Synthesis and Determination Extinction Coefficient of Gold Nanoparticles with Different Sizes and Different Capping Ligands

Extinction coefficients of gold nanoparticles with different sizes were determined by Zetasizer particle analyser and UV–vis absorption spectroscopic measurement. Four different types of gold nanoparticles were prepared and studied: citrate-stabilized nanoparticles in two different sizes; ionic liquid-protected gold nanoparticles and CTABprotected gold nanoparticles. A linear relationship between the logarithms of extinction coefficients and core diameters of gold particles was found independent of the capping ligands on the particle surface. This linear relation may be used as a calibration curve to determine the concentration or average size of an unknown nanoparticle or nanoparticle– biomolecule conjugate sample.

Keywords:

Gold nanoparticles , Extinction coefficient , Zetasizer , CTAB , Ionic liquid