Gold-Embedded Hollow Silica Nanogolf Balls for Imaging and Photothermal Therapy

Hybrid nanocarriers with multifunctional properties have wide therapeutic and diagnostic applications. We have constructed hollow silica nanogolf balls (HGBs) and gold-embedded hollow silica nanogolf balls (Au@SiO₂ HGBs) using the layer-by-layer approach on a symmetric polystyrene (PS) Janus template; the template consists of smaller PS spheres attached to an oppositely charged large PS core. Potential measurement supports the electric force-based template-assisted synthesis mechanism. Electron microscopy, UV-vis, and near-infrared (NIR) spectroscopy show that HGBs or Au@SiO₂ HGBs are composed of a porous silica shell with an optional dense layer of gold nanoparticles embedded in the silica shell. To visualize their cellular uptake and imaging potential, Au@SiO₂ HGBs were loaded with quantum dots (QDs). Confocal fluorescent microscopy and atomic force microscopy imaging show reliable endocytosis of QD-loaded Au@SiO₂ HGBs in adherent HeLa cells and circulating red blood cells (RBCs). Surface-enhanced Raman spectroscopy of Au@SiO₂ HGBs in RBC cells show enhanced intensity of the Raman signal specific to the RBCs' membrane specific spectral markers. Au@SiO₂ HGBs show localized surface plasmon resonance and heat-induced HeLa cell death in the NIR range. These hybrid golf ball nanocarriers would have broad applications in personalized nanomedicine ranging from in vivo imaging to photothermal therapy.