Biomaterials can do almost everything petroleum-based materials can. But one of their weaknesses remains water.
Certain biomaterials quickly degrade in moist conditions. This restricts their roll-out in applications like food packaging and building construction, which demand protection and durability.
To solve this, researchers have been developing new biomaterials that withstand humidity and moisture.
Some of these materials are not just water-resistant but water-responsive. This means they alter their properties when moist and, in some cases, get stronger.
Here are the water-responsive biomaterials that could ramp up biobased performance and drive wider industry adoption.
Shape-shifting proteins
Inside living organisms, materials are constantly changing in response to their environment. Think of how your pores open when it’s warm or how your skin hairs contract when it’s cold.
Can we build biomaterials with this shape-shifting capability? Researchers at CUNY have demonstrated that they can.
In 2026, they published a biomaterial they constructed in the lab. Made of proteins called peptides, it changes structure dramatically when ambient humidity changes, resulting in a harder or softer material.
The researchers made the biomaterial using the peptides leucine and isoleucine, then combined them in solution. By slowly removing excess water, the peptides formed a solid, porous material with a stiff 3D honeycomb structure. When the structure lost more water, it became softer.
This movement from solid to soft was reversible. The team could switch the material’s state multiple times without it losing strength. In other words, the material was stable and strong, but also adaptable.
“These are not small tweaks or gentle breathing motions,” said Vignesh Athiyarath, the first author of the research paper. “The material completely reorganises how its molecules are packed.”
According to the researchers, their concept could be useful for products like food packaging that need to restrict humidity. They could also be used as smart structural materials or functional coatings.
Be like water
The CUNY research addresses a perennial problem in biomaterials, which is that they tend to be hydrophilic – they attract rather than repel water.
This water-attracting property in biomaterials is a a double-edged sword. On the one hand, their vulnerability to water is one of the things that makes them so readily biodegradable, even in natural environments.
However, hydrophilic properties can negatively impact performance. Water can weaken biobased packaging or coatings long before their product lifespan is over.
This can make it harder for biobased packaging to meet regulatory standards, especially for medical or food packaging, where contents must be sealed from the possibility of bacterial infection.
In developing their new peptide material, however, the CUNY researchers flipped this biobased weakness on its head: with some clever bio-engineering, water can actually be used to a biomaterial’s advantage.
What’s important about the peptide material is that it actually puts water molecules in its surroundings to work.
The water itself becomes key to the materials structural integrity: they lodge inside the peptide structures, keeping them rigid. Water molecules are also the energy source which the peptides use to fuel their molecular re-organisations.
This CUNY innovation shows how water need not be an achilles heel for biobased materials. Water can also be integral to their construction, durability, and functionality.
Designing biomaterials to be water repellent may not be the only way towards more useful renewable materials. Instead, we can build water-responsive biomaterials, whose structures are neither weakened by moisture nor reject it outright, but actually use it to adapt to the demands of a changing environment.
Just add water
Spanish research labs have developed another material that changes properties depending on the moisture levels around it.
A team led by Javier G. Fernández at the Institute for Bioengineering of Catalonia showed it was possible to build a biomaterial that actually becomes stronger when wet.
Chitosan is the main material used here. This is a natural substance found throughout the animal world inside seashells and insect exoskeletons.
Although versatile and plastic-like, chitosan’s major flaw is that it is low on water resistance.
Yet Fernández’ team showed that enriching the chitosan with metal nickel makes the biomaterial grow stronger rather than weaker upon contact with water
Of course, the drawback of this new material is that it is laced with nickel – a potentially toxic compound – meaning that it is not safely biodegradable in natural environments.
However, the research does show that relatively simple tweaks to a biobased material can alter its properties dramatically – including strengthening it against the effects of water.
A bio-glue to plug leaks
Packaging is not the only area where biomaterials could benefit from water resistance. Adhesives are another important segment where materials must hold up under moist conditions.
One of the more recent breakthroughs in water-resistant bio-adhesives came in 2025, when Japanese and Chinese researchers published a new protein-based glue. What was special about the substance is that it sticks even when completely underwater.
Data science was fundamental to the research findings. The researchers combed a dataset of 24, 707 adhesive proteins, ranging across species in the domains of archaea, bacteria, eukaryotes, and viruses – even artificial proteins.
After selecting the most promising adhesive-producing species for further analysis, they used machine learning to formulate a brand new, superior-strength hydrogel.
Then came the practical tests. They used one of the hydrogel candidates to fix a rubber duck to a seaside rock, where it successfully withstood waves and tides. They also used the substance to plug a high-pressure leak at the base of a tap water pipe.
The research demonstrates the power of biology to inform biobased design and how petrochemicals need not be the only option when it comes to high performance materials.
Bioinspired water repellence
The food industry is always on the hunt to reduce costs and waste. The right sort of packaging is key to achieving both.
By keeping moisture and bacteria out, packaging can extend shelf life and cut losses during transit. Historically, the food industry has reached for oil-based plastics to do this. Yet their destructive impacts are fuelling a search for alternatives.
One way to achieve both biodegradability and water repellence is by looking to nature. The team around Professor Easan Sivaniah of Kyoto University found a way to make polymer materials white and water repellent without toxic chemicals.
The team found they can render ordinary materials white, as well as water repellent, by using very precise porous structures. These structures are engineered to interact with light in particular ways, reproducing the light-scattering behavior of foams found in nature.
The important thing about this tool is that it can brighten and water-proof a material without either titanium dioxide or PFAS – the toxic chemicals commonly used today to achieve those effects.
The advantage of using bio-inspired structures to achieve these effects, rather than particular chemicals, is that it removes the need to develop entirely new substances.
Instead, existing materials – including biomaterials – can be shaped in ways that achieve certain properties, including water repellence.
Highly evolved water resistance
Bio-inspired water resistance is a hot topic in biomaterials research today. Scientists are continually developing potential packaging material concepts that mimic how nature keeps moisture at bay.
One of these was published in July 2026 by researchers at the Engineering Research Center in St. Louis, the University of Missouri, and Texas A&M University. They reported on LEAFF, a biomaterial they developed that is both biodegradable and water resistant.
LEAFF is mostly composed of biomaterials that are already on the market – cellulose and polylactic acid PLA. Usually, these biomaterials tend to fall short on water resistance, limiting wider adoption in applications like packaging.
In LEAFF, however, the biomaterials are arranged to mimic the internal morphology of a plant leaf – a natural biodegradable surface that also functions as a water barrier.
Again, mimicking shapes found in nature creates an overall material with much more water resistance than if materials are deployed in their ordinary state. What a material is made from is less important, from a performance perspective, than how it is arranged.
Going beyond synthetics
Recent innovations in water-responsive biomaterials tackle one of the most serious barriers to biobased substitution: the tendency of renewable materials to degrade in moist conditions.
Commercial biomaterials that guard food, construction, and more from the ravages of moisture could drive higher biobased adoption through the commercial packaging and coatings industry.
The science of water-responsive materials shows us how biobased options can offer distinct advantages over synthetic chemicals. Usually, synthetic materials are fixed in their properties. Yet a responsive biomaterial can perform under different environments, adapting to multiple use cases, markets, and industries.
Water-responsive biomaterials are a prime example of renewable materials offering much more than simply mimicking synthetics. Rather, they are capable of unlocking new capabilities and efficiencies that are harder to achieve using synthetic feedstocks.
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