Tag Archives: cellulose nanofibers

A lotus root-inspired hydrogel fiber for surgical sutures

By FotoosRobin – originally posted to Flickr as Lotus root, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=4826529

The lotus (Nelumbo nucifera) rhizome (mass of roots) is not the prettiest part of the lotus but its fibers (and presumably fiber from other parts of the lotus plant) served as inspiration for a hydrogel that might be used as a surgical suture according to a Jan. 14, 2021 news item on phys.org (Note: Links have been removed),

“The lotus roots may break, but the fiber remains joined”—an old Chinese saying that reflects the unique structure and mechanical properties of the lotus fiber. The outstanding mechanical properties of lotus fibers can be attributed to their unique spiral structure, which provides an attractive model for biomimetic design of artificial fibers.

In a new study published in Nano Letters, a team led by Prof. Yu Shuhong from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) reported a bio-inspired lotus-fiber-mimetic spiral structure bacterial cellulose (BC) hydrogel fiber with high strength, high toughness, excellent biocompatibility, good stretchability, and high energy dissipation.

A Jan. 14, 2021 University of Science and Technology of China press release on the Chinese Academy of Sciences website (also on EurekAlert), which originated the news item, describes the new hydrogel in more detail,

Unlike polymer-based hydrogel, the newly designed biomimetic hydrogel fiber (BHF) is based on the BC hydrogel with 3D cellulose nanofiber networks produced by bacteria. The cellulose nanofibers provide the reversible hydrogen bonding network that results in unique mechanical properties.

The researchers applied a constant tangential force to the pretreated BC hydrogel along the cross-sectional direction. Then, the two sides of the hydrogel were subjected to opposite tangential forces, and local plastic deformation occurred.

The hydrogen bonds in the 3D network of cellulose nanofibers were broken by the tangential force, causing the hydrogel strip to twist spirally and the network to slip and deform. When the tangential force was removed, the hydrogen bonds reformed between the nanofibers, and the spiral structure of the fiber was fixed.

Benefited from lotus-fiber-mimetic spiral structure, the toughness of BHF can reach ?116.3 MJ m-3, which is more than nine times higher than those of non-spiralized BC hydrogel fiber. Besides, once the BHF is stretched, it is nearly non-resilient.

Combining outstanding mechanical properties with excellent biocompatibility derived from BC, BHF is a promising hydrogel fiber for biomedical material, especially for surgical suture, a commonly used structural biomedical material for wound repair.

Compared with commercial surgical suture with higher modulus, the BHF has similar modulus and strength to soft tissue, like skin. The outstanding stretchability and energy dissipation of BHF allow it to absorb energy from the tissue deformation around a wound and effectively protect the wound from rupture, which makes BHF an ideal surgical suture.

What’s more, the porous structure of BHF also allows it to adsorb functional small molecules, such as antibiotics or anti-inflammatory compounds, and sustainably release them on wounds. With an appropriate design, BHF would be a powerful platform for many medical applications.

Here’s a link to and a citation for the paper,

Bio-Inspired Lotus-Fiber-like Spiral Hydrogel Bacterial Cellulose Fibers by Qing-Fang Guan, Zi-Meng Han, YinBo Zhu, Wen-Long Xu, Huai-Bin Yang, Zhang-Chi Ling, Bei-Bei Yan, Kun-Peng Yang, Chong-Han Yin, HengAn Wu, and Shu-Hong Yu. Nano Lett. 2021, XXXX, XXX, XXX-XXX DOI: https://doi.org/10.1021/acs.nanolett.0c03707 Publication Date:January 5, 2021 Copyright © 2021 American Chemical Society

This paper is behind a paywall.

Removing viruses from water with a ‘mille-feuille’ filter

Mille-feuille is a pastry and it’s name translates to ‘a thousand leaves’, which hints at how a ‘mille-feuille’ nanofilter is constructed. From a May 18, 2016 news item on Nanowerk,

A simple paper sheet made by scientists at Uppsala University can improve the quality of life for millions of people by removing resistant viruses from water. The sheet, made of cellulose nanofibers, is called the mille-feuille filter as it has a unique layered internal architecture resembling that of the French puff pastry mille-feuille (Eng. thousand leaves).

Caption: The sheet made of cellulose nanofibers in the mille-feuille filter which can remove resistant viruses from water. Research led by Albert Mihranyan, Professor of Nanotechnology at Uppsala University, Image by Simon Gustafsson. Credit: Simon Gustafsson

Caption: The sheet made of cellulose nanofibers in the mille-feuille filter which can remove resistant viruses from water. Research led by Albert Mihranyan, Professor of Nanotechnology at Uppsala University, Image by Simon Gustafsson. Credit: Simon Gustafsson

A May 18, 2016 Uppsala University (Sweden) press release on EurekAlert, which originated the news item, expands on the theme,

With a filter material directly from nature, and by using simple production methods, we believe that our filter paper can become the affordable global water filtration solution and help save lives. Our goal is to develop a filter paper that can remove even the toughest viruses from water as easily as brewing coffee’, says Albert Mihranyan, Professor of Nanotechnology at Uppsala University, who heads the study.

Access to safe drinking water is among the UN’s Sustainable Development Goals. More than 748 million people lack access to safe drinking water and basic sanitation. Water-borne infections are among the global causes for mortality, especially in children under age of five, and viruses are among the most notorious water-borne infectious microorganisms. They can be both extremely resistant to disinfection and difficult to remove by filtration due to their small size.

Today we heavily rely on chemical disinfectants, such as chlorine, which may produce toxic by-products depending on water quality. Filtration is a very effective, robust, energy-efficient, and inert method of producing drinking water as it physically removes the microorganisms from water rather than inactivates them. But the high price of efficient filters is limiting their use today.

‘Safe drinking water is a problem not only in the low-income countries. Massive viral outbreaks have also occurred in Europe in the past, including Sweden, continues Mihranyan referring to the massive viral outbreak in Lilla Edet municipality in Sweden in 2008, when more than 2400 people or almost 20% of the local population got infected with Norovirus due to poor water. ‘ Cellulose is one of the most common filtering media used in daily life from tea-bags to vacuum cleaners. However, the general-purpose filter paper has too large pores to remove viruses. In 2014, the group has described for the first time a paper filter that can remove large size viruses, such as influenza virus.

Small size viruses have been much harder to get rid of, as they are extremely resistant to physical and chemical inactivation. A successful filter should not only remove viruses but also feature high flow, low fouling, and long life-time, which makes advanced filters very expensive to develop. Now, with the breakthrough achieved using the mille-feuille filter the long awaited shift to affordable advanced filtration solutions may at last become a reality. Another application of the filter includes production of therapeutic proteins and vaccines.

Here’s a link to and a citation for the paper,

Mille-feuille paper: a novel type of filter architecture for advanced virus separation applications by Simon Gustafsson, Pascal Lordat, Tobias Hanrieder, Marcel Asper,  Oliver Schaeferb, and Albert Mihranyan, Mater. Horiz., 2016, Advance Article DOI: 10.1039/C6MH00090H First published online 18 May 2016

This paper is behind a paywall.

Final words on TAPPI’s June 2014 Nanotechnology for Renewable Materials conference

A July 8, 2014 news item on Nanowerk provides some statistics about the recently ended (June 23 – 26, 2014) TAPPI (Technical Association for the Pulp, Paper, Packaging and Converting Industries) Conference on Nanotechnology for Renewable Materials,

Over 230 delegates from 25 countries gathered in Vancouver, British Columbia, Canada last week at TAPPI’s 9th International Conference on Nanotechnology for Renewable Nanomaterials. “This year’s conference was exceptional,” noted co-chair Wadood Hamad, Priniciple Scientist, FPInnovations. “The keynote and technical presentations were of very high quality. The advancements made in many applications show great promise, and we will see expanded commercial use of these renewable biomaterials.”

An identical news item dated July 7, 2014 on Nanotechnology Now,notes the commercial announcements made during the conference,

Several key commercial announcements were made at this year’s conference, highlighting the tangible growth in this emerging market area of renewable biopolymers:

Celluforce, which opened their commercial plant in January 2012, shared six advanced commercial projects.

Imerys announced the launch of their new FiberLean™ MFC innovative composite, which enables a 10-15% reduction in fiber usage for papermaking applications.

Representatives from the newly formed BioFilaments shared information on their unique high performance biomaterial derived from wood cellulose to be used as reinforcing agents and rheological modifiers.

Blue Goose Biorefineries presented their patent-pending process for producing cellulose nanocrystals from wood pulp.

Nippon Paper Industries introduced Cellenpia, their cellulose nanofibers produced from their pre-commercial plant.

GL&V presented their commercial system, developed with the University of Maine, to produce cellulose nanofibrils at a very low energy cost.

American Process Inc. presented their latest results of producing lignin-coated nanocellulose particles using their AVAP® technology which produces a material that is more easily dispersed and has enhanced properties.

I wish them good luck with their projects.

Paper and Fibre Research Institute holds nanocellulose party/seminar

My ears always prick up when I come across a nanocellulose story and this Sept. 26, 2012 news item on Nanowerk features a nanocellulose seminar hosted by the Paper and Fibre Institute (PFI) in Norway (Note: I have removed a link),

PFI has the pleasure to organize the 4th research seminar about cellulose and their nanomaterials. The seminar will take place at PFI in Norway, on November 14-15, 2012. This will be a follow-up of the successful seminars in Trondheim 2006, 2008, 2010. The seminar offers an excellent scientific program, including topics which reflect the most recent advances from basic research to practical applications.

During the last years it has been considerable interest in cellulose nanofibrils [emphasis mine] due to the wide range of potential areas of application. This includes replacement for plastics, reinforcement of composite materials, boosting paper properties, barrier material in packaging and bio-medical applications.

As per the term I highlighted, cellulose nanofibrils, KarenS very kindly dropped by my Aug. 2, 2012 posting on nanocellulose research to explain some of the terminology that gets tossed around,

From my understanding, nanocrystaline cellulose (NCC), cellulose nanocrystals (CNC), cellulose whiskers (CW) and cellulose nanowhiskers (CNW) are all the same stuff: cylindrical rods of crystalline cellulose (diameter: 5-10 nm; length: 20-1000 nm). Cellulose nanofibers or nanofibrils (CNF), on the contrary, are less crystalline and are in the form of long fibers (diameter: 20-50 nm; length: up to several micrometers).

There is still a lot of confusion on the nomenclature of cellulose nanoparticles, but nice explanations (and pictures!) are given here (and also in other papers from the same [TAPPI 2012 in Montréal] conference):

http://www.tappi.org/Downloads/Conference-Papers/2012/12NANO/12NANO49.aspx

Thank you KarenS, I really appreciate the clarification and the link to additional information.

Back to the main event, I went to the webpage for the 4th research seminar about cellulose and their nanomaterials and found a listing of the speakers,

Tsuguyuki Saito (University of Tokyo):  “Material Properties of TEMPO-Oxidized Cellulose Nanofibrils: In bulk and Individual Forms”
Lars Berglund (KTH): “Unexplored materials property space – does nanofibrillated cellulose provide new possibilities?”
Michel Schenker (Omya): “Toward Nano-fibrillated Pigmented Cellulose Composites”
Anette Hejnesson-Hulten (Eka):  “Chemically Pretreated  MFC – Process, Manufacturing and Application”
Kriistina Oksman (Luleå Univ.of Techn): “Nanocelluloses extracted from  bio residues and their use in composites”
J.M. Lagaron (CSIC): “Nanocellulose as a reinforcing material in packaging films”
Tomas Larsson (Innventia): “Determining the specific surface area of NFC by CP/MAS 13C-NMR”
Tekla Tammelin, (VTT): “Dense NFC films with several opportunities for additional functionalities”
Kristin Syverud (PFI): “A biocompatibility study of microfibrillated cellulose”
Øyvind Gregersen (NTNU): “The effect of microfibrillated cellulose on the pressability and paper properties of TMP and ground calcium carbonate (GCC) based sheets”
Gary Chinga Carrasco (PFI): “Characterization of the fibrillation degree of various MFC materials and its implication on critical properties”
Marianne Lenes (PFI): “MFC as barrier material – possibilities and challenges”
Laura Alexandrescu (NTNU): “MFC filters for environmental particle filtration”
Per Stenius (NTNU): “Nanofibrils – do they fulfill the promises?”

Dag Høvik (Research Council of Norway): “Strategic research programmes within Nanotechnology and Advanced Materials in Norway, 2002-2021”.

Interestingly given our work in this field, there don’t seem to be any Canadians on the speaker list.  I imagine that this is largely due to the fact that they have healthy and active research community in Norway and this is not really an international affair.