Water’s Reactive Properties
[Alaina Rumrill] Dr. Richard Zare delves into the remarkable potential applications of water droplets in the realm of chemistry, highlighting their unique properties and reactivity. By focusing on water in its droplet form, Dr. Zare capitalizes on its inherently reactive nature, driven by the dynamic interplay between its hydrophilic core and hydrophobic exterior [1]. Within these small droplets, a fascinating phenomenon emerges—the formation of an electric double layer at the interfaces. This configuration results in the separation of charges across the droplet’s surface, generating an electric field [1]. This electric field plays a pivotal role in a process known as contact electrification, where static charges accumulate upon the interaction of two materials [2]. Specifically, the electric field within water droplets facilitates contact electrification by facilitating the removal of a proton from water, yielding the highly reactive hydroxyl radical OH- [1]. Dr. Zare underscores the pivotal role of hydroxyl radicals in environmental cleanup, emphasizing their significance in purifying our atmosphere. Moreover, beyond its electric properties, water’s inherent reactivity stems from its expansive surface area, enabling extensive interactions between water molecules and other substances [1]. Essentially, the increased contact area enhances the likelihood of chemical reactions.
Nitrogen Fixation
One of Dr. Richard Zare’s most significant advancements utilizing water droplets involves nitrogen fixation, a process pivotal for agricultural productivity and sustainability. To comprehend this innovation, it’s crucial to grasp the conventional method known as the Haber-Bosch process, pioneered in the 20th century by German chemists Fritz Haber and Carl Bosch [1]. This process revolutionized agriculture by enabling the mass production of ammonia from nitrogen and hydrogen, effectively fueling global food production [3]. However, the Haber-Bosch process is notorious for its energy-intensive nature, currently accounting for approximately 2% of the world’s energy consumption [1]. Moreover, its reliance on vast amounts of fossil fuels contributes substantially to greenhouse gas emissions [1].
In contrast, Dr. Zare’s approach to nitrogen fixation offers a shift in sustainability. By taking nitrogen from the air and combining it with water droplets at room temperature, Dr. Zare bypasses the need for electricity, light, photochemistry, or electrochemistry typically associated with conventional methods [1]. This micro-scale reaction holds promise for scalability, presenting the potential to revolutionize nitrogen fixation on a global scale. Not only does Dr. Zare’s eco-friendly approach mitigate environmental impact, but it also offers a pathway towards sustainable agriculture, paving the way for a greener, more efficient future.
Tissue Imaging
Dr. Richard Zare introduces a project that could revolutionize the way we understand and diagnose diseases through his groundbreaking work on using water droplets for tissue imaging. By sending droplets and splattering them off a tissue surface, then intercepting the resultant splash with a mass spectrometer, researchers can determine the chemical composition of the tissue [1]. This technique allows for the identification of all the chemicals dissolved within the droplets, providing valuable insights into the molecular makeup of the tissue [1]. By manipulating the size of the droplets and moving the droplet source around, researchers can rasterize the tissue and generate a chemical map. This map serves as a diagnostic tool, revealing areas of sickness, as well as distinguishing between cancerous and benign regions within the tissue [1].
Setting his approach apart is its reliance on artificial intelligence. By leveraging AI algorithms to analyze the complex chemical data obtained from tissue imaging, Dr. Zare’s team can identify intricate patterns within the molecular landscape [1]. Rather than relying on single biomarkers, this approach utilizes a multitude of biomarkers arranged in distinct patterns [1]. By training the computer with examples of both healthy and diseased tissue, the AI can learn to recognize these patterns and accurately identify new tissue samples. When analyzing the chemical composition of fluids such as sweat, urine, and saliva, his team can glean valuable insights into an individual’s health status [1]. This non-invasive approach has the potential to revolutionize personalized medicine, allowing for early detection and monitoring of various diseases. saliva analysis can detect oral cancer, while urine analysis can indicate the presence of bladder cancer [1]. Such breakthroughs underscore the transformative power of chemistry in advancing medical diagnostics and treatment.
Evidence for Life on Mars
The question of whether there is life on Mars has long captivated the imagination of scientists and the public alike. Dr. Zare’s journey into the realm of Martian exploration began with a meticulous examination of organic molecules preserved within meteorites. Employing a sophisticated laser technique, he illuminated the meteorites with an infrared laser, rapidly heating them to evaporate molecules without decomposition. A second laser, operating in the ultraviolet spectrum, ionized these molecules, allowing a mass spectrometer to analyze their mass-to-charge ratios and identify their chemical composition [1].
What Dr. Zare discovered within these meteorites was truly groundbreaking. Not only did the organic molecules exhibit isotopic compositions distinct from those found on Earth, but they also contained polycyclic aromatic hydrocarbons (PAHs) – compounds often associated with biological activity [1]. The Martian meteorite named ALH 84001 was discovered in Antarctica and sent to Dr. Zare by NASA [1]. The results of his analysis, published in the prestigious journal Science under the title “Search for past life on Mars: possible relic biogenic activity in Martian meteorite ALH 84001,” sparked intense scientific debate [1]. While the question of life on Mars remains open, Dr. Richard Zare’s pioneering research has significantly advanced our understanding of this enigmatic planet.
Learn More
If you’d like to hear more about Dr. Richard Zare’s journey and his research on water droplets, visit us on Spotify, Apple Podcasts, and many other streaming services to listen to our ChemTalk Podcast with Dr. Richard Zare, a Marguerite Blake Wilber Professor of Natural Science and a Professor of Chemistry at Stanford University.
Find the ChemTalk podcast here.
Works Cited
[1] Zare, Richard. Personal Interview. Conducted by Olivia Lambertson and Yeongseo Son. 12 August 2023.
[2] Zhang, Hang, Sankaran Sundaresan, and Michael A. Webb. “Thermodynamic Driving Forces in Contact Electrification between Polymeric Materials.” Nature News, March 23, 2024. https://www.nature.com/articles/s41467-024-46932-2#:~:text=Contact%20electrification%2C%20or%20contact%20charging,contact%20charging%20remains%20poorly%20understood.
[3] “Haber-Bosch Process.” Haber-Bosch Process – an overview | ScienceDirect Topics. https://www.sciencedirect.com/topics/engineering/haber-bosch-process.