Stabilization of metal nanoparticles in highly concentrated colloids

Abstract

Gold and silver nanoparticles (NPs) have a great potential in nanomedicine. For their use in biological studies there is a need to increase significantly the metal content (active substance) in the dose volume for the injection. Therefore, an urgent task is to find the experimental ways to prevent NPs aggregation in highly concentrated colloidal systems. In this work colloids of Ag NPs, Au NPs and AgAu NPs were prepared in the presence of amino acid as metal ion reducer and particle stabilizer. The polymer pluronic F68 was proposed to increase the stability of NPs and the experimental conditions for the long-term stabilization of colloidal systems with a metal content of 0.4-0.8 mg/ml were developed. It was shown that nanoparticles in all systems maintained nanodimensionality during and after the increasing metal concentration in colloids by 40 times, namely the average size of formed particles was around 10-20 nm. Their optical characteristics remained unchanged, namely, the maxima of the localized surface plasmon resonance band in the absorption spectra had typical position and were placed between 415 and 528 nm depending on molar ratio of metal in nanoparticle.