Ratiometric Oxygen Sensor Based On Quadruple Hydrogen-bonded Supramolecular Polymers

Oxygen plays a pivotal role in living organisms and biological systems, the oxygen levelin human tissue is tightly related with human health. There are growing interests in detectionof oxygen levels in human tissue with real-time and accuracy, because it’s beneficial forsickness prevention, clinic treatment and development of new drug. Oxygen sensor based onphosphorescence quenching is highly appreciated for its unique advantage. phosphorescentsensor can penetrate into living cells with little injury, and interaction with dissolved oxygento cause obvious changes of phosphorescence intensity. With the help of confocal laserscanning microscopy imaging, visualization detecting of cellular oxygen can be achieved.Many efforts have been focused on developing optical sensors for oxygen, but stillcannot satisfy all the requirements and system for O2measurements due to their sophiscatedsynthesis, poor water solubility, moderate photostability, poor biocompatibility, highcytotoxicity, as well as difficulty in biogradation. It is of great urgence to develop thebiodegradable oxygen sensor with low cytotoxicity and good biocompability. Thenanosensors based on the supramolecular assembly are hopeful to solve these problems.In this dissertation, a new kind of oxygen nanosensor based on the assembly ofquadrupolar hydrogen bonding is synthesized and investigated for its application in thedetection of oxygen of different levels. This thesis can be divided into the following threeparts:1. The phosphorescence molecule Z2and fluorescent molecule Z3both containingquadruple hydrogen bonding were synthesized and characterized by1H NMR,13C NMR andhigh resolution mass spectra. And their photophysical properties in chloroform were alsoinvestigated. 2. Two kinds of supramolecular nanoparticles, Z2-T2-T3and T1-T2-T3were fabricatedby the microemulsion method. The two nanoparticles are firstly characterized by scanningelectron microscopy (SEM) and the T1-T2-T3nanoparticle is better candidate forconstruction of the oxygen sensor. Then the T1-T2-T3nanoparticles were furthercharacterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS).The nanoparticle about is55nm in diameter with high monodispersity. After a series ofcharacterization as spectral measurement, Stern-Volmer linear fit and lifetime determination,the nanosenor based on the T1-T2-T3nanoparticles displayed high sensitivity towardsoxygen.3. The cytotoxicity and photostability test showed that the nanosenor has favourablebiocompability and photostability, and could be used for cellular oxygen imaging with thehelp of confocal laser scanning microscopy. The nanosensor provided a potential tool in thedetection of cellular oxygen and assessment of the efficacy of drug.