Thermostable polymeric nanomicelles of iridium(III) complexes with aggregation-induced phosphorescence emission characteristics and their recyclable double-strand DNA monitoring

Using 4,7-diphenyl-1,10-phenanthroline (DIP) as a main ligand and ethyl cyanoacrylate (ECA) as both an auxiliary ligand and a polymer skeleton, polymer iridium(III) complexes (DIP)2Ir(ECA) and their nanomicelles with aggregation-induced phosphorescence emission (AIPE) activity were synthesized. The morphology, chemical structure and composition of (DIP)2Ir(ECA) nanomicelles were characterized using transmission electron microscopy, size distribution/zeta potential analysis, nuclear magnetic resonance, and Fourier transform infrared spectroscopy. Their AIPE-active effects and double-stranded DNA (dsDNA) monitoring abilities were determined using phosphorescence spectroscopy using a spectrophotofluorometer. The results showed that (DIP)2Ir(ECA) nanomicelles had a good thermostability within 0–100 °C and their size distribution was 29.14 ± 1.46 nm. These nanomicelles showed AIPE-active effects and their phosphorescence intensity increased nearly 30-fold in water compared to in acetone. These nanomicelles could be used in AIPE-active intracellular imaging and dsDNA monitoring. Owing to the specific phosphorescence quenching that occurred when dsDNA encountered (DIP)2Ir(ECA) nanomicelles, thermostable (DIP)2Ir(ECA) nanomicelles could quickly detect dsDNA with high sensitivity and could be conveniently applied not only in monitoring DNA degradation in a wider pH range (specifically in an acidic environment), but also during PCR procedures. More importantly, both (DIP)2Ir(ECA) nanomicelles and immobilized DNase I could be recycled and utilized at least four times using our novel phosphorescence “quenching-recovery” dsDNA detection procedure. The polymeric (DIP)2Ir(ECA) nanomicelles were fast, sensitive, and convenient in monitoring dsDNA and could be recycled four times owing to their thermostability, indicating their great potential in biomedical and environmental applications.