Novel ethylenediamine-ß-cyclodextrin grafted membranes for the chiral separation of mandelic acid and its derivatives.

In the present study, flat cellulose acetate ultrafiltration membranes were prepared first by nonsolvent induced phase separation method. Then chiral membranes for separating the enantiomers were prepared by grafting the ultrafiltration membranes using ethylenediamine-ß-cyclodextrin as the chiral selector and epichlorohydrin as the spacer arm. The pure water permeability of the ultrafiltration membrane was around 115 L·m-2·h-1·bar-1. The properties of the chiral membranes were characterized using infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The chiral membrane performance in enantiomer separation was evaluated with racemates, such as mandelic acid (MA), 2-chloromandelic acid (2-ClMA), 4-chloromandelic acid (4-ClMA), and methyl mandelate (MM). The influence of feed concentration on the separation efficiency was also investigated. The results indicated that the enantiomeric excess percentages (e.e%) of the racemic mixtures for these four chiral compounds were up to 31.8%, 25.4%, 17.8%, and 32.6%, respectively. The binding free energy of the chiral selector with the (S)-enantiomer calculated by molecular dynamics simulations was stronger than that with the (R)-enantiomer, which was consistent with the experimental results (higher concentration of (R)-enantiomer in the permeate). This supports the affinity absorption-separation mechanism.

Sensitization to ethylenediamine dihydrochloride in patients with contact dermatitis in northeastern Italy from 1996 to 2021.

BACKGROUND: Ethylenediamine dihydrochloride is a versatile aliphatic amine found in numerous medications and industrial compounds and is a known sensitiser. The sensitization prevalence is affected by geographical and socio-cultural factors. OBJECTIVES: The objectives are to analyse the temporal trend of sensitization to ethylenediamine dihydrochloride in northeastern Italy and to investigate associations with occupations. METHODS: Between 1996 and 2021, 30 629 patients with suspected allergic contact dermatitis were patch tested with the Triveneto baseline series. Individual characteristics were collected through a standardised questionnaire. RESULTS: The overall prevalence of ethylenediamine dihydrochloride sensitization was 1.29% with percentages similar in both sexes. We observed a significant decreasing trend over time (p < 0.001), yielding a sensitization prevalence <1% in recent years. Among departments, residence in Pordenone area was protective for sensitization. No significant associations were observed with specific occupations. We found significant associations between ethylenediamine dihydrochloride sensitization and being 26-35 years old (odds ratio [OR], 1.47; 95% confidence interval [CI]: 1.05-2.08), and sensitization for many haptens, such as paraben mix (OR, 5.3; 95% CI: 3.3-8.5), epoxy resin (OR, 5.1; 95% CI: 3.0-8.7), neomycin sulphate and mercaptobenzothiazole. CONCLUSIONS: Our study showed a downward time trend of ethylenediamine dihydrochloride sensitization in northeastern Italian population and pointed to an update of the Triveneto baseline series.

Analytical determination of ethylenediamine impurity in tripelennamine hydrochloride by gas chromatography-mass spectrometry using phthalaldehyde as the derivatizing agent.

In the pharmaceutical industry, effective risk management and control strategies for potential genotoxic impurities are of paramount importance. The current study utilized GC-MS to evaluate a precise, linear, and accurate analytical method for quantifying ethylenediamine present in tripelennamine hydrochloride using phthalaldehyde as a derivatizing agent. When phthalaldehyde is sonicated for 10 min at room temperature, it reacts with ethylenediamine to form (1z,5z)-3,4-dihydrobenzo[f][1,4]diazocine. This approach minimizes matrix interference issues and resolves sample preparation difficulties encountered during ethylenediamine identification in GC-MS. In this method, helium serves as the carrier gas, while methanol acts as the diluent. The stationary phase consists of a DB-5MS column (30 m × 0.25 mm × 0.25 µm) with a flow rate of 1.5 mL/min. The retention time of (1z,5z)-3,4-dihydrobenzo[f][1,4]diazocine was determined to be 6.215 min. The method validation demonstrated limits of detection and quantification for (1z,5z)-3,4-dihydrobenzo[f][1,4]diazocine at 0.4 and 1.0 ppm, respectively, with a linearity range spanning from 1 to 30 ppm concentration with respect to the specification level. System suitability, precision, linearity, and accuracy of the current method were assessed in accordance with guidelines, yielding results deemed suitable for the intended use.

Creatinine clearance in selection of living kidney donor among the Malaysian population: is it safe?

BACKGROUND: Assessment of donor renal function is made by the measurement of Glomerular Filtration Rate (GFR). Exogenous markers are preferred over creatinine clearance and are widely used for measuring GFR. However, they are difficult to obtain, costly and laborious. This is a study to look into the safety and accuracy of creatinine clearance for renal assessment among the living kidney donors in the Malaysian population. METHODS: This is a retrospective, single-centre study comprising 105 living kidney donor candidates from the year 2007 to 2020. By comparing against 51-Chromium ethylenediamine-tetraacetic acid (51Cr-EDTA), we analysed creatinine clearance for correlation, bias, precision and accuracy. RESULTS: The study group had a mean age of 45.68 ± 10.97 years with a mean serum creatinine of 64.43 ± 17.68 µmol/L and a urine volume of 2.06 ± 0.83 L. Mean measured GFR from 51Cr-EDTA was 124.37 ± 26.83 ml/min/1.73m2 whereas mean creatinine clearance was 132.35 ± 38.18 ml/min/1.73m2. Creatinine clearance overestimated 51Cr-EDTA significantly with a correlation coefficient of 0.48 (p < 0.001) and an accuracy of 78.10% and 64.0% within 30% and 20% respectively of 51Cr-EDTA. CONCLUSION: Creatinine clearance is an acceptable and affordable alternative for donor renal assessment in the absence of exogenous markers with an emphasis on adequate urine collection followed by using measured GFR in selected cases.

A Retrospective Analysis to Investigate Contact Sensitization in Greek Population Using Classic and Machine Learning Techniques.

Allergic contact dermatitis (ACD) is an inflammatory reaction affecting all age groups and both sexes. ACD is characterized by a delayed-type hypersensitivity reaction IV caused by skin contact with haptens. Chronic exposure typically leads to a decrease in erythema accompanied by lichenification (thickening and hardening of the skin) and persistent itching. The current study aims to investigate the patterns of contact sensitization in the Greek population using patch test data analysis. Patch test data from 240 patients (120 Males/120 Females) with allergic contact dermatitis were collected at the Laboratory for Patch Testing, National Reference Center for Occupational Dermatoses "Andreas Syggros" Hospital in Athens Greece. The contact allergic reactions were caused by ethylenediamine dihydrochloride 1%, thimerosal 0.5%, and methyldibromo-glutaronitrile 0.1% from the European baseline series of allergens; information was also collected for ICDRG evaluation, an extended MOAHLFA index and patient-reported outcomes (daily routine questionnaire). The chi-square test for independence and Spearman's rank were used to evaluate the association and correlation, respectively, between patient characteristics and ACD-related factors. Multiple correspondence analysis (MCA), which is a data analysis approach, was used to find and depict underlying structures in the data collection for nominal categorical data. Statistically significant associations were found between the following pairs of characteristics: eczema triggers and gender and eczema triggers and hand dermatitis. The results from MCA showed that there is correlation between allergic contact dermatitis onset, allergens, and demographic variables.

Utilization of Fe-Ethylenediamine-N,N'-Disuccinic Acid Complex for Electrochemical Co-Catalytic Activation of Peroxymonosulfate under Neutral Initial pH Conditions.

The ethylenediamine-N,N'-disuccinic acid (EDDS) was utilized to form Fe-EDDS complex to activate peroxymonosulfate (PMS) in the electrochemical (EC) co-catalytic system for effective oxidation of naphthenic acids (NAs) under neutral pH conditions. 1-adamantanecarboxylic acid (ACA) was used as a model compound to represent NAs, which are persistent pollutants that are abundantly present in oil and gas field wastewater. The ACA degradation rate was significantly enhanced in the EC/PMS/Fe(III)-EDDS system (96.6%) compared to that of the EC/PMS/Fe(III) system (65.4%). The addition of EDDS led to the formation of a stable complex of Fe-EDDS under neutral pH conditions, which effectively promoted the redox cycle of Fe(III)-EDDS/Fe(II)-EDDS to activate PMS to generate oxidative species for ACA degradation. The results of quenching and chemical probe experiments, as well as electron paramagnetic resonance (EPR) analysis, identified significant contributions of •OH, 1O2, and SO4•- in the removal of ACA. The ACA degradation pathways were revealed based on the results of high resolution mass spectrometry analysis and calculation of the Fukui index. The presence of anions, such as NO3-, Cl-, and HCO3-, as well as humic acids, induced nonsignificant influence on the ACA degradation, indicating the robustness of the current system for applications in authentic scenarios. Overall results indicated the EC/PMS/Fe(III)-EDDS system is a promising strategy for the practical treatment of NAs in oil and gas field wastewater.

Diamine Groups on the Surface of Silica Particles as Complex-Forming Linkers for Metal Cations.

Novel spherically shaped organosilica materials with (propyl)ethylenediamine groups were obtained via a modified one-pot Stöber co-condensation method. The porosity of these materials was tuned with the controlled addition of three silica monomers acting as structuring agents (tetraethoxysilane and bridged silanes with ethylene and phenylene bridges). The morphologies and structures of the synthesized materials were studied by SEM, DRIFT spectroscopy, CHNS elemental analysis, low-temperature nitrogen adsorption-desorption, and electrokinetic potential measurements. Their sizes were in the range of 50 to 100 nm, depending on the amount of structuring silane used in the reaction. The degree of the particles' agglomeration determined the mesoporosity of the samples. The content of the (propyl)ethylenediamine groups was directly related with the amount of functional silane used in the reaction. The zeta potential measurements indicated the presence of silanol groups in bissilane-based samples, which added new active centers on the surface and reduced the activity of the amino groups. The static sorption capacities (SSCs) of the obtained samples towards Cu(II), Ni(II), and Eu(III) ions depended on the porosity of the samples and the spatial arrangement of the ethylenediamine groups; therefore, the SSC values were not always higher for the samples with the largest number of groups. The highest SSC values achieved were 1.8 mmolCu(II)/g (for ethylene-bridged samples), 0.83 mmolNi(II)/g (for phenylene-bridged samples), and 0.55 mmolEu(III)/g (for tetraethoxysilane-based samples).

Halogen-Dependent Diversity and Weak Interactions in the Heterometallic Ni/Cd Complex Solids: Structural and Theoretical Investigation.

Three novel heterometallic Ni/Cd coordination compounds [Ni(en)3][CdCl4]∙3dmso (1), [Ni(en)2(dmf)2][CdBr4] (2), and [Ni(en)3]2[CdI4](I)2 (3) have been synthesized through the self-assembly process in a one-pot reaction of cadmium oxide, nickel salt (or nickel powder), NH4X (X = Cl, Br, I), and ethylenediamine in non-aqueous solvents dmso (for 1) or dmf (for 2 and 3). Formation of the one- (1) or three-dimensional (2 and 3) hydrogen-bonded frameworks has been observed depending on the nature of the [CdX4]2- counter-anion, as well as on the nature of the solvent. The electronic structures of [Ni(en)3]2+ and [Ni(en)2(dmf)2]2+ cations were studied at the DFT and CASSCF levels, including the ab initio ligand field theory (AILFT) calculations. The non-covalent intermolecular contacts between the cationic nickel and anionic cadmium blocks in the solid state were investigated by the QTAIM analysis. The mechanism of ligand substitution at the nickel center in [Ni(en)2(dmf)2]2+ was theoretically investigated at the ωB97X-D4/ma-def2-TZVP//DLPNO-CCSD(T)/ma-def2-TZVPP level. The results demonstrate that thermodynamic factors are structure-determining ones due to low energy barriers of the rotation of dmf ligands in [Ni(en)2(dmf)2]2+ (below 3 kcal mol-1) and the reversible transformation of [Ni(en)2(dmf)2]2+ into [Ni(en)3]2+ (below 20 kcal mol-1).

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica.

The chemical immobilization of cobalt(II) ions in a silica aerogel matrix enabled the synthesis of the first representative example of aerogel-based single-ion magnets. For the synthesis of the lyogels, methyl-trimethoxysilane and N-3-(trimethoxysilyl)propyl ethylenediamine were co-hydrolyzed, then the ethylenediamine groups that were immobilized on the silica matrix enabled the subsequent binding of cobalt(II) ions. Lyogels with various amounts of ethylenediamine moieties (0.1-15 mol %) were soaked in isopropanol solutions of cobalt(II) nitrate and further supercritically dried in carbon dioxide to obtain aerogels with a specific surface area of 210-596 m2·g-1, an apparent density of 0.403-0.740 cm3·g-1 and a porosity of 60-78%. The actual cobalt content in the aerogels was 0.01-1.50 mmol per 1 g of SiO2, which could easily be tuned by the concentration of ethylenediamine moieties in the silica matrix. The introduction of cobalt(II) ions into the ethylenediamine-modified silica aerogel promoted the stability of the diamine moieties at the supercritical drying stage. The molecular prototype of the immobilized cobalt(II) complex, bearing one ethylenediamine ligand [Co(en)(MeCN)(NO3)2], was synthesized and structurally characterized. Using magnetometry in the DC mode, it was shown that cobalt(II)-modified silica aerogels exhibited slow magnetic relaxation in a nonzero field. A decrease in cobalt(II) concentration in aerogels from 1.5 mmol to 0.14 mmol per 1 g of SiO2 resulted in a weakening of inter-ion interactions; the magnetization reversal energy barrier likewise increased from 4 to 18 K.

Electronic Tuning in Reaction-Based Fluorescent Sensing for Instantaneous and Ultrasensitive Visualization of Ethylenediamine.

Manipulation of a multi-physical quantity to steer a molecular photophysical property is of great significance in improving sensing performance. Here, an investigation on how a physical quantity rooted in the molecular structure induces an optical behavior change to facilitate ultrasensitive detection of ethylenediamine (EDA) is performed by varying a set of thiols. The model molecule consisting of a thiol with dual-carboxyl exhibits the strongest fluorescence, which is ascribed to the electron-donating ability and prompted larger orbital overlap and oscillator strength. The elevated fluorescence positively corelated to the increased EDA, endowing an ultrasensitive response to the nanomolar-liquid/ppm-vapor. A gas detector with superior performance fulfills a contactless and real-time management of EDA. We envisage this electron-tuning strategy-enabled fluorescence enhancement can offer in-depth insight in advancing molecule-customized design, further paving the way to widening applications.

EDTA as a chelating agent in quantitative 1H-NMR of biologically important ions.

Biologically important ions such as Ca, K, Mg, Fe, and Zn play major roles in numerous biological processes, and their homeostatic balance is necessary for the maintenance of cellular activities. Sudden and severe loss in homeostasis of just one biologically important ion can cause a cascade of negative effects. The ability to quickly, accurately, and reliably quantify biologically important ions in samples of human bio-fluids is something that has been sorely lacking within the field of metabolomics. 1H-NMR spectra. The foundation of our investigation was the a-priori knowledge that free ethylenediaminetetraacetic acid (EDTA) produces two clear single peaks on 1H-NMR spectra, and that EDTA chelated to different ions produces unique 1H-NMR spectral patterns due to 3D conformational changes in the chemical structure of chelated-EDTA and varying degrees of electronegativity. The aim of this study was to develop and test a 1H-NMR-based method, with application specifically to the field of metabolomics, to quantify biologically important ions within the physiological pH range of 6.50-7.50 using EDTA as a chelating agent. Our method produced linear, accurate, precise, and repeatable results for Ca, Mg, and Zn; however, K and Fe did not chelate with EDTA.

Bruceine A induces cell growth inhibition and apoptosis through PFKFB4/GSK3ß signaling in pancreatic cancer.

Pancreatic cancer is one of the most aggressive cancers with a poor prognosis and 5-year low survival rate. In the present study, we report that bruceine A, a quassinoid found in Brucea javanica (L.) Merr. has a strong antitumor activity against human pancreatic cancer cells both in vitro and in vivo. Human proteome microarray reveals that 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 4 (PFKFB4) is the candidate target of bruceine A and both fluorescence measurement and microscale thermophoresis suggest bruceine A binds to PFKFB4. Bruceine A suppresses glycolysis by inhibiting PFKFB4, leading to cell cycle arrest and apoptosis in MIA PaCa-2 cells. Furthermore, glycogen synthase kinase-3 ß (GSK3ß) is identified as a downstream target of PFKFB4 and an PFKFB4-interacting protein. Moreover, bruceine A induces cell growth inhibition and apoptosis through GSK3ß, which is dysregulated in pancreatic cancer and closely related to the prognosis. In all, these findings suggest that bruceine A inhibits human pancreatic cancer cell growth via PFKFB4/GSK3ß-mediated glycolysis, and it may serve as a potent agent for curing human pancreatic cancer.

Adsorption of REEs from Aqueous Solution by EDTA-Chitosan Modified with Zeolite Imidazole Framework (ZIF-8).

Chitosan (CS) modified with ethylenediamine tetraacetic acid (EDTA) was further modified with the zeolite imidazole framework (ZIF-8) by in situ growth method and was employed as adsorbent for the removal of rare-earth elements (REEs). The material (EDTA-CS@ZIF-8) and ZIF-8 and CS were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and nitrogen adsorption/desorption experiments (N2- Brunauer-Emmet-Teller (BET)). The effects of adsorbent dosage, temperature, the pH of the aqueous solution, contact time on the adsorption of REEs (La(III), Eu(III), and Yb(III)) by EDTA-CS@ZIF-8 were studied. Typical adsorption isotherms (Langmuir, Freundlich, and Dubinin-Radushkevich (D-R)) were determined for the adsorption process, and the maximal adsorption capacity was estimated as 256.4 mg g-1 for La(III), 270.3 mg g-1 for Eu(III), and 294.1 mg g-1 for Yb(III). The adsorption kinetics results were consistent with the pseudo-second-order equation, indicating that the adsorption process was mainly chemical adsorption. The influence of competing ions on REE adsorption was also investigated. After multiple cycles of adsorption/desorption behavior, EDTA-CS@ZIF-8 still maintained high adsorption capacity for REEs. As a result, EDTA-CS@ZIF-8 possessed good adsorption properties such as stability and reusability, which have potential application in wastewater treatment.

Removal of Cu(II) Contamination from Aqueous Solution by Ethylenediamine@ß-Zeolite Composite.

The low cost ß-zeolite and ethylenediamine modified ß-zeolite (EDA@ß-zeolite) were prepared by self-assembly method and used for Cu(II) removal from contaminated aqueous solution. Removal ability of ß-zeolite toward Cu(II) was greatly improved after ethylenediamine (EDA) modification, the removal performance was greatly affected by environmental conditions. XPS results illustrated that the amide group played important role in the removal process by forming complexes with Cu(II). The EDA@ß-zeolite showed desirable recycling ability. The finding herein suggested that the proposed composite is a promising and suitable candidate for the removal of Cu(II) from contaminated natural wastewater and aquifer.

Metabolic engineering of Amycolatopsis japonicum for optimized production of [S,S]-EDDS, a biodegradable chelator.

The actinomycete Amycolatopsis japonicum is the producer of the chelating compound [S,S]-ethylenediamine-disuccinc acid (EDDS). [S,S]-EDDS is an isomer of ethylenediamine-tetraacetic acid (EDTA), an economically important chelating compound that suffers from an extremely poor degradability. Frequent use of the persistent EDTA in various industrial and domestic applications has caused an accumulation of EDTA in soil as well as in aqueous environments. As a consequence, EDTA is the highest concentrated anthropogenic compound present in water reservoirs. The [S,S]-form of EDDS has chelating properties similar to EDTA, however, in contrast to EDTA it is readily biodegradable. In order to compete with the cost-effective chemical synthesis of EDTA, we aimed to optimize the biotechnological production of [S,S]-EDDS in A. japonicum by using metabolic engineering approaches. Firstly, we integrated several copies of the [S,S]-EDDS biosynthetic genes into the chromosome of A. japonicum and replaced the native zinc responsive promoter with the strong synthetic constitutive promoter SP44*. Secondly, we increased the supply of O-phospho-serine, the direct precursor of [S,S]-EDDS. The combination of these approaches together with the optimized fermentation process led to a significant improvement in [S,S]-EDDS up to 9.8 g/L with a production rate of 4.3 mg/h/g DCW.

Self-interrupted synthesis of sterically hindered aliphatic polyamide dendrimers.

2,2-Bis(azidomethyl)propionic acid was prepared in four steps and 85% yield from the commercially available 2,2-bis(hydroxymethyl)propionic acid and used as the starting building block for the divergent, convergent, and double-stage convergent-divergent iterative methods for the synthesis of dendrimers and dendrons containing ethylenediamine (EDA), piperazine (PPZ), and methyl 2,2-bis(aminomethyl)propionate (COOMe) cores. These cores have the same multiplicity but different conformations. A diversity of synthetic methods were used for the synthesis of dendrimers and dendrons. Regardless of the method used, a self-interruption of the synthesis was observed at generation 4 for the dendrimer with an EDA core and at generation 5 for the one with a PPZ core, whereas for the COOMe core, self-interruption was observed at generation 6 dendron, which is equivalent to generation 5 dendrimer. Molecular modeling and molecular-dynamics simulations demonstrated that the observed self-interruption is determined by the backfolding of the azide groups at the periphery of the dendrimer. The latter conformation inhibits completely the heterogeneous hydrogenation of the azide groups catalyzed by 10% Pd/carbon as well as homogeneous hydrogenation by the Staudinger method. These self-terminated polyamide dendrimers are enzymatically and hydrolytically stable and also exhibit antimicrobial activity. Thus, these nanoscale constructs open avenues for biomedical applications.

Preparation, characterization, and sonodynamic antitumor effect of the folate receptor targeted FA-EN-ß-CD containing hematoporphyrin in vitro.

To improve water solubility, reduce phototoxicity and increase the tumor-targeting ability of hematoporphyrin (Hp) as a sonosensitizer for sonodynamic therapy under ultrasonic conditions, a novel folate receptor (FR)-targeted, folate-conjugated ethylenediamine-ß-cyclodextrin (FA-EN-ß-CD) containing Hp (FA-EN-ß-CD-Hp) was constructed. ß-Cyclodextrin containing Hp (ß-CD-Hp) was also established as a nontargeted control. The inclusion efficiencies of Hp in FA-EN-ß-CD-Hp and ß-CD-Hp were determined to be 90.4 ± 2.7% (wt/wt) and 92.5 ± 3.4% (wt/wt), respectively. Growth inhibition rates in HepG-2 cells in vitro were assessed upon ultrasound exposure. The results indicated that the growth inhibition rates of FA-EN-ß-CD-Hp, ß-CD-Hp, and F-Hp (Hp: 150 µg/ml) reached 96.4 ± 3.6%, 53.4 ± 3.4%, and 48.2 ± 2.8%, respectively. These results indicated that FA-EN-ß-CD-Hp is a promising drug delivery system in the field of sonodynamic cancer therapy.

Surface functionalization of recycled polyacrylonitrile fibers with ethylenediamine for highly effective adsorption of Hg(II) from contaminated waters.

In this research, recycled polyacrylonitrile fibers (PANFs) acquired from the textile recycling process were amino-functionalized in one simple step by means of ethylenediamine (EDA). The amino-functionalized polyacrylonitrile fibers (AF-PANFs) were utilized for adsorption of Hg(II) ions from aquatic media. Temperature and contact time during the synthesis were optimized by the Central Composite Design (CCD) method. FE-SEM, EDS, BET, and FT-IR analysis, and pHZPC measurement were conducted to characterize the features of the AF-PANFs. The average diameter of raw fiber was 20 µm, which increased 20 percent after functionalizing. The impact of independent parameters on the adsorption process was investigated using the Box-Behnken Design (BBD) method during the batch experiments. The column tests were conducted in a semi-continuous system with the removal efficiency of over 99% for various initial concentrations after specific cycles. Freundlich, Langmuir, UT, Redlich-Peterson, and Temkin isotherm models were employed to analyze the relation between the final concentration of Hg(II) (Co) and the equilibrium adsorption capacity (qe) of the AF-PANFs. According to the isotherm models and experimental results, the maximum qe of the AF-PANFs was 1116 mg g-1 at initial Hg(II) concentration of 850 mg L-1, contact time of 120 min, solution pH of 6, and at 40 °C. Kinetic and thermodynamic studies illustrated the approximate equilibrium time and endothermicity or exothermicity of the process. Regeneration of the AF-PANFs was accomplished for seven times without efficiency drop. The superb performance of the AF-PANFs in the presence of co-existing ions did not decline.

Fabrication of the robust and recyclable tyrosinase-harboring biocatalyst using ethylenediamine functionalized superparamagnetic nanoparticles: nanocarrier characterization and immobilized enzyme properties.

Immobilized tyrosinase onto the functionalized nanoparticles with the ability to be reused easily in different reaction cycles to degrade phenolic compounds is known as a substantial challenge, which can be overcome through surface modification of the particles via proper chemical groups. Herein, the synthesis and silica coating of superparamagnetic nanoparticles using a simple procedure as well as their potential for tyrosinase immobilization were demonstrated. Therefore, N-[3-(trimethoxysilyl)propyl]ethylenediamine was used to functionalize the silica-coated nanoparticles with amine groups. Then, the ethylenediamine functionalized magnetic nanoparticles (EMNPs) were suspended in a solution containing tetrahydrofuran and cyanuric chloride (as an activating agent) to modify nanocarriers. To immobilize enzyme, a mixture of tyrosinase and cyanuric chloride functionalized magnetic nanoparticle (Cyc/EMNPs) was shaken at room temperature. The particles were characterized by EDX, TGA, SEM, FTIR, and TEM. As a result, the successful functionalization of the magnetic nanoparticles and covalent attachment of tyrosinase onto the Cyc/EMNPs were confirmed. The fabricated nano-biocatalyst particles were semi-spherical in shape. The immobilized tyrosinase (Ty-Cyc/EMNPs) exhibited remarkable reusability of six consecutive reaction cycles while no considerable loss of activity was observed for the first three cycles. Moreover, the excellent stability of the biocatalyst at different temperatures and pHs was proved. The Ty-Cyc/EMNPs with interesting features are promising for practical applications in biosensor development and wastewater treatment.

Simultaneous electrochemical determination of dopamine and epinephrine using gold nanocrystals capped with graphene quantum dots in a silica network.

Gold nanocrystals (AuNCs) were synthesized by economical and green strategy in aqueous medium by using N[3(trimethoxysilyl)propyl]ethylenediamine (TMSPED) as both a reducing and stabilizing mediator to avoid the aggregation of gold nanocrystals. Then, the AuNCs were capped with graphene quantum dots (GQDs) using an ultrasonic method. The resulting nanocomposites of GQD-TMSPED-AuNCs were characterized by X-ray photoelectron, X-ray diffraction, Raman, UV-vis and FT-IR spectroscopies. The size and shape of the nanocomposites were confirmed by using transmission electron microscopy and atomic force microscopy. The GQD-TMSPED-AuNCs placed on a glassy carbon electrode enable simultaneous determination of dopamine (DA) and epinephrine (EP) with peak potentials at 0.21 and 0.30 V (vs. Ag/AgCl). The response is linear in the 5 nM - 2.1 µM (DA) and 10 nM - 4.0 µM (EP) concentration ranges, with detection limits of 5 and 10 nM, respectively. The sensor shows good selectivity toward DP and EP in the presence of other molecules, facilitating its rapid detection in practical applications. Graphical abstract Schematic representation of gold nanocrystals capped with graphene quantum dots in the modified electrodes for simultaneous detection of dopamine and epinephrine.