Many of us may think of a cell membrane as the structure that holds a cell together, creating a building block of life. To Wei Zhou, however, it can also be a barrier to understanding what lies within.

Zhou, an assistant professor in the Bradley Department of Electrical and Computer Engineering, seeks to help scientists understand the physical and chemical processes inside living cells. 

He is building tools and processes on the nanometer level — smaller than the width of a strand of hair — to peek beneath the cell membrane. Understanding the activities and signals inside a living cell is key to understanding disease and improving medical diagnoses and therapies, he said.

Zhou received a Young Investigator Award from the U.S. Air Force Office of Scientific Research to develop a nanoscale multimodal transducer — a miniature device that takes advantage of optical and electrical properties at the nanometer level — to monitor and control the biological processes unfolding inside a living cell. 

Combining fields at the nano level

Because of the distinct natures of electrons and photons, the operation and design rules of the device’s nanoelectronic and nanophotonic components are totally different. They are products of separate fields with long, established histories, explained Zhou, who specializes in both.

“Unsurprisingly, there is very limited research on hybrid electrical-optical nanodevices for interfacing with biological systems,” said Zhou.

A key innovation for his project is something called the plasmonic nano-optoelectrode, a device that gains access to the cell to sense biomolecular fingerprints, and detect and adjust local bioelectrical activities.

“This technology will go beyond the capability of purely electrical or purely optical methods,” said Zhou. “No existing device has the ability to measure and modulate both optical and electrical signals in the same nanoscale location at the same time.” 

A prototype of culture multiwell plates integrated with nanoscale multimodal transducers for real-time monitoring of living cells.

Overcoming the cell membrane barrier 

Before the nanodevices can interface with the cell, they need to slip inside it. Zhou will equip them with a way to create a “side door” from which they can observe activity or send signals in a controlled and minimally invasive manner. 

By converting light into heat, the device can generate a miniscule vapor bubble to open a nano-sized hole on the cell’s membrane. 

By slipping into the bubble, the device can be internalized into the cell itself, where it will perform its electrical and optical duties. 

“Establishing a reliable intracellular interface between living cells and external materials or devices can lead to significant opportunities not only for cell studies, but also for health-care diagnosis and therapy,” said Zhou.

Nanoantenna and nanoelectrode

Once inside, the device will gather information about real-time biochemical signals within the cell and map the bioelectrical activity that provides communication, processing, and coordination throughout large networks of cells. 

Measuring drug response

When the nanoscale multimodal transducer is operational, Zhou and his team plan to monitor and study the correlation between bioelectrical and biochemical activities of cells in response to drugs. Among others, they plan to study the effects of norepinephrine, because it can function in the heart and brain as a hormone and neurotransmitter.

Written by Kelly Izlar