Quercetin nanoparticles decorated on Arabic gum and polyvinyl alcohol composite as a film sensor for fluorescence detection of meropenem.

Moving towards green chemistry to minimize the diverse effect of chemicals on human health and environment has become a great issue in chemistry. On the other hand, determination of pharmaceuticals is an important issue for both human health and environment. In this regard two natural and benign compounds such as quercetin a polyphenolic flavonoid and Arabic Gum (AG) a polysaccharide were used to construct a sensor for meropenem. Herein, a new method was established for the synthesis of AG and polyvinyl alcohol (PVA) composite decorated by quercetin nanoparticles (QUENPs) as a fluorimetric film sensor to measure meropenem. In order to embed QUENPs in the polymer composite substrate, first QUENPs were synthesized and then added to the prepared composite solution under optimal conditions. The characteristics of AG and PVA composite (AG-PVA) and AG-PVA composite decorated by QUENPs films (QUENPs-AG-PVA), before and after the addition of meropenem was studied by TEM, FT-IR and EDX-Mapping. The developed film sensor was placed in a holder made with 3D printer. The difference in the fluorescence intensity of the fabricated film before and after the addition of meropenem was taken as the signal for measuring meropenem. The effect of different parameters on the fabrication of film fluorimetric sensor such as the concentration of polymer solutions, the volume of QUENPs and the volume of glycerol were investigated. Factors affecting the measurement of meropenem such as pH, type of buffer, volume of meropenem solution added on the sensor and time were also investigated. Under the obtained optimum conditions, the calibration graph was linear in the concentration range of 50-800 ng mL-1 with a correlation coefficient (r) of 0.9976 and the detection limit was 42.6 ng mL-1. The relative standard deviation was 3.5% and 1.4%, for eight replicate determinations of 100 ng mL-1 and 400 ng mL-1 of meropenem, respectively. The proposed method was successfully utilized for determination of meropenem in blood serum, human urine and pharmaceutical samples.

Gold nanoparticles embedded Fe-BTC (AuNPs@Fe-BTC) metal-organic framework as a fluorescence sensor for the selective detection of As(III) in contaminated waters.

In this article, a new off-mode fluorescent platform based on the metal-organic framework (MOF) is introduced as a highly selective and rapid chemical sensor for the detection of As(III) in water and wastewater samples. A typical Fe-BTC (BTC = 1,3,5-benzenetricarboxylate or trimesic acid) MOF was used as a porous template for loading gold nanoparticles (AuNPs@Fe-BTC MOF). The physicochemical properties of AuNPs@Fe-BTC MOF were characterized by Fourier-transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EAX), element mapping (MAP) and X-ray diffraction (XRD) analysis. This sensing method for As(III) ions is based on the fact that the fluorescence intensity of AuNPs@Fe-BTC MOF sensor decreases in proportion to the increase in As(III) concentration. The main effective factors on the performance of the sensor signal such as MOF dosage, sonication time, pH and reaction time were optimized. Under optimized conditions, the calibration graph was linear in the concentration range of 0.5-380 ng mL-1 of As(III) and the limit of detection was 0.2 ng mL-1. The proposed method was successfully validated by addition/recovery experiments by the determination of As(III) in four river water and two wastewater effluent samples.

Development of a fluorescent probe for cefazolin detection based on solvent-based de-emulsification dispersive liquid-liquid microextraction of silver nanoparticles.

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.

A nano curcumin-multi-walled carbon nanotube composite as a fluorescence chemosensor for trace determination of celecoxib in serum samples.

A novel method is presented here for trace determination of celecoxib by fluorescence detection using curcumin nanoparticles (CurNPs) loaded on multi-walled carbon nanotubes with carboxyl functional groups (CurNPs-MWCNT-COOH). For the synthesis of CurNPs-MWCNT-COOH, CurNPs were retained on carbon nanotubes with the aid of ultrasound waves. The sensing method is based on monitoring the quenching of synthesized CurNPs-MWCNT-COOH fluorescence by celecoxib. The morphology of CurNPs-MWCNT-COOH was studied by transmission electron microscopy (TEM) of the composite alone and in the presence of celecoxib. The effects of several parameters on the production of CurNPs-MWCNT-COOH and determination of celecoxib such as the Triton X-100 concentration, the amount of MWCNT-COOH and the pH were evaluated and optimum conditions were established. The calibration graph was found to be linear in the range of 20-220 ng mL-1 for celecoxib in the initial solution. The detection limit based on three times the standard deviation of the blank was 5.8 ng mL-1 for celecoxib and relative standard deviations (RSD) of 3.6% and 1.8% were obtained for eight replicate determinations of 60 ng mL-1 and 180 ng mL-1 of celecoxib, respectively. The method was applied to the determination of celecoxib in serum samples.

Design of a Sensitive Fluorescent Zn-Based Metal-Organic Framework Sensor for Cimetidine Monitoring in Biological and Pharmaceutical Samples.

A new highly fluorescent zinc-organic framework [Zn2(btca)(DMSO)2]n (Zn-MOF) was prepared via in situ ligand formation by the solvothermal reaction of Zn(NO3)2·6H2O and pyromellitic dianhydride (PMDA) in DMSO solvent. During the solvothermal reaction, PMDA was gradually hydrolyzed to a pyromellitic acid, 1,2,4,5-benzene tetracarboxylic acid (H4btca), to provide a tetracarboxylic acid as a linker in the reaction medium. Single-crystal X-ray diffraction analysis exhibits a 3D porous structure with open tetragonal channels running along the crystallographic c-axis. The Zn-MOF was explored as an on-mode fluorescent sensor for tracing cimetidine in biological fluids and pharmaceutical samples in the presence of interfering species. The results show a quick response in a short time range. The characteristics of this sensor were investigated by field-emission scanning electron microscopy, dynamic light scattering, energy-dispersive X-ray analysis, powder X-ray diffraction, Fourier transform infrared and UV-vis spectroscopy as well as thermogravimetric, and elemental analyses.

Vortex-assisted Dispersive Solid-phase Extraction Using Schiff-base Ligand Anchored Nanomagnetic Iron Oxide for Preconcentration of Phthalate Esters and Determination by Gas Chromatography and Flame Ionization Detector.

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.

Phytochemicals toward Green (Bio)sensing.

Because of numerous inherent and unique characteristics of phytochemicals as bioactive compounds derived from plants, they have been widely used as one of the most interesting nature-based compounds in a myriad of fields. Moreover, a wide variety of phytochemicals offer a plethora of fascinating optical and electrochemical features that pave the way toward their development as optical and electrochemical (bio)sensors for clinical/health diagnostics, environmental monitoring, food quality control, and bioimaging. In the current review, we highlight how phytochemicals have been tailored and used for a wide variety of optical and electrochemical (bio)sensing and bioimaging applications, after classifying and introducing them according to their chemical structures. Finally, the current challenges and future directions/perspective on the optical and electrochemical (bio)sensing applications of phytochemicals are discussed with the goal of further expanding their potential applications in (bio)sensing technology. Regarding the advantageous features of phytochemicals as highly promising and potential biomaterials, we envisage that many of the existing chemical-based (bio)sensors will be replaced by phytochemical-based ones in the near future.

A review on advances in graphene-derivative/polysaccharide bionanocomposites: Therapeutics, pharmacogenomics and toxicity.

Graphene-based bionanocomposites are employed in several ailments, such as cancers and infectious diseases, due to their large surface area (to carry drugs), photothermal properties, and ease of their functionalization (owing to their active groups). Modification of graphene-derivatives with polysaccharides is a promising strategy to decrease their toxicity and improve target ability, which consequently enhances their biotherapeutic efficacy. Herein, functionalization of graphene-based materials with carbohydrate polymers (e.g., chitosan, starch, alginate, hyaluronic acid, and cellulose) are presented. Subsequently, recent advances in graphene nanomaterial/polysaccharide-based bionanocomposites in infection treatment and cancer therapy are comprehensively discussed. Pharmacogenomic and toxicity assessments for these bionanocomposites are also highlighted to provide insight for future optimized and smart investigations and researches.

A Green Chemosensor for Colorimetric Determination of Phosphate Ion in Soil, Bone, and Water Samples Using Curcumin Nanoparticles.

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 network composed of gold nanoparticles and a poly(vinyl alcohol) hydrogel for colorimetric determination of ceftriaxone.

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.

MgO and ZnO nanoparticles anti-nociceptive effect modulated by glutamate level and NMDA receptor expression in the hippocampus of stressed and non-stressed rats.

The anti-nociceptive mechanisms of MgO and ZnO nanoparticles have not been thoroughly investigated; in this study, we evaluated the effects of anti-nociceptive dose of MgO and ZnO NPs on glutamate level and NMDA receptor subunits expression (NR1, NR2 and NR2B) in the rat whole hippocampus with and without acute restraint stress. Adult rats were divided into control, MgO and ZnO NPs 5 mg/kg, the stress of 90 min alone and with MgO or ZnO NPs 5 mg/kg groups. All components injected intraperitoneally and the nociceptive response was measured with hot plate apparatus 90 min after injections or stress induction. Magnesium, zinc, glutamate levels and NMDA receptor subunits expression were measured in the animal hippocampus. MgO NPs, ZnO NPs and acute stress induced anti-nociceptive effect. MgO NPs observably decreased glutamate and increased magnesium levels and NR2B subunit expression. ZnO NPs decreased glutamate level. Stress elevated endogenous magnesium and zinc levels and also the NR2B expression, but did not change glutamate level. MgO and ZnO NPs in the presence of stress increased the glutamate level and ZnO NPs increased the zinc and the NR2A expression. Stress decreased endogenous magnesium in the hippocampus. MgO and ZnO NPs could affect pain perception by changing glutamate level in the whole hippocampus tissue, while ion level changes followed by injection could probably affect the gene expression in the presence and the absence of stress. It seems that stress indirectly could adverse nanoparticles effects on glutamate level and increase zinc ion releasing from ZnO NPs by activating the gene expression without affecting pain perception.

Hydrogel based aptasensor for thrombin sensing by Resonance Rayleigh Scattering.

In this research, a novel Resonance Rayleigh Scattering (RRS) aptasensor was developed for thrombin monitoring using in-situ synthesized and embedded Au nanoparticles (AuNPs) into poly vinyl alcohol -borax hydrogel (PBH). Thiolated-thrombin binding aptamer (thiolated-TBA) was attached to the surface of AuNPs embedded into PBH to design the PBH-aptasensor for thrombin detection (thiolated-TBA@AuNPs-PBH). To verify the characteristic and morphology of PBH nanocomposite, energy dispersive X-ray analysis, TEM, average particle size analizer and UV-Vis spectra were performed. The difference in RRS intensities in the absence and presence of thrombin was calculated and selected as the monitoring signal. Effect of different parameters on the RRS signal was investigated at excitation wavelength of 500 nm. Under the approved conditions, the linear detection range was validated over the concentration of 0.70 pM- 0.02 µM. The limit of detection based on 3Sb was 0.10 pM. The relative standard deviation for 5.6 pM and 3.6 nM were 4.0 and 2.7% (n = 10), respectively. The proposed aptasensor was successfully applied as an experimental model for thrombin detection in serum samples of healthy volunteers with acceptable results.

Green synthesized carbon quantum dots from Prosopis juliflora leaves as a dual off-on fluorescence probe for sensing mercury (II) and chemet drug.

In this article, a facile and green dual fluorescence sensor was developed for mercury and chemet as an anti-poisoning drug for heavy metal ions. The method is based on "off-on" fluorescence of carbon quantum dots (CQDs) prepared from Prosopis juliflora leaves as a green and low cost source. The synthesis of CQDs was easily performed with a rapid one pot process and the prepared CQDs exhibited a blue luminescence with a 5% quantum yield. The off fluorescent is observed in the presence of different concentrations of mercury (II) that is specifically recovered with the addition of chemet. The gradually recovered fluorescence is due to the high affinity of chelating property of succimer drug towards mercury (II) with a good restoration. Under the optimized condition, two linear calibrations were validated in the range of 5-500 ng mL-1 and 2.5-22.5 ng mL-1 for Hg (II) and chemet, respectively. The limit of detection (LOD) based on 3Sb was 1.26 ng mL-1 (or 6.3 nM) for Hg (II) and 1.4 ng mL-1 for chemet. The relative standard deviation of the fluorescent probe for 50 ng mL-1 of Hg (II) and 10 ng mL-1 of chemet was 4.5% and 1.3% (n = 10), respectively. This methodology was applied to successful measurements of Hg (II) and chemet in the water and human serum samples, respectively.

Colorimetric sensing of palladium ions based on in situ generation of palladium nanoparticles as an activator for the thionine-hydrazine reaction.

In this article, a simple and rapid colorimetric sensing method was developed for the determination of palladium ions. The method is based on in situ generation of palladium nanoparticles (PdNPs) upon reduction by hydrazine which then acts as an activator on the reduction reaction of thionine by hydrazine. The formation of PdNPs was characterized by UV-Vis spectrophotometry, particle size analysis and TEM images. The reaction was followed by measuring the thionine absorbance at 599 nm with time. Several factors influencing analytical performance of the kinetic method such as concentration of reactants and electrolyte, pH of the sample solution and temperature were investigated to achieve the optimum conditions and highest sensitivity. This method showed a linear calibration curve in the concentration range of 8-1200 ng mL-1 for palladium ions. The limit of detection (LOD) was 6.5 ng mL-1 and the relative standard deviations were 3.8% and 1.3% (n = 8) for two palladium ion concentrations of 60 and 300 ng mL-1, respectively. The method was successfully applied to the determination of palladium in river water, pond water, wastewater and soil samples.

Neurobehavioral and biochemical modulation following administration of MgO and ZnO nanoparticles in the presence and absence of acute stress.

In this work, the effects of MgO and ZnO nanoparticles were investigated on some behavioral, hormonal and biochemical changes following acute stress. Wistar male rats were divided into groups of control, different times of restraint stress (90, 180 and 360 min), nano-MgO or nano-ZnO alone and with acute restraint stress. Anxiety-like behaviors and pain perception were evaluated by elevated plus maze and hot plate apparatus respectively. Levels of corticosterone hormone, malondialdehyde (MDA) and catalase activity, Mg, Zn, Fe and Ca were evaluated in the serum and hippocampus. The results showed that nano-MgO and nano-ZnO improved anxiety induced by restraint stress and reduced locomotor activity significantly at high doses, while at low doses could induce analgesia in the non-restraint group. Corticosterone level increased temporarily in the presence of 360 min stress while it was reduced in the stress of 90 min just 2 h after stress induction. The highest dose of nano-MgO increased the corticosterone level in non-restraint animals while nano-ZnO reduced it in all the groups. The 90 min stress was increased MDA level and nanoparticles decreased catalase activity in the hippocampus significantly. Influences of both nanoparticles on levels of Mg, Zn, Fe and Ca in the serum and hippocampus seem to be more visible than the other measured biochemical factors. Accordingly, in acute stress conditions, low doses of nano-MgO and nano-ZnO had suitable effects on behavioral responses. It seems that these effects were mostly through the central and peripheral changes of mentioned element's content and acute stress could increase nanoparticles toxicity.

In situ synthesized and embedded silver nanoclusters into poly vinyl alcohol-borax hydrogel as a novel dual mode "on and off" fluorescence sensor for Fe (III) and thiosulfate.

Herein, a novel method has been developed for in situ synthesis and embedding of silver nanoclusters (AgNCs) into polyvinyl alcohol and borax hydrogel (PBH) without adding any reducing agent. A three-dimensional network of polyvinyl alcohol and borax is formed, and at the same time the silver ions penetrate into the hydrogel, reduced to silver and trapped into the hydrogel bed. The characteristics of this hydrogel nanocomposite were investigated by energy dispersive X-ray spectroscopy and transmission electron microscopy (TEM). It was also observed that the fluorescence intensity of embedded AgNCs into polyvinyl alcohol and borax hydrogel (AgNCs-PBH) was enhanced and quenched in the presence of Fe (III) and thiosulfate, respectively. Therefore a novel dual on-off fluorescence sensor was developed based on polyvinyl alcohol-borax hydrogel for the first time. After preparing this new probe, the effect of Fe (III) and thiosulfate was investigated. The size- depending of label free AgNCs was found to be responsible for the enhancing and quenching of the fluorescence as well as obvious color changing. Under the approved condition, the linear ranges were validated over the concentration of 0.14-27.0µmolL-1 and 0.1-1.0µmolL-1 for Fe (III) and thiosulfate, respectively. The limit of detection based on three times the standard deviation of the blank was 0.045 and 0.060µmolL-1 for Fe (III) and thiosulfate, respectively. The relative standard deviation for intra-day and inter-day determinations of both Fe (III) and thiosulfate were in the range of 3.23-5.17% (n = 10). This sensing probe was used for Fe (III) detection in some food samples and thiosulfate in water samples with acceptable results and good recoveries.

A combination of dispersive liquid-liquid microextraction and surface plasmon resonance sensing of gold nanoparticles for the determination of ziram pesticide.

We have developed a reliable, fast, and highly sensitive analytical method utilizing dispersive liquid-liquid microextraction and gold nanoparticles probes for ziram (zinc bis(dimethyldithiocarbamate)) determination. The method is based on the in situ formation of gold nanoparticles in carbon tetrachloride as an organic phase. It was found that the trace levels of ziram influenced the formation of gold nanoparticles, leading to absorbance change of a sedimented phase. The results of the colorimetric ziram determination were in the concentration range of 0.12-2.52 ng/mL with a limit of detection of 0.06 ng/mL. The formation of the stable and dispersed gold nanoparticles in the organic phase provides a good precision for dispersive liquid-liquid microextraction method, resulting in the relative standard deviation of 3.8 and 1.2% for 0.56 and 1.58 ng/mL of ziram, respectively. This method has been successfully used for the ziram determination in samples of well and river water, soil, potato, carrot, wheat, and paddy soil.

Colorimetric sensing of oxalate based on its inhibitory effect on the reaction of Fe (III) with curcumin nanoparticles.

In this research, a new colorimetric method for the determination of oxalate using curcumin nanoparticles (CURNs) in the presence Fe (III) is introduced. The method is based on the inhibitory effect of oxalate ion on the reaction of (CURNs) with Fe (III) in acidic media. This reaction was monitored by measuring the increase in absorbance of CURNs-Fe3+ complex in the presence of oxalate ion at 427nm. The effect of different parameters such as the pH of the sample solution, concentration of Fe (III), concentration of CURNs and the reaction time was examined and optimized. Under optimum experimental conditions, the absorption intensity was linear with the concentration of oxalate in the range of 0.15 to 1.70µgmL-1. The limit of detection (LOD) was 0.077µgmL-1 and the relative standard deviations (RSD) for 8 replicate measurements of 0.40 and 1.05µgmL-1 of oxalate were 4.20% and 2.74%, respectively. The developed method was successfully employed to the determination of oxalate in water, food and urine samples with satisfactory results.

Fabrication of magnetic Fe3O4@nSiO2@mSiO2-NH2 core-shell mesoporous nanocomposite and its application for highly efficient ultrasound assisted dispersive µSPE-spectrofluorimetric detection of ofloxacin in urine and plasma samples.

In this research, a sensitive, simple and rapid ultrasound assisted dispersive micro solid-phase extraction (USAD-µSPE) was developed using a synthesized core-shell magnetic mesoporous nanocomposite (Fe3O4@nSiO2@mSiO2-NH2) as an efficient adsorbent for the preconcentration and spectrofluorometric determination of ofloxacin (OFL) in biological samples. The synthesized adsorbent was characterized using FT-IR spectroscopy, transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), energy dispersive X-ray (EDX) spectroscopy, thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) analysis. The application of this magnetic nanocomposite as a sensitive solid phase for removal, preconcentration and spectrofluorometric quantification of trace amount of OFL was developed. Influence of various variables including pH, sorbent dosage, desorption solvent properties and sonication time on present method response was studied and optimized. The results showed that using the proposed method OFL can be determined in the linear concentration range of 1.0-500.0µgL-1 with a limit of detection as low as 0.21µgL-1 and relative standard deviation less than 2.5 (%). The results of human urine and blood plasma analysis showed that the method is a good candidate for biological sample analysis purposes.

Resonance Rayleigh scattering method for determination of 2-mercaptobenzothiazole using gold nanoparticles probe.

A sensitive, simple and novel method was developed to determine 2-mercaptobenzothiazole (2MBT) in water samples. This method was based on the interaction between gold nanoparticles (AuNPs) and 2MBT followed by increasing of the resonance Rayleigh scattering (RRS) intensity of nanoparticles. The change in RRS intensity (ΔIRRS) was linearly correlated to the concentration of 2MBT over the ranges of 5.0-100.0 and 100.0-300.0 µg L(-1). 2MBT can be measured in a short time (5 min) without any complicated or time-consuming sample pretreatment process. Parameters that affect the RRS intensities such as pH, concentration of AuNPs, standing time, electrolyte concentration, and coexisting substances were systematically investigated and optimized. Interference tests showed that the developed method has a very good selectivity and could be used conveniently for determination of 2MBT. The limit of detection (LOD) and limit of quantification (LOQ) were 1.0 and 3.0 µg L(-1), respectively. Relative standard deviations (RSD) for 20.0 and 80.0 µg L(-1) of 2MBT were 1.1 and 2.3, respectively. Possible mechanisms for the RRS changes of AuNPs in the presence of 2MBT were discussed and the method was successfully applied for the analysis of real water samples.