Light Generates Cellular Energy... Korean Researchers Develop Artificial Cell Organelle [Reading Science]

UNIST-POSTECH Joint Study: Near-Infrared Light Regulates ATP Production
Confirms Changes in Artificial Cell Shape and Improved Cell Survival in Tissue Models

A technology has been developed that uses light to produce cellular energy molecules and, in turn, change the shape of artificial cells. In tissue models exposed to oxidative stress, the technology also restored energy levels and increased cell survival rates. It is expected to be used in developing artificial tissues whose energy supply can be regulated with light.

Ulsan National Institute of Science and Technology (UNIST) said on November 5 that a research team led by Professor Cho Yoonkyung of its Department of Biomedical Engineering had developed an artificial cell organelle, called PNO (Plasmonic Nano-Organelle), that responds to light by producing adenosine triphosphate (ATP), in collaboration with a research team led by Professor Lee Insoo of the Department of Chemistry at Pohang University of Science and Technology (POSTECH).

PNO, developed by the research team, is an artificial cell organelle that absorbs light to produce ATP, the cell's energy molecule. Image generated by the research team using AI.

ATP is an energy molecule that cells use to move, change shape, and repair damaged areas. In actual cells, organelles such as mitochondria use energy obtained from nutrients to produce ATP. The research team replicated this energy-producing function in an artificial structure and enabled its activity to be controlled by shining light on it from outside.

Light as the Switch, Glucose as the Fuel... ATP Production

The PNO developed by the research team consists of gold-platinum nanostructures wrapped in an Escherichia coli-derived membrane containing ATP synthase. When exposed to light, the gold-platinum nanostructures promote chemical reactions, while ATP synthase uses the resulting difference in hydrogen ion concentration to produce ATP.

When PNO is placed in a solution containing glucose and oxygen and exposed to near-infrared light, the gold-platinum nanostructures promote a reaction between the glucose and oxygen, generating hydrogen ions. As hydrogen ions build up inside the membrane, a concentration difference develops across it. The hydrogen ions then pass through ATP synthase, producing ATP.

Structure and operating principle of PNO, an artificial organelle that produces ATP using light (left), and an actual electron micrograph (right). PNO, made by wrapping gold and platinum nanostructures in a biologically derived membrane, produces ATP using the difference in acidity across the membrane when exposed to near-infrared light. The scale bar in the electron micrograph represents 50 nm. The schematic is not drawn to scale. Provided by the research team.

The process works much like using the difference in water levels at a dam to turn a waterwheel. Light acts as the switch that starts energy production, while glucose serves as the fuel.

The research team created artificial cells containing PNO and actin proteins to verify that the system worked. Actin is a protein involved in cell shape and movement. When the artificial cells were exposed to light, actin assembled into long fibers using ATP produced by the PNO. These fibers pushed against the cell membrane, changing the shape of the artificial cells.

When the light was turned off, the artificial cells returned to a nearly round shape. The team also confirmed that their shape could be changed repeatedly by turning the light on and off.

ATP Restored to 84% in Oxidative Stress Tissue Model

The research team also created a three-dimensional tissue model by embedding living muscle precursor cells and PNO in alginate gel. Exposure to near-infrared light increased the formation of actin fibers inside the cells, and the tissue model became about 1.9 times stiffer than before exposure. The energy produced by the artificial cell organelles thus led to a change in the tissue model's physical properties.

The technology also showed an effect in an oxidative stress environment, where cells are prone to damage. After supplying glucose to tissue models subjected to oxidative stress and exposing them to near-infrared light, the team found that ATP levels in models containing PNO recovered to about 84% of their pre-stress levels. In the control group without PNO, ATP levels remained at about 22%.

Under the same conditions, the cell survival rate in tissue models containing PNO was about twice that of the control group. The result shows that externally supplied artificial cell organelles can supplement energy production and help cells survive in an oxidative stress environment.

Research team photo. From left: Professor Cho Yoonkyung, Dr. Sumit Kumar, and Dr. Mamata Karmacharya. Photo courtesy of UNIST.

However, this study involved experiments using artificial cells and three-dimensional tissue models; it did not demonstrate that the technology can treat damage to actual living tissue or restore its function. Further validation of its stability in living organisms and long-term performance is needed.

"For artificial cells to function like actual living cells, it is important to have technology that can regulate energy supply at the right time and place," said Cho Yoonkyung, a professor at UNIST. "We expect this technology to help develop artificial tissues whose shapes and properties change in response to light, and to study how cells use energy."

This study was supported by the Ministry of Science and ICT and the National Research Foundation of Korea. The findings were published in the international journal Advanced Materials on September 29.

This content was produced with the assistance of AI translation services.