Drug attachment is important in drug delivery for cancer chemotherapy. The elucidation of the release mechanism and biological behavior of a drug is essential for the design of delivery systems. Here, we used a hydrazone bond or an amide bond to attach an anticancer drug, doxorubicin (Dox), to gold nanoparticles (GNPs) and compared the effects of the chemical bond on the anticancer activities of the resulting Dox-GNPs. The drug release efficiency, cytotoxicity, subcellular distribution, and cell apoptosis of hydrazone-linked HDox-GNPs and amide-linked SDox-GNPs were evaluated in several cancer cells. HDox-GNPs exhibited greater potency for drug delivery via triggered release comediated by acidic pH and glutathione (GSH) than SDox-GNPs triggered by GSH alone. Dox released from HDox-GNPs was released in lysosomes and exerted its drug activity by entering the nuclei. Dox from SDox-GNPs was mainly localized in lysosomes, significantly reducing its efficacy against cancer cells. In addition, in vivo studies in tumor-bearing mice demonstrated that HDox-GNPs and SDox-GNPs both accumulate in tumor tissue. However, only HDox-GNPs enhanced inhibition of subcutaneous tumor growth. This study demonstrates that HDox-GNPs display significant advantages in drug release and antitumor efficacy.
Keywords: anticancer activity; doxorubicin; drug delivery; gold nanoparticle.