High-yield synthesis of gold bipyramids for in vivo CT imaging and photothermal cancer therapy with enhanced thermal stability

Monodisperse gold bipyramids (AuBPs) with controlled aspect ratio and tunable surface plasmon resonance (SPR) property have been synthesized using cetyltrimethylammonium bromide (CTAB) and sodium oleate (NaOL). The morphological yield of AuBPs is about 90% without any purification step. The presence of NaOL plays an important role in promoting the morphological yield of AuBPs by pre-reduce Au3+ to Au+. The obtained AuBPs exhibit strong absorbance in the near infrared region (NIR) that can be systematically tuned from 740 nm to 960 nm. After functionalized with polyethylene glycol (PEG), the as-prepared AuBPs have shown excellent photothermal stability and great biocompatibility, which could be used for high contrast computed tomography (CT) imaging and photothermal cancer therapy. This work provides not only a simple method for the synthesis of AuBPs with high morphological yield, but also a promising theranostic agent for cancer therapy.