Novel zwitterionic Natural Deep Eutectic Solvents as environmentally friendly media for spontaneous self-assembly of gold nanoparticles

The potential application of some novel zwitterionic Natural Deep Eutectic Solvents, NADESs, based on betaine N,N,N-trimethylglycine and carboxylic acids (glycolic, phenylacetic and oxalic acid), has been evaluated in the synthesis of gold nanoparticles (AuNPs). AuNPs have been successfully obtained by reduction of gold(III) chloride trihydrate by ascorbic acid or sodium borohydride as reducing agents, without the use of any surfactant or capping agent. The effect of the different experimental conditions (nature of the reducing agent, temperature) has been discussed.