Cationic liposomes enable shape control in surfactant-free synthesis of biocompatible gold nanorods

• Main Authors: Gudlur, Sushanth, Goyal, Garima, Pradhan, Arpan, Ho, James Chin Shing, Srivastava, Rohit, Liedberg, Bo
• Other Authors: School of Materials Science and Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Science::Chemistry::Inorganic chemistry::Synthesis; Science::Chemistry::Inorganic chemistry::Metals; Nanorod; Gold
• Online Access: https://hdl.handle.net/10356/151931
• Institution: Nanyang Technological University

Shape-directing agents that promote anisotropic growth are frequently employed in the synthesis of gold nanorods (GNRs), a typical example of which is the surfactant cetyltrimethylammonium bromide (CTAB). Owing to their cytotoxicity, surfactant-passivated GNRs have little use in biological applications unless made biocompatible via additional downstream processing. Reported herein is the first instance of liposome-directed anisotropic growth of GNRs synthesized in the absence of surfactants. The as-synthesized phospholipid-passivated GNRs are readily biocompatible. Among the phospholipids tested, only liposomes prepared from 1,2-dioleoyl-sn-glycero-3-ethylphosphocholine (DOEPC) - a cationic transfection agent employed in lipid-mediated gene transfer in vitro - were capable of exerting shape control. By modifying a previously reported photochemical synthesis method, we developed a one-pot, seedless, DOEPC-mediated thermochemical synthesis method that yielded GNRs with an average size of 80-100 nm and an average aspect ratio of ∼3.5 and whose tips shape transformed from smooth to sharp during the course of the synthesis. Further characterization of the as-synthesized phospholipid-passivated GNRs confirmed its stability, excellent biocompatibility, photothermal transduction ability, and application in plasmonic photothermal therapy which was validated via GNR-mediated photothermal ablation of cancer cells in vitro, thus making this route of synthesis attractive for biological applications.