Gold Decoration on Palladium Barley Stripe Mosaic Virus Biotemplate: Implications for Drug Delivery Applications

Barley stripe mosaic virus (BSMV) is a promising biotemplate for the mineralization of metal–organic nanorods. Biomineralization of palladium occurs without an external reducing agent; however, the reduction of gold on wild-type BSMV requires a reducing agent. Recently, histidine has been adopted as a capping and reducing agent for the mineralization of gold nanoparticles. BSMV virus-like particles (BSMV-VLPs) tagged with histidine were investigated for direct gold deposition. However, gold nanoparticles were not formed during the mineralization process. Therefore, the aim of this research was to decorate gold nanoparticles onto palladium-coated BSMV (Pd-BSMV). The gold decoration was achieved through the addition of free histidine. X-ray absorption spectroscopy and energy-dispersive X-ray spectroscopy were used to verify the formation of metallic gold, and a kinetic study of the gold decoration process and the pH effect on the morphologies of gold particles was performed. The development of gold-decorated Pd-BSMV will be crucial for therapeutic applications, such as drug delivery, gene therapy, and photothermal therapy.