Gene editing is an important genetic engineering technique that enables gene manipulation at the molecular level. It mainly relies on engineered nucleases of biological origin, whose precise functions cannot be replicated in any currently known abiotic artificial material. Here, we show that chiral cysteine-modified CdTe nanoparticles can specifically recognize and, following photonic excitation, cut at the restriction site GAT'ATC (' indicates the cut site) in double-stranded DNA exceeding 90 base pairs, mimicking a restriction endonuclease. Although photoinduced reactive oxygen species are found to be responsible for the cleavage activity, the sequence selectivity arises from the affinity between cysteine and the conformation of the specific DNA sequence, as confirmed by quantum-chemical calculations. In addition, we demonstrate non-enzymatic sequence-specific DNA incision in living cells and in vivo using these CdTe nanoparticles, which may help in the design of abiotic materials for gene editing and other biological applications.