Synthesis of Ag@GQD and their application in photoacoustic imaging and chemical/photothermal combination therapy and bacteriostasis

Bacterial infections are closely associated with tumor growth and metastasis. Bacteriostasis can not only inhibit the growth and metastasis of tumors during their early diagnosis and treatment but also prevent bacterial infections after recovery. In this study, we synthesized Ag@GQD which consisted of nitrogen-doped graphene quantum dots (N-GQD) wrapped around Ag NPs through the photocatalytic reduction method. Multifunctional nanoprobes (Ag/DOX@GQD) were obtained by doxorubicin (DOX) loading. Ag@GQD exhibited high stability, low cytotoxicity, and good photoacoustic imaging performance. The effective photothermal performance of Ag@GQD enabled us to achieve the controlled release of DOX from probes using near-infrared light and pH response during the treatment of tumors using chemo-photothermal combination therapy. Results from cell-based experiments revealed that combination therapy was superior to single-drug therapy. Besides, Ag@GQD could effectively kill Staphylococcus aureus and Escherichia coli and can be expected to inhibit the growth and metastasis of tumors caused by bacteria and in reducing bacterial infections after recovery.