surface, and PLGA nanoparticles were round with a smooth surface. The results show that the "gold standards" for morphometric characterization of polymeric nanoemulsion and PLGA nanoparticles were, respectively, SEM without gold coating and TEM with negative staining.
纳米颗粒的形态计量学表征对于确定其生物学效应和获得配方模式至关重要。确定最佳技术需要了解被分析的颗粒、颗粒的预期应用以及所考虑技术的局限性。本文的目的是介绍用于分析两种不同纳米结构（即聚合物纳米乳液和聚乳酸 - 乙醇酸共聚物（PLGA）纳米颗粒）的透射电子显微镜（TEM）和扫描电子显微镜（SEM）协议，并将这些结果与传统的动态光散射（DLS）测量结果进行比较。聚合物纳米乳液纳米结构的平均流体动力学直径、多分散指数和zeta电位分别为370.5±0.8 nm、0.133±0.01和 -36.1±0.15 mV，PLGA纳米颗粒的分别为246.79±5.03 nm、0.096±0.025和 -4.94±0.86 mV。聚合物纳米乳液的TEM分析显示平均直径为374±117 nm。SEM分析显示镀金前平均直径为368±69 nm，镀金后为448±70 nm。PLGA纳米颗粒在TEM中的直径为131±41.18 nm，在SEM中的直径为193±101 nm。在形态上，在TEM分析中，聚合物纳米乳液呈球形，电子密度可变，很少有显示电子致密核心的，其他的显示电子致密表面。PLGA纳米颗粒是圆形的，有电子透明核心和电子致密表面。在SEM中，聚合物纳米乳液也是表面粗糙的球形，PLGA纳米颗粒是表面光滑的圆形。结果表明，聚合物纳米乳液和PLGA纳米颗粒形态计量学表征的“金标准”分别是未镀金的SEM和负染色的TEM。
