Stable gold nanoflowers modified by zwitterionic sulfhydryl sulfobetaine for enhanced antitumor efficiency

Gold nanoflowers are flower-like gold nanoparticles with high photothermal conversion efficiency. Unfortunately, many gold nanoflowers have complicated synthesis methods using toxicity molecules and lack colloidal stability. In this work, in order to improve the long-term colloidal stability of existing gold nanoflowers, sulfhydryl sulfobetaine (SB-SH) was modified on the surface of gold nanoflowers by S-Au bonds to produce SB-SH stabilized gold nanoflowers (SB-SH@AuNFs). SB-SH@AuNFs did not generate any precipitation within 24 h and had a high photothermal conversion efficiency at 38.9%. In addition, the relative cell viability of A549 cells was only 11% with 0.193 mM SB-SH@AuNFs under laser irradiation. More importantly, SB-SH@AuNFs had the best antitumor effect in vivo under 808 nm laser irradiation. Thus, stable SB-SH@AuNFs with high photothermal conversion efficient were synthesized by using zwitterionic molecules. The modification of gold nanoflowers using zwitterionic molecules here is a new method to improve the antitumor efficiency of noble metal photothermal agents.