Nanoscale Research Letters This Provisional PDF corresponds to the article as it appeared upon acceptance Fully formatted PDF and full text (HTML) versions will be made available soon Cross-linking cellulose nanofibrils for potential elastic cryo-structured gels Nanoscale Research Letters 2011, 6:626 doi:10.1186/1556-276X-6-626 Kristin Syverud (kristin.syverud@pfi.no) Harald Kirsebom (Harald.Kirsebom@biotek.lu.se) Solmaz Hajizadeh (Solmaz.Hajizadeh@biotek.lu.se) Gary Chinga-Carrasco (gary.chinga.carrasco@pfi.no) ISSN Article type 1556-276X Nano Express Submission date 26 September 2011 Acceptance date 12 December 2011 Publication date 12 December 2011 Article URL http://www.nanoscalereslett.com/content/6/1/626 This peer-reviewed article was published immediately upon acceptance It can be downloaded, printed and distributed freely for any purposes (see copyright notice below) Articles in Nanoscale Research Letters are listed in PubMed and archived at PubMed Central For information about publishing your research in Nanoscale Research Letters go to http://www.nanoscalereslett.com/authors/instructions/ For information about other SpringerOpen publications go to http://www.springeropen.com © 2011 Syverud et al ; licensee Springer This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited Cross-linking cellulose nanofibrils for potential elastic cryo-structured gels Kristin Syverud*1, Harald Kirsebom2, Solmaz Hajizadeh2, and Gary Chinga-Carrasco1 Paper and Fibre Research Institute (PFI), Høgskolerringen 6b, Trondheim, NO-7491, Norway Department of Biotechnology, Lund University, P.O Box 124, Lund, SE-22100, Sweden *Corresponding author email: kristin.syverud@pfi.no Email addresses: KS: kristin.syverud@pfi.no HK: Harald.Kirsebom@biotek.lu.se SH: Solmaz.Hajizadeh@biotek.lu.se GCC: gary.chinga.carrasco@pfi.no Abstract Cellulose nanofibrils were produced from P radiata kraft pulp fibers The nanofibrillation was facilitated by applying 2,2,6,6-tetramethylpiperidinyl-1-oxyl-mediated oxidation as pretreatment The oxidized nanofibrils were cross-linked with polyethyleneimine and poly Nisopropylacrylamide-co-allylamine-co-methylenebisacrylamide particles and were frozen to form cryo-structured gels Samples of the gels were critical-point dried, and the corresponding structures were assessed with scanning electron microscopy It appears that the aldehyde groups in the oxidized nanofibrils are suitable reaction sites for cross-linking The cryostructured materials were spongy, elastic, and thus capable of regaining their shape after a given pressure was released, indicating a successful cross-linking These novel types of gels are considered potential candidates in biomedical and biotechnological applications Keywords: cellulose nanofibrils; MFC; cryogelation; cross-linking Background Cellulose nanofibrils The main raw material for the production of microfibrillated cellulose [MFC] is cellulose fibers, produced from wood by chemical pulping Properly produced MFC contains a major fraction of cellulose nanofibrils [1] Nanofibrils are composed of bundles of cellulose molecules, arranged in crystalline and amorphous areas Nanofibrils have threadlike shapes, with diameters in the nanometer scale (