TTK21 is an activator of the histone acetyltransferases CBP/p300. It activates CBP/p300 histone acetyltransferase activity in a concentration-dependent manner with a maximal effect at a concentration of 275 µM. TTK21 passes the blood–brain barrier, induces no toxicity, and reaches different brain parts when conjugated to glucose-based carbon nanosphere (CSP).