Washington State University scientists have created a powerful artificial enzyme using single-atom architecture with potential applications for medicine, food safety and agriculture.

Enzymes are produced naturally by organisms to help cells perform basic functions like turning food to energy. But, natural enzymes degrade easily and deactivate over time. Scientists have been trying to develop artificial enzymes that can mimic the natural versions but last longer. One kind of artificial enzyme, called a nanozyme, is made from nanostructured materials.

Now, WSU Research Professor Dan (Annie) Du from the School of Mechanical and Materials Engineering has led a group of researchers in creating a nanozyme consisting of single iron atoms embedded in nitrogen-doped carbon nanotubes. Detailed in the journal Small, the team has solved a longstanding problem with nanozymes – their inability to match the catalytic activity of natural enzymes.

The WSU team, which included Nan Cheng, Jin-Cheng Li, Dong Liu and Yuehe Lin, found that the newly-discovered, single-atom nanozyme offers high catalytic activity matching that of natural enzymes, along with a highly enzyme-like chemical nature that makes it an excellent candidate for biosensing.

Closeup of Annie Du
Dan (Annie) Du

“The nanozyme we created faithfully mimics the behavior of peroxidases, a large group of enzymes which play an important role in the bioassays,” Du said.

The team was able to generate more active catalytic sites within the structure of the nanozyme, bringing its catalytic activity closer to that of a natural enzyme. The higher activity means that it also has better sensitivity and detection ability.

“Due to the improved enzyme-like activity, the nanozyme-based biosensor can sensitively detect a specific molecule like hydrogen peroxide, giving it the potential to be used for long-term continuous monitoring of hydrogen peroxide and other biological agents,” Cheng said.

The single-atom technology they used also results in much better stability. Such nanozymes could be used for a long time in harsh environments where natural enzymes deactivate rapidly.

“In the food and beverage industry, these materials could be used to detect pesticide residues and dangerous pathogens like E. coli,” Du said.

The team is working on using a single-atom nanozyme to build smartphone-based biosensors for on-site rapid detection of pesticides and food pathogens. Such nanozymes potentially can also be used as a medicine for cancer therapy and antibiotics application, she added.

Compared to natural enzymes, the new single-atom nanozyme would also be less expensive, more sensitive and could be stored for long periods of time, according to Du.

This work is supported by the USDA National Institute of Food and Agriculture, AFRI project (2018-67021-27970).