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

Abstract

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.