Revealing the structure of high-water content biopolymer networks: Diminishing freezing artefacts in cryo-SEM images

Efthymiou, C; Williams, MAK; McGrath, KM

Revealing the structure of high-water content biopolymer networks: Diminishing freezing artefacts in cryo-SEM images

Efthymiou, C Williams, MAK McGrath, KM

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Publication Type:: Journal Article
Citation:: Food Hydrocolloids, 2017, 73 pp. 203 - 212
Issue Date:: 2017-12-01

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Field	Value	Language
dc.contributor.author	Efthymiou, C	en_US
dc.contributor.author	Williams, MAK	en_US
dc.contributor.author	McGrath, KM https://orcid.org/0000-0003-3531-0562	en_US
dc.date.issued	2017-12-01	en_US
dc.identifier.citation	Food Hydrocolloids, 2017, 73 pp. 203 - 212	en_US
dc.identifier.issn	0268-005X	en_US
dc.identifier.uri	http://hdl.handle.net/10453/125383
dc.description.abstract	© 2017 Elsevier Ltd High-water content biopolymer gels are widely used in diverse areas of research and in many commercial processes, including a significant proportion of importance to the food and pharmaceutical industries. The internal structures of these hydrogels are complex and span many length scales, the specifics of which are important in determining functionality. Elucidating these structures is critically important in extending and tailoring their use. Cryo-scanning electron microscopy (cryo-SEM) is a popular method for structural elucidation. A critical step in this imaging technique is cryo-fixation. However, consideration of the literature reveals that images of inefficiently cryo-fixed networks remain widely reported as being representative of the native structure of gels despite being significantly damaged by ice formation. Here, we show that the application of slow freezing methods, like the very commonly used slushy nitrogen method, indeed yield erroneous structures and produce singularly common structures for both protein and polysaccharide hydrogels. On the contrary, we demonstrate, by rapidly freezing thin samples of low concentration protein amyloid fibril hydrogels using a propane jet freezer, that cryo-SEM imaging of biopolymer hydrogels in their native state is feasible. In contrast, while the use of cryo-protectants is successful in reducing ice crystallisation, it can affect the bonding within hydrogels and hence, modify the structure under examination.	en_US
dc.relation.ispartof	Food Hydrocolloids	en_US
dc.relation.isbasedon	10.1016/j.foodhyd.2017.06.040	en_US
dc.subject.classification	Food Science	en_US
dc.title	Revealing the structure of high-water content biopolymer networks: Diminishing freezing artefacts in cryo-SEM images	en_US
dc.type	Journal Article
utslib.citation.volume	73	en_US
utslib.for	0908 Food Sciences	en_US
utslib.for	0904 Chemical Engineering	en_US
utslib.for	0912 Materials Engineering	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/DVC (Research)
utslib.copyright.status	closed_access
pubs.publication-status	Published	en_US
pubs.volume	73	en_US

Abstract:

© 2017 Elsevier Ltd High-water content biopolymer gels are widely used in diverse areas of research and in many commercial processes, including a significant proportion of importance to the food and pharmaceutical industries. The internal structures of these hydrogels are complex and span many length scales, the specifics of which are important in determining functionality. Elucidating these structures is critically important in extending and tailoring their use. Cryo-scanning electron microscopy (cryo-SEM) is a popular method for structural elucidation. A critical step in this imaging technique is cryo-fixation. However, consideration of the literature reveals that images of inefficiently cryo-fixed networks remain widely reported as being representative of the native structure of gels despite being significantly damaged by ice formation. Here, we show that the application of slow freezing methods, like the very commonly used slushy nitrogen method, indeed yield erroneous structures and produce singularly common structures for both protein and polysaccharide hydrogels. On the contrary, we demonstrate, by rapidly freezing thin samples of low concentration protein amyloid fibril hydrogels using a propane jet freezer, that cryo-SEM imaging of biopolymer hydrogels in their native state is feasible. In contrast, while the use of cryo-protectants is successful in reducing ice crystallisation, it can affect the bonding within hydrogels and hence, modify the structure under examination.

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http://hdl.handle.net/10453/125383