Quaternary alloy quantum dots with widely tunable emission – a versatile system to fabricate dual-emission nanocomposites for bio-imaging

Abstract

Tuning the composition is an efficient strategy to control the photoluminescence (PL) emission of multiplex alloy quantum dots (QDs), just as the size is for binary QDs. Hence, in this paper, a quaternary alloy system was selected as a model. By controlling the composition, the quaternary QDs exhibit favorable, wide ranging composition-tuned PL emissions, while ZnS overcoating may further improve their PL quantum yields (QYs). Specifically, Zn–Ag–In–Se(ZAISe)/ZnS QDs have a tunable PL peak from 550 (green) to 820 (NIR) nm with up to 70% PL QY; the parameters for Zn–Cu–In–Se(ZCISe)/ZnS QDs are almost same as those for ZAISe/ZnS QDs. In addition, these quaternary QDs were proven to be versatile for bioimaging, serving as a promising alternative for Cd- and Pb-based QDs, by using biodegradable RGD-modified N-succinyl-N′-octyl-chitosan (RGD-SOC) micelles as the water transfer agent to fabricate dual-emission nanocomposites.