An Eco-Friendly Detergent Made From Wood Fibers and Corn Protein

Most commercial detergents you use in your home contain a powerful cocktail of grease- and stain-fighting chemicals. Some of these primary detergent components include surfactants, which allow water to better penetrate fabrics; enzymes, which can help speed up stain-fighting chemical reactions; alkalis, which help emulsify grease and oils; and other washing aids such as water softeners, optical brighteners, and preservatives. While these chemicals help keep our clothes, dishes, and living spaces clean, they cause great environmental harm, both during their manufacturing process and upon their release into the wider environment via wastewater. In particular, the release of phosphates has been linked to the eutrophication of water bodies¹—causing accelerated algal growth, oxygen depletion, and damage to fragile ecosystems—and many areas of the world have either banned their use in detergents entirely or placed heavy restrictions on its inclusion.

There is a clear need for green, safe, and efficient detergents, but the only natural cleaning agents currently on the market are plant-derived surfactants. Although these may have greener credentials, they also have low productivity, high manufacturing costs, and can destroy more delicate fabrics like wool or silk.² Cellulose nanocrystals extracted and sustainably processed from wood, cotton, or bacterial cellulose have been identified as an excellent eco-friendly alternative.³ These are solid colloidal particles, which means they form what is called a Pickering emulsion⁴—and research has shown that natural starch granules can play an essential role in the cleansing process, influencing the oil–water interface.⁵

Pickering emulsions use only solid particles as stabilizers, which accumulate at the oil–water interface to create a physical barrier that prevents droplets from coalescing.⁶ This is the most notable difference between Pickering and classical emulsions, which are stabilized by molecular surfactants. The solid particles require a balanced wettability (hydrophilicity/hydrophobicity) to adsorb irreversibly at the oil–water interface, which is what drives the superior stability. These emulsions have attracted attention due to their low cost, minimal environmental impact, and enhanced stability. The science suggests that Pickering particles might be able to remove a variety of everyday surface stains, but few studies have explored the effectiveness on different surfaces.

Now, new work published in Langmuir investigates combining Zein (a class of protein found in the endosperm of maize corns) with cellulose nanofibers from wood to create a potential eco-friendly cleaning agent based on the Pickering effect.⁷

The rationale is that positively charged Zein is an effective hydrophobic modifier for cellulose, and applying it to the cellulose nanofiber surface should ideally strengthen the interaction with the oil–water interface and enhance the stability of the Pickering emulsion. The researchers tested the solution against deposits of ink, ketchup, and chili oil on various substrates such as cotton, glass, stainless steel, ceramic, and plastic plates. The zein/cellulose detergent demonstrated superior washing ability compared to traditional detergent powder for the removal of the dirt from all materials tested. Additionally, the zein/cellulose detergent left no residue on cotton fabric during testing. The authors report that these results show that this natural detergent could one day be a green, cost-effective alternative to traditional commercial cleaning agents.

Further Explorations: Pickering Emulsions

Understanding how Pickering emulsions behave over time can be useful for improving the stability of many consumer goods such as cosmetics, foods, and pharmaceuticals. In a 2024 study also published in Langmuir, researchers wanted to better understand the stability of cellulose nanofiber Pickering emulsions over one month’s time.⁸ They used fast low-angle shot (FLASH) and rapid acquisition with relaxation enhancement (RARE) MRI sequences to capture the separation of four different Pickering emulsions into free oil, the emulsion layer, and the serum layer—and the distribution of flocculated/coalesced oil droplets. The images provided excellent visualization, showing that the droplets started to clump together and merge (coalescence) around one month after emulsification. They also showed that the speed at which the molecules moved was affected by both the type of oil used and the concentration of the cellulose nanofibers.

Such colloidal systems might also be useful in very specific cleaning scenarios, such as for artwork. In another work in ACS Applied Polymer Materials, a team in Italy set out to create a cleaning gel that could remove hydrophobic contaminants from artwork surfaces without using harmful solvents.⁹ They created a Pickering emulsion gel using a seaweed-derived biopolymer, halloysite clay nanotubes, and isooctane. The researchers found that the gel was able to completely remove a hydrophobic contaminant commonly found on artwork in just two minutes. They also tested the emulsion gel on a real oil painting from a private collection, further confirmed that it offers a promising alternative to toxic solvents typically used for art restoration.

Pickering emulsions have other applications beyond cleaning. For example, they could one day be used to create more sustainable cosmetic products and reduce the strain on global water resources. Previous research has explored the structuration of highly concentrated oil–water emulsions solely stabilized by particles—a form referred to as high internal phase Pickering emulsions (HIPPEs).¹⁰ This has shown that meticulously selecting particle parameters, including chemical composition, size, and origin, allows chemists to tailor the HIPPE architecture to achieve a set of desired characteristics and functionalities.

There’s evidence that Pickering emulsions could also be used in food processing, specifically as enzymatic catalytic systems. A 2025 review in ACS Food Science & Technology explores this idea in detail, with a focus on Pickering-assisted catalysis and Pickering interfacial catalysis.¹¹ Finally, Pickering emulsions could also be useful as drug delivery systems, since they can encapsulate a wide variety of cargo materials.¹² Additionally, the unique surface chemistry of stabilizer nanoparticles induces attachment with cell membranes, allowing these nanoemulsions to effectively deliver drugs directly into the cytosol of cells.

As evidenced by these recent studies, Pickering emulsions are showing great promise in a variety of fields, opening new possibilities in cleaning products, cosmetics, food processing, pharmaceuticals, and beyond. As scientists continue to explore and refine these techniques, we can hope to see even more innovative and sustainable applications in the future.

References

1. Li, B. et al. Chlorella-Based Biohybrid Microrobot for Removing Both Nutrient and Microalgae toward Efficient Water Eutrophication Treatment. Nano Lett. 2025, 25, 1, 48–55.
2. Cortez, J. et al. Transglutaminase treatment of wool fabrics leads to resistance to detergent damage. Journal of Biotechnology 2005, 116, 4, 379-386.
3. Fournier, R. et al. Apparent Failures in Interpretation of Interfacial Characterization When Formulating Emulsions Stabilized by Cellulose Nanocrystals. Langmuir 2023, 39, 39, 13921–13931.
4. Pinto, R. T. et al. Oil Recovery Improvements Based on Pickering Emulsions Stabilized by Cellulose Nanoparticles and Their Underlying Mechanisms: A Review. ACS Omega 2025, 10, 4, 3262–3281.
5. Lian, X. et al. Natural Rice Starch Granules for Green Cleaning. Langmuir 2019, 35, 40, 13157–13164.
6. Yang, J. et al. An Overview of Pickering Emulsions: Solid-Particle Materials, Classification, Morphology, and Applications. Front Pharmacol. 2017, 8, 287.
7. Liu, W. et al. Physical Cross-Linking of Cellulose Nanofibrils with Zein Particles as an Eco-Friendly Detergent. Langmuir 2025, 41, 8, 5147–5157.
8. Kanai, N. et al. Evaluating the Stability of Cellulose Nanofiber Pickering Emulsions Using MRI and Relaxometry. Langmuir 2023, 39, 11, 3905–3913.
9. D’Agostino, G. et al. Pickering Emulsion Gel Based on Funori Biopolymer and Halloysite Nanotubes: A New Sustainable Material for the Cleaning of Artwork Surfaces. ACS Appl. Polym. Mater. 2024, 6, 13, 7679–7690.
10. Cafiero, M. et al. Natural-Based Microparticles as Sole Stabilizers of High Internal Phase Pickering Emulsions. ACS Omega 2025, 10, 5, 4534–4547.
11. Oñate Narciso, J. et al. Pickering Emulsions as Catalytic Systems in Food Applications. ACS Food Sci. Technol. 2025, 5, 1, 29–35.
12. Sahoo, R. et al. Vegetable Oil–Based Pickering Nanoemulsions As Carriers for Cytosolic Drug Delivery. ACS Appl. Nano Mater. 2024, 7, 13, 15702–15709.