Scientists at CSIR-Central Leather Research Institute (CLRI), Chennai, have created a new artificial enzyme that could significantly improve how energy is managed within cells. The enzyme, called Cu-Phen, is a metallo-nanozyme designed to mimic natural enzymes by regulating electron transfer—a key process in cellular energy production. While nanozymes have been gaining interest for their potential in medicine, energy, and environmental solutions, many current versions face a major drawback: their lack of control over electron flow. This can result in the production of toxic byproducts like reactive oxygen species (ROS), which may lead to cellular damage and reduced ATP (energy) production. To address this, Dr. Amit Vernekar and his Ph.D. student, Adarsh Fatrekar, developed Cu-Phen using a “catalyst-by-design” approach. The nanozyme is made by coordinating copper ions (Cu²?) with phenylalanine, an amino acid, creating a structured assembly with a clearly defined active site. This structure helps ensure precise electron flow, similar to how natural enzymes work inside cells. Cu-Phen interacts specifically with cytochrome c, a protein central to the electron transport chain in cells. The nanozyme binds in a receptor-ligand fashion and uses a unique mechanism called proton-coupled electron transfer to efficiently reduce oxygen into water—avoiding the creation of harmful ROS in the process. These findings, recently published in the Journal of Materials Chemistry A, highlight the importance of active site design in the development of next-generation nanozymes. With better control over electron transfer, these artificial enzymes could play a key role in sustainable energy, medical innovations, and bio-compatible technologies. The study opens new doors for nanozyme research, showing how carefully engineered catalysts can seamlessly integrate into biological systems and safely enhance energy pathways.