Researchers at North Carolina State University have harnessed inspiration from the ingenious tactics of small birds’ nest-building processes to develop an eco-friendly and cost-effective method for developing cellulose gels. This freeze-thaw technique is not only straightforward but also holds promise for creating cellulose gels that find application in diverse fields, including the development of timed drug delivery systems. What’s more, this process is suitable to bamboo and other plant fibers containing lignin. Cellulose stands out as a versatile material in the production of hydrogels, indispensable in various applications, from contact lenses to wound care and drug delivery. However, the usual methods for creating hydrogels from cellulose often involve the use of toxic processes. Usually, making cellulose-based hydrogels requires dissolving cellulose and then forming the desired structure. This often involves using difficult, unstable, or unsafe chemicals. As Lucian Lucia, a professor at NC State, points out, “Normally, you have to first dissolve the cellulose and then induce it to crosslink or form the structure of interest, which often requires the use of difficult to handle, unstable, or toxic solvents.”

Little swift, Apus affinis, at Kruger National Park, South Africa, crop

In a stroke of biomimicry, the researchers drew inspiration from the Swift family of birds, known for employing their saliva as a natural adhesive to bind twigs together during nest construction. The saliva encourages the fibers in the nest to interconnect, a phenomenon they sought to replicate with dissolved cellulose for crafting hydrogels. The process involved using water-soluble cellulose, specifically carboxymethyl cellulose (CMC), into an acid solution, which was then dissolved. Powdered cellulose fiber was introduced to the solution, which was then subjected to four rounds of freezing and thawing, resulting in the creation of a cellulose gel. Lucia likened this process to adding a thickening agent to water, akin to thickening a pie filling. By adjusting the CMC’s pH, the water becomes thicker, making it act like glue. The successive freezing and thawing cycles cause the cellulose to compact and interweave, similar to the natural nest-building process of Swifts, but without the need for beaks and saliva. Freeze-drying the gels further led to the production of cellulose foam. The researchers successfully replicated this process using bamboo fibers, suggesting its potential applicability to a wide range of lignin and cellulose-containing fibers. These cellulose gels exhibit resilience and stability at room temperature and can be altered to degrade as needed, making them well-suited for a range of applications, including drug delivery. This approach offers an environmentally friendly means of processing otherwise insoluble cellulosic materials, harnessing the principles of biomimicry. This research has been documented in the journal Advanced Composites and Hybrid Materials, with Noureddine Abidi from Texas Tech University serving as a co-corresponding author. This article on developing eco-friendly cellulose gels using biomimicry in the nest-building process of Swift birds connects to the topics learned in AP Biology. In AP Biology, macromolecules are an essential topic that is studied, and cellulose, the substance examined in the article, is a complex carbohydrate (polysaccharide) that is one of the primary structural components of plant cell walls. It is composed of long chains of glucose molecules that link together to create a tough and rigid structure. This rigid structural integrity of plant cell walls or cellulose is what scientists sought to use to create an adaptable and compatible gel for scientific/medicinal use. After discovering the intriguing properties of cellulose based gels and there potential variety of uses in the medical field, Im left wondering about the potential evolution of cellulose utilization. Did you learn anything new about cellulose and its amazing properties?


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