Effect of Different Types of Surface Ligands on the Structure and Optical Property of Water-Soluble PbS Quantum Dots Encapsulated by Amphiphilic Polymers

Abstract

Successful transfer of near-infrared emitting quantum dots (QDs) into water is critical for many biological applications. In this paper, PbS QDs capped by several types of most commonly used capping ligands are transferred from an organic solvent into water via poly(maleic anhydride-alt-1-octadecene)-co-poly(ethylene glycol). It is found that the variation of the structure and optical property of QDs upon water transfer highly depends on the type of capping ligands because of their different interactions with their surroundings (such as solvent molecules, polymers, and QD surface). This is in clear contrast to the common concept that amphiphilic polymers will not disturb the ligand structure on the QD surface during the transfer process, and thus the type of ligands will not bear any direct relevance with the variation of QDs and their properties. This work demonstrates that when oleic acid (OA) or OA/trioctylphosphine (TOP) ligands are used, the amphiphilic polymer approach is able to maintain the initia...