Facile synthesis of gold nanorod-decorated silk fibroin spheres with enhanced NIR-sensitive photo-thermal activity

Abstract

Novel gold nanorod-decorated silk fibroin (SF@GNR) spheres were synthesized through in situ decoration of gold nanorod (GNRs) on silk fibroin (SF) spheres. SF spheres were synthesized by freezing and deforesting the SF/ethanol solution and then incubated in GNR suspension at the concentration of 0–0.4 mg/mL to produce SF@GNR spheres. Microstructure and photo-thermal activity of the resultant SF@GNR spheres were evaluated. SEM and TEM observations revealed that the SF@GNR spheres were spherical in shape with the diameter of 1068 ± 98 nm. Their surface was decorated with lots of GNRs. XRD patterns showed that SF@GNR spheres had the typical peaks at 38°, 44° and 64° for GNR components and 21° and 24° for SF components. The formation of SF@GNR spheres was mainly attributed to the electrostatic interaction between negatively charged SF spheres and positively charged GNRs. Under the irradiation of 808 nm-near-infrared (NIR) light, the temperature of the suspension of SF@GNR spheres was increased from 25 °C to 50 °C, indicating that the SF@GNR spheres were NIR-sensitive and showed the photo-thermal activity. Moreover, it was found that the photo-thermal activity of SF@GNR spheres were controllable by tuning length/width aspect ratio of GNRs and concentration of GNRs in the staring system.