Gold nanorods (GNRs) are small particles whose surface plasmon resonance (SPR) frequencies can be altered by modifying their length and width, giving them properties useful in a host of applications, including diagnostics, optical biomedical imaging, and photothermal therapies, to name a few. One of the major barriers in the application of GNR-based materials, however, especially for in-vivo applications such as hyperthermal cancer treatment, is the presence of cetyltrimethylammonium bromide (CTAB), a cytotoxic, cationic surfactant used exclusively in the large scale synthesis of GNRs. CTAB attacks and kills cells in the body in 2 ways: by creating nanoscale holes within affected cell membranes and depriving cells of energy, ultimately killing the cell in both cases.

The concentration of CTAB that is most often used in the synthesis of gold nanorods is typically 100 times its critical concentration, meaning a significant amount of CTAB remains in the bulk of the solution after the GNRs are made. A number of methods have been used to “remove” or partially exchange the CTAB, however, these surface modified GNRs are often still contaminated with residual CTAB.

For GNRs to be safely and more readily integrated into in vivo applications, removal of CTAB is essential. This is where Sona’s patented technology comes in. Our revolutionary process of GNR synthesis completely eliminates CTAB from the equation all together!