2024-08-08 03:51:20
Researchers from Dartmouth have developed a self-powered pump that utilizes natural light and chemistry to specifically target the removal of certain water pollutants, according to a new report in the journal Science.
Experimental setup for a light-activated pump developed by researchers at Dartmouth (center). The blue light on the right side of the filter indicates the filtration and capture of chlorides and bromides by synthetic molecules designed by the researchers for specific pollutants.
Ivan Aprahamian
When water enters the pump, a wavelength of light activates a synthetic molecular receptor that binds to negatively charged ions or anions, a class of pollutants associated with metabolic disorders in plants and animals. A second wavelength deactivates the receptors when the water leaves the pump, prompting them to release the pollutants and trap them in a non-reactive substrate until they can be safely disposed of.
“This is proof of concept that you can use a synthetic receptor to convert light energy into chemical potential to remove a pollutant from a waste source,” says the study’s lead author, Ivan Aprahamian, professor and chair of the Chemistry Department at Dartmouth.
The pump is currently calibrated for the pollutants chloride and bromide, but the researchers are working to extend its use to other anion-rich pollutants, Aprahamian says, such as radioactive waste and the phosphates and nitrates found in agricultural runoff that cause massive dead zones.
“Ideally, you could have multiple receptors in the same solution and activate them with different wavelengths of light,” says Aprahamian. “This way, you can capture and collect each of those anions individually.
The unusual ability of the synthetic receptor to both capture and release negatively charged molecules allowed the researchers to control the flow of chloride ions from a low concentration solution at one end of a U-shaped tube to a high concentration solution at the other end. Over a 12-hour period, the study reports, they moved 8% of the chloride ions against the concentration gradient through a membrane embedded with the synthetic receptors.
The researchers focused on chloride for two reasons. In winter, rainwater laden with road salt raises chloride levels in waterways, which is harmful to plants and animals. Secondly, the transport of chloride ions also plays a key role in the healthy functioning of cells. The disease cystic fibrosis is caused by cells’ inability to pump out excess chloride. The trapped ions lead to dehydration of the cells, resulting in a build-up of thick mucus, particularly in the lungs.
In absolute terms, the chloride ions were driven nearly 1.4 inches – the width of the membrane separating the two ends of the tube. Given the tiny size of the receptor, they covered an impressive distance, all with the aid of light. “That’s like kicking a soccer ball the length of 65,000 soccer fields,” says Aprahamian.
Aprahamian’s lab has long been working on a class of synthetic compounds known as hydrazones, which turn on and off in response to light. During the COVID pandemic, graduate student Baihao Shao came up with the idea to enhance the hydrazone receptor so that it could both capture and release target anions when switching on and off.
Aprahamian tried to dissuade him. “I told him that while this was a great idea, I didn’t think it could compete with the other impressive photo-switchable receptors in the literature,” he says. “Fortunately, Baihao ignored me and actually developed the receptor.”
The receptor can not only be controlled by a renewable energy source – light – but is also relatively easy to make and modify, Aprahamian notes. The researchers created the receptor by assembling it using “click chemistry,” a Nobel Prize-winning technique that chemist Barry Sharpless was involved in inventing years after his graduation from Dartmouth.
Another connection to the Nobel Prize: The study demonstrates the potential of molecular machines eight years after the 2016 Chemistry Nobel Prize was awarded to three chemists for their work in developing synthetic versions. Molecular machines are widespread in nature and are powered in animal cells by ATP and in plant cells by sunlight. In humans, tiny molecular machines perform much of the work that occurs in cells, from replicating DNA to transporting materials across the cell membrane.
For decades, scientists have been attempting to recreate these miniaturized workhorses outside of the body to use them for tasks such as environmental remediation, drug delivery, and the diagnosis and treatment of diseases. However, artificial molecular machines are easier to design on paper than to implement in practice.
“We want to mimic such biological processes and use sunlight as an energy source to create autonomous and self-sustaining filtration systems,” says Aprahamian.
Innovative Water Purification: The Future of Self-Activated Pump Technology
The recent development of a self-operated pump by researchers at Dartmouth presents a forward-thinking approach to addressing water contamination. This technology harnesses natural light and synthetic chemistry to target specific water pollutants, heralding a new era in environmental remediation.
Utilizing synthetic molecular receptors that react to different wavelengths of light, the pump enables selective removal of harmful anions, such as chloride and bromide, commonly associated with environmental degradation and health issues in flora and fauna. With the ongoing challenge of pollution from agricultural runoff and winter salting, the necessity for innovative filtration methods has never been more critical.
As researchers expand the application of this technology to encompass other anion-rich contaminants—including radioactive waste and harmful phosphates—there is immense potential for widespread environmental benefits. The prospects of fine-tuning multiple receptors within the same solution, activated by specific light wavelengths, could lead to a highly efficient and versatile system for water purification.
Significantly, the concept not only aims to address environmental recovery but also encapsulates the broader trends of utilizing renewable energy sources in technological applications. The potential for solar energy to power autonomous filtration systems aligns perfectly with global sustainability goals and advances in green chemistry.
Furthermore, this development symbolizes a burgeoning intersection between synthetic chemistry and molecular biology, paving the way for innovative applications beyond water purification. From pharmaceuticals to targeted disease treatment, the principles demonstrated through this research could inspire breakthroughs in varied fields, enhancing the capabilities of molecular machines for practical use in everyday life.
The growing focus on creating systems that mimic biological processes underlines an important shift in scientific research—working toward solutions that are not only effective but also sustainable and self-sufficient. As we advance, such technology could redefine our approach to environmental management, underscoring the importance of interdisciplinary collaboration.