Ethylenediamine Research Articles

Determining factor of enzyme conjugates, bridge heterology and analytical variables of immunogens in prednisolone ELISA

In this study, adipic acid dihydrazide (ADH), carbohydrazide (CH), ethylenediamine (EDA), and urea (U) were used as spacer molecules, covalently linking prednisolone (PSL) to carrier proteins for immunogen preparation, and PSL to enzymes for enzyme conjugate preparation using N-hydroxysuccinimide (NHS)-mediated carbodiimide reactions. The resulting immunogens were used to generate antiserum in New Zealand white rabbits. Antibodies produced against immunogens with various spacers were tested for immunoreactivity with enzyme conjugates, both with and without spacers, in a total of twenty different combinations. All combinations demonstrated binding and were subsequently evaluated through displacement studies. Sensitivity and specificity tests revealed that the combination of PSL-21-HS-U-BSA-antibody with PSL-21-HS-HRP enzyme conjugate exhibited the best sensitivity (0.032 ng/mL) and limited cross-reactivity with other steroids. This combination was further examined for analytical parameters, showing recovery rates of 93.87–101.19 % for PSL from spiked human serum samples, with intra- and inter-assay CVs of <8.88 %. The serum PSL values obtained by this method showed strong correlation with a commercially available ELISA kit (r2 = 0.97, n = 78).

Study on the enhancement effect of EDTA and oxalic acid on phytoremediation of Cr(VI) from soil using Datura stramonium L.

This study investigated the enhancing effects of soil treatment with ethylene diamine tetraacetic acid (EDTA) and oxalic acid (OA) on the remediation of Cr(VI) contaminated soil by Datura stramonium L. A greenhouse pot experiment was conducted, where Cr(VI) contaminated soil was treated with 100 mg/kg Cr(VI) and varying concentrations of EDTA (5 and 10 mmol/kg) and OA (5 and 10 mmol/kg). The effects of these soil treatments on biomass, chlorophyll content, antioxidant enzyme activities, and Cr(VI) enrichment and translocation efficiency of D. stramonium were evaluated. The results showed that added OA to soil significantly increased the biomass and chlorophyll content of D. stramonium. The addition of 10 mmol/kg of OA to soil increased the plant biomass by 67.16 % and chlorophyll b content by 40.01 %. In addition, OA soil treatment significantly enhanced the activities of superoxide dismutase (SOD) by 6.36 %, peroxidase (POD) by 163.13 %, catalase (CAT) by 36.92 %, and ascorbate peroxidase (APX) by 32.12 %, which effectively alleviated the oxidative stress induced by Cr(VI). In contrast, soil treatment with a high concentration of EDTA (10 mmol/kg) significantly reduced plant biomass and chlorophyll content, although it increased the biological concentration factor (BCF) of the stem and leaf, as well as the translocation factor (TF). In conclusion, appropriate amounts of EDTA and OA added to soil can enhance the phytoremediation efficiency of D. stramonium grown in Cr(VI) contaminated soil, with OA added to soil being more effective than addition of EDTA. This study revealed the potential mechanisms of chelating agents EDTA and OA in enhancing the phytoremediation of Cr(VI) contaminated soil by D. stramonium, providing a scientific basis for further optimization of phytoremediation techniques.

A new type of geopolymer with good thickening and strength properties using Na2C2O4+Ca(OH)2 as the activator

Geopolymer materials exhibit excellent resistance to CO2 corrosion and low carbon emission characteristics, which are very suitable for cementing in CCUS/CCS wells. However, it is difficult to control its thickening time, which limits its popularization and application. The substitution of NaOH with Na2C2O4 and Ca(OH)2 to activate geopolymers was tried to investigate their influence on thickening time and strength of the geopolymer. The precursors used were fly ash sinker beads and slag (the mass ratio is 8:2). Results indicate that at 75°C, the thickening time of geopolymers activated by NaOH is difficult to extend with retarders, whereas those activated by Na2C2O4+Ca(OH)2 can be effectively extended using D-Gluconic acid sodium (D-GA) or ethylene diamine tetra methylene phosphonic acid sodium (EDTMPS). Additionally, geopolymers activated by Na2C2O4+Ca(OH)2 exhibit good strength properties, with compressive strengths of 25.3MPa for 24h and 25.6MPa for 48h at 75°C. Furthermore, geopolymer curing next to water-bearing rocks showed that geopolymer can also achieve excellent solidification when surrounded by water-bearing rocks, which is favorable for its application under the well cementing construction.

The Effect of Ethylene Diamine Tetra(Methylene Phosphonic Acid) Sodium on the Hydration of Tricalcium Silicate at 80 °C

The Effect of Ethylene Diamine Tetra(Methylene Phosphonic Acid) Sodium on the Hydration of Tricalcium Silicate at 80 °C

Efficient Cleavage of pUC19 DNA by Tetraaminonaphthols.

In an attempt to create models of phosphodiesterases, we previously investigated bis(guanidinium) naphthols. Such metal-free anion receptors cleaved aryl phosphates and also plasmid DNA. Observed reaction rates, however, could not compete with those of highly reactive metal complexes. In the present study, we have replaced the guanidines by ethylene diamine side chains which accelerates the plasmid cleavage by compound 13 significantly (1 mM 13: t1/2=22 h). Further gains in reactivity are achieved by azo coupling of the naphthol unit. The electron accepting azo group decreases the pKa of the hydroxy group. It can also serve as a dye label and a handle for attaching DNA binding moieties. The resulting azo naphthol 17 not only nicks (1 mM 17: t1/2~1 h) but also linearizes pUC19 DNA. Although the high reactivity of 17 seems to result in part from aggregation, in the presence of EDTA azo naphthol 17 obeys first order kinetics (1 mM 17: t1/2=4.8 h), reacts four times faster than naphthol 13 and surpasses by far the former bis(guanidinium) naphthols 4 and 5.

Unraveling the roles of atomically-dispersed Au in boosting photocatalytic CO2 reduction and aryl alcohol oxidation

Atomically-dispersed metal-based materials represent an emerging class of photocatalysts attributed to their high catalytic activity, abundant surface active sites, and efficient charge separation. Nevertheless, the roles of different forms of atomically-dispersed metals (i.e., single-atoms and atomic clusters) in photocatalytic reactions remain ambiguous. Herein, we developed an ethylenediamine (EDA)-assisted reduction method to controllably synthesize atomically dispersed Au in the forms of Au single atoms (AuSA), Au clusters (AuC), and a mixed-phase of AuSA and AuC (AuSA+C) on CdS. In addition, we elucidate the synergistic effect of AuSA and AuC in enhancing the photocatalytic performance of CdS substrates for simultaneous CO2 reduction and aryl alcohol oxidation. Specifically, AuSA can effectively lower the energy barrier for the CO2→*COOH conversion, while AuC can enhance the adsorption of alcohols and reduce the energy barrier for dehydrogenation. As a result, the AuSA and AuC co-loaded CdS show impressive overall photocatalytic CO2 conversion performance, achieving remarkable CO and BAD production rates of 4.43 and 4.71 mmol g−1 h−1, with the selectivities of 93% and 99%, respectively. More importantly, the solar-to-chemical conversion efficiency of AuSA+C/CdS reaches 0.57%, which is over fivefold higher than the typical solar-to-biomass conversion efficiency found in nature (ca. 0.1%). This study comprehensively describes the roles of different forms of atomically-dispersed metals and their synergistic effects in photocatalytic reactions, which is anticipated to pave a new avenue in energy and environmental applications.

Development of Novel Cardanol-Derived Reactive Dispersing Agents for Bio-Based Anionic–Nonionic Waterborne Polyurethane

This study successfully developed a bio-based, photocurable, anionic–nonionic dual-functional chain extender, and sulfonated cardanol-based polyethylene glycol (SCP), derived from renewable resources—cardanol and polyethylene glycol—for application in waterborne polyurethane dispersions (WPUDs). Utilizing SCP as a chain extender, WPUDs were prepared through a typical acetone process with poly(butylene adipate) (PBA), isophorone diisocyanate (IPDI), and ethylene diamine (EDA) at a constant NCO/OH ratio of 1:1. This research focused on the effects of polyethylene glycol molecular weight and SCP dosage on the particle size, stability, and film-forming properties of the WPUD. Optimal dispersion stability and film-forming performance were achieved with a polyethylene glycol molecular weight of 1500 and a PBA to SCP molar ratio of 4:1, yielding a particle size of 0.326 ± 0.010 μm and excellent storage stability over six months. The resulting WPU coatings exhibited a tensile strength of 11.4 MPa, which increased to 16.8 MPa after UV irradiation owing to the formation of a semi-interpenetrating network via the photopolymerization of cardanol’s unsaturated side chains. UV cross-linking also enhanced water resistance, reducing the water absorption rate (WAR) from 18.68% to 4.21% and the water vapor transmission rate (WVTR) from 6.59 × 10−5 g·m⁻¹·Pa⁻¹·d⁻¹ to 2.26 × 10⁻⁵ g·m⁻¹·Pa⁻¹·d⁻¹, while also improving thermal stability. These findings demonstrate that SCP offers a sustainable and effective solution for developing high-performance WPU coatings.

Role of ionic nature of surfactants on zinc stannate nanostructure and their application towards supercapacitors

This work demonstrates the role of cationic, anionic, and non-ionic surfactants [ethylene diamine (EDA), sodium lauryl sulfate (SLS), and triton X100 (TX100)] in synthesizing the phase pure zinc stannate (ZTO) nanostructures via hydrothermal technique. The X-ray diffraction (XRD) pattern reveals that EDA is a suitable surfactant for fabricating high crystalline ZTO nanostructures. The nature of surfactants alters the size and shape of the ZTO nanostructures, as evidenced by the FESEM micrographs. Specifically, hemi-pyramid embedded with fine spherical particles (EDA-assisted) and sphere-like particles (non and other surfactants) morphological features are observed. Their energy storage performance is evaluated through a three-electrode system. EDA-assisted ZTO delivered the specific capacitance value of 31 F/g at 1 A/g current density, slightly higher than that of the non-surfactant ZTO (27 F/g @ 1 A/g) electrode. Furthermore, the role of calcination is investigated, and it was found that the specific capacitance value is increased to 77 F/g (from 31 F/g) for the EDA-ZTO sample calcined at 600 °C for 3 h in an ambient atmosphere.Graphical abstract

Role of Morphology on Zinc Oxide Nanostructures for Efficient Photoelectrochemical Activity and Hydrogen Production.

Energy generation today heavily relies on the field of photocatalysis, with many conventional energy generation strategies now superseded by the conversion of solar energy into chemical or thermal energy for a variety of energy-related applications. Global warming has pointed to the urgent necessity of moving away from non-renewable energy sources, with a resulting emphasis on creating the best photocatalysts for effective solar conversion by investigating a variety of material systems and material combinations. The present study explores the influence of morphological changes on the photoelectrochemical activity of zinc oxide nanostructures by exploiting electrodeposition and capping agents to control the growth rates of different ZnO facets and obtain well-defined nanostructures and orientations. A zinc nitrate (Zn (NO3)2) bath was used to electrodeposit ZnO nanostructures on an indium tin oxide glass (ITO) substrate at 70 °C with an applied potential of -1.0 V. Ethylenediamine (EDA) or ammonium fluoride (NH4F) were added as capping agents to the zinc nitrate bath. Extensive evaluation and characterization of the photoelectrochemical (PEC) capabilities of the resulting morphology-controlled zinc oxide nanostructures confirmed that altering the ZnO morphology can have positive impacts on PEC properties.

Evaluation of the excellent adsorption performance for lead ions of (sodium alginate/ waste para-aramid)-based polymer composite functionalized by ethylene diamine tetra (methylene phosphonic acid)

Evaluation of the excellent adsorption performance for lead ions of (sodium alginate/ waste para-aramid)-based polymer composite functionalized by ethylene diamine tetra (methylene phosphonic acid)

A Uniform Conductive Carbon Coating of Nitrogen‐Doped Carbon Improves the Electrochemical Performance of LiMn0.7Fe0.3PO4 Cathode Material for Lithium‐ion Batteries

AbstractThe practical application of LiMn1−xFexPO4 as a cathode material is hindered considerably by its poor electronic conductivity and slow lithium‐ion diffusion. In the present study, a uniform nitrogen‐doped carbon coating on LiMn0.7Fe0.3PO4 (LiMn0.7Fe0.3PO4@NC) was achieved using ethylene diamine tetraacetic acid (EDTA) as a chelating agent and carbon source. The nitrogen‐doped carbon layer enhanced the electronic conductivity and ionic diffusion of the LiMn0.7Fe0.3PO4 cathode. Furthermore, the uniform carbon layer prevented metal ion dissolution and stabilized the crystal structure. The resulting LiMn0.7Fe0.3PO4@NC‐2 sample demonstrated superior performance with a specific capacity of 152.5 mAh g−1 at 0.1 C and preserved 93.7 % of this capacity over 200 cycles at 1 C. Meanwhile, the LiMn0.7Fe0.3PO4@NC‐2 sample demonstrated a high Li+ diffusion coefficient (3.98×10−11 cm2 s−1) and electrical conductivity (1.47×10−2 S cm−1). This study presents a novel approach to designing high‐performance cathode materials using a cost‐effective and straightforward process.

Streptomyces sp. from desert soil as a biofactory for antioxidants with radical scavenging and iron chelating potential

Iron homeostasis is vital for normal physiology, but in the majority of circumstances, like iron overload, this equilibrium is upset leading to free iron in the plasma. This condition with excess iron is known as hemochromatosis, which has been linked to many side effects, including cancer and liver cirrhosis. The current research aimed to investigate active molecules from Streptomyces sp. isolated from the extreme environment of Bahawalpur deserts. The strain was characterized using 16 S rRNA sequencing. Chemical analysis of the ethyl acetate cure extract revealed the presence of phenols, flavonoids, alkaloids, and tannins. Multiple ultraviolet (UV) active metabolites that were essential for the stated pharmacological activities were also demonstrated by thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Additionally, Gas chromatography/mass spectrometry (GC-MS) analysis revealed the primary constituents of the extract to compose of phenol and ester compounds. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to assess the extract’s antioxidant capacity, and the results showed a good half-maximal inhibitory concentration (IC50) value of 0.034 µg/mL in comparison to the positive control ascorbic acid’s 0.12 µg/mL. In addition, iron chelation activity of extract showed significant chelation potential at 250 and 125 µg/mL, while 62.5 µg/mL showed only mild chelation of the ferrous ion using ethylene diamine tetra acetic acid (EDTA) as a positive control. Likewise, the extract’s cytotoxicity was analyzed through 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using varying concentrations of the extract and showed 51% cytotoxicity at 350 µg/mL and 65% inhibition of cell growth at 700 µg/mL, respectively. The bioactive compounds from Streptomyces sp. demonstrated strong antioxidant and iron chelating potentials and can prolong the cell survival in extreme environment.

Fullerene‐Free p–i–n Perovskite Solar Cells: Direct Deposition of Tin Oxide on Perovskite Layer Using Ligand Bridges

AbstractIn p–i–n perovskite solar cells (PSCs), fullerene derivatives are predominantly used as an electron transport material (ETM) despite their disadvantages, such as parasitic absorption in the short wavelength range and high cost. State‐of‐the‐art n‐i‐p PSCs are fabricated using SnO2 as the ETM due to their high charge transfer ability, transparency, and low cost. However, in p–i–n PSCs, dispersing SnO2 nanoparticles in a solvent that does not damage the perovskite and forming a uniform layer is challenging. Herein, a strategy of directly depositing SnO2 quantum dots (QDs) on perovskite using ethylenediamine (EDA) for high‐performance applications is reported, which involves a SnO2 QD solution designed with a damage‐free cosolvent. Treating the SnO2 QD layer with the EDA strategy creates a conformal SnO2 QD layer and improves charge transport. This strategy achieves a high power conversion efficiency (PCE) of 18.9% in PSCs with a 1.77 eV bandgap, which is the highest PCE reported for wide bandgap p–i–n PSCs using an inorganic ETM. The top SnO2 layer enables ITO deposition without sputtering damage and achieves a bifacial factor of 99% due to the high transmittance of SnO2 QD. The resulting four‐terminal all‐perovskite tandem exhibited a PCE of 27.0%.

The influence of Fe2+ on the self-assembly of a bipyridine containing homopolymer: From bowl-shaped nanoparticles to vesicles

Metal ion coordination has critical influence on the self-assembly behavior of amphiphilic polymers and the morphology of the obtained assemblies. Herein, an amphiphilic homopolymer with 2,2′-bipyridine (BPy) as side chain is synthesized (noted as PBPyAA), which can self-assemble into bowl-shaped nanoparticles (BNPs) in tetrahydrofuran (THF)/water. Taking advantage of the coordination interaction between BPy and metal ions, Fe2+ is chosen to regulate the self-assembly behavior and the morphology of the assemblies of PBPyAA in two pathways. (Ⅰ) The aqueous solution of Fe2+ with various concentrations is added to the THF solution of PBPyAA during self-assembly. (Ⅱ) Fe2+ is added into the THF solution of PBPyAA before self-assembly, followed by the addition of deionized water to promote the self-assembly. The results show that the pathway Ⅰ facilitates the coordination of BPy and Fe2+. With the increase of the concentration of Fe2+ aqueous solution, the coordination efficiency of BPy increases from 0.419 % to 7.789 %, leading to the transformation of BNPs to vesicles. Though the coordination efficiency of BPy also increases with the concentration of Fe2+ in pathway Ⅱ, which is still quite low of 0.274 % to 0.366 %, and the morphology of the BNPs barely changes. In addition, ethylene diamine tetraacetic acid (EDTA), a strong chelating agent, is also added to promote the competitive complexation with BPy, resulting in the dissociation of BPy and Fe2+ and the reversible transformation from vesicles to BNPs. Overall, the effect of Fe2+ coordination on the self-assembly behavior of PBPyAA in two pathways is investigated and the reversible transformation of BNPs to vesicles is also achieved.

Insights into the flotation performance of ethylenediamine surface modified hemimorphite: Experimental and DFT study

Upon utilizing micro-flotation, contact angle, AFM, ToF-SIMS, XPS, ICP-OES, and DFT calculations, the influence of ethylenediamine (EDA) on the flotation mechanism of hemimorphite was investigated. The addition of EDA to the flotation system led to a 25.15 % increase in flotation recovery efficiency. Contact angle and AFM analysis indicated that EDA enhanced both the hydrophobicity and surface roughness of hemimorphite. Subsequently, ToF-SIMS deep profiling analysis indicated that EDA modification facilitated the incorporation of sulfur ions into the internal structure of hemimorphite, forming a uniform zinc sulfide film. Furthermore, XPS and ICP-OES analysis demonstrates an increase in sulfides on the surface of the hemimorphite after EDA modification. Additionally, the results of DFT calculations showed that the adsorption energy of an EDA molecule on the hemimorphite (1 1 0) surface was −956.492 kJ/mol.

Cobalt and tungsten single-metal atom catalyst coupled with TiO2–BiCu2VO6 metal oxide on the graphene for efficient solar fuel production and chromium reduction

There is immense promise in photocatalysis for utilizing single-atomic-layer cobalt and tungsten oxide (CoW) on TiO2–BiCu2VO6, ethylene diamine, and reduced graphene-oxide-supported materials. Although there is great excitement surrounding single-metal atom oxide catalysts, converting bulk metal oxides into single-atom oxides remains challenging. In addition, creating high-performance materials for photocatalytic hydrogen (H2) generation and Cr(VI) reduction is crucial and challenging. This work presents a precise catalyst achieved by anchoring a high loading of CoW single metal atom oxide onto the surface of TiO2–BiCu2VO6-rGO through a simple sonication process, even at low temperatures. The prepared TiO2–BiCu2VO6–CoW-ED-rGO (TBCR) catalysts exhibited improved stability when used for hydrogen (H2) generation and Cr(VI) reduction under visible-light illumination. The single Co and W atoms on the TiO2–BiCu2VO6 catalyst demonstrated exceptional performance in H2 generation and Cr(VI) reduction. Through careful experimentation, optimizing the loading of single atoms on the interstitial atomic line of TiO2–BiCu2VO6 significantly enhanced its visible-light absorption capabilities. Using HAADF-STEM, EXAFS, and XANES investigations, cobalt/tungsten single metal atom oxide was determined to be uniformly dispersed over the TiO2–BiCu2VO6 material. The developed photocatalyst showed impressive results with improved H2 generation (36.48 mmol/g/h) and maximum reduction of Cr(VI) (99.4 %). Moreover, by harnessing solar radiation, the photocatalyst can efficiently replace existing noble metal catalysts as a highly effective and durable single-atom catalyst for renewable H2 generation and Cr(VI) reduction.

Influence of Viscosity and Temperature on Rotational Dynamics of 3-(1H-benzo[d]Imidazol-2-yl)-7-(Diethyl Amino)-2H-chromen-2-one (Polar Laser dye) in Highly Viscous Solvent: Low and High Viscous Range.

Temperature-dependent rotational dynamics of 3-(1H-benzo[d]imidazol-2-yl)-7-(diethyl amino)-2H-chromen-2-one (3HBI-7D-2HChromen-2-one) has been studied in highly viscous glycerol solvent. Over the entire studied temperature range rotational reorientation time values vary linearly with temperature. Experimental obtained rotational results are analyzed using hydrodynamic and quasi-hydrodynamic models over the entire temperature range as well as low and high viscous range. 3HBI-7D-2HChromen-2-one rotational dynamics has been described using Stoke's-Einstein-Debye (SED) slip boundary conditions.

Fixed-bed natural gas CO2 adsorption performance of ZSM-5 zeolites impregnated with amines

This research studies the fixed-bed natural gas carbon dioxide (CO2) adsorption performance of ZSM-5 zeolites impregnation with different amines: monoethanolamine (MEA), ethylenediamine (ED), ethylenediaminetetraacetic acid (EDTA), and 4-aminophenol. The structural, morphological, and performance characteristics of the modified zeolites were examined through the use of several analytical techniques. These techniques featured Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The thermogravimetric analysis revealed weight losses in two stages linked to the removal of bound water molecules and the breakdown of the hydroxyl structure. Through fixed bed adsorption experiments, it was discovered that ZSM-5 zeolites functionalized with MEA/ED showed the CO2 adsorption capacity. This study investigated how well four different mathematical models—Clark, Yoon-Nelson, Thomas, and Adams-Bohart—could predict CO2 adsorption breakthrough curves from natural gas using non-linear regression methods. The results showed that all models had very high adjusted determination coefficients (Adj. R²) of over 0.99, indicating they matched the experimental data really well for various adsorbents. The analysis highlighted the models' effectiveness in reflecting adsorption kinetics and capacities, particularly noting the superior performance of the Thomas, Adams-Bohart, and Yoon-Nelson models in capturing uniform breakthrough behaviors. These findings underscore the models' utility in enhancing CO2 removal processes in natural gas purification, which is pivotal for optimizing industrial gas processing systems. These results highlight the efficiency of amine-functionalized ZSM 5 zeolites in capturing CO2 from natural gas streams.

Characterization and linear / nonlinear optical aspects of polyaniline (PANI) films incorporated with Ethylenediamine for low-cost limiting optical technologies

Polymer composite combined film with Polyaniline (PANI) and Ethylenediamine (EDA) were successfully synthesized via the spin coating technique on a glass substrate followed by different thermal annealing degrees and times. Successful incorporation of EDA into the PANI polymer matrix and the effect of the annealing temperature have been demonstrated by XRD, FTIR, FESEM and TEM. Using UV–Vis optical spectroscopy, we determine the absorption coefficient, band edge, and Urbach energy. The effects of different annealing temperatures and times on linear/nonlinear optical characteristics were investigated. The band gap of EDA-doped PANI films is reduced with the different thermal annealing from 3.43 eV to 3.19 eV, while the Urbach tail of the 100 °C/4h film which is 0.492 eV was decreased to 0.469 eV for 150 °C/1h sample. However, the absorbance and optical conductivity were both increased. Besides, the optical limiting effect assesses their potential to mitigate intense light. It was found from the study that for green wavelength 100 °C/4h film decreases the input power by 16.5 % whereas the 150 °C/1h sample shows superior limiting behavior of 99.96 %. It has been found that thermal annealing of the EDA-doped PANI films enhances the synthetic composite's optical characteristics, making the 150 °C/1h sample of EDA-doped PANI films appropriate for utilization in both energy applications and optoelectronics.

Sequential Detection of Hg2+ and TNT Using a Nitrogen‐Doped Polymeric Carbon Dots On–Off–On Fluorescence Sensor

ABSTRACTThis work presents a fluorescence sensor based on nitrogen‐doped carbon dots (N‐CDs) utilized for sequential detection of Hg2+ and TNT. The N‐CDs were produced by a simple and efficient hydrothermal process involving the combination of black bean extract with citric acid (CA) and ethylenediamine (EDA). The resulting N‐CDs exhibit a steady blue fluorescence with a significant quantum yield of 12%. We conducted a thorough investigation into the mechanism by which the fluorescence of NCDs is reduced in the presence of Hg2+. Our analyses, which included Stern–Volmer quenching tests, confirmed the development of a stable complex between N‐CDs and Hg2+. When the NCDs‐Hg2+ complex was exposed to TNT, the fluorescence was selectively restored. This sequential “on–off–on” sensing capacity allows for efficient monitoring of both Hg2+ and TNT, demonstrating good sensitivity and selectivity. The sensor has a low detection limit (LOD) of 3.1 and 46 nM for Hg2+ ions and TNT in a linear range of 0–40 and 0–30 μM, respectively. This study emphasizes the potential application of N‐CDs for detecting heavy metals and explosives at the same time. It highlights their usefulness in sophisticated environmental sensing technologies that are suitable for important applications.