Activatable ultrasmall gold nanorods for theranostics in breast cancer cells

Abstract

Objective To develop a fluorescence signal activatable multifunctional molecular probe with theranostics function through combining ultrasmall gold nanorods(UGNRs) with fluorescein, and to evaluate its therapeutic effect on photothermal therapy (PTT) in breast cancer cells. Methods The UGNRs were synthesized by the one-pot seedless method, then the functionalized modification of UGNRs were conducted using cysteamine. Finally, the activatable ultrasmall gold nanorods (AUGNRs) were synthesized by amide condensation of -NH2 of cysteamine and -COOH of carboxylated fluorescein Cy5. The cell uptake ability and GSH-mediated imaging ability of AUGNRs were studied using breast cancer 4T1 cells. 4T1 cells co-cultured with AUGNRs were irradiated with 808 nm excitation light, and the PTT effects were assessed by MTT colorimetric staining and calcein-AM/PI staining. Results The AUGNRs were synthesized successfully, which could be uptaken by 4T1 cells quickly and efficiently, and could achieve intracellular glutathione (GSH) triggered fluorescence recovery. No obvious cytotoxicity of AUGNRs to 4T1 cells was observed in the co-cultivation. Moreover, obvious PTT effects could be induced by 808 nm laser, which could effectively kill 4T1 cancer cells. Conclusion The fluorescence signals of AUGNRs can be induced by intracellular GSH, and tumor cell destruction can be achieved by 808 laser-excitated PTT effects. Key words: Ultrasmall gold nanorods; Photothermal therapy; Fluorescence; Glutathione