Synthesis of Hollow Gold Nanoparticles - Impact of Variables on Process Optimization

Hollow gold nanoparticles (HAuNPs) are gold nanostructures with hollow interior. These particles have attracted a lot of interest due their excellent physicochemical and optical properties and their potential applications in diagnostics, sensing, imaging and assisting in tumor tracing and evaluating the effect of chemotherapy on tumor size, drug delivery and photothermal therapy. Sacrificial galvanic replacement using cobalt core is the most commonly used method for synthesis of HAuNPs. However, lack of reproducibility in synthesizing particles with desired surface plasmon resonance (SPR) is one of the major concerns for clinical application of these particles. In this work, we have identified and categorized various factors that could affect uniformity of cobalt core and subsequent formation of gold shell. Using slight modifications in the method, we have been able to synthesize HAuNPs with SPR in near infrared region at 808 nm with size of particles around 50-80 nm. HAuNPs can be further functionalized with suitable ligands like glutathione, polyethylene glycol, nucleic acids, sugars, fatty acids, proteins and peptides to promote enhanced permeability and retention in cancer cells and thus can serve as potential candidates in treatment of cancer.