One-step synthesis of gold nanoparticles for catalysis and SERS applications using selectively dicarboxylated cellulose and hyaluronate

Properties and applications of gold nanoparticles (AuNPs) depend on their characteristics which are intrinsically connected to the reducing and capping agents used in their synthesis. Although polysaccharides are commonly used for Au salt reduction, the control over the result is often limited. Here, the selectively dicarboxylated cellulose (DCC) and hyaluronate (DCH) with adjustable composition and molecular weight are used for the first time as reducing and capping agents for AuNPs preparation in an environmental friendly one-step synthesis. Mechanism of reduction and structure-function relationships between the composition of oxidized poly-saccharides and properties of formed AuNPs are elucidated and the variances in the macromolecular architecture of dicarboxypolysaccharides are applied to guide the growth of AuNPs. While the homogenous structure and high density of carboxyl groups of fully-oxidized DCC induced isotropic growth of small and uniform AuNPs with good catalytic performance (d =-20 nm, TOF = 7.3 min(-1), k = 1.47 min(-1)), the lower stabilizing potential and slower reduction rates of the DCH induced the anisotropic growth of larger polyhedral -50 nm nanoparticles, which increased the Surface-Enhanced Raman Scattering efficacy (9x stronger Raman signals on average compared to AuDCC). The use of dicarboxypolysaccharides with adjustable composition and properties thus introduced a new degree of freedom for the preparation of AuNPs with desired properties.

Automated summary

The properties and applications of gold nanoparticles are influenced by the reducing and capping agents used in their synthesis. In this study, selectively dicarboxylated cellulose and hyaluronate were used as environmentally friendly reducing and capping agents for gold nanoparticle preparation. The research revealed the mechanism of reduction and the structure-function relationships between the composition of polysaccharides and the properties of gold nanoparticles. The results showed that different polysaccharide structures and properties can guide the growth of gold nanoparticles with desired properties.