Fluorescence Spectrophotometry Research Articles

Molecular Architecture of A Novel Indoline-Fused Chromenylium-Cyanine Probe Carrying Methionine Biomolecule for Ultrasensitive Analyzing Hg2+ Ion in Real Samples

In this study, by decorating the chromenylium-cyanine structure with an indoline ring, a new sensor platform CSI with a highly rigid structure and improved photophysical properties was developed for the first time. The CSI platform was modified with glyoxal and L-methionine methyl ester to produce a new NIR, ratiometric, and switch-on probe (CIME). This probe is biocompatible, water soluble, and has a specific binding mode for Hg2+ ion selectivity. The crystal structure of CSI was determined by x-ray crystallography, and its electronic characteristics, including HOMO-LUMO energy levels were determined by quantum mechanical calculations. CIME is the first instance of an indoline-fused chromenylium-cyanine used for quantification of trace level of Hg2+ in both the living cells and the environment. The new probe has a high level of selectivity and sensitivity for Hg2+ in aqueous media, with broad linear ranges (0-300μM for UV-Vis and 0-225μM for fluorescence). It has a rapid response time of 30seconds, and UV-Vis and fluorescence detection limits of 7.4ng/mL and 0.13ng/mL, respectively. Probe quantitatively detected Hg2+ in real samples using UV-Vis, fluorescence spectrophotometry and a smartphone. The interaction between CIME and Hg2+ was verified by FTIR, HRMS and DFT calculations. Furthermore, the ability of CIME to sense Hg2+ in living cells was confirmed in both MCF-7 cells and 3T3 cells.

Polyurethanes derived from triazole-based monomers and their application as fluorescent probe for Zn2+

Polyurethanes are one of the most encountered polymer classes in both industry and scientific research, with their tremendous physical and chemical properties, as well as numerous advantages such as a wide range of raw materials, the ratio of groups to be used during polymerization and adjustable mechanical properties. In this study, four distinct polyurethanes were synthesized using toluene diisocyanate (TDI) and hexamethylenediisocyanate (HMDI) derived from Schiff bases formed by reacting 3,5-diamino-1,2,4-triazole (DAT) and 4 different aldehydes (2-hydroxybenzaldehyde, 4-hydroxybenzaldehyde, 2-hydroxy napthaldehyde, o-vanillin). The structural characterizations of the synthesized Schiff bases and polyurethanes were elucidated using 1H- 13C NMR and FT-IR, thermal stability was assessed via TGA, molecular weights of the polymers were determined using GPC, electrochemical properties were evaluated by CV, and optical properties were examined using UV–Vis and fluorescence spectrophotometry. The molecular weights of polyurethanes ranged from 4500 to 10300 Da. TGA analysis of the synthesized polyurethanes demonstrated significant thermal stability, maintaining integrity up to 310 °C. The band gap energy (E’g) values of polyurethanes were found to range from 2.30 to 2.51 eV, which is lower than that of their corresponding monomers, exhibiting semiconductor properties. It was determined that DATSA-PU, one of the synthesized polyurethanes, exhibited potential as a “turn-on” fluorescent sensor for Zn2+ ion with a LOD value of 2.03 x 10-7 M.

Novel Schiff base decorated cyclotriphosphazene chemosensors for Fe and Cu ions detection

In this study, new 2-aminobenzothiazole derivative Schiff base decorated cyclotriphosphazene compounds (SBCTP 1 and 2), which are likely to have chemical sensor properties, were designed and synthesized successfully. The compounds were structurally characterized by mass analysis and NMR (1H, 13C and 31P) spectroscopies. Photophysical and chemosensory properties of SBCTP 1 and 2 against some analytes were examined by UV–vis and Fluorescence spectrophotometry. While a significant increase was observed in the UV–vis absorption signals observed at 350 nm with the addition of Fe3+ and Fe2+ ions and a new absorption band was observed at 290 nm with the addition of Cu2+. In addition, according to Job's plot obtained from UV–vis absorption titrations, the complex stoichiometries of SBCTP 1 and 2 with selective analytes were determined as 1:1 (L/M) and 1:2 (L/M), respectively. The selective interaction of donor atoms on SBCTP 1 and 2 with Cu2+, Fe2+ and Fe3+ ions give these compounds chemosensory properties. This study showed that the synthesized Schiff base decorated cyclotriphosphazene compounds (SBCTP 1 and 2) could be new chemosensors with high selective and immediate sensitivity for the detection of iron and copper ions.

Selective solid phase extraction of folic acid from tomato as a biological source with a magnetic molecularly imprinted polymer measured by fluorescence spectroscopy

AbstractA novel magnetic molecular-imprinted polymer (MMIP) was used to selectively extract folic acid directly from real samples. Folic acid was used as template molecule, Fe3O4/SiO2-3-triethoxysilyl-propyl-acrylamide as functional monomer, azobisisobutyronitrile as initiation, ethylene glycol dimethacrylate as crosslinker agent, and acrylamide as the secondary monomer in a mixed ethanol-water solvent. The effect of different parameters on the extraction efficiency was studied, and the optimum conditions were established as follows: the concentrations of crosslinking and template were fixed at 0.05 and 0.06 g, absorption percentage was 96.5, pH was adjusted to 8, and extraction time was 8 h with a temperature of 25 °C. By examining the effect of pH, we tried to investigate the effect of the amide groups that present in MMIP and its intermolecular hydrogen interaction with folic acid. After optimising the effective parameters in polymer synthesis and adsorption rate, a magnetic imprinting dispersive solid-phase extraction method combined with fluorescence spectrophotometry at λem = 367 nm (MMIP-DSPE-FL) was constructed for sensitive determination of folic acid in tomato samples. The limit of quantification (LOQ) and limit of detection (LOD) values were 30.00 ± 0.01 μg L−1 and 10.00 ± 0.03 μg L−1, respectively, after the MMIP-DSPE preconcentration. Three tomato samples were analysed to give recoveries in the range of 80.2–81.6%, with relative standard deviation values below 0.6% (n = 3). The prepared MMIP-DSPE showed high selectivity toward folic acid, which could be used six times without changing adsorption capacity. The adsorption isotherm of the folic acid-imprinted polymer pursued the Langmuir model (RL = 0.029), and the kinetics model followed pseudo-first-order (R2 = 0.9974).

Reducing the water quenching processes using heavy water in capillary electrophoresis with fluorescence detection

Water, ubiquitous in analytical methods, is renowned for its fluorescence quenching properties, influencing techniques like fluorescence spectrophotometry or techniques with fluorescence detection. This study explores the impact of water (H₂O) substitution for heavy water (D₂O) on the fluorescence behavior of anthraquinones and anthracyclines. Anthraquinones and anthracyclines play crucial roles in pharmacy, serving as essential components in various therapeutic formulations, particularly in cancer treatment and other pharmacological interventions. Capillary electrophoresis (CE) with heavy water as the background electrolyte (BGE) solvent offers superior sensitivity to the separation and detection of these analytes. Experimental results demonstrate the improved detection limits and separation efficiency of selected anthraquinones rhein (RH), aloe-emodin (AE), and anthracyclines doxorubicin (DOX), epirubicin (EPI) and daunorubicine (DAU) in heavy water-based buffers, highlighting the potential of heavy water in advancing analytical chemistry.

Fabrication of a Reversible Fluorescence Sensor Based on Nitrogen‐Sulfur Co‐Doped Multiwalled Carbon Nanotubes for Detection of Mercury Ions: Experimental and DFT Insights

AbstractAn eco‐friendly approach involving hydrothermal treatment followed by thermal annealing was adopted for the preparation of nitrogen‐sulfur co‐doped multi‐walled carbon nanotubes (NS‐CNT@600) using melamine and thiourea as precursors. The prepared NS‐CNT@600 were characterized using X‐Ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), X‐Ray Diffraction (XRD), High‐Resolution Transmission Electron Microscopy (HR‐TEM), Ultraviolet and Visible Spectroscopy (UV‐Vis). They were applied for the fluorescent detection of Hg2+ ions in water. A fluorescence quenching sensor for sensitive and precise detection of Hg2+ ions was developed by making use of the sensitivity of NS‐CNT@600 to fluorescence quenching behavior caused by interaction with Hg2+ ions. Additionally, the selectivity of NS‐CNT@600 towards Hg2+ ions was thoroughly investigated in the presence of other interfering metal ions. There was a linear relationship between fluorescence intensity and Hg2+ concentration from 10 to 50 nM with a limit of detection (LOD) of 6.3 nM. The proposed method was also tested on real water samples with positive results. Physicochemical features and interaction mechanism of analyte‐material transduction were exclusively studied by combining fluorescence spectrophotometry and density functional theory (DFT) calculation techniques. The strategy provides an easy way to develop low‐cost, selective and sensitive probes for rapid fluorescent sensing of Hg2+ ions in aqueous solutions.

Evaluation of Pro-Drug Properties in a Novel Schiff Base-Incorporated Pt(II) Complex

The present investigation involved the synthesis of a new Schiff base and its platinum complex. The chemical structures of both the ligand and the complex were determined through the utilization of various analytical techniques, including 1H-NMR, 13C-NMR, FT-IR, and elemental analysis. Moreover, the interaction between the synthesized complex and Amyloid-Beta, a crucial factor in the pathogenesis of Alzheimer's disease, was explored. This interaction was assessed by means of fluorescence spectrophotometry. Additionally, the influence of the histidine amino acid, which has been reported in the literature to play a significant role in the interaction between Amyloid-Beta and coordination compounds, was monitored using 1H-NMR. These investigations have the potential to enhance our comprehension of the chemical structure and biological effects of ligands and complexes. Furthermore, they may contribute to the advancement of knowledge regarding important neurodegenerative disorders such as Alzheimer's disease, as well as the development of potential therapeutic strategies.

Biogenic and Anthropogenic Secondary Organic Aerosols Become Fluorescent after Highly Acidic Aging.

Primary biological aerosol particles (PBAPs) and secondary organic aerosol (SOA) both contain organic compounds that share similar chemical and optical properties. Fluorescence is often used to characterize PBAPs; however, this may be hindered due to interferences from fluorophores in SOA. Despite extensive efforts to understand the aging of SOA under elevated particle acidity conditions, little is known about how these processes affect the fluorescence of SOA and thereby their interference with the measurements of PBAPs. The objective of this study is to investigate the fluorescence of SOA and understand the influence of acidity on the optical properties of organic aerosols and potential interference for the analysis of bioaerosols. The SOA was generated by O3- or OH-initiated oxidation of d-limonene or α-pinene, as well as by OH-initiated oxidation of toluene or xylene. The SOA compounds were then aged by exposure to varying concentrations of aqueous H2SO4 for 2 days. Absorption and fluorescence spectrophotometry were used to examine the changes in the optical properties before and after aging. The key observation was the appearance of strongly light-absorbing and fluorescent compounds at pH = ∼-1, suggesting that acidity is a major driver of SOA aging. The aged SOA from biogenic precursors (d-limonene and α-pinene) resulted in stronger fluorescence than the aged SOA from toluene and xylene. The absorption spectra of the aged SOA changed drastically in shape upon dilution, whereas the shapes of the fluorescence spectra remained the same, suggesting that the fluorophores and chromophores in SOA are separate sets of species. The fluorescence spectra of aged SOA overlapped with the fluorescence spectra of PBAPs, suggesting that SOA exposed to highly acidic conditions can be confused with PBAPs detected by fluorescence-based methods. These processes are likely to play a role in the atmospheric regions where high concentrations of H2SO4 persist, such as the upper troposphere and lower stratosphere.

Hua-Shi-Bai-Du decoction inactivates NLRP3 inflammasome through inhibiting PDE4B in macrophages and ameliorates mouse acute lung injury

BackgroundHua-Shi-Bai-Du decoction (HSBD) exerts significant effects on the prevention and treatment of COVID-19 in China. The activation of the NLRP3 inflammasome of macrophages plays a vital role in COVID-19 pathology. However, no previous studies have focused on this pathological process to explore the effect of HSBD. PurposeOur aim is to uncover the effect of HSBD on NLRP3 inflammasome activation and the underlying mechanisms. MethodsThe NLRP3-activated J774A.1 cells primed by LPS and activated by nigericin/ATP/MSU were used to evaluate NLRP3 activation in vitro. ASC oligomerization and speck formation were assessed by western blot and immunofluorescence imaging. Intracellular K+ levels were determined by the colorimetric assay. Mitochondrial ROS (mtROS) level was detected by the flow cytometry and the fluorescence spectrophotometry. The intracellular cAMP level was determined by chemiluminescence method and ELISA, while phosphodiesterase (PDE) activity was measured using the fluorescent substrate MANT-cAMP. siRNA was applied to knockdown PDE4B. Two in vivo mouse models, MSU-induced peritonitis and LPS-induced acute lung injury (ALI), were used to evaluate the effects of HSBD on IL-1β and other inflammatory cytokines. Pathological changes in lung tissue were observed by histopathological examination. ResultsHSBD not only decreased supernatant IL-1β, caspase-1 p20, and cleaved gasdermin D (GSDMD) in NLRP3-activated J774A.1 cells, but also reduced IL-1β in the peritoneal lavage fluid of mice with MSU-induced peritonitis, demonstrating the suppressive effect on NLRP3 inflammasome activation. The mechanism study showed that HSBD blocked ASC oligomerization and speck formation without affecting K+ efflux or mtROS production. Furthermore, it prevented the decrease of intracellular cAMP by inhibiting PDE4B activity. And in the PDE4B-deficient cells, its suppressive effect on IL-1β release was abolished. In LPS-induced ALI mice, oral administration of HSBD decreased several proinflammatory cytokines (IL-1β, IL-6, TNF-α, and CXCL-1) and attenuated the pathological damage to the lung. ConclusionHSBD suppresses the activation of NLRP3 inflammasome by inhibiting PDE4B activity to counteract the decrease of intracellular cAMP, thereby blocking ASC oligomerization in macrophages. Our findings may provide new insight into the clinical effets of HSBD for the treatment of COVID-19.

Effect of gold mine activity on water quality and human health

ABSTRACT This study aimed to investigate the levels of heavy metals in surface and groundwater sources within the vicinity of a gold mine in Iran, as well as to evaluate the associated health and carcinogenic risks. A total of 45 water samples were collected from the mine effluent, the downstream of a river receiving the effluent of the mine, and downstream water resources. Subsequent to laboratory digestion of the samples, arsenic levels were determined using atomic fluorescence spectrophotometry, while other heavy metals were quantified using inductively coupled plasma mass spectrometry (ICP-MS). Data analysis was conducted utilizing IBM SPSS software (Version 22). The health risks and carcinogenic potentials associated with arsenic, lead, cadmium, chromium, cobalt, manganese, mercury, nickel, copper, and zinc were assessed for both pediatric and adult populations. The findings revealed that, in most instances, heavy metal concentrations exceeded the recommended standards for drinking water quality. Furthermore, the health and carcinogenic risks posed to both children and adults were found to surpass the maximum acceptable levels.

Polyethyleneimine capped silver nanoclusters based turn-off-on fluorescence sensor for the determination of glutathione

A polyethyleneimine capped silver nanoclusters (PEI-AgNCs) based turn-off-on fluorescence sensor has been developed to determine glutathione (GSH) effectively. The fluorescence intensity of silver nanoclusters (AgNCs) has been quenched by Cu(II) and recovered by adding GSH. The quenching of fluorescence intensity of PEI-AgNCs by Cu(II) and recovery of the emission intensity of PEI-AgNCs after the addition of GSH is supposed to be ground state adduct formation. Due to the greater affinity of Cu(II) towards GSH compared to that to PEI-AgNCs, the defragmentation of PEI-AgNCs-Cu(II) adduct occurs after the addition of GSH to the solution, resulting in the recovery of emission intensity of PEI-AgNCs. Characterisation studies of the probe have been done using FT-IR spectroscopy, XPS analysis, XRD analysis, UV–visible and Fluorescence spectrophotometry, EDX spectroscopy and TEM analysis. Different experimental parameters were optimised. Under optimised analytical conditions, the sensor showed a wide linear range for the quantification of GSH from 1.00 × 10−4 M to 3.00 × 10−6 M with a detection limit (LOD) of 8.00 × 10−7 M. Selectivity and interference studies were done in the presence of different structurally similar and coexisting species of GSH in blood. The practical utility of the proposed sensor has been validated in artificial blood serum.

Facile conjugate electro-spinning to achieve nanofiber yarns with concurrent color-tunable photoluminescence and tailored superparamagnetism

In this work, we have successfully fabricated hetero-structured nanofiber yarns (NFYs) with a conjugate electro-spinning technique, integrating a dual-functional capability of tunable color photoluminescence and tailored superparamagnetism. These hetero-structured NFYs are comprised of [Eu(BA)3phen + Tb(BA)3phen]/polyacrylonitrile (PAN) photoluminescent nanofibers (NFs) and Fe3O4/PAN superparamagnetic NFs, which allow for the effective isolation of dark-colored Fe3O4 nanoparticles (NPs) from rare earth complexes. This design leads to enhanced photoluminescent performance for the hetero-structured NFYs. Detailed investigations into the morphologies and performances of these NFYs were conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), fluorescence spectrophotometry, and vibrating sample magnetometry (VSM). The emitting light color, ranging from red to yellow to green, can be tuned under a specific excitation wavelength (276 nm) of ultraviolet (UV) light by regulating the proportion of rare earth complexes. Furthermore, the superparamagnetism of the NFYs can be tailored by varying the amounts of Fe3O4 NPs. The designing philosophy and preparative technique can be utilized to manufacture other polyfunctional nanomaterials.

Hesperidin/Salinomycin Combination; a Natural Product for Deactivation of the PI3K/Akt Signaling Pathway and Anti-Apoptotic Factors in KG1a Cells.

AML is a highly aggressive malignant clonal disease of hematopoietic origin. Hesperidin as a polyphenol glycoside, Activates the apoptotic pathway and salinomycin as a k + selective ionophore. We examined how hesperidin and salinomycin induce pro-apoptotic effects in KG1a cells. Cells were divided into four groups; 1) control cells (CRTL), 2) cells treated with hesperidin 85μM, 3) cells treated with 2μM salinomycin, 4) cells treated with combination of salinomycin and hesperidin. The MTT assay was implemented to determine the IC50 of hesperidin and salinomycin in KG1a cell lines. Propidium iodide staining and flow cytometry were used to analyze the distribution of the cell cycle. The level of ROS was evaluated by fluorescent microscopy and spectrophotometry. Additionally, Akt, XIAP, Bad, and FOXO1 gene expression was analyzed by real-time PCR. Hesperidin/Salinomycin decreased the viability of KG1a leukemic cells more than Hesperidin and Salinomycin separately. Changes in the shape of apoptotic cells and rise in ROS levels were detected after Hesperidin/Salinomycin treatment. Our findings showed that following Hesperidin/Salinomycin treatment, the expression of PI3K/AKT signaling pathway related genes (AKT, PTEN and FOXO1), were in line with the destruction of KG-1a cells. Furthermore, XIAP and BAD mRNA were regulated to trigger apoptosis in cancer cells. The study discovered that hesperidin and salinomycin, could effectively hinder the PI3K/Akt signaling pathway in leukemia cancer cells. Also, the combination of hesperidin and salinomycin has the potential to be a treatment option for acute myeloid leukemia.

Determination of glucose oxidase activity by tyrosine fluorescence spectrophotometry

A novel Fe2+/Tyr/H2O2 fluorescence reaction system has been established for the purpose of analyzing glucose oxidase activity. This system involves the catalysis of glucose oxidase on glucose to produce H2O2, which in turn oxidizes tyrosine to a highly fluorescent substance under the catalysis of Fe2+. The fluorescence intensity is subsequently employed to ascertain the enzymatic activity of glucose oxidase. The enzymatic oxidation reaction and tyrosine fluorescence reaction conditions were optimized based on the H2O2 standard curve equation. Direct fluorescence spectrophotometry was used to determine the activity range and detection limit of glucose oxidase, which were found to be 7.00 × 10−5–7.00 × 10−2 U/mL and 3.36 × 10−5 U/mL (Enzyme-like activity is 6.72 × 10−4 U/mL, The enzyme reaction time is 5 min), respectively, with a relative standard deviation of less than 3.2 %. This method has been successfully applied to determine the activity of glucose oxidase in food additives, with a recovery rate ranging from 96.00 % to 102.0 %.

Evaluation of the interaction between new holmium(III) complex and DNA: A comprehensive study

In this research, we conducted a comprehensive investigation into the interactions between the holmium(III)-curcumin complex ([Ho(Cur)2]+) and DNA. To elucidate these interactions, we employed various analytical techniques including cyclic voltammetry (CV), UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), fluorescence spectrophotometry, thermal gravimetric analysis (TGA), and molecular docking calculations. Our findings revealed compelling evidence of strong binding between [Ho(Cur)2]+ and DNA, as indicated by hypochromic effects in absorbance and fluorescence quenching. The binding affinity of [Ho(Cur)2]+ to DNA was substantiated by the evaluation of maximum absorption of the [Ho(Cur)2]+ spectra at different DNA concentrations. Furthermore, fluorescence resonance energy transfer experiments demonstrated that the distance between the donor (DNA) and acceptor ([Ho(Cur)2]+) was favorable for energy transfer. The combination of experimental data and molecular docking results suggested that non-covalent binding likely played a significant role in the binding of [Ho(Cur)2]+ to DNA. FT-IR spectra and molecular docking analyses provided further insights, indicating specific binding primarily between [Ho(Cur)2]+ and the base pairs of DNA. Electrochemical measurements indicated a groove binding mode between [Ho(Cur)2]+ and DNA, with a binding ratio of 1:1. Notably, our results indicated that increasing the amount of DNA resulted in a significant reduction in the current intensity of [Ho(Cur)2]+ under optimal conditions.

Nano-Assembled Polyphosphazene Delivery System Enables Effective Intranasal Immunization with Nipah Virus Subunit Vaccine.

The ultimate vaccine against infections caused by Nipah virus should be capable of providing protection at the respiratory tract─the most probable port of entry for this pathogen. Intranasally delivered vaccines, which target nasal-associated lymphoid tissue and induce both systemic and mucosal immunity, are attractive candidates for enabling effective vaccination against this lethal disease. Herein, the water-soluble polyphosphazene delivery vehicle assembles into nanoscale supramolecular constructs with the soluble extracellular portion of the Hendra virus attachment glycoprotein─a promising subunit vaccine antigen against both Nipah and Hendra viruses. These supramolecular constructs signal through Toll-like receptor 7/8 and promote binding interactions with mucin─an important feature of effective mucosal adjuvants. High mass contrast of phosphorus-nitrogen backbone of the polymer enables a successful visualization of nanoconstructs in their vitrified state by cryogenic electron microscopy. Here, we characterize the self-assembly of polyphosphazene macromolecule with biologically relevant ligands by asymmetric flow field flow fractionation, dynamic light scattering, fluorescence spectrophotometry, and turbidimetric titration methods. Furthermore, a polyphosphazene-enabled intranasal Nipah vaccine candidate demonstrates the ability to induce immune responses in hamsters and shows superiority in inducing total IgG and neutralizing antibodies when benchmarked against the respective clinical stage alum adjuvanted vaccine. The results highlight the potential of polyphosphazene-enabled nanoassemblies in the development of intranasal vaccines.

A novel g-C3N4@La:Y2O3 nanocomposite fluorescence sensor for simultaneous determination and photocatalytic degradation of Ulipristal acetate and Tacrolimus using Doehlert design optimization

Graphitic carbon nitride nanocomposite doped with La:Y2O3 was used as a new sensor for detection and determination of two hazardous active pharmaceutical compounds, Tacrolimus and Ulipristal acetate, by fluorescence spectrophotometry. This novel nanosensor has a fantastic ability to detect these drugs quickly, accurately, and simultaneously. The effect of Tacrolimus on this nanosensor is the quenching of fluorescence emission intensity at the wavelength of 369 nm while the Ulipristal acetate increases the fluorescence emission at 433 nm. Doehlert design was used to optimize the effective factors to reach the maximum fluorescence emission intensity of the nanosensor. Factors including pH, buffer solution concentration and the ratio of La:Y2O3 dopant in the nanocomposite structure. Under optimal conditions, the limit of detection of 17 nM and the limit of qualification of 58 nM for Tacrolimus and the limit of detection of 11 nM and the limit of qualification of 36 nM for Uipristal acetate were obtained with good accuracy. The prepared g-C3N4@La:Y2O3 nanocomposite has a reasonable ability to photodegrade these two drugs. In this regard, the process of photocatalytic degradation of Tacrolimus and Ulipristal acetate was investigated under visible light irradiation. The effect of active species in photocatalytic degradation was evaluated in order to determine the exact degradation mechanism, and the effect of Fenton factors on analytes degradation was also investigated.

Synthesis of Green Carbon Dots from Nephelium Lappaceum L. Seeds

In this study, rambutan (Nephelium Lappaceum L.) seeds were used to fabricate green carbon dots (gCDs) by employing a hydrothermal process. The synthesized CDs were evaluated using Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) for the structural properties as well as UV-Vis and fluorescence spectrophotometry for the optical properties. UV-Vis examination revealed that the produced gCDs showed emission-dependent photoluminescence excitation, with two absorption peaks at 265 nm and 330 nm. The presence of functional groups and chemical composition such as C=C, C=O, -COOH, and -OH on the surface of gCDs was confirmed by the results of FTIR and XPS spectra. Consequently, gCDs present several opportunities for exploration in a range of applications.

Tuning and high temperature fluorescence properties of LaPO4:Sm3+ nanophosphors

A series of LaPO4:x%Sm3+ nanophosphors were successfully synthesized through a one-step hydrothermal method, where the acidity of the reaction system was meticulously modulated without the addition of any organic compounds. The influence of pH values and Sm3+ doping concentration on the structure, morphology, and luminescent properties of LaPO4:x%Sm3+ was systematically investigated. The composition, structure, morphology, and luminescent properties of the products were characterized and analyzed using advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM, EDS), transmission electron microscopy (TEM), and fluorescence spectrophotometry (FL). The results indicate that the acidity of the reaction system effectively influences the morphology and size of the nanophosphors, facilitating the controlled synthesis of nanorod-shaped, nano-spherical, and ellipsoidal phosphors. When the Sm3+ doping concentration is 2 %, the phosphors exhibit maximum luminescent intensity and fluorescence lifetime. The energy transfer between Sm3+ ions in LaPO4:x%Sm3+ is identified as electric dipole-electric dipole interaction, with a critical distance for energy transfer established at 1.593 nm. LaPO4:2%Sm3+ exhibits good thermal stability, characterized by a thermal quenching activation energy of 0.1660 eV. The main outcome of this research, LaPO4:2%Sm3+ phosphor, exhibits significant potential for use in optical sensors, as well as promising applications in solar cells and biological fields.

Dual Stimulus Responsive GO-Modified Tb-MOF toward a Smart Coating for Corrosion Detection.

Smart-sensing coatings that exhibit multistimulus response, rapid indication, and reusability are in urgent need to effectively enhance the practicability of coatings while accurately detecting metal corrosion. In this work, a reusable corrosion self-reporting coating with multiple pH and Fe3+ stimulus responses was first constructed by the integration of a composite fluorescent probe into the resin matrix. This composite sensor was constructed by combining a lanthanide metal-organic framework (Ln-MOF) based on terbium and trimeric acid (H3BTC) with graphene oxide (GO) nanosheets (GO@Tb-BTC). The incorporation of GO formed a sea-urchin-like structure, thereby increasing the specific surface area and active sites of the probe. The coatings were characterized by using electrochemical impedance spectroscopy (EIS), visual observation, and fluorescence spectrophotometry. The surface morphology, wettability, and adhesion of the coating samples were analyzed using SEM, XPS, hydrostatic contact angle test, and an adhesion test. EIS measurements in 3.5 wt % NaCl solution for 72 h demonstrated the superior corrosion protection performance of the 0.3 wt %/GO@Tb-BTC/WEP coating compared to blank coating, with the charge-transfer resistance reaching 4.33 × 107 Ω·cm2, which was 9.5 times higher than that of the pure coating. The bright green fluorescence of GO@Tb-BTC/WEP coating exhibited a turn-off response when there was an excess of OH-/H+, but it demonstrated a reversible turn-on fluorescence when the ambient pH returned to neutral. Furthermore, such Fe3+-triggered fluorescence quenching responded to concentrations as low as 1 × 10-6 M. The fluorescence quenching rate of both intact and damaged coatings surpassed that of visual and EIS detection methods. Significantly, the fluorescence in scratches was effectively quenched within 25 min using 0.3 wt %/GO@Tb-BTC/WPU coating for visual observation. GO@Tb-BTC demonstrated exceptional corrosion self-reporting capabilities in both epoxy and polyurethane systems, making it a versatile option beyond single-coating applications.