Formation of water-soluble gold and silver nanocrystals using a phase transfer method based on surface-bound interactions

In this paper, several amphiphilic oligomers were synthesized using a low molecular weight polymaleic anhydride and different aliphatic alcohols. Water-soluble Au/Ag noble nanocrystals (NCs) were then prepared by an organic-aqueous phase transfer method with appropriate amphiphilic oligomers based on surface-bound interactions. The obtained water-soluble Au/Ag NCs have the same visible color and UV–vis spectra as those formed initially in organic solvent. We found that hydrophobic ester chain length of the amphiphilic oligomer can dramatically affect the phase transfer efficiency, which was explained by the impact of local hydrophobic environment on the stability of NCs in water. A biocompatible test also showed that the water-soluble Au/Ag NCs were very stable in various physiological conditions without particle aggregation.