Herein, we introduce a new strategy for green, in-situ generation of silver nanoparticles using flexible and transparent bacterial cellulose nanopapers. In this method, adsorbed silver ions on ...bacterial cellulose nanopaper are reduced by the hydroxyl groups of cellulose nanofibers, acting as the reducing agent producing a bionanocomposite “embedded silver nanoparticles in transparent nanopaper” (ESNPs). The fabricated ESNPs were investigated and characterized by field emission scanning electron microscopy (FE-SEM), UV–visible spectroscopy (UV–vis), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and energy-dispersive X-ray spectroscopy (EDX). The important parameters affecting the ESNPs were optimized during the fabrication of specimens. The resulting ESNPs were used as a novel and sensitive probe for the optical sensing of cyanide ion (CN−) and 2-mercaptobenzothiazole (MBT) in water samples with satisfactory results. The change in surface plasmon resonance absorption intensity of ESNPs was linearly proportional to the concentration in the range of 0.2–2.5µgmL−1 and 2–110µgmL−1 with a detection limit of 0.012µgmL−1 and 1.37µgmL−1 for CN− and MBT, respectively.
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•Green, in-situ generation of silver nanoparticles using bacterial cellulose nanopapers.•Embedded silver nanoparticles in transparent nanopaper (ESNPs) were used as a chemosensor.•The fabricated ESNPs were characterized by spectroscopic techniques.•ESNPs were used as a novel probe for the optical sensing of cyanide and 2-mercaptobenzothiazole.
This article describes the design and fabrication of a novel lab-on-paper device for pH sensing using curcumin nanoparticles (CURNs). In order to fabricate the lab-on-paper, the wax dipping method ...was used. The color of loaded paper with CURNs changed from yellow to orange and red to brown in the pH range of 7–13. The image of the lab-on-paper was taken by a digital camera and the picture was processed and analyzed using Adobe Photoshop software. The change in mean color intensity with pH was recorded and employed as an analytical signal for quantitative sensing of pH. The parameters affecting the pH sensor were optimized to enhance the selectivity and sensitivity of the method. Under optimum conditions, the mean color intensity was linearly proportional to the pH in the range of 8–13. The relative standard deviations of 10 replicate measurements of pH 9 and pH 12 were 2.3% and 1.5%, respectively. The developed sensor was successfully applied to the determination of pH in different water samples with satisfactory results.
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•Curcumin nanoparticles (CURNs) are introduced for green sensing of pH.•A novel lab-on-paper device for pH sensing has been designed.•The sensor responds to pH in alkaline medium in the range of 8–13.•First application of CURNs in a chemical probes.•pH Sensor is environmental friendly by using CURNs, paper, beeswax for its design.
This article presents a simple and efficient measurement system for quantitative sensing of blood hemoglobin (Hgb) using curcumin nanoparticles (CURNs). The Hgb monitoring is based on CURNs ...aggregation in the presence of Hgb, which leads to a decrease in the absorption intensity of CURNs. In this study the analytical signal for the measurement of blood Hgb concentration was defined as the difference in absorption intensity of the CURNs in the absence and presence of Hgb. The method was optimized to enhance the selectivity and sensitivity of the method by investigating the effect of variables such as pH of the sample solution, buffer concentration, required amount of CURNs, equilibrium time and tolerance limit of various probable interferences. Under optimum conditions, the difference in absorption intensity of the CURNs was linearly proportional to the concentration of Hgb in two ranges 1-40 μg mL
−1
and 150-1200 μg mL
−1
with a detection limit of 0.1 μg mL
−1
. The relative standard deviation for ten replicate measurements of 20 μg mL
−1
and 600 μg mL
−1
of Hgb was 3.6% and 3.1% respectively. The sensing method was successfully applied for the measurement of Hgb in human blood with satisfactory results.
This article presents a simple and efficient measurement system for quantitative sensing of blood hemoglobin (Hgb) using curcumin nanoparticles (CURNs).
Phthalate esters are synthetic chemicals that are widely used in plastic industries as plasticizer. They are harmful to humans and could be carcinogenic. In this research, a new nanosorbent was ...prepared via a Schiff-base reaction between p-dimethylaminobenzaldehyde and Fe3O4@SiO2-NH2 nanoparticles. A characterization of the sorbent was performed by Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, and energy-dispersive spectroscopy. A modified nanosorbent has a core shell structure, and shows a great tendency towards the sorption of phthalate esters. Hence, it was utilized for the dispersive solid-phase extraction of six phthalate esters and determination by gas chromatography–flame ionization detection. Several variables, such as the pH, sorbent amount, salt effects, extraction and desorption time, extraction solvent type and volume, were investigated to establish the optimal conditions. Calibration graphs were linear in the range of 1.0 – 150.0 μg L−1 for dimethyl phthalate, bis-(2-ethylhexyl) phthalate, di-n-octyl phthalate and 0.1 – 200.0 μg L−1 for diethyl phthalate, di-n-butyl phthalate and butyl benzyl phthalate, respectively. The obtained limits of detections (S/N = 3) were in the range of 0.02 – 0.31 μg L−1. Application of the method for the enrichment and determination of phthalate esters in mineral water, natural low fat yogurt and sodium chloride infusion (0.9%, w/v) was investigated.
A hydrogel network was prepared from poly(vinyl alcohol) (PVA) and borax, and then was modified with gold nanoparticles (AuNPs) that were obtained by in-situ nucleation and growth. This modified ...network is shown to be a viable optical nanoprobe for the drug ceftriaxone (CTRX) in biological samples. The properties and morphology of the modified network were investigated using energy dispersive X-ray analysis, transmission electron microscopy, zeta-sizing and viscosimetry. The UV-vis spectrum was recorded to verify the nanosynthesis of the red AuNPs, and the maximum absorption is found at 517 nm. This AuNP-poly(vinyl alcohol)-borax hydrogel nanoprobe (AuNP/PBH) is introduced as an optical nanoprobe for ceftriaxone in biological samples. The AuNPs have a better ability to attach the sulfur functional groups than amino functional groups. Hence, the probable mechanism is based on the attachment of sulfur functional groups of CRTX structure with AuNPs located in the PBH. As a result of this interaction, the surface plasmon resonance of AuNPs is altered in the presence of CTRX and the absorption of the nanoprobe is decreased at 517 nm. The effects of pH value, borax and PVA concentration were investigated. Under optimum conditions, the calibration graph is linear in the 1–90 μg mL
−1
CTRX concentration range, and the limit of detection is 0.33 μg mL
−1
. The relative standard deviation for ten replicate measurements of at levels of 20 and 70 μg mL
−1
of CTRX was 4.0% and 2.2%, respectively. The nanoprobe was successfully applied to the determination of CTRX in (spiked) serum and urine samples. The performance of the nanoprobe was compared with HPLC method and the results were satisfactory.
Graphical abstract
Schematic representation of a new nanoprobe based on in situ formation of AuNPs into poly(vinyl alcohol) (PVA)-borax (PBH) hydrogel fabricated for ceftriaxone detection. The hydrogel acts as the reducing agent for production and embedding of AuNPs in the network.
This article presents a sensitive and straightforward colorimetric chemosensor for the determination of phosphate ion utilizing curcumin nanoparticles (CUNPs) as the sensing system. The color of ...as-prepared CUNPs can be changed from yellow to orange upon adding iron(III) ions due to the formation of a complex with CUNPs. However, in the presence of phosphate ions, iron(III) ions prefer to bind to phosphate ions and, subsequently the color of CUNPs is selectively recovered because of releasing the iron(III) ions from the CUNPs-iron(III) complex. Therefore, in this work the selective color changing of the CUNPs-iron(III) system upon the addition of phosphate ions was used for the quantitative sensing of phosphate ions. Various factors, such as the pH, concentration of iron(III) and volume of CUNPs, were examined and the optimum conditions were established. A linear calibration graph over the range of 10 – 400 ng mL−1 for phosphate (r = 0.9995) was achieved using the optimal conditions. The limit of detection (LOD) of the proposed method for phosphate was 7.1 ng mL−1 and the relative standard deviation (RSD) for measuring 50 ng mL−1 of phosphate was 3.7% (n = 8). The developed method was applied for the measurement of phosphate in water, soil, and bone samples. Satisfactory results were obtained.
A novel, simple, and rapid method has been developed for the fluorimetric determination of trace levels of cefazolin. The method is based on the synthesis of silver nanoparticles (AgNPs) as ...fluorescent probes using resorcinol as a reducing and capping agent and then their extraction into the 1-octanol by a highly efficient solvent-based de-emulsification dispersive liquid–liquid microextraction technique. The interaction of cefazolin with silver affected the fluorescence intensity of AgNPs in the organic phase that creates a micro-probe fluorimetric detection of this antibiotic at excitation/emission wavelengths of 410/527 nm. Under the established optimum conditions, the linear analytical range was from 0.80 to 12.00 ng mL
−1
of cefazolin with a detection limit of 0.55 ng mL
−1
. The relative standard deviation for ten replicate measurements of 2 and 10 ng mL
−1
of cefazolin was 4.18 and 1.88%, respectively. The suggested method was successfully applied to the determination of cefazolin in pharmaceutical formulation, human urine and plasma.
Graphical abstract
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•Au nanoparticles (AuNPs) were in situ synthesized into alginate polysaccharide biopolymer.•The AuNPs entrapped in the alginate networks were functionalized by thiourea and shaped as ...a film.•Functionalized thiourea AuNPs-alginate biopolymer film was used for palladium(II) detection.•The characteristics of thiourea/AuNPs alginate film was performed by TEM, DLS, EDAX and UV–vis spectrophotometry.
A simple process was developed for the fabrication of alginate biopolymer film embedded by thiourea-functionalized AuNPs (thiourea/AuNPs) for palladium(II) detection. A mixture of sodium alginate and HAuCl4 was prepared as the main matrix and the AuNPs were in situ synthesized in alkali media provided by borax. The AuNPs entrapped in the alginate network were functionalized by thiourea and fabricated as a transparent film. The characteristics of thiourea/AuNPs alginate biopolymer film were investigated by Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDX) and UV–vis spectrophotometry. The UV–vis absorption spectrum showed the maximum wavelength of thiourea/AuNPs was at 530 nm. The effect of various parameters such as pH and thiourea concentration on the sensing of palladium(II) ions was investigated. The prepared alginate biopolymer film showed good stability over the time. The calibration graph was linear in the range of 0.05−2.10 μg mL−1 with a detection limit of 0.038 μg mL−1. The relative standard deviation (n = 10) for 0.6 and 1.2 μg mL−1 of palladium(II) was 4.6% and 3.5%, respectively. The sensing system was successfully applied for the determination of palladium in walnut leaves, wastewater, dental amalgam, and ceramic capacitor samples.
A simultaneous preconcentration method was developed for determination of trace amounts of Cu, Fe and Pb by atomic absorption spectrometry. The method is based on the retention of their methylthymol ...blue complexes by naphthalene methyltrioctyl ammonium chloride adsorbent in a column. The adsorbed metal complexes were eluted from the column with nitric acid and Cu, Fe and Pb were determined by flame atomic absorption spectrometry. Several parameters such as pH of the sample solution, ligand concentration, volume of the sample and the amount of methyltrioctyl ammonium chloride loaded on naphthalene were evaluated. The effect of diverse ions on the preconcentration was also investigated. A preconcentration factor of up to 100 or more can easily be achieved depending on the volume of the sample taken. The calibration graphs were obtained in the range of 5–40, 10–100 and 10–200
ng
ml
−1 for Cu, Fe and Pb in the initial solution, respectively, when using 500
ml of the solution. The detection limit based on three standard deviations of the blank was 0.54, 3.1, and 4.5
ng
ml
−1 for Cu, Fe and Pb, respectively. The relative standard deviations (R.S.D.) of 0.62–1.4% for Cu, 1.9–3.4% for Fe and 1.0–2.2% for Pb were obtained. The method was applied to the determination of Cu, Fe and Pb in river and wastewater samples.
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•A new dispersive liquid–liquid microextraction method designed for β-cyclodextrin.•d-limonene and β-carotene as two natural compounds are introduced in this ...method.•Spectrophotometric determination of β-cyclodextrin in pharmaceutical samples is performed.•β-Cyclodextrin enhances the absorption intensity of β-carotene in green d-limonene.
In this paper d-limonene and β-carotene are introduced as two natural products in a dispersive liquid–liquid microextraction (DLLME) method for spectrophotometric determination of β-cyclodextrin (β-CD). Dissolved β-carotene in d-limonene exhibits strong absorption exhibits strong absorption intensity after performing. The absorption intensity of the extracted phase is increased in the presence of β-CD due to its interaction (complex formation) with β-carotene. This increase in the absorbance of the extracted phase is related to the β-CD concentration and was utilized as an analytical signal for determination of β-CD. The effect of chemical variables such as pH of the sample solution, nature and volume of dispersive solvent, volume of extraction solvent and extraction time on the DLLME method was studied and optimum conditions were established. The calibration curve was linear in the range of 1×10−4–6×10−3molL−1 (r=0.9956) with a limit of detection 4×10−5molL−1. The relative standard deviation for eight replicate determinations of 1×10−3molL−1 and 5×10−3molL−1 of β-CD was 1.82% and 0.88% respectively. The proposed method was successfully applied to the determination of β-CD in spiked water and pharmaceutical samples and good recoveries in the range of 94.2–108.0% were obtained.
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