Preparation of cellulose nanofibrils for imaging purposes: comparison of liquid cryogens for rapid vitrification
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Artifact-free imaging of cellulose nanofibrils (CNFs) from aqueous nanocellulose suspensions is nontrivial due to frequent irreversible agglomeration and structure damage during the course of sample preparation, especially as water is solidified prior to freeze-drying. In this study, we have examined the morphologies of CNF suspensions prepared by rapid vitrification in two different liquid cryogens—nitrogen and ethane—followed by freeze-drying. Results obtained by scanning electron microscopy confirm that vitrification in liquid ethane not only greatly improves the survivability of fine-scale CNF structural elements but also significantly reduces the propensity for CNF to agglomerate.
KeywordsNanocellulose Cellulose nanofibril Freeze-drying Cryopreparation Scanning electron microscopy
This work was supported by the Research Counsel of Norway through the NANO 2021 program (Grant Number 239172) and NANO-MBE projects. We are grateful to I. Leirset and A. Reitan for technical assistance and to Sødra for supplying the pulp.
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