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Fluorescence coupled with electrochemical approach at the bulk and the interface region of hydrogen-bonding self assemblies of urea derivatives with DDP dye in aqueous solution
摘要： Photophysical and electrochemical techniques were employed to hydrogen-bonding self assemblies forming solutes (Urea, Dimethylurea and Tetramethylurea) in the presence of 4-dicyanomethylene 2, 6-dimethyl-4H-pyran (DDP) dye. Addition of urea derivatives to DDP dye (Intramolecular Charge Transfer (ICT)) results in a fluorescence enhancement accompanied with a significant shift. Fluorescence lifetime behavior exhibits a tri-exponential decay with a large variation in the fluorescence lifetime and relative amplitude distribution. The co-existence of three different fluorescence lifetime components of DDP with urea derivatives signifies the existence of heterogeneous micro environment. The dye is surrounded by varying proportion of solute and water molecules are established from fluorescence lifetime studies. Urea derivatives govern the excited state characteristics of DDP dye resulting in the formation and promotion of different microenvironment which are clearly distinguishable. The existence of multi environment attributed to urea-water structural behaviour is authenticated by electrochemical impedance spectral studies (EIS). A large variation in the contour pattern, shape and intensity in 3D fluorescence contour spectra of dye with urea validate the existence of dye in a heterogeneous micro environment. The hydrophobicity of urea derivatives along with the hydrogen-bonding properties of urea-water and urea-urea influence the photophysical and electrochemical nature of dye is emphasized.
关键词： Hydrogen-bonding,Urea derivatives,Fluorescence lifetime,Electrochemical impedance spectra,Fluorescence emission,DDP dye
更新于2025-09-12 10:27:22
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Carbon Nitride Dots: A Selective Bioimaging Nanomaterial
摘要： In contrast to the recent immense attention in carbon nitride quantum dots (CNQDs) as a heteroatom-doped carbon quantum dot (CQD), their biomedical applications have not thoroughly investigated. The targeted cancer therapy is a prominently researched area in biomedical field. Here, the ability of CNQDs as a selective bioimaging nanomaterial was investigated to assist the targeted cancer therapy. CNQDs were first synthesized using four different precursor sets, involving urea derivatives and the characteristics were compared to select the best candid material for bioapplications. Characterization techniques such as UV-vis, luminescence X-ray photoelectron spectroscopy, nuclear magnetic resonance spectroscopy and transmission electron microscopy were used. These CNQDs were analyzed in in vitro studies of bioimaging and labeling using pediatric glioma cells (SJGBM2) for possible selective biolabeling and nano-distribution inside the cell membrane. The in vitro cellular studies were conducted under long-wavelength emission without the interference of blue autofluorescence. Thus, excitation-dependent emission of CNQDs was proved to be advantageous. Importantly, CNQDs selectively entered SJGBM2 tumor cells while it did not disperse in to normal human embryonic kidney cells (HEK293). The distribution studies in the cell cytoplasm indicated that CNQDs disperse into lysosomes within approximately 6 h after the incubation. The CNQDs exhibited great potential as a possible nanomaterial in selective bioimaging and drug-delivery for targeted cancer therapy.
关键词： Pediatric glioma cells,Long-wavelength emission,Urea derivatives,Carbon nitride Quantum dots,Fluorescence,Selective bioimaging
更新于2025-09-04 15:30:14