Highly selective and efficient AIEE active fluorescence probe for the detection of doxycycline in biological and environmental samples with extensive DFT support.

A highly selective naphthalimide based fluorescent probe PBQ was designed for investigation of doxycycline (DOX) in various real samples. The synthesized probe PBQ showed maximum emission intensity at 395 nm and exhibited selective quenching response-based on photoinduced electron transfer (PET) mechanism even in the presence of various competing and interfering drugs, amino acids, cations and anions. Furthermore, probe PBQ showed excellent AIEE properties with red shift in maximum emission wavelength due to formations of J-aggregates. The enlargement in size of probe PBQ with the formation of aggregates was verified through DLS analysis. The LOD of probe PBQ was found 66 nM for DOX. The nature of interaction and sensitivity of probe PBQ for DOX has been assessed through UV-visible, fluorescence, SEM, 1H NMR, LC-MS and FTIR titration experiments. The non-covalent nature of interaction, π-π stacking, transfer of charge density, and reduction of HOMO LUMO energy gap between probe PBQ and PBQ-DOX complex has also been revealed by DFT calculations. Furthermore, probe PBQ was extensively utilized for detection of DOX in blood, urine and other industrial wastewater samples.