Preparation of Gold Nanoparticles Using Polysaccharide Dialdehydes and Study of Their Catalytic Activity

Gold nanoparticles (AuNPs) find application in various areas depending on their properties, shape and size distribution, which are mainly influenced by the preparation conditions. Moreover, due to the trend in recent years, toxic reducing and stabilizing agents are being abandoned during the synthesis of AuNPs, and alternative substances for one-pot green synthesis are being sought. Examples of such substances are polysaccharides, which are non-toxic, biocompatible, and biodegradable. In addition, they have the advantage that they can serve as reducing and stabilizing agents simultaneously during the reaction. Nevertheless, polysaccharides are structurally highly diverse compounds with a wide range of molecular weights and often non-stoichiometric composition. By selective oxidation of polysaccharides, these problems can be at least partially eliminated, and we can control the molecular weight, degree of oxidation and overall resulting properties of polysaccharides. Therefore, our work focused on preparing gold nanoparticles using the dialdehyde polysaccharides, specifically dialdehyde dextran (DADXA), dialdehyde hyaluronan (DAH), dialdehyde cellulose (DAC) and dialdehyde alginate (DAAL). After synthesis, the AuNPs were characterized, and their catalytic efficiency was tested on the reduction of 4-nitrophenol to 4-aminophenol. According to the study, all samples were found to be suitable catalysts for this reaction, with the best results obtained for AuDADXA, with initial TOF 37.1 min(-1) and k = 0.78 min(-1).