What is an enzyme?

People may first think of proteins, nucleic acids and other catalytic biological active substances. Enzymes are involved in almost all life activities in the human body. The high catalytic efficiency of biological enzymes guarantees the rapid substance conversion and energy metabolism in the body all the time. For example, alcohol metabolism in human body mainly depends on alcohol dehydrogenase and acetaldehyde dehydrogenase two biological enzymes. Today we introduce "nanase", which will further expand the definition and scope of enzymes:

Inorganic nanoparticles can also be enzymes.

Like many great discoveries, the discovery of nanase began with a "failed" experiment. In order to apply nanotechnology to biomedicine, Yan Xiyin of the Institute of Biophysics, Chinese Academy of Sciences combined CD146 antibody labeled with horseradish peroxidase with ferric oxide nanoparticles to explore a new method of tumor diagnosis. Because of the horseradish peroxidase attached to the antibody, the substrate can be colored. The result, however, was a "weird" phenomenon: the negative control magnetic nanoparticles mysteriously reacted with the peroxidase substrate. After repeated verification and elimination of all factors that might affect the experimental results, it was finally shown that the ferric oxide nanoparticles do have properties similar to horseradish peroxidase, and thus the existence of nanase was discovered.

This research by Yan's team was published in Nature Nanotechnology in 2007 as the first systematic study of the enzymatic properties of inorganic nanomaterials from the perspective of enzymology. A review published in the Proceedings of the Royal Society of Chemistry described it as a landmark event in the history of enzymology. It can be said that the discovery of nanomases has blurred the boundary between inorganic materials and organic organisms, and promoted the integration of nano science and medicine.

Since the first discovery of nanase in 2007, 375 laboratories in 31 countries have published research results on nanase. Since 2019, the annual publication of nanase has exceeded 1000 papers, in 2020 more than 2500 papers, and in 2021 more than 4500 papers. A large number of nanomaterials such as metal nanoparticles, metal oxide nanoparticles, carbon-based nanomaterials and metal-organic frameworks have been shown to function like natural enzymes.

The appearance of nano-enzyme not only changes people's understanding of enzyme, but also provides broad application value. If studies have found that Prussian blue nanoparticles (PBNPs) have multi-enzyme activities such as POD, CAT and superoxide dismutase (SOD), and can effectively remove ROS. In addition, the researchers achieved targeted detection of antigens by labeling antibodies with ferric oxide nanomases, which have been developed into strips to detect pathogens such as influenza and Ebola viruses.

It is reported that the current research focus on seven aspects: self-assembled nanocapsules and drug delivery, carbon-based nanomaterials and bioimaging, nanoelectrochemical biosensors, peroxidase catalytic mechanism, iron based nanomases and immune detection, nanomases involved in chemiluminescence, cancer detection and tumor therapy. In the near future, nano-enzymes will make more contributions to human health, energy regeneration and environmental protection.