Nanochemistry and biotechnology 

Formation of gold colloids with tunable size of nanoparticles
Mukha Iu.1, Vityuk N.1, Rusinchuk N.2, Lozovski V.2, Lokshyn M.3, Lysenko V.3 
1 O.O. Chuiko Institute of Surface Chemistry, NAS of Ukraine, Kyiv, Ukraine.    
E-mail: iu.mukha@gmail.com 
2 Institute of High Technologies, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
3 V.E. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Kyiv, Ukraine.  

Gold nanoparticles (Au NPs) have found a broad application in different areas, particularly in medical practice ‒ for drug delivery, biomolecular imaging, diagnostics and therapy of various diseases. The therapeutic and possible toxic effects of nanosized gold are one of the main topics in modern nanoscience. The activity of Au NPs strongly depends on the size and association of particles in colloid. In its turn, the morphology and stability of Au NPs are greatly affected by experimental approaches and parameters of the reaction. Even classical procedure of obtaining of Au NPs like “citrate method” can be a challenge.
In the present work we applied different experimental approaches to affect the process of gold nanoparticles formation. While accurate size of nanoparticles can be measured in electron microscope, dynamic light scattering (DLS) method is suitable for the investigation of hydrodynamic diameter and the whole size distribution of nanoparticles in Au NPs colloid. Comparative analyses of UV-vis spectra with DLS data by number, volume and intensity basis allow us to trace the changes in Au NPs colloid.
We performed a comparative UV-vis and DLS analyses on series of Au NPs stabilized via the electrostatic factor that was provided by sodium citrate or amino acid tryptophan. Gold nanoparticles were obtained by chemical and photochemical methods using different experimental procedures and varying the ratio of reagents, their concentrations, temperature of reaction, duration of heating, the order of introduction of reagents into the reaction mixture, pH and so on. Optimal conditions were found to produce Au NPs with tunable size and prolonged stability. 

This work was supported by National Research Foundation of Ukraine, Project 2020.02/0352.