Journal of Fluorescence最新文献

In this study, we report a novel and practical tandem approach for synthesizing symmetric ketazines derived from the reaction of hydrazine hydrate and Acetophenone using nickel phosphate (NiP) as a heterogeneous nano-catalyst for the first time. The catalyst underwent comprehensive characterization using several techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Ultraviolet-visible Spectroscopy (UV-Vis), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDS), X-ray diffraction (XRD), and N₂ adsorption-desorption isotherm using BET and BJH methods to define their structure and properties. The results demonstrate that the catalyst exhibited a high surface area of 266.10 m²/g and a heterogeneous nano- structure with high stability and reusability. The synthesized ketazines were analysed using Infrared Spectroscopy (IR) and Nuclear Magnetic Resonance (NMR) spectroscopy. Additionally, the fluorescence properties of the ketazines were tested under various conditions, such as different concentrations and solvents. Also, the same molecules were used in the detection of Fe²⁺ and Pb²⁺ ions in water. Notably, significant alterations in the fluorescence properties were observed.

The rational design of stable, earth-abundant quantum dots with tuneable electronic and optical properties is crucial for advancing sustainable optoelectronic and photocatalytic technologies. In this work, density functional theory (DFT) is employed to investigate pristine and 3d transition-metal (TM)-doped armchair hexagonal silicon carbide quantum dots (AH-SiC-QDs, Si₅₇C₅₇H₃₀). Structural analysis reveals that pristine AH-SiC-QDs exhibit high stability (5.612 eV), surpassing previously reported SiC- and AlN-based QDs. Upon TM incorporation, stability remains robust, with Ni-doping providing the strongest binding and Sc-doping the weakest. Electronic structure calculations show significant dopant-induced modifications in HOMO-LUMO distributions and bandgaps, where Ti- and Sc-doped systems achieve remarkable bandgap narrowing (1.056 and 0.919 eV), indicating strong hybridization between dopant and host states. Optical absorption studies demonstrate pronounced red-shifts into the visible and near-infrared regions, with Sc- and V-doped systems offering extended light-harvesting potential. Mulliken charge and natural bond orbital (NBO) analyses confirm strong donor-acceptor interactions, orbital rehybridization, and enhanced charge transfer, directly linking dopant chemistry to improved catalytic and optoelectronic behaviour. These findings establish TM-doped AH-SiC-QDs as versatile and highly tuneable platforms for next-generation photocatalysis and energy conversion applications.

Cancer remains a major global health challenge, requiring the development of novel therapeutic agents with high efficacy and minimal side effects. In this study, we designed and synthesised a series of hybrid molecules incorporating triazoles, Schiff bases and substituted aromatic motifs, targeting the key oncogenic proteins Bcl-2 and EGFR. The compounds were characterised using spectroscopic techniques and their physicochemical and computational insights were assessed using in silico tools. ADMET showed poor toxicity, Molecular docking studies revealed high binding affinities for both Bcl-2 (docking energies: -6.9 to -7.1 kcal/mol) and EGFR (-9.6 to -10.0 kcal/mol), with compound 5d showing the highest affinity. Molecular dynamics simulations confirmed the stability of the protein-ligand complexes over 200 ns, with RMSD, RMSF, Rg and SASA analyses confirming favourable binding interactions. The compounds showed excellent similarity to drugs, high gastrointestinal absorption and low risk of toxicity. These results suggest that the synthesised hybrids hold great promise as as potential dual-targeted anti-cancer agents warranting further experimental investigation.

In this study, we present a theoretical investigation of Graphene Quantum Dots (GQDs), a zero-dimensional derivative of two-dimensional graphene, as potential Förster Resonance Energy Transfer (FRET) probes. Using a cost-effective semi-empirical approach, we explore how surface functionalization with hydrogen (H), hydroxyl (-OH), and amino (-NH₂) groups systematically tunes the optical and electronic properties of GQDs. The passivation-dependent red-shifts observed in the emission spectra provide clear design rules for generating donor-acceptor pairs with strong spectral overlap. In particular, the yGQDs-rGQDs pair exhibits a Förster radius (R_o) of 6.47 nm, enabling efficient energy transfer over nanoscale distances. These results demonstrate that even simplified modeling can uncover fundamental trends in structure-property relationships of GQDs and predict their FRET performance with remarkable agreement to reported experimental spectra (< 5% error). Our findings highlight the potential of functionalized GQDs as versatile FRET probes and establish semi-empirical simulations as a practical screening tool for guiding the development of 2D material-derived fluorophores in biosensing and optoelectronic applications.

Structure-switching aptamers (SSAs) generate measurable signals through target-induced conformational changes, serving as sensitive molecular recognition elements. We developed a dual-fluorescence SSA for ochratoxin A (OTA) detection by inserting 2-aminopurine (2AP) into the OTA aptamer and hybridizing a complementary DNA (cDNA) strand at the 5' end. OTA binding induced the aptamer-cDNA duplex to form a G4, enhancing 2AP fluorescence at 370 nm. Together with the intrinsic fluorescence of OTA at 450 nm, this enabled ratiometric dual-fluorescence measurements without external quenchers or fluorophores. To elucidate the molecular mechanism, all-atom molecular dynamics (MD) simulations and spectroscopic experiments assessed the effects of cDNA hybridization sites and strand lengths on sensing performance. Simulations further examined OTA binding at various 2AP insertion sites. Apt@2AP-cDNA1, with cDNA hybridized to bases 1-12, exhibited a binding pattern closely resembling the original aptamer. Umbrella sampling simulations revealed similar binding affinities: 46.3 kJ/mol for Apt@2AP-cDNA1 and 43.2 kJ/mol for the original aptamer. Experimentally, Apt@2AP-cDNA1 converted to G-quadruplexes more efficiently than other designs. A ratiometric dual-fluorescence aptasensor using Apt@2AP-cDNA1 was developed, with a linear detection range of 10-800 nM, a detection limit of 5.9 nM. The dual-fluorescence ratiometric aptasensor has good selectivity and was proven effective for detecting OTA in beer samples.

In this research study, the effect of different electron transport layers (ETLs) and hole transport layers (HTLs) on the performance of aluminum quinolate (Alq₃)-based organic light-emitting diodes (OLEDs) was investigated. The research focused on material selection, interface optimization, and the tuning of parameters to enhance device performance. Oghmanano software was employed to analyze various electrical characteristics, including current-voltage (I-V), current density-voltage (J-V), photon flux-voltage (Φ-V), charge density-voltage (Qt-V), recombination rate-voltage (K-V), and photon flux-current (Φ-I) relationships for the initial modeled structure with the layer configuration indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS)/Alq₃/C₆₀/lithium fluoride (LiF)/aluminum (Al). The initial simulated structure exhibited performance parameters of turn-on voltage (Vk) = 2.5 V, current density (J) = 1.85 × 10³ A cm^- 2, photon flux (Φ) = 3.57 × 10^- 7 W m^- 2, charge density (Qt) = 1.65 × 10²³ m^- 3, and recombination rate (K) = 8.13 × 10^- 16 m³ s^- 1. Furthermore, the effects of varying the thicknesses of the emissive and charge conduction layers were studied to determine the optimal parameters for maximum performance. Among the examined materials, PEDOT: PSS as the HTL and bathophenanthroline (BPhen) as the ETL exhibited superior charge conduction and band alignment with Alq₃. The optimized simulated structure demonstrated improved parameters: Vk = 2.8 V, J = 2.63 × 10³ A m^- 2, Φ = 7.35 × 10^-4 Wm^- 2, Qt = 1.89 × 10²³ m^- 3, and K = 2.79 × 10^- 16 m³ s^- 1. These results suggest that the optimized OLED structure can serve as an effective alternative to conventional configurations for advanced optoelectronic applications in the visible spectrum. Moreover, the enhanced fluorescence efficiency and tunable visible emission of the optimized OLED structure highlight its potential for fluorescence-based biomedical applications such as bioimaging, biosensing, and photodynamic therapy.

This study developed a fluorescent molecularly imprinted sensor (CDs@MIPs) for the highly selective detection of the anticancer drug 6-mercaptopurine (6-MP). 6-MP is an anti-cancer drug with myelosuppressive and hepatotoxic effects. If used improperly, it can cause serious adverse reactions in humans and other organisms. The sensor was fabricated via the sol-gel method using blue-emissive nitrogen-doped carbon dots (CDs) as the fluorophore and 3-aminopropyl triethoxysilane (APTES) as the functional monomer. The sensor leveraged molecularly imprinted technology to construct specific recognition cavities, which enabled highly efficient and sensitive detection of 6-MP. Under the optimal experimental conditions and at 325 nm excitation, with the increase of 6-MP concentration, the fluorescence intensity of the sensor at the emission of 415 nm gradually decreases. The sensor demonstrated a linear detection range of 5.0-120.0 µM (Y = - 6.55X + 792.39) with a detection limit of 1.67 µM (S/N = 3). It exhibited strong anti-interference capability, excellent reproducibility and stable fluorescence performance. When applied to the detection of Mercaptopurine tablets, the method achieved recovery rate of 97.80%-108.63%, providing a highly sensitive and cost-effective analytical approach for clinical drug monitoring.

In this research, we focused the detailed study of the interaction and bio-conjugate formation of grown NIR responsive nanostructured Cu₂ZnSnS₄ (CZTS) and Cu₂ZnSnSe₄ (CZTSe) with model bovine serum albumin (BSA) protein. The dynamics of binding showed that corona formation time for CZTS NPs-BSA (~ 806 min) was larger than CZTSe NPs-BSA (~ 15 min). Time for reorganization of BSA due to binding with CZTS NPs (~ 24 min) was much less than that of CZTSe NPs (~ 311 min). BSA binding was more significant than unfolding at the interface of CZTS whereas for CZTSe NPs-BSA unfolding was more significant than binding. The protein secondary structural denaturation through quenching and denaturation has been observed. In case of CZTSe NPs-BSA, the strong positive cooperative reaction (n ~ 1.95) was more prominent than CZTS NPs-BSA (n ~ 1.44). Both Trp and Tyr residues responded at the surface of CZTS whereas only Trp responded at the surface of CZTSe during quenching of protein. CZTS NPs-BSA showed formation of both soft and hard corona, whereas very small sizes CZTSe NPs (~ 5 nm) were selectively formed hard corona on their surface. The average ultrafast life time (τ) of CZTS NPs-BSA varied from 3.76 ns to 3 ns, whereas CZTSe NPs-BSA showed life time (τ) variation from 3.75 ns to 3.53 ns.

Tb³⁺ doped LaPO₄ nanophosphors were synthesised by using simple co precipitation method in deionised water at various pH values of the precursor solutions (1, 3,4, 6, and 9) keeping concentration as constant. The synthesised samples were characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy dispersive X-ray Analysis (EDX) and Photoluminescence (PL) Studies. X-ray diffraction studies indicated a reduction in size beyond pH = 4, which is in close agreement with TEM images. The crystallinity index calculation from XRD showed that the crystallinity of Tb³⁺ doped LaPO₄ increased and then decreased beyond pH value of 4. The photoluminescence studies (PL) also show that there were increased in the intensity with rise in pH values and then decreased at higher pH value which may be due to change in crystallinity, surface defect and also with the quenchers (H⁺, OH^- )concentrations. TEM and SEM images of the nanophosphors reveal nanorods structure. The functional groups and elemental composition of the nanoparticles were studied using FTIR and EDX. The samples appeared greenish blue colour when exposed to UV lamp, thus, it can be used in display, lighting, sensor or bioimaging.

A novel aminochalcone, (E)-1-(4-aminophenyl)-3-(1-benzyl-pyrrol-2-yl)prop-2-en-1-one, was synthesized via Claisen-Schmidt condensation and fully characterized using FT-IR, NMR spectroscopy, and GC-MS analysis. The compound's photophysical properties were studied using UV-Vis absorption and fluorescence spectroscopy in solvents of varying polarity. These studies revealed marked solvatochromic and solvatofluorochromic behavior, which is consistent with an intramolecular charge-transfer process. In polar media, the compound exhibited strong bathochromic shifts and a solvent-dependent fluorescence quantum yield of 0.012 ± 0.001, 0.061 ± 0.004 and 0.098 ± 0.007 in methanol, acetonitrile and chloroform, respectively. Ground- and excited-state dipole moments calculated from Lippert-Mataga and Bakhshiev correlations confirmed an increase upon excitation. DFT calculations at the B3LYP/6-311G(d, p) level corroborated the experimental results, indicating a minimal HOMO-LUMO gap and a planar conjugated system exhibiting donor-acceptor properties. Furthermore, the compound effectively functioned as a fluorescent probe for protein labeling under mildly acidic conditions (pH = 4.0) via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide-mediated coupling, yielding consistent emission across proteins of different molecular weights. Altogether, these results indicate that this new aminochalcone possesses structural tunability, stable fluorescence, and bioconjugation capability, positioning it as a promising scaffold for fluorescence-based biochemical applications.