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Phospholipid stabilized gold nanorods: Towards improved colloidal stability and biocompatibility


Biocompatible and colloidally stable gold nanorods (GNRs) of well-defined plasmonic properties are essential for biomedical and theranostic applications. The as-synthesized GNRs in the seed-mediated method is stabilized by cetyltrimethylammonium bromide (CTAB) surfactant, which is known for its cytotoxicity in many cell lines. Biocompatible GNRs synthesized from known protocols exhibit some extent of cytotoxicity and colloidal instability because of incomplete removal of CTAB. We report a facile method for the efficient removal of CTAB molecules with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) phospholipids, which are naturally present in cell membranes. The ligand exchange kinetics is studied using surface-enhanced Raman scattering (SERS) and corroborated with matrix assisted laser desorption/ionization (MALDI) mass spectrometry. From colloidal stability studies using dynamic light scattering (DLS) and UV-Vis spectroscopy, the optimal lipid concentration and duration required for successful ligand exchange of CTAB by DMPC are reported. Using thermogravimetric analysis, the surface concentration of DMPC on colloidally stable GNRs is found to be approximately 9 molecules per nm2. The 3-(4,5-dimethylthiozol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays show that the surface modified DMPC-GNRs have significantly better biocompatibility compared to CTAB-GNRs. Studies on ligand exchange, colloidal stability and biocompatibility of DMPC-GNRs of aspect ratios in the range of 2.2 - 4.2 demonstrate the robustness of the proposed method. The results provide insight on the important factors to be considered to design biocompatible GNRs suitable for applications in nanomedicine.

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Publication details

The article was received on 21 May 2017, accepted on 19 Jun 2017 and first published on 19 Jun 2017

Article type: Paper
DOI: 10.1039/C7CP03403B
Citation: Phys. Chem. Chem. Phys., 2017, Accepted Manuscript
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    Phospholipid stabilized gold nanorods: Towards improved colloidal stability and biocompatibility

    P. B. Santhosh, N. Thomas, S. Sudhakar, A. Chadha and E. Mani, Phys. Chem. Chem. Phys., 2017, Accepted Manuscript , DOI: 10.1039/C7CP03403B

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