Highly efficient degradation of basic dyes using gold-coated nature-based supermagnetic iron oxide nanoparticles as eco-friendly nanocatalysts.

Nowadays, organic dyes are prevalent components in wastewater discharges due to their extensive use in various industries, posing a significant threat to public health across different organisms. As a result, wastewater treatment has become an indispensable requirement. In this study, we synthesized supermagnetic iron oxide (Fe3O4 NPs) and gold-iron oxide bimetallic nanoparticles (Au@Fe3O4 BNPs) using an eco-friendly method that involved natural compounds extracted from brown Egyptian propolis. We employed UV-visible spectroscopy, FTIR, XRD, VSM, SEM, HRTEM, EDX, Zeta potential and XPS techniques to examine the optical characteristics, chemical structure, crystalline structure, magnetic properties, morphology, size, and chemical composition of these biosynthesized nanoparticles. Furthermore, these nanoparticles were used as nanocatalysts for the removal of cationic dyes. The photocatalytic results indicated high efficiency in the removal of methylene blue (MB), crystal violet (CV), and malachite green (MG) dyes from aqueous solutions using Fe3O4 NPs and Au@Fe3O4 BNPs. The removal rates of MB, CV, and MG were about 95.2% in 70 min, 99.4% in 50 min, and 96.2% in 60 min for Fe3O4 NPs, and 97.1% in 50 min, 99.1% in 30 min, and 98.1% in 50 min for Au@Fe3O4 BNPs, respectively. The study also assessed the potential anti-radical properties of the extract, Fe3O4 NPs, and Au@Fe3O4 BNPs using the DPPH assay, and the results demonstrated their antioxidant activity. Finally, these Fe3O4 NPs and Au@Fe3O4 BNPs have the potential to serve as efficient antioxidants and photocatalysts for removing basic dyes from water.

Detailed investigation and influence of oxidation degree on synthesis, characterization and antibacterial activity of ß- cyclodextrin.

Oxidation of ß-cyclodextrin (ß-CD) using varying molar ratios of sodium periodate (NaIO4) was investigated in detail on synthesis, characterization and antibacterial property. Synthesis and characterization results showed that Oxidized ß-cyclodextrins (OX-ß-CDs) were obtained and aldehyde (CHO) groups were successfully introduced. Our results demonstrated that aldehyde content and yield increased with increasing NaIO4 molar amount. However, the structure of ß-CD was degraded as a result of glycosidic ring opening with increasing stoichiometric ratio of NaIO4/ß-CD to 5/1 and 7/1. Aldehyde functional groups in OX-ß-CDs were characterized by employing FTIR, 1H NMR, XRD, SEM techniques and confirmed by the detection of CHO peak at 1730 cm-1 in the FTIR and detection of the aldehyde H peak between 9 to 10 ppm in the 1H NMR spectrum. In addition, SEM and XRD of OX-ß-CDs showed alterations in the morphological and crystal structure (transforming from crystalline to amorphous) of ß-CD as a result of increasing oxidation. Especially, antibacterial activity of OX-ß-CDs was investigated against both Gram-negative and Gram-positive bacteria by using the minimal inhibitory concentration (MIC) and the Disk diffusion method. The results showed that OX-ß-CDs possessed good antibacterial activity, which can destroy the bacterial cell wall, and may be used as an antibacterial agent.

Enhanced Analytic Approach for Describing pH Triggered Fast Drug Release Systems.

BACKGROUND: pH sensitive dendrimers attached to nanocarriers, as one of the drug release systems, have become quite popular due to their ease of manufacture in experimental conditions and the ability to generate fast drug release in the targeted area. This kind of fast release behavior cannot be represented properly in most of the existing kinetic mathematical models. Besides, these models have either no pH dependence or pH dependence added separately. Therefore, they remained one dimensional. OBJECTIVE: The aim of this study was to establish the proper analytic equation to describe the fast release of drugs from pH sensitive nanocarrier systems, and to combine it with the pH dependent equation for to establish a two-dimensional model for whole system. METHODS: We used four common kinetic models for the comparison and we fitted them to the release data. As a result, only Higuchi and Korsmeyer-Peppas models show acceptable suitable results. None of these models have pH dependence. To get a better description for pH triggered fast release, we observed the behavior of the slope angle of the release curve. Then we proposed a new analytic equation by using relation between the slope angle and time. RESULT: By adding a pH dependent equation, we assumed the drug release is "on" or "off" above/below specific pH value and we modified a step function to get a desired behavior. CONCLUSION: Our new analytic model shows good fitting, not only one-dimensional time dependent release, but also two-dimensional pH dependent release, that provides a useful analytic model to represent release profiles of pH sensitive fast drug release systems.

Rapid determination of trace level copper in tea infusion samples by solid contact ion selective electrode.

A new solid contact copper selective electrode with a poly (vinyl chloride) (PVC) membrane consisting of o-xylylenebis(N,N-diisobutyldithiocarbamate) as ionophore has been prepared. The main novelties of constructed ion selective electrode concept are the enhanced robustness, cheapness, and fastness due to the use of solid contacts. The electrode exhibits a rapid (< 10 seconds) and near-Nernstian response to Cu2+ activity from 10-1 to 10-6 mol/L at the pH range of 4.0-6.0. No serious interference from common ions was found. The electrode characterizes by high potential stability, reproducibility, and full repeatability. The electrode was used as an indicator electrode in potentiometric titration of Cu(II) ions with EDTA and for the direct assay of tea infusion samples by means of the calibration graph technique. The results compared favorably with those obtained by the atomic absorption spectroscopy (AAS).

Spectral and thermal characterization of salophen type Schiff base and its implementation as solid contact electrode for quantitative monitoring of copper(II) ion.

Salophen templated Schiff base 2,3-bis(salicylaldimino)pyridine (H2IF) has been synthesized and fully characterized by a series of different spectroscopic methods and thermogravimetric analysis (TGA). It has been also further probed electrochemically and explored as a cation recognition ionophore in the form of a polymeric membrane as selective sensor for quantitative monitoring of Cu(2+). Dielectric properties of the membrane have been studied by electrochemical impedance spectroscopy (EIS). The potentiometric results have demonstrated that the sensor exhibits very good selectivity and sensitivity towards Cu(2+) over a wide variety of cations. The electrode has a linear response to Cu(2+) with a detection limit of 4.46×10(-8) and displays a Nernstian slope (29.14 mV/decade) between pH 3.0 and 6.0 with a fast response time less than 10s. The solid contact electrodes have been exploited over five mounts period with good reproducibility. The analytical availability of the proposed electrode has been evaluated by applying in the determination of Cu(2+) ions in water samples. The structural features and complexation of ionophore with Cu(2+) have been monitored by UV-Vis spectroscopy and spectral findings have been further supported by DFT and TD-DFT calculations.

An efficient ab initio DFT and PCM assessment of the potentiometric selectivity of a salophen type Schiff base.

As a neutral carrier component for the preparation of a potentiometric membrane sensor, the affinity and selectivity of the salophen type Schiff base ligand obtained by 1:2 condensation of 2.3-diaminopyridine with salicylaldehyde toward a series of common cations has been fully examined by DFT/B3LYP and integral equation formalism polarizable continum model (IEF-PCM or only given with PCM as default input in the computations) in combination with the experimental data. Both the potentiometric measurements and DFT calculations have exhibited that the ionophore shows appreciable selectivity for Cu(2+) ion over other cations. Four different approaches where the last three are the modified version of each other have been evaluated and compared with potentiometric data. Based upon the results of comparison among the approaches suggested to verify the selective behavior of ionophore toward Cu(2+), PCM implemented approach having a whole computational groundwork has given well-matched results with the observed data and with the method augmented with experimental hydration energies. The foremost interferences were detected by determining potentiometric selectivity coefficients for each metal ion relative to Cu(2+) and compared to the results obtained by the DFT calculations.

Potentiometric monitoring of cobalt in beer sample by solid contact ion selective electrode.

A new solid contact cobalt selective electrode was constructed with 4-tert-butylthiacalix[4]arene as ionophore. The best performance was observed with the membrane having an ionophore/polyvinyl chloride/sodium tetraphenylborate/nitrophenyl octyl ether ratio of 3.5:33:1.5:62 (w/w; mg). The electrode, under steady-state conditions, exhibited a working concentration range of 1 × 10-1 - 1 × 10-6 mol/L with a near-Nernstian slope of 25.3 mV/decade and a detection limit of 3.5 × 10-7 mol/L. The electrode had a very short response time (<10 seconds) and good reproducibility at a working pH range of 4.0-6.5. The electrode was used for 4 months without any significant change in its sensitivity. The potentiometric performance of the electrode in partially nonaqueous medium [up to 20 % (v/v) alcohol] was found satisfactory. The performance of the prepared electrode for the analysis of beer samples using direct potentiometric method is very encouraging.

A simple flow-injection spectrofluorimetric method for the determination of mercury.

A highly sensitive flow-injection spectrofluorimetric method is presented for the rapid and simple determination of Hg (II) in environmental and pharmaceutical samples. Murexide (ammonium purpurate) was used as the fluorescence reagent in the carrier stream. An emission peak of murexide, which is decreased linearly by addition of Hg (II), occurs at 435 nm in aqueous solution with excitation at 335 nm. A linear calibration was obtained for 5-200 ng ml(-1) Hg (II) with the relative standard deviation 2.5% (n = 5) for a 20 microl injection volume Hg (II). The limit of the detection was 1 ng ml(-1) and the sampling rate was 80 h(-1). No significant interference was found by the ions commonly found in the most environmental samples. The proposed method was successfully applied for the determination of trace mercury in real samples and the validation of the proposed methodology is provided.

Flow-injection spectrophotometric determination of nanogram levels of iron(III) with N,N-dimethylformamide.

A simple and fast flow-injection spectrophotometric method has been described for the determination of iron(III). The method is based on the measurement of absorbance intensity of the complex that is formed between iron(III) and N,N-dimethylformamide (DMF) at 310 nm. The carrier stream was just a mixture of water and DMF at ratio 5% (v/v). The method is highly selective; most of the 30 metal ions and anions tested did not effect on the determination of iron(III) even when present up to 1000-fold excess over iron(III). The calibration graph for iron(III) obtained under optimized conditions were linear in the range 5 - 90 ng ml(-1) with a detection limit of 0.1 ng ml(-1) for a 20 microl injection volume. The reproducibility was satisfactory, with a relative standard deviation of 2.4% (n = 5) in the range of 5-90 ng ml(-1) of iron(III). The sampling rate was over 60 h(-1). The developed method was succesfully applied to the determination of total iron in river water, seawater, hot spring water and iron alloy samples. The accuracy of the method was evaluated using the standard addition method and checked by the certified reference metal alloy samples.

Spectrophotometric flow-injection analysis of mercury(II) in pharmaceuticals with p-nitrobenzoxosulfamate.

A new, simple and rapid spectrophotometric FI method for the accurate and precise determination of Hg(II) in pharmaceutical preparations has been developed. The method is based on the measuring the decrease of absorbance intensity of p-nitrobenzoxosulfamate (NBS) due to the complexation with Hg(II). The absorption peak of the NBS, which is decreased linearly by addition of Hg(II), occurs at 430 nm in 2x10(-4) moll(-1) HNO(3) as a carrier solution. Optimization of chemical and FI variables has been made. A micro column consisting of several packing materials applied instead of reaction coil was also investigated. A background level of Fe(III) maintained in reagent carrier solution with NBS was found useful for sensitivity and selectivity. Under the optimized conditions, the sampling rate was over 100 h(-1), the calibration curve obtained were linear over the range 1-10 mugml(-1), the detection limit was lower than 0.2 mugml(-1) for a 20 mul injection volume, and the precision [S(r)=1% at 2 mugml(-1) Hg(II) (n=10)] was found quite satisfactory. Application of the method to the analysis of Hg(II) in pharmaceutical preparations resulted a good agreement between the expected and found values.

A simple and selective flow-injection spectrophotometric determination of copper(II) by using acetylsalicylhydroxamic acid.

A new simple, and rapid flow-injection spectrophotometric method is developed for the determination of trace amounts of Cu(II) by using a new chromogenic reagent acetylsalicylhydroxamic acid (AcSHA). The method is based on the formation of colored Cu(II)-(AcSHA)(2) complex. The optimum conditions for the chromogenic reaction of Cu(II) with AcSHA is studied and the colored (green) complex is selectively monitored at lambda(max) 700 nm. With the reagent carrier solvent (dimethylsulfoxide (DMSO) and acetate buffer, pH 4.2) flow-rate of 1 ml min(-1), a detection limit (2S) of 1 mug l(-1) Cu(II) was obtained at a sampling rate of 80 sample h(-1). The calibration graph was linear in the Cu(II) concentration range 5-120 mug l(-1). The relative standard deviation (n=10) was 0.64% for a sample containing 60 mug l(-1) Cu(II). The detailed study of various interferences confirmed the high selectivity of the developed method. The method was successfully applied to determine trace amounts of copper(II) in river and seawater samples. The accuracy of the method was demonstrated by the analysis of standard reference materials C12X3500 and C14XHS 50.