CuInS(2) quantum dots/poly((L)-glutamic acid)-drug conjugates for drug delivery and cell imaging.

A new anticancer drug delivery system was developed based on the electrostatic complex of positively charged CuInS2 quantum dots (QDs) and negatively charged poly(l-glutamic acid) (PGA) conjugated with the model anticancer drug doxorubicin (DOX). Water-soluble near-infrared CuInS2 QDs capped with l-cysteine were directly synthesized by a hydrothermal method. DOX can quench the photoluminescence of CuInS2 QDs in QDs/PGA-DOX nanoparticles through a photoinduced electron transfer process, thus CuInS2 QDs are in the fluorescence "turn-off" state. After the QDs/PGA-DOX nanoparticles are exposed to carboxypeptidase or are taken up by cancer cells, PGA is hydrolysed to release DOX, inducing activation of the CuInS2 QDs fluorescence to the "turn-on" state. The QDs/PGA-DOX nanoparticles can deliver DOX to targeted cancer cells and monitor the DOX release based on the fluorescence "turn-on" signal of CuInS2 QDs, and this could be simultaneously used for the imaging of cancer cells. The multifunctional QDs/PGA-DOX nanoparticles have great potential in terms of their clinical application for cancer therapy.