Dynamic assembly of DNA-ceria nanocomplex in living cells generates artificial peroxisome.

Intracellular accumulation of reactive oxygen species (ROS) leads to oxidative stress, which is closely associated with many diseases. Introducing artificial organelles to ROS-imbalanced cells is a promising solution, but this route requires nanoscale particles for efficient cell uptake and micro-scale particles for long-term cell retention, which meets a dilemma. Herein, we report a deoxyribonucleic acid (DNA)-ceria nanocomplex-based dynamic assembly system to realize the intracellular in-situ construction of artificial peroxisomes (AP). The DNA-ceria nanocomplex is synthesized from branched DNA with i-motif structure that responds to the acidic lysosomal environment, triggering transformation from the nanoscale into bulk-scale AP. The initial nanoscale of the nanocomplex facilitates cellular uptake, and the bulk-scale of AP supports cellular retention. AP exhibits enzyme-like catalysis activities, serving as ROS eliminator, scavenging ROS by decomposing H 2 O 2 into O 2 and H 2 O. In living cells, AP efficiently regulates intracellular ROS level and resists GSH consumption, preventing cells from redox dyshomeostasis. With the protection of AP, cytoskeleton integrity, mitochondrial membrane potential, calcium concentration and ATPase activity are maintained under oxidative stress, and thus the energy of cell migration is preserved. As a result, AP inhibits cell apoptosis, reducing cell mortality through ROS elimination.