Abstract
Nanoparticle morphology, size and dispersion are key parameters for the application of cellulose nanomaterials in various areas, such as polymer nanocomposites, catalysts, gel and so on. Transmission electron microscopy (TEM) is the most suitable technique for the morphological characterization of these particles. However, nanocellulose low contrast in TEM images is the major drawback for their adequate morphological characterization and size determination. Even though it is widespread knowledge that negative staining using uranyl acetate is the best approach for intensifying cellulose contrast, up to now few have succeeded in achieving high quality images and reliable size measurements of these nanomaterials. This protocol presents an optimization of the standard uranyl acetate protocol commonly used for biological specimens in order to suit cellulose nanomaterials. Drying method and grid conditions were proven to be the most significant variables for effective TEM specimen preparation. These guidelines could also be successfully applied to enhance the cellulose nanomaterial contrast in polymer matrices.
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Acknowledgments
This research was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (Grant No. 2016/02414-5), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (Grant No. 426197/2016-0), National Institute of Science, Technology and Innovation in Complex Functional Materials (Inomat/INCT). We also acknowledge LNNano/CNPEM for the access to the electron microscopy facility, proposal TEM-20485, TEM-21412.
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da Silva, L.C.E., Cassago, A., Battirola, L.C. et al. Specimen preparation optimization for size and morphology characterization of nanocellulose by TEM. Cellulose 27, 5435–5444 (2020). https://doi.org/10.1007/s10570-020-03116-7
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DOI: https://doi.org/10.1007/s10570-020-03116-7