Evaluating Phospholipid-Functionalized Gold Nanorods for in vivo Applications

Gold nanorods (AuNRs) have attracted a great deal of attention due to their potential for use in a wide range of biomedical applications. However, their production typically requires the use of the relatively toxic cationic surfactant cetyltrimethylammonium bromide (CTAB) leading to continued demand for protocols to detoxify them for in vivo applications. In this study, a robust and facile protocol for the displacement of CTAB from the surface of AuNRs using phospholipids is presented. After the displacement, CTAB was not detectable by NMR spectroscopy, SERS, or using pH-dependent ζ-potential measurements. The phospholipid functionalized AuNRs demonstrated superior stability and biocompatibility (IC50 > 200 μg⋅mL−1) compared to both CTAB and polyelectrolyte functionalized AuNRs and were well tolerated in vivo. Furthermore, they have high NIR absorbance and produce large amounts of heat under NIR illumination, hence such particles are well suited for plasmonic medical applications.