Direct Synthesis of Water-Soluble Ultrathin CdS Nanorods and Reversible Tuning of the Solubility by Alkalinity

摘要

Semiconductor nanocrystals have attracted much attention thisndecade.n1nThe traditional solution-phase organometallic approachnprovides an effective way to synthesize high quality hydrophobicnsemiconductor nanocrystals.n2nHowever, in many cases, such asnbiological labeling and drug delivery, the hydrophobic nanocrystalsnare limited and water-soluble nanocrystals are desired.n3nThentraditional methods employ an extra step to replace the ligands bynhydrophilic ones or in situ grow a hydrophilic shell on a presyn-nthesized nanocrystal.n4nBy contrast, direct synthesis is more con-nvenient and effective to produce water-soluble nanocrystals. Somenmethods have been developed, for example, by using smallnmolecules with polar groups as ligands, such as thioglycolic acid,n5nor using water-soluble polymers, such as polyvinylpyrrolidonen(PVP).n6nHowever, directly synthesizing water-soluble ultrathinnquantum rodsn7nremains a challenging task. It is difficult to find ansuitable water-soluble ligand which can bind to the nanocrystalnfirmly, so that it can protect the nanocrystal well and further inducenthe anisotropic growth.