Gold Nanoparticles Coated with Silica Shells as High-Performance Fluorescence Nanoprobe

Traditional methods of decorating silica shells with gold nanoparticles (Au NPs) have problems with being time-consuming (usually over 10 h) and easy agglomeration. An ultrasonic–polymer collaborative-assisted synthesis method is presented in this article for the preparation of monodisperse gold nanoparticles decorated with controlled SiO2 shells (Au NPs@SiO2). Mercaptan-based poly(ethylene glycol) (SH-PEG) was used to modify Au NPs to improve dispersibility. Then, an ultrasound technique was introduced to accelerate the formation of Au NPs@SiO2 with superior monodispersity within 2 h. Controlling the SiO2 shell thickness (7.2–31.1 nm) can be accomplished by changing the injection of tetraethyl orthosilicate (TEOS) during the synthesis process. An ultrasonic–polymer collaborative-assisted synthesis approach is proposed for the rapid and precise synthesis of monodisperse Au NPs@SiO2 nanoparticles with controllable shell thicknesses. In addition, a fluorescence nanoprobe with an adjustable shell Au NPs@SiO2 was constructed, resulting in a strong enhancement factor of 17 717. Moreover, 29 mg of Au NPs@SiO2 can be synthesized at once (generally less than 10 mg). This method will improve the synthesis of core–shell-structured nanomaterials and promote their application in the biomedical field.