From ocean bubbles to life-saving nanomedicines: Feng manipulates soft materials via interfacial dynamics
Now an assistant professor in MechSE, Feng is working on understanding multi-phase transport phenomena to interpret the impact of bubble dynamics in nature. His research also works toward producing advanced nanomaterials for energy, environmental remediation, and nanomedicines, with specific applications such as more efficient delivery of water-insoluble drug molecules via nanoencapsulation.
While studying bubble dynamics for his PhD, Feng specifically looked at bubbles forming and bursting in an oil-water-air interface, such as an oil spill in the ocean. When bubbles form at the surface level, they encapsulate particles of oil and bio matter. As the bubbles grow, move, and burst, they can mix these particles and send them into flow beneath the surface.
“In oceans, these small pockets might be easily digested by the biological train, so you could have a positive effect or a negative effect,” Feng said of the dispersion of bio matter and oil molecules. “Essentially, there is an unrealized form of mass transport behind such a phenomenon.”
Applying this approach could play an important role in many industrial mixing systems. For one, the method of bubbling to produce nanoemulsions uses much less energy than traditional mixers, making it cheaper and more efficient. This discovery directly connects to Feng’s other research platform—using a novel micromixer for production of nanoparticles through flash nanoprecipitation.Flash nanoprecipitation stabilizes insoluble compounds through rapid mixing, often finishing with a drying process that leaves molecules encapsulated in nanoparticles with a surface coating. The mixing process involves using turbulent dynamics to control the multi-phase mixing, and Feng has designed mixers that will allow the final output to be scalable.
“We can scale up without changing the size or properties of the final product,” he said. “I can increase the production rate of these nanoparticles without affecting their properties.”
As a post-doctoral research associate at Princeton University, Feng wanted to make the production of nanomedicines more efficient for controlled release, targeting infectious diseases like malaria and Cryptosporidium that are prevalent in developing countries. Currently, pills that contain water-insoluble drugs are still taken with water to aid digestion in the body. However, the hydrophobic properties of the drug mean that absorption is less efficient, and a more robust regimen of pills is necessary to get the full dosage.
The more efficiently a drug can be absorbed into the body from a single pill, the fewer pills a patient would require. Encapsulating into nanoparticles is a strategy that ensures efficient delivery and bioavailability enhancement of the hydrophobic drug molecules. In developing countries where medicine is not as easily attained, the “less is more” adage can increase the likelihood that patients will receive their required dose.
“If I can engineer nanoparticles, then when they reach the intestinal fluid, the drug molecules can be released with a much higher solubility,” Feng said. “I can use this nanoparticle engineering to significantly increase the solubility of the drug and enhance its absorption.”
He has already begun experimenting with flash nanoprecipitation and spray drying to create powdered nanoparticles that encapsulate drug molecules. Because of his scalable technique, he is able to ensure a homogeneous mixture every time, whether the scale of output is in milligrams or kilograms. He is able to complete this process in his lab, the Fluids, Interfaces, and Nano-Therapeutics (FIT) Laboratory.
His lab focuses on fundamental flow physics and chemistry for micro-scale manipulation of soft materials, with broad categories of research within these topics: energy and the environment, and human health. Feng hopes to further investigate ultrafine aerosol particle generation associated with collective micro-scale bubble dynamics for air quality modeling, as well as the mechanisms and dynamics of how nanoparticles are delivered into the human body—for instance, how to deliver nanoparticles of medicine to the body through aerosols that go directly to the lungs.
“I want to study how the flow physics, such as aerodynamics, will affect the delivery of these nanomedicines into the human body,” he said.
Feng received his bachelor’s and master’s degrees in energy and power engineering from Tsinghua University in China in 2009 and 2011 respectively, and his PhD in mechanical and aerospace engineering from Princeton University in 2016. He currently teaches TAM 333 (Introductory Fluid Mechanics).