Synthesis of less toxic gold nanorods by using dodecylethyldimethylammonium bromide as an alternative growth-directing surfactant.

Gold nanoparticles having a rod-like morphology are regularly investigated as potential nano-therapeutic materials owing to their interesting optical properties, facile surface modification, tunable aspect ratios, and low cytotoxicity. Gold nanorods are historically prepared starting from HAuCl4 in the presence of ascorbic acid, silver nitrate, and the growth directing surfactant, cetyltrimethylammonium bromide (CTAB). While CTAB drives a rod-like morphology, it is known to be cytotoxic. This inherent toxicity is often addressed by removing or masking the native CTAB surfactant present on the nanorod surface. In the current study we have investigated a less toxic alternative surfactant, dodecylethyldimethylammonium bromide (C12EDMAB), as a possible growth-directing agent. Monodisperse gold nanorods having various lengths have been grown in the presence of C12EDMAB. SEM data suggests that the quantity of C12EDMAB on the rod's surface is much higher than that of CTAB. Toxicity assays were performed on HEp-2 and A549 cells showing lower toxicity at select concentrations for C12EDMAB coated rods.