Shedding light on cellulose quality

Swedish researchers from Linköping University have developed in collaboration with others a molecule that changes colour when it binds to different forms of cellulose. The researchers demonstrate in a new study, published in the Nature journal Scientific Reports, how the molecule can be used to make rapid, optical measurements of cellulose quality. Possible applications include the development of renewable energy sources.

Cellulose is an important component of all plants and one of the most widely used molecules on the planet. It is a long and strong polymer used in, among other things, packaging and textiles such as viscose and lyocell. It can also be broken down to give biogas or bioethanol, and comprehensive research is currently being conducted in using cellulose as an alternative to fossil fuels in the quest for renewable energy sources.

The problem with cellulose is that it is seldom found in a pure form and its quality can differ. The ability to assess the quality and purity of cellulose, therefore, is very important for the development of clean, renewable energy sources and for the recycling of cellulose.

The work reported in the current article is a collaboration between Karolinska Institutet, Linköping University and the Royal Institute of Technology. The research group at Linköping University, led by Professor Peter Nilsson, has created the molecule used in the study. These tracer molecules have a part that enables them to find a specific target molecule and bind to it. When this happens, the molecule changes its shape slightly.

Photo credit: Karin S?derlund Leifler“What makes these molecules special is that they emit light of different colours, depending on their conformation. The molecule has one colour when it is on its own, and this changes when it binds to its target molecule. This makes it a sort of optical fingerprint,” says Peter Nilsson.

Chameleon molecules

Thus, the colour changes depending on the surroundings, in a manner that reminds us of a chameleon. One of the results that the researchers present in the study shows how these chameleon molecules can be used to follow in real time the process in which cellulose is broken down. This is important for the production of cellulose-based bioethanol.

The methods currently used to quantify the quality of cellulose are technically difficult. They require tough pretreatment with concentrated and corrosive chemicals, breaking down the polymer chains for analysis. The new method has the potential to reduce dependence on concentrated chemicals in the quality assessment of cellulose, and to improve the quality of the analyses.

“For example, our new technology could be used for quality control or process control in several industries that depend on cellulose,” says Peter Nilsson.

The research has been financed with the support of Carl Bennet AB, the Erling-Persson Family Foundation and the European Research Council. Some of the researchers who work in the study are part-owners in a company that may commercialise the molecules.

Top photo: Three different types of cellulose, studied by fluorescent confocal microscopy using the optical tracer molecule. Photo: Choong, F. X. et al. Nondestructive, real-time determination and visualization of cellulose, hemicellulose and lignin by luminescent oligothiophenes. Sci. Rep. 6, 35578; doi: 10.1038/srep35578 (2016). Creative Commons Attribution 4.0 International License

The article: Nondestructive, real-time determination and visualization of cellulose, hemicellulose and lignin by luminescent oligothiophenes, Ferdinand X. Choong, Marcus Bäck, Svava E. Steiner, Keira Melican, K. Peter R. Nilsson, Ulrica Edlund, Agneta Richter-Dahlfors, (2016), Scientific Reports, 6, 35578, published online 19 October 2016, DOI: 10.1038/srep35578