DEVELOPMENT OF A METHOD FOR THE SYNTHESIS OF PLASMONIC GOLD NANOPARTICLES FOR A WIDE SPECTRAL REGION 520-720 nm

A method of the synthesis of plasmon gold nanoparticles by the reduction of HAuCl4 with organic reductants, such as formalin, sodium citrate and hydroquinone has been studied. It is shown that, depending on the concentration of the reagents, the temperature of synthesis and the type of the reducing agent, the position of the maximum of the plasmon band varies in a wide range from 520 nm to 720 nm. A one-stage method using hydroquinone as a reducing agent for the synthesis of long-wave plasmonic gold nanoparticles that form agglomerates of smaller particles with a plasmon absorption band in the red region of the spectrum is proposed. Since the resulting sol is rapidly precipitated due to the aggregation processes, it has been found necessary to use stabilizers for its subsequent application. The influence of some stabilizers (gelatin, as well as surface-active substances polydimethyldiallylammonium chloride and cetyltrimethylammonium bromid) on the stability of the gold sol synthesized by the hydroquinone method has been studied. It is shown that all the types of investigated stabilizers even in a minimal quantity provide the colloidal stability of the sol for several hours. However, only a natural polymer, gelatin, stabilizes the sol so that the maximum absorption of the plasmon band remains in the long-wavelength region of the spectrum