There’s a question most people are too afraid to ask: why can’t we eat grass? Well technically, you can eat grass (it just won’t digest). The answer to what’s stopping humanity from a fresh, ample food source is actually quite simple—cellulose. Found in vegetation ranging from trees to fruits, cellulose is the most abundant biopolymer.
Cellulose’s linear chain of glucose molecules collects into microfibrils that form the main structure of plant tissue (1). These dense fibrils—made from beta acetal linkages—make it difficult for humans to digest cellulose, as we lack the necessary enzymes that break down beta acetal linkages. However, small amounts of cellulose found in foliage such as vegetables can pass straight through the digestive tract intact (6).
So we can’t eat it, but that doesn’t necessarily mean cellulose is fruitless. Scientists use cellulose to make everyday items such as paper and wood products, and even explosives. Nitrocellulose, the main ingredient in smokeless gunpowder, is made by treating cellulose with sulfuric and nitric acids, which then decomposes explosively (7).
Nitrocellulose is also being studied as a tool for the characterization and examination of DNA-protein interactions. Understanding DNA-protein interactions is vital, as the breakdown of transcription regulation relates to a variety of different diseases. In the past, biochemical assays—an in-vitro procedure to study the activity of a biological molecule—have been used to characterize these DNA-protein interactions, with sub-par results (8,9). However, the use of the nitrocellulose filter binding assay allows for fast manipulations for kinetic studies (8).
From an environmental standpoint, cellulose has the potential for fuel production as an abundant biomass. A recent study published this past January revealed that cellulose can be converted into Methylcyclopentadiene (MCPD)—a monomer important for the production of rocket fuel and in the creation of products such as medicines and gasoline (2). The study outlines a method that produces a direct synthesis of renewable MCPD from cellulose using the hydrogenolysis of cellulose and selective hydrodeoxygenation of 3-methylcyclopent-2-enone (MCP) to MCPD (2). While MCPD is currently produced using the byproducts of petroleum cracking tar, this method has a low yield and high cost. On the other hand, cellulose provides the advantages of being CO2-free, easily available, and renewable.
However, cellulose applications don’t just stop there. Certain bacteria, the most prominent species being Komagataeibacter xylinus, are able to produce their own cellulose, which has its own, advantageous properties. Compared with plant cellulose, bacterial cellulose (BC) exhibits high amounts of flexibility, water holding capacity, moldability, and hydrophilicity—making it extremely helpful in different facets of medicine ranging from engineering artificial skin to implants for cartilage repair (3).
In terms of wound dressing, the first commercially available product based on BC is Biofill. The Biofill product is used as a temporary skin substitute in the treatment of ailments such as basal cell carcinoma and chronic ulcers. In studies, Biofill was associated with pain relief and reduced treatment times, yet also limited elasticity. Since then, other wound dressing products based on BC have been introduced in clinical practice (3).
Similarly, BC can be effective as a dressing to deliver antiseptics. Antiseptics are used to combat biofilm-based infections for chronic wounds through the application of a dressing chemisorbed with antimicrobials. According to a study conducted this year, when compared to a control sample of silver dressing, dressings made of BC chemisorbed with certain molecules exhibited a similar or higher ability to combat biofilm compared to the control sample (4).
Other recent developments in the utilization of BC include BC-based hydrogel as a drug delivery system and biomaterial scaffolds for tumor cell culture and cancer treatment. That being said, BC still has a long way to go in terms of practical application. As of now, most applications of BC are purely experimental, requiring further, long-term research for clinical situations (5).
While the potential of cellulose within the scientific community is glaringly prevalent, its true scope remains unclear. However, its current exploration shines a spotlight on how we can study and harness the organic structures Nature has meticulously curated.