Quantitative ratiometric phosphorescence hypoxia–sensing nanoprobes based on quantum dots/Ir(III) glycerol monoolein cubic-phase nanoparticles

A novel protocol is developed to prepare quantum dot (QD)/Ir(III) complex glycerol monoolein (GMO) cubic-phase nanoparticles (Qd/Ir GMCPNPs) as hypoxia nanoprobes, in which hypoxia probe Tris [1-phenylisoquinoline-C2, N] Iridium(III) [Ir(piq) 3 ] and the reference QDs are separately loaded at hydrophilic and hydrophobic channels to avoid interference. Qd/Ir GMCPNPs were nearly spherical in shape, with an average size of 20–30   nm. Their phosphorescence spectra showed that nanoprobes have a wide excited wave length range of 360–500   nm, which is suitable for different types of measurement instruments . When the oxygen content decreased from 21% to 1%, the luminescent intensity ratio of Qd/Ir GMCPNPs in the solution and cells increased 4-fold and 2.8-fold, respectively, with an acceptable linear relationship. Particularly, extensive preliminary quantitative ratiometric oxygen sensing and long tumor imaging monitoring can be achieved with these nanoprobes.