Nanomedicine targets endogenous copper ions for disease diagnosis and therapy

•Copper ion participates in many fundamental biological processes and its homeostasis needs strict regulation.•Nanoprobes can detect copper levels in real-time, on-site, and through systematic analysis.•Copper chelators/ionophores suffer from non-targeting ability, poor selectivity, and short half-life time.•Nanoagents can deplete copper ions to reshape copper homeostasis or release copper ions to kill abnormal cells.