Vitamin B₆ Cofactor-Derived AIEE Active Luminogen for Detecting Ciprofloxacin and Levofloxacin

The present study reports an aggregation-induced emission enhancement (AIEE) luminogen (AIEEgen) NPL derived by condensing equimolar amount of vitamin B₆ cofactor pyridoxal 5'-phosphate (PLP) and 3-hydroxy-2-naphthohydrazide. The AIEE characteristics of NPL was explored in mixed DMSO-HEPES buffer (pH 7.4, 10 mM) medium. The weakly yellow emissive NPL in DMSO turns to cyan emissive NPL as the fractions of HEPES (f_HEPES) increased from 10% to 95% in DMSO. The results of dynamic light scattering (DLS) and scanning electron microscope (SEM) analysis supported the formation of self-aggregates of NPL. When the fluorescence spectral changes of AIEEgen NPL (f_HEPES 95%, λ_ex = 370 nm, λ_em = 485 nm) were examined by adding different drugs, the presence of ciprofloxacin and levofloxacin increased the fluorescence intensity of AIEEgen NPL. The changes found in the UV-Vis absorption, DLS, zeta potential and SEM supported the formation of new complex species between AIEEgen NPL and the selective drugs. The detection limits of AIEEgen NPL for ciprofloxacin and levofloxacin were estimated as low as 2.84 and 0.21 μM, respectively. Additionally, the analytical usefulness of AIEEgen NPL was investigated by quantifying ciprofloxacin and levofloxacin in real human blood serum.