Research at the Brazilian Center for Research in Energy and Materials (CNPEM) on the cover of Nanoscale
Researchers at the Brazilian Center for Research in Energy and Materials (CNPEM), an organization overseen by the Ministry of Science, Technology and Innovation (MCTI), have just published an article featured on the cover of Nanoscale magazine describing a pioneering experiment that deepens knowledge about the interaction between cellulose and lignin. The adhesion between these two biological macromolecules makes it difficult to break down biomass in industrial processes to refine and obtain bioproducts.
“The interaction between lignin and cellulose gives the biomass what we call recalcitrance, what makes the fibers very cohesive. The processes used to break apart biomass and separate biopolymers of interest requires high temperatures, pressure, and very large quantities of chemicals,” explains researcher Juliana Bernardes.
In many processes, even after stages to separate these materials, lignan may again be deposited on cellulose surfaces, complicating the action of enzymes used to break cellulose down into sugars and nanostructures.
“An in-depth understanding of how this interaction occurs, considering the crystalline structure of cellulose, is extremely important to develop more efficient processes to transform biomass into biofuels, biochemicals, and biomaterials,” adds researcher Carlos Driemeier.
Pioneering experiment
For the first time, scientists combined advanced microscopy resources, machine learning tools, and molecular dynamics simulations to differentiate crystalline facets of cellulose and measure the relation of forces that act in the interaction with lignin.
To do so, they initially used an atomic force microscope (AFM), an instrument that can map the surface of materials in high resolution, measure variations on the nano scale, and obtain precise data on the relation of forces between them.
The microscope’s probe, which is 10 nanometers in diameter, was modified to receive a layer of lignin, a technique developed at the CNPEM.
Because the contact areas on the facets of the cellulose surface are only nanometers in size (and sometimes only on the molecular scale), the probe can differentiate the different facets of cellulose and measure indentation and interaction.
“We created 1024 x 1024 pixel images, with each pixel representing a force-distance curve. Multiple experiments collected thousands of data points from the force-distance curve, which are fundamental parameters for understanding adhesion or lack of affinity between cellulose and lignin,” says Juliana Bernardes.
Machine learning algorithms were utilized to group the curves measured in types of interactions between cellulose and lignin. This typing was confirmed by computational simulations carried out with resources from the Santos Dumont supercomputer at the National Scientistic Computation Laboratory (LNCC).
Results
The experiments revealed never-before-seen details about the interactive properties of the two biomolecules and showed that a wide variety of conditions can affect adhesion between lignin and cellulose.
The presence of water as a solvent was seen to be an important mediator of cohesion, since hydrophobic and hydrophilic properties also vary among the various cellulose facets that are exposed to the interaction with lignin.
Next steps
The approach established in this study expands the potential of data science and machine learning algorithms used together with AFM, which can then be applied to other systems in which nano-scale surface irregularities play an important role in adhesive interactions.
“This more fundamental understanding, identifying the forces that act under different conditions, is very important because it helps us to propose new methods that can help destabilize these interactions and obtain more efficient separation,” conclude the researchers.
Funding
This research received important support from FAPESP, FAPERJ, and the National Scientific Computation Laboratory (LNCC).
About CNPEM
Sophisticated and effervescent environment for research and development, unique in Brazil and present in few scientific centers in the world, the Brazilian Center for Research in Energy and Materials (CNPEM) is a private non-profit organization, under the supervision of the Ministry of Science, Technology and Innovation (MCTI). The Center operates four National Laboratories and is the birthplace of the most complex project in Brazilian science – Sirius – one of the most advanced synchrotron light sources in the world. CNPEM brings together highly specialized multi-thematic teams, globally competitive laboratory infrastructures open to the scientific community, strategic lines of investigation, innovative projects in partnership with the productive sector and training of researchers and students. The Center is an environment driven by the search for solutions with impact in the areas of Health, Energy and Renewable Materials, Agro-environment, and Quantum Technologies. As of 2022, with the support of the Ministry of Education (MEC), CNPEM expanded its activities with the opening of the Ilum School of Science. The interdisciplinary higher course in Science, Technology and Innovation adopts innovative proposals with the aim of offering excellent, free, full-time training with immersion in the CNPEM research environment. Through the CNPEM 360 Platform, it is possible to explore, in a virtual and immersive way, the main environments and activities of the Center, visit: https://pages.cnpem.br/cnpem360/
