Journal of Fluorescence最新文献

A 1,8-naphthalimide-based tripodal fluorescent ligand (L3) was synthesized through the copper (I) catalyzed Huisgen azide-alkyne cycloaddition reaction of 2-(2-azidoethyl)-6-morpholino-1 H-benzo[de]isoquinoline-1,3(2 H)-dione with triproparagylamine. Naphthalimide acts as the fluorophore while the triazole and amine nitrogens chelate the metal ion. L3 showed a selective fluorescence turn-off for Cu(II) over other metal ions in aqueous acetonitrile solution. A Job’s plot, Benesi-Hildbrand plot and high-resolution mass spectrometry data confirm a 1:1 binding stoichiometry with a binding constant of 7.8 х10⁵ M^− 1 while addition of disodium EDTA demonstrates its reversibility. The structure and stability of the complex was supported by theoretical calculations. The limit of detection for Cu(II) was calculated to be 0.3 µM which is considerably lower than WHO recommended Cu(II) limit in drinking water.

A novel binuclear palladium complex has been synthesized by the reaction of tetramethylethylenediamine palladium nitrate and sodium salt of pyromellitic acid. UV vis, NMR as well as fluorescent titration techniques show that this binuclear palladium complex interacts with neurotransmitter dopamine. The fluorescence of the palladium complex in aqueous solution gets enhanced with the gradual addition of the neurotransmitter dopamine which makes this complex to act as a turn on fluorescent sensor for neurotransmitter dopamine.

In this paper the binding of noscapine (NOS) as an anticancer drug with poor bioavailability and low solubility with beta and methyl-beta cyclodextrins (β-CD and M-β-CD) as the biocompatible drug carriers were discussed using ultraviolet-visible, fluorescence and nuclear magnetic resonance spectroscopy, as well as molecular docking. The absorption of NOS changed when it was bound to both cyclodextrins, resulting in a hyperchromic shift. It formed a 1:1 stoichiometry inclusion complex with both cyclodextrins according to the Benesi-Hildebrand equation. The binding affinity was larger in NOS-M-β-CD (5.9 (± 0.66) × 10³ M^- 1) than NOS-β-CD (3.7 (± 0.22) × 10³ M^- 1) complex. The fluorescence emission band of NOS at 408 nm was quenched when NOS was complexed with β-CD, and enhanced in the presence of M-β-CD, while the shoulder at 350 nm was enhanced selectively when NOS was complexed with M-β-CD. The fluorescence quenching of NOS with β-CD showed a negative deviation from the Stern-Volmer. The thermodynamic parameters have been estimated with the help of the Van't Hoff equation in different temperatures, and a dynamic mechanism was proposed for quenching. Also, both ΔH and ΔS have positive values thus the main interactions result in hydrophobic forces. Moreover, the negative value of ΔG indicates that the bonding process is spontaneous. ¹H NMR chemical shift changes were observable for NOS and both CDs protons due to the chemical environment changes of some nuclei upon complexation. The molecular docking results revealed that the 1:1 inclusion complex possesses a good molecular shape complementarity score for their most probable structures, and indicated that the M-β-CD inclusion system gave the higher complexation efficiency. The binding energy values for β-CD and M-β-CD were determined to be -6.7 and - 9.5 kcal/mol, respectively. These findings suggest the same as the result of experimental tests that the NOS-M-β-CD complex is more stable than the NOS-β-CD complex.

Hydrogen sulfide (H₂S), as an important small molecule bioregulator, plays a key role in many physiological activities and signaling, and abnormal fluctuations in H₂S concentration can lead to a variety of diseases. Therefore, it is of great significance to develop a near-infrared fluorescence probe to visualize fluctuations in H₂S levels. This work is based on Sulfur-substituted dicyanomethylene-4 H-chromene (DCM), A novel NIR fluorescent probe (E) -3 - (2 - (4 - (dicyanomethylene) -6-methyl-4 H-Thiochromen-2-yl)vinyl-1-methylquinolin-1-ium (DMT) was synthesized successfully. Research has found that in weakly alkaline environments, the probe DMT reacts rapidly with H₂S (only 10 s), the fluorescence intensity at 684 nm is enhanced by about 60 fold, the detection limit is as low as 0.1623 µM, the Stokes shift is large (94 nm), and strong selectivity as well as anti-interference ability towards H₂S. This will provide a new method for the rapid detection and further application of H₂S.

As a new type of zero-dimensional nanomaterial, carbon dots are widely applied in various fields. However, most of the carbon dots have aggregation fluorescence quenching properties, which limited their practical applications. In this study, a novel sulfur-doped carbon dots (S-CDs) was prepared by solvothermal method. The properties of the S-CDs in ethanol solution and in solid state were investigated respectively. The results showed that the S-CDs have an excited wavelength dependent emission of blue fluorescence in ethanol solution, and have orange fluorescence emission in solid state and composite films, indicating the prepared S-CDs has aggregation-induced emission (AIE) performance. The main reason was that the presence of S-S bonds and the intramolecular rotation of aromatic rings were limited in solid state, resulting in its emission of orange fluorescence. Furthermore, the S-CDs could be applied to identify fingerprints, anti-counterfeiting.

A kind of nitrogen and sulfur co-doped CDs (N, S-CDs) was facilely synthesized using thiourea and citric acid as precursors, which established an "on-off-on" fluorescence probe to sequential detecting mercury and iodine ions inside water and biology samples. Under 360 nm excitation, CDs emit blue fluorescence with an optimal emission peak of 425 nm (on). The fluorescence of CDs experiences a significant quenching effect upon interaction with Hg²⁺ ions due to the electron transfer between CDs and Hg²⁺. This quenching effect is subsequently recovered upon the addition of I^- owing to the formation of complexes between Hg²⁺ and I^-. The probe exhibits high selectivity and sensitivity toward Hg²⁺ and I^- with broad linearity in the range of 5-50 μM and 15-60 μM, respectively, and a low detection limit of 14.336 nM and 38.213 nM, respectively. The constructed fluorescence probe N, S-CDs has been successfully applied to the detection of Hg²⁺ and I^- in water and biological samples with great recoveries. More importantly, the bioimaging study demonstrated that N, S-CDs are suitable for live monitoring in biological imaging scenarios of Hg²⁺ and I^- in living cells.

Hepatocellular carcinoma (HCC) is a common malignant tumor originating from liver cells, characterized by complex pathogenesis and limited treatment options such as surgery, chemotherapy, and transplantation. Cisplatin, an effective chemotherapeutic agent, disrupts cancer cell DNA but is hindered by side effects and the need for controlled sustained release to optimize efficacy. Metal-organic frameworks (MOFs) have emerged as promising nanocarriers for precise local drug delivery, reducing required doses and mitigating side effects of chemotherapeutic drugs, thus offering a potential avenue for hepatocellular carcinoma (HCC) treatment. In this research, a rectangular channel MOF (Rumgay H, Ferlay J, Martel C, Georges D, Ibrahim AS, Zheng R, Wei W, Lemmens VEPP, Soerjomataram I (2022) Global, regional and national burden of primary liver cancer by subtype. Eur J Cancer 161:108-118) carrier was synthesized using ligand L as the organic linker coordinated with Cu(II) and I(I). The MOF's structure and fluorescence properties were characterized. Additionally, to enhance substrate biocompatibility, composite carrier materials were prepared by incorporating polylactic acid (PLA) with 1, utilized for cisplatin loading. To evaluate the inhibitory effect of PLA-1@cisplatin on HCC, HepG-2 and Huh-7 HCC cell lines were treated with varying concentrations of the drug for 48 h, and their cell viability was assessed. The results demonstrated a significant dose-dependent reduction in cell viability of both HepG-2 and Huh-7 cells. To explore the potential inhibitory mechanism of PLA-1@cisplatin on HCC, the mRNA levels of GADD45A and NACC1 in HepG-2 and Huh-7 cells post-treatment were measured. GADD45A expression, initially low in HCC cells, was significantly upregulated after drug treatment, while NACC1, typically highly expressed in HCC, showed a significant decrease in mRNA levels with increasing concentrations of PLA-1@cisplatin. These findings indicate that PLA-1@cisplatin effectively upregulates GADD45A expression and downregulates NACC1 expression. Overall, the developed cisplatin-loaded nanoparticle system holds promise for HCC treatment by reducing chemotherapy side effects and enhancing drug efficacy.

A series of Dy³⁺ ions doped NaBaB₉O₁₅ phosphors with different dopant concentration was synthesized by solid state reaction. The phase purity was checked by X-ray diffraction analysis and the functional groups present in as prepared phosphors was investigated with the help of FTIR spectral analysis. Under 386 nm excitation, the photoluminescence spectra exhibit three emission bands around 482 nm, 574 nm and 664 nm due to ⁴F_9/2→⁶H_J/2 (J = 15, 13, 11) transions respectively. The optimum doping concentration of Dy³⁺ ions was found to be 5 mol%. The color coordinates are estimated from the emission spectra to check the dominant emission color and the color coordinates of the studied phosphors are fall on white region of CIE 1931 diagram. The decay curve analysis was made to determine the lifetime of excited state of Dy³⁺ ions and the decay curves are exhibited bi-exponential behavior irrespective of Dy³⁺ ion concentration. All these measurents are done in room temperature and the results obtained from these studies are discussed in detail to claim their usage in light emitting devices.

An Indane-1-one derivative 11-(1-benzyl-1H-indol-3-yl)-10,12-dihydrodiindeno[1,2-b:2',1'-e]-pyridine (BDP) has been synthesized by the reaction of Indan-1-one with 1-benzyl-1H-indole-3-carbaldehyde. FT-IR, ¹H-NMR, ¹³N-NMR and Mass spectroscopic techniques has been used to confirmed the structure of BDP. The observed photophysical changes in BDP across various solvents were associated. The impact of various interactions on photophysical parameters, including Stokes shift, dipole moment, oscillator strength, and fluorescence quantum yields, has been assessed in relation to solvent polarity. Moreover, BDP demonstrates potential as a selective fluorescent chemosensor for detecting Fe³⁺ ion within a range of cations in an aqueous DMSO environment. A thorough investigation into the recognition mechanism of BDP towards Fe³⁺ ion has been conducted using Benesi-Hildebrand and Stern-Volmer, measurements. BDP forms a 2:1 complex with the Fe³⁺ ion, exhibiting fluorescent quenching behaviour.

In this study, fluorescent gold nanoclusters (AuNCs) conjugated with pyridoxal-5-phosphate (PLP) were synthesized, characterized, and used for Zn²⁺ fluorescence turn-on sensing. PLP was conjugated over the surface of papain-stabilized fluorescent gold nanoclusters (pap-AuNCs; λ_ex = 380 nm, λ_em = 670 nm) by forming imine linkage. Due to this modification, the red color emitting pap-AuNCs changed to orange color emitting nanoclusters PLP_pap-AuNCs. The nano-assembly PLP_pap-AuNCs detect Zn²⁺ selectively by showing a notable fluorescence enhancement at 477 nm. Zn²⁺ detection with PLP_pap-AuNCs was quick and easy, with an estimated detection limit of 0.14 µM. Further, paper strips and cotton buds coated with PLP_pap-AuNCs were developed for affordable on-site visual detection of Zn²⁺. Finally, the detection of Zn²⁺ in actual environmental water samples served as validation of the usefulness of PLP_pap-AuNCs.