Oligonucleoside assisted one pot synthesis and self-assembly of gold nanoparticles

A Nimrodh Ananth, Goutam Ghosh, S Umapathy and M A Jothi Rajan

Abstract

Gold nanoparticles (AuNPs) were synthesized using two different mono-deoxynucleosides, namely, deoxycytidine (dC) and deoxyadenosine (dA) and the size of the nanoparticles in aqueous dispersions was measured to be approximately 10 and 23 nm, respectively. It was also observed that the AuNPs, synthesized using deoxycytidine (dC), self-assembled to a stable cauliflower-type structure of size approximately 230 nm over a long period of ageing, during which the solution colour was seen continuously changing from pale yellow to deep green. The self-assembly of dC–Au nanoparticles (dC–AuNPs) with time was investigated using UV–visible spectroscopy and dynamic light scattering (DLS) techniques. We have also observed that the self-assembly of dC–AuNPs was dependent on the solution pH; i.e. the aggregates could be dissociated and re-associated upon varying the solution pH which we assumed to be due to breaking and forming of hydrogen bonds between  and  groups of dC among the neighbouring dC–AuNPs. In contrast, AuNPs synthesized using deoxyadenosine (dA–AuNPs) were quite stable in aqueous medium