A Phosphorescent Iridium(III) Complex-Modified Nanoprobe for Hypoxia Bioimaging Via Time-Resolved Luminescence Microscopy.

Wen Lv,Kenneth Yin Zhang,Fuyou Li,Tianshe Yang,Hua Liang,Qiang Zhao,Qi Yu,Wei Huang,Shujuan Liu

doi:10.1002/advs.201500107

Abstract

Oxygen plays a crucial role in many biological processes. Accurate monitoring of oxygen level is important for diagnosis and treatment of diseases. Autofluorescence is an unavoidable interference in luminescent bioimaging, so that an amount of research work has been devoted to reducing background autofluorescence. Herein, a phosphorescent iridium(III) complex‐modified nanoprobe is developed, which can monitor oxygen concentration and also reduce autofluorescence under both downconversion and upconversion channels. The nanoprobe is designed based on the mesoporous silica coated lanthanide‐doped upconversion nanoparticles, which contains oxygen‐sensitive iridium(III) complex in the outer silica shell. To image intracellular hypoxia without the interferences of autofluorescence, time‐resolved luminescent imaging technology and near‐infrared light excitation, both of which can reduce autofluorescence effectively, are adopted in this work. Moreover, gradient O2 concentration can be detected clearly through confocal microscopy luminescence intensity imaging, phosphorescence lifetime imaging microscopy, and time‐gated imaging, which is meaningful to oxygen sensing in tissues with nonuniform oxygen distribution.

Highlights

Oxygen plays a crucial role in many biological processes
Gradient O2 concentration can be detected clearly through confocal microscopy luminescence intensity imaging, phosphorescence lifetime imaging microscopy, and time-gated imaging, which is meaningful to oxygen and reversibly
The phosphorescence of these transition-metal complexes can be quenched by oxygen molecules, owing to energy transfer caused by diffusion-controlled collisional interaction between the sensing in tissues with nonuniform oxygen distribution

Summary

Introduction

Oxygen plays a crucial role in many biological processes. Accurate monitoring the most important features of many disof oxygen level is important for diagnosis and treatment of diseases. To image intracellular hypoxia without the interferences of autofluorescence, time-resolved metal complexes, such as platinum(II) and palladium(II) porphyrins, and ruthenium(II) and iridium(III) complexes,[7,8,9,10] have been employed to sense and image the oxygen levels in living luminescent imaging technology and near-infrared light excitation, both organisms in real time nondestructively of which can reduce autofluorescence effectively, are adopted in this work. Gradient O2 concentration can be detected clearly through confocal microscopy luminescence intensity imaging, phosphorescence lifetime imaging microscopy, and time-gated imaging, which is meaningful to oxygen and reversibly. The phosphorescence of these transition-metal complexes can be quenched by oxygen molecules, owing to energy transfer caused by diffusion-controlled collisional interaction between the sensing in tissues with nonuniform oxygen distribution.

Methods

Results

Conclusion