Abstract: In this work，we employed Graphene quantum dots（GQDs）as a carrier loading two RNA⁃cleaving Deoxyribonuclease（DNAzymes）to explore their activities at molecular and cellular levels. The two DNAzymes were designed and synthesized based on the mRNA of TNF⁃α（TNF⁃DNAzyme1 and TNF⁃DNAzyme2）. We demonstrated that the TNF⁃DNAzymes／GQDs conjugates were stable in solution，and the catalytic activity of the DNAzymes remained in the presence of GQDs. The expression level of TNF⁃α in Hela cells was significantly decreased after the incubation with TNF⁃DNAzymes and GQDs. In contrast，the expression level of TNF⁃α in Hela cells was barely changed after the incubation with TNF⁃DNAzymes alone，which indicated that GQDs could be used as a carrier to deliver TNF⁃DNAzymes into cells，thus the activity of TNF⁃DNAzymes in cellular level could be greatly improved. Based on the control experiments，we inferred that the improved activity of DNAzymes could be due to their improved stability with GQDs. However，we could not rule out which caused by the higher accumulation of DNAzymes in the cells or other mechanisms

Key words: DNAzyme, graphene quantum dots, stability, TNF?α