Surface Chemistry Manipulation of Gold Nanorods Displays High Cellular Uptake In Vitro While Preserving Optical Properties for Bio-Imaging and Photo-Thermal Applications

Due to their anisotropic shape, gold nanorods (GNRs) possess a number of advantages for biosystem use, including enhanced surface area and tunable optical properties within the near infrared region (NIR). However, a combination of cetyltrimethylammonium bromide (CTAB) related cytotoxicity, overall poor cellular uptake following surface chemistry modifications and loss of NIR optical properties due to material intracellular aggregation remain as obstacles for nano-based biomedical GNR applications. The current report demonstrated that in vitro exposure to tannic acid (TA) coated 11 -mercaptoundecyl trimethylammonium bromide (MTAB) GNRs (MTAB-TA) in A549 human alveolar epithelial cells showed no significant decrease in cell viability or stress activation. In addition, MTAB-TA GNRs demonstrate a substantial level of cellular uptake while displaying a unique intracellular clustering pattern. This clustering pattern significantly reduces intracellular aggregation, pre serving the GNRs NIR optical properties, vital for biomedical applications. MTAB-TA GNRs demonstrated significantly greater two photon luminescence microscopy image intensity and photo-thermal cellular ablation compared to bare MTAB GNRs. These results demonstrate how TA surface chemistry modification enhances biocompatibility and allows for a high rate of internalization while preserving the GNRs NIR optical properties. These findings identify MTAB-TA GNRs as prime candidates for use in nano-based bio-imaging and photo-thermal applications. The original document contains color images.