ATP Aptamer-Modified Quantum Dots with Reduced Glutathione/Adenosine Triphosphate Dual Response Features as a Potential Probe for Intracellular Drug Delivery Monitoring of Vesicular Nanocarriers

: Nanoparticles have great promise in drug delivery, but their functional mechanisms are very complicated. Monitoring the payloads or carriers by conventional labeling strategies may result in an inaccurate perception of the effectiveness of nano drug delivery systems (NDDSs). A GSH/ATP dual-responsive fluorescence enhancement probe was developed by manipulating the electron transfer pathways of surface-modified quantum dots (QDs). Because the intracellular concentrations of GSH and ATP are one hundred times greater than those in the extracellular environment, the intracellular drug release process could be observed by the fluorescence signal of this probe after it is loaded into NDDSs as drug simulants. As a proof-of-concept investigation, the intracellular drug release behaviors of classical liposomes were studied by loading this probe, and the observed results strongly support the known drug delivery mechanism of these systems. Although more studies are needed to investigate the in vivo performance of the probe, this study may encourage further investigations of other intracellular environment-responsive smart probes for deciphering the in vivo fate of NDDSs.