LAUSR

Gold nanoparticles (GNPs) and their conjugates are widely used as labels in bioanalytical methods. One of the main characteristics that determine their unique plasmon properties is their size. In this work, the growth of bare and protein-modified (with streptavidin) GNPs in the presence of hydrogen tetrachloroaurate and hydroxylamine was studied. Three initial preparations of GNPs with average diameters of 30.5 ± 7.7, 19.2 ± 1.6, and 4.4 ± 0.6 nm were obtained. An increase in size of GNPs at different initial particle sizes, reagent concentrations, presence/absence of protein coating was characterized using the methods of optical spectrophotometry, dynamic laser light scattering and transmission electron microscopy. The presence of sorbed proteins was shown to reduce the growth rate and affect the morphology of the forming nanoparticles. The conditions (1–10 mM hydroxylamine, 30 mM hydrogen tetrachloroaurate) that ensure the maximum increase in the size of GNPs (up to ≈70 nm) and their conjugates in homogeneous systems without the formation of unstable aggregates were determined.