HEFEI, Oct. 18 (Xinhua) -- A new study from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences offers a new solution to one of agriculture's most persistent problems: pesticides that wash off crop leaves before they can do their job.
The study, published in the Journal of Controlled Release, drew inspiration from the tiny, hair-like structures that help bacteria cling to the human gut.
By mimicking this natural adhesion trick, the research team built rough-surfaced silica nanoparticles that grip leaf surfaces far better than conventional formulations, potentially cutting pesticide waste and reducing the need for repeated spraying.
According to the researchers, conventional pesticide spraying is remarkably inefficient. Leaf surfaces are coated in a waxy, water-repellent layer that causes spray droplets to bounce off. Rain washes away what does land, while sunlight and evaporation break down the active ingredients. Previous studies showed that as much as 90 percent of a pesticide may never reach its target, forcing farmers to spray again and again. This drives up costs and worsens pollution and ecological damage.
The research team turned to bacteria for the answer. Some gut bacteria have tiny, hair-like parts called pili. These pili work like little hooks. They grab onto surfaces so the bacteria don't get flushed away. The researchers copied this idea. They made tiny hollow silica particles and covered their surfaces with little spikes. Then they filled these particles with imidacloprid, a common insecticide.
Detailed analysis confirmed that when sprayed onto leaves, the spiky nanoparticles act just like bacterial pili. They dig into the waxy leaf surface and lock on, like tiny anchors. They also form hydrogen bonds -- weak chemical connections that work like tiny magnets -- which make the grip even stronger.
"This double grip helps the pesticide stay put, even in rain. The carriers also release the pesticide slowly and resist UV damage, making them even more efficient," said Wang Guozhong, a researcher at the institute.
The research team tested the new formulation on cotton, soybean and tomato leaves. After simulated rainfall, the amount of pesticide left on the leaves was more than 4.8 times higher than with a commercial imidacloprid product.
"Safety tests on plants and zebrafish showed no clear signs of harm, suggesting the new pesticide is environmentally friendly and could help pave the way for low-dose, high-efficiency, green pesticide products," Wang added. ■
