Aggregation Enhanced Excimer Emission Supported, Monomeric Fluorescence Quenching of Dendritic Hyperbranched Polyglycerol Coupled 1-Pyrene Butyric Acid Lumophore as a Sensing Probe for FeO Nanoparticles.

Pyrene butyric acid (PBA) is a well studied lumophore for its exciting fluorescent properties. The current study focussed on a dendritic modification of PBA with hyperbranched polyglycerols (HPG) by Steglich esterification and further doping with iron oxide nanoparticles (IONP) of α-FeO phase. The covalent coupling between HPG and PBA was confirmed by FTIR and H-NMR spectra. The main objective of the study was to monitor the fluorescent properties of the modified and doped products. Steady state PL emission studies showed a considerable decrease in fluorescence intensity on HPG modification which almost completely disappeared on doping with IONP. This suggests that this fluorosensing property can be explored in identification and estimation of iron oxide nanoparticles which has a great significance in biomedical field both in diagnostics and therapeutics. Lifetime measurements with TCSPC suggested an aggregation enhanced quenching of HPG-PBA conjugates and mixed static and dynamic mechanisms in IONP doped HPG-PBA conjugates. Graphical Abstract ᅟ.