Aliquat 336 stabilized multi-faceted gold nanoparticles with minimal ligand density

Using Methyltrioctylammonium chloride (Aliquat 336) as a shaping and stabilizing agent for the first time, quasi-spherical and multi-faceted gold (Au) nanoparticles (NPs) are synthesized via seed mediated protocol. These slightly elongated NPs devoid of any centre of symmetry are found to possess some twin defects on their surfaces as confirmed by TEM analysis. Their Surface plasmon resonance band is evidenced at 534 nm. The growth progression is examined through the formation of translational Au NPs during the reaction. Such Aliquat 336 stabilized NPs are demonstrated to achieve minimal ligand density. This is attributed to the formation of hexagonally patterned self-assembled monolayer of ligand molecules over the surface of Au NPs. TGA and DLS experiments are performed to quantify the ligand density on the surface of these multi-faceted Au NPs. EDX, FTIR, and XPS measurements are accomplished to determine the structure and binding of ligand molecules to Au surface. Further, these NPs are found to be luminescent with violet emission under an excitation at 320 nm. The admirable features of the results suggest that our method may constitute a basis for the facile synthesis of functionalized and luminescent multi-faceted Au NPs with minimal ligand density, potential for sundry biomedical applications.