Cellulose is tough yet flexible; fibrous yet soft; and highly attracted to water, though completely insoluble in it. All these qualities have contributed to its use for thousands of years, but the most abundant material on planet Earth also has a nanoscale side with enormous potential. “The same cellulose found in cotton or paper, which we use so many times a day for various purposes, has an organization that houses tiny nanostructures with unparalleled physical and chemical properties,” explains José Miguel González, a researcher at the Spanish National Research Council (CSIC) and author of ‘Nanocellulose,’ a book that presents the most paradigmatic example of nanotechnology generated by nature itself. “In addition to being strong and lightweight, nanocellulose is also a renewable, biodegradable, and completely natural material. It is a ‘treasure’ that has remained hidden in the structures of plants and other living beings, and thanks to current research, it is being transformed into a very valuable resource,” notes the scientist from the Institute of Carboquímica (ICB).

After a brief overview of the foundations of nanoscience and nanotechnology, the new book in the "What Do We Know About?" series focuses on "nature as the largest and best producer of nanomaterials." To illustrate this, it uses examples such as magnetotactic bacteria, which are capable of generating magnetic nanoparticles within themselves to navigate using the Earth's magnetic field. It then describes the characteristics of cellulose and its industrial uses before delving into all the nanotechnological advances made possible by the nanocellulose derived from it: from being a tool for the sustainable processing of other materials to solving major challenges in areas as important as energy, the environment, food processing, and biomedicine.

Nanomaterials Hidden in Plants

Cellulose is the main component of plants, especially stems, trunks, and woody parts, and is also present in bacteria, fungi, algae, and even some animals. “It is a biopolymer formed by the repetitive bonding of glucose molecules, and its morphology appears very simple, but when we analyze it in detail, we can find crystalline nanostructures with exceptional properties,” the author points out.

If we look at the most basic structure of cellulose, when the first polymerized glucose chains try to intertwine to form more ordered fibers, two situations can occur: the chains can pack themselves tightly, compactly, and regularly, or they can fail to organize themselves in any specific way and remain jumbled or tangled. In fact, both situations coexist within a single cellulose fiber.

“When the cellulose skein is separated through physical or chemical treatments, a lightweight, resistant, and moldable nanostructure emerges called a cellulose nanofiber, composed of fibers 10–100 nanometers (nm) in diameter and several microns in length,” the researcher explains. “When we isolate the most compact and perfectly ordered areas, small crystalline ‘chips’ called cellulose nanocrystals appear,” he adds. These tiny, needle-shaped structures, measuring between 5-20 nm in diameter and 100-300 nm in length, have mechanical strength similar to titanium or aluminum.

In addition to plant nanomaterials, there is also bacterial nanocellulose. “Through a complex machinery of proteins, enzymes, and biological catalysts, bacteria generate cellulose nanofibers that intertwine, trapping water inside,” the researcher explains. In this way, bacterial cellulose forms a gelatinous film and exhibits excellent physical and chemical properties.

A Real Alternative to Plastic

In the case of food packaging and protective coatings, the need to replace single-use plastics is urgent, and nanocellulose is emerging as an ecological and functional alternative for the development of biodegradable, compostable, and recyclable food preservation materials. Nanocellulose-based films exhibit tensile strength, low oxygen permeability, and high transparency, making them ideal for applications requiring contact with food. “Furthermore, their oxygen-rich surface allows for chemical modifications that improve moisture resistance or incorporate active functionalities such as antioxidants, antimicrobials, or freshness sensors,” notes the ICB scientist.

In addition to all these advantages, the scalability of nanocellulose production from agricultural waste, recycled paper, or the activity of microorganisms reinforces its economic and environmental viability.

Nanocellulose in the Service of Health

Another major area of application for this nanomaterial is in the biomedical field. Jose Miguel González emphasizes that nanocellulose is an ideal nanomaterial for interacting with biological systems and environments, since “its biocompatibility, water retention capacity, sterilizability, and porous structure facilitate cell adhesion and tissue regeneration in a safe and functional manner.”

Examples of nanocellulose use in medicine are as diverse as they are surprising: they act as a three-dimensional scaffold to support cell growth for bone, cartilage, or skin regeneration, and are used to release bioactive compounds in a controlled manner.

Furthermore, its ability to form thin, transparent films makes it useful in smart dressings that monitor the condition of a wound or release medication based on external stimuli, a development that “is transforming wound treatment because, among other qualities, nanocellulose dressings are non-toxic, improve tissue development during reconstitution, and, with specific modifications, can also have antimicrobial activity,” explains the author. “Bacterial nanocellulose has been found to improve the treatment of skin burns by cooling the surface through evaporation and facilitating healing without requiring frequent dressing changes,” he adds.

Degradable Electronic Devices

Although cellulose lacks sufficient conductivity, electronics can also benefit from its use. “Being lightweight, transparent, and chemically stable, it is ideal for substrates in displays, printed circuit boards, and wearable sensors,” notes the CSIC researcher. Although “if there is one star application in the field of electronic devices or energy storage, it is ephemeral electronics, based on the use of materials and devices that degrade in a controlled manner without leaving harmful residues.”

Another major application is related to water treatment and analysis. “At the Institute of Carboquímica, in collaboration with the Metropolitan Technological University of Chile and the University of Almería, we are investigating an electrochemical sensor for the rapid, sensitive, and environmentally friendly detection of sulfamethoxazole, an antibiotic classified as a contaminant of emerging concern, in water,” the scientist explains.

The nanotechnology horizon of cellulose is as diverse as it is promising, but almost all of these applications are in the experimental phase, at the laboratory scale. In any case, the researcher emphasizes that the plastics, medical, and electronics sectors account for a large part of current nanocellulose research and represent strategic areas for the ecological transition. “The convergence of sustainability, functionality, and technological innovation makes nanocellulose a key material for the future, capable of transforming entire industries and contributing to the UN Sustainable Development Goals,” he concludes.

Nanocellulose is number 175 in the What Do We Know About? collection (CSIC-Catarata). To request interviews with the author or for more information, please contact: comunicacion@csic.es (+34 91 568 14 77).

About the author

José Miguel González Domínguez is a tenured scientist at the Spanish National Research Council (CSIC) at the Institute of Carboquímica (ICB-CSIC) in Zaragoza. He has been developing his research career since 2007 in the field of carbon nanostructure chemistry. Since 2018, he has focused on emerging nanomaterials from nature, such as nanocellulose and nanochitin, achieving a more biocompatible and environmentally friendly nanotechnology. He created the educational initiative INCLUCIENCIA, coordinates the Scientific Outreach and Communication Unit of the ICB-CSIC, and belongs to the Inclusive Science working group of the Deputy Vice-Presidency for Scientific Culture and Citizen Science of the CSIC. He was designated by the International Union of Pure and Applied Chemistry (IUPAC) as one of the most representative young chemists worldwide, awarding him the element Carbon in its periodic table of young chemists.