Tricolor core/shell polymeric ratiometric nanosensors for intracellular glucose and oxygen dual sensing

Abstract

Monitoring cell metabolism is crucial for understanding cell life activity and cytopathic mechanism. Glucose and oxygen are very important parameters for cell metabolism. In this work, core/shell nanomaterials as novel tricolor ratiometric luminescence nanosensors were prepared for real-time monitoring of intracellular oxygen and glucose levels. The nanosensors were achieved by covalently embedding of red emitting oxygen probes and yellow emitting reference probes into the hydrophobic cores and covalently grafting blue emitting glucose probes onto hydrophilic shells. This system realized simultaneous detection of glucose and oxygen through two different luminescent signals without enzyme assistance, and the two kinds of detection signals didn’t interfere with each other. The nanosensors could sensitively detect glucose in the range of 0.01 to 5.0 mM and simultaneously detect dissolved oxygen in the range of 0.05 to 39.3 mg/L, indicating the suitableness for intracellular glucose and oxygen monitoring. Because of the small sizes (< 60 nm), biocompatible core-shell structures, covalently imparted dye leaking-free construction of the nanosensors, these nanomaterials showed good cell permeability and low cytotoxicity. Cell imaging and intracellular sensing of the nanosensors were studied by confocal luminescence microscopy. Hela cells stained with the nanosensors showed an increase in blue emission when glucose was added and an increase in red emission when oxygen was reduced. While, the yellow emission from the reference probes was not affected by glucose or oxygen. This work is expected to lead to the design of intracellular glucose and oxygen sensors, and can be extended to other multiple sensors in biological systems.