Polymer nanoparticles integrated with excited-state intramolecular proton transfer-fluorescent modules as sensors for the detection of vitamin B1

Excited-state intramolecular proton transfer (ESIPT)-exhibiting polymer nanoparticles (e-PNPs) were prepared using 2-hydroxy-5-methylisophthalaldehyde and melamine as reactants. These e-PNPs possess abundant aromatic o -OH, C N and NH 2 groups, which are responsible for ESIPT modules and molecular recognition . Compared with small ESIPT compounds, e-PNPs displayed ultrabright luminescence and high fluorescence quantum yield owing to their rich ESIPT-chromophores and appropriate hydrophobic environment for ESIPT reaction. The e-PNPs can emit strong green fluorescence and exhibit typical dual emission in a HEPES buffer (20 mM, pH 7.5). Upon the addition of VB 1, the ESIPT reaction of e-PNPs was inhibited, eliciting obvious decrease in ESIPT fluorescence. By making use of this signaling mechanism, a tautomeric fluorescence quenching-based method for detecting VB 1 was established. A good linear range of 0.1–25 μM.L −1 was observed, bringing about an excellent detection limit of 2.6 nM.L −1 . Moreover, this assay shows good selectivity over other water-soluble vitamins and some biologically related species. The employment of e-PNPs for the determination of VB 1 in kiwi and grape juice samples showed remarkable abilities in terms of the simplicity, stability, reproducibility and sensitivity, which conforms its great potential for real sample analysis. Therefore, e-PNPs can offer a simple, highly sensitive and selective sensing model for fluorescence detection of VB 1 .