Green-synthesized chitosan­carbon dot nanocomposite as turn-on aptasensor for detection and quantification of Leishmania infantum parasite.

Leishmania is one of the most common diseases between human and animals, caused by Leishmania infantum parasite. Here, we have developed an ultra-selective turn-on fluorescent probe based on an aptamer and Chitosan-CD nanocomposite. The CD used in this study were synthesized using Quercus cap extract and a microwave-assisted approach. The Chitosan-CD nanocomposite was optimized using several microscopic and spectroscopic techniques to possess a bright fluorescence emission before adding aptamer and totally quenched fluorescence after addition of aptamer. The designed probe was proficient in the detection and quantification Leishmania infantum parasite by selective targeting of poly(A) binding protein (PABP) on the surface of the parasite. The designed fluorescent biosensor with high sensitivity, excellent selectivity, and a limit of detection (LOD) of 94 cells/mL of the Leishmania infantum parasite as well as a linear response in the ranges of 188-750 cells/mL and 3000-6000 cells/mL (R2 ≥ 0.98 for both linear ranges). Additionally, the selectivity of the designed probe was evaluated in the presence of different pathogenic species such as Trypanosoma brucei parasite and Staphylococcus aureus bacteria, as well as LiIF2α and LiP2a and BSA proteins as interference substances. The results of this study shows that using Chitosan-CD nanocomposite is a great strategy for developing selective turn-on probes with extraordinary accuracy and sensitivity in identifying Leishmania infantum parasite, especially in the early stages of the disease, and it is promising for the future clinical applications.

Ultrasound-assisted adsorption approach for desulfurization of n-heptane using nitrogen-doped magnetic carbon dot nanocomposite.

Desulfurization is an important process that not only affects the quality and performances of fuels but also is of great importance from environmental aspects. In this research, nitrogen-doped magnetic carbon dots nanocomposite was synthesized and characterized, and it's potential in adsorptive removal of thiophenes (i.e., thiophene, benzothiophene, and dibenzothiophene) from n-heptane (i.e., as model fuel) was investigated. After optimization of adsorption process, the removal efficiency was obtained above 95% for all of studied thiophenes. Besides that, it was concluded that using ultrasound during the adsorption process could enhance the maximum adsorption capacity. Langmuir model was able to appropriately describe the adsorption isotherm data, where the maximum equilibrium adsorption capacities for thiophene, benzothiophene and dibenzothiophene were obtained as 90.22, 96.51 and 100.38 mgg-1, respectively. The analysis of kinetic data also revealed that all thiophenes were being adsorbed following Pseudo-second-order model. To regenerate the adsorbent, the desorption process was also investigated using different solvents under different conditions, methanol was found as effective solvent for regeneration. The proposed adsorbent was used successfully for the removal of pollutants in a gasoline sample.

Solar energy-based electromembrane extraction using agarose gel for the determination of nonsteroidal anti-inflammatory drugs from biological samples: An environmentally friendly strategy.

This paper presents the application of solar energy as a renewable resource in gel electromembrane extraction (G-EME). The extraction driving force (electrical field) generated from solar energy is stored through photovoltaic panels and significantly contributes to reducing the emission of greenhouse gasses. Moreover, the replacement of the polypropylene membrane and organic extracting solvents with biodegradable agarose membrane and the aqueous extracting solutions makes the presented approach compatible with the principles of green chemistry. Naproxen (NAP) and ibuprofen (IBF) were extracted from urine samples to the aqueous acceptor phase containing an anode electrode situated on the other side of the agarose gel membrane. Acceptable linearity was obtained in the concentration ranges of 6-100 and 9-100 µg. L - 1 with detection limits of 2 and 3 µg. L - 1 for NAP and IBF, respectively.

Competition of hydrogen, tetrel, and halogen bonds in COCl2-HOX (X=F, Cl, Br, I) complexes.

The present study investigates the competition between hydrogen, halogen, and tetrel bonds from the interaction of COCl2 with HOX using quantum chemistry simulations at the MP2/aug-cc-pVTZ computational level, in which five configurations were optimized, including adducts I -V. Two hydrogen bonds, two halogen bonds, and two tetrel bonds were obtained for five forms of adducts. The compounds were investigated using spectroscopic, geometry, and energy properties. Adduct I complexes are more stable than others, and adduct V halogen bonded complexes are more stable than adduct II complexes. These results are in agreement with their NBO and AIM results. The stabilization energy of the XB complexes depends on the nature of both the Lewis acid and base. The stretching frequency of the O-H bond in adducts I, II, III, and IV displayed a redshift, and a blue shift was observed in adduct V. The results for the O-X bond showed a blue shift in adducts I and III and a red shift in adducts II, IV, and V. The nature and characteristics of three types of interactions are investigated via NBO analysis and atoms in molecules (AIM).

Electromembrane extraction using biodegradable deep eutectic solvents and agarose gel as green and organic solvent-free strategies for the determination of polar and non-polar bases drugs from biological samples: A comparative study.

Two modes of electromembrane extraction (EME) were evaluated in this work, one using deep eutectic solvents (DESs) as liquid membrane, and another was gel electromembrane extraction (G-EME) based on solid agarose membrane. Both EME modes have eliminated organic solvents and are recognized as green strategies. Unlike classic EME in which polypropylene membrane and organic extracting solvents play an essential role in the extraction process, new modes of EME are based on biodegradable membranes and aqueous extracting solutions. Approaches of EME based on the new designs follow the green chemistry principles. Each mode of EME was evaluated for the determination of polar and non-polar bases drugs from human urine samples using high-performance liquid chromatography (HPLC) equipped with a diode array detector (DAD). EME using DES A was suitable for determining polar and non-polar bases drugs in a large polarity window. While extraction recoveries for all six drugs studied by G-EME were lower than EME using DES A. Comparing the two EME modes shows similar results in the analytical figures of merit. However, differences in extraction recoveries of the drugs by two EME modes were observed which is related to the difference in membranes structure. Our findings indicate that the differences between membranes properties used in two EME modes, including the permeability, hydrophilicity, hydrophobicity, and variety of interactions, are influencer factors on extraction efficiency. The two EME modes provided good linearity in the ranges of 16-100 and 19-100 µg. L-1 for G-EME and EME using DES A, respectively with (r2 > 0.993). Also, the detection limits (LODs) were 19-32 and 19-29 µg. L-1 for G-EME and EME using DES A, respectively.

Enrichment of psychotropic drugs using rhamnolipid bioaggregates after electromembrane extraction based on an agarose gel using a rotating electrode as a green and organic solvent-free strategy.

We here present an efficient approach for the tandem extraction of psychotropic drugs using biodegradable materials. In this regard, gel electromembrane extraction (G-EME) was combined with the emulsification-based microextraction (ME) technique by rhamnolipid bioaggregates as a green extraction approach. The tandem extraction technique consists of two stages: (i) extraction of psychotropic drugs from human urine samples to the acceptor phase situated on the other side of the agarose gel membrane, and (ii) transfer of analytes from the acceptor phase into a colloidal phase of rhamnolipid biosurfactants. The colloidal phase was formed by adding rhamnolipid biosurfactants to the extracted phase of the first step. The colloidal phase was finally injected into a liquid chromatographic system for quantitative analysis. G-EME mechanism is based on electrokinetic migration of charged species toward oppositely charged electrode located in the acceptor solution under the influence of the electric field. After extraction, the analytes were trapped in an emulsion phase floating on the surface of the solution and at the end were injected into the liquid chromatographic system. The method provided good linearity in the ranges of 5-100 and 10-100 µg. L-1 for methamphetamine and amphetamine, respectively with (r2 > 0.992). Also, the detection limits (LODs) were 1 and 5 µg. L-1 for methamphetamine and amphetamine, respectively. The mean extraction recoveries by G-EME-ME for real samples at three spiked concentrations were in the range 95.9-101.1% and complete analytical workflow within only 18 min.

Thymol polymeric nanoparticle synthesis and its effects on the toxicity of high glucose on OEC cells: involvement of growth factors and integrin-linked kinase.

BACKGROUND: Nowadays, the drug delivery system is important in the treatment of diseases. PURPOSE: A polymeric nanoparticle modified by oleic acid (NPMO) as a Thymol (Thy) drug release system was synthesized from Thymbra spicata and its neurotrophic and angiogenic effects on rat's olfactory ensheathing cells (OECs) in normal (NG) and high glucose (HG) conditions were studied. METHODS: The NPMO was characterized by using different spectroscopy methods, such as infrared, HNMR, CNMR, gel permeation chromatography, dynamic light scattering, and atomic force microscopy. Load and releasing were investigated by HPLC. The toxicity against OECs diet-induced by MTT assay. ROS and generation of nitric oxide (NO) were evaluated using dichloro-dihydro-fluorescein and Griess method, respectively. The expression of protein integrin-linked kinase (ILK), vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) were evaluated by Western blotting. RESULTS: ThyNPMO is desirable for transferring drug as a carrier. The amount of Thy and extract (E) loaded on NPMO estimated at 43±2.5% and 41±1.8%, respectively. Then, 65% and 63% of the drug load were released, respectively. Thy, ThyNPMO, E, and ENPMO prevented HG-induced OECs cell death (EC50 33±1.5, 22±0.9, 35±1.8, and 25±1.1 µM, respectively). Incubation with Thy, ThyNPMO, E ,and ENPMO at high concentrations increased cell death with LC50 105±3.5, 82±2.8, 109±4.3, and 86±3.4 µM, respectively in HG states. CONCLUSION: OECs were protected by ThyNPMO and ENPMO in protective concentrations by reducing the amount of ROS and NO, maintaining ILK, reducing VEGF, and increasing BDNF and NGF. The mentioned mechanisms were totally reversed at high concentrations.

Bio-dispersive liquid liquid microextraction based on nano rhaminolipid aggregates combined with magnetic solid phase extraction using Fe3O4@PPy magnetic nanoparticles for the determination of methamphetamine in human urine.

In the present investigation, extraction and preconcentration of methamphetamine in human urine samples was carried out using a novel bio-dispersive liquid liquid microextraction (Bio-DLLME) technique coupled with magnetic solid phase extraction (MSPE). Bio-DLLME is a kind of microextraction technique based nano-materials which have potential capabilities in many application fields. Bio-DLLME is based on the use of a binary part system consisting of methanol and nano rhaminolipid biosurfactant. Use of this binary mixture is ecologically accepted due to their specificity, biocompatibility and biodegradable nature. The potential of nano rhaminolipid biosurfactant as a biological agent in the extraction of organic compounds has been investigated in recent years. They are able to partition at the oil/water interfaces and reduce the interfacial tension in order to increase solubility of hydrocarbons. The properties of the prepared Fe3O4@PPy magnetic nanoparticles were characterized using Fourier transform infrared spectroscopy and X-ray diffraction methods The influences of the experimental parameters on the quantitative recovery of analyte were investigated. Under optimized conditions, the enrichment factor was 310, the calibration graph was linear in the methamphetamine concentration range from 1 to 60µgL-1, with a correlation coefficient of 0.9998. The relative standard deviations for six replicate measurements was 5.2%.

Biosorption-based dispersive liquid-liquid microextraction combined with polypyrrole-coated magnetic nanoparticles as an effective sorbent for the extraction of ibuprofen from water samples using magnetic solid-phase extraction.

In this paper, biosorption-based dispersive liquid-liquid microextraction (BioDLLME) in combination with magnetic solid-phase extraction (MSPE) has been developed as a sample pretreatment method with high enrichment factor for the sensitive determination of ibuprofen in water samples. At first, magnetic Fe3 O4 /polypyrrole nanoparticles were synthesized and employed as sorbent for the MSPE of ibuprofen. After the elution of the desired compound from the sorbent by using methanol, BioDLLME technique was performed on the obtained solution. After MSPE, the eluent of MSPE was used as the disperser solvent for BioDLLME, so that the extra preconcentration factor could be achieved. The properties of the prepared magnetic sorbent were characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction methods. Experimental parameters affecting the extraction efficiency were studied and optimized. Under optimum conditions, the enrichment factor was 274. The linear dynamic range and limit of detection are 0.25-80 and 0.083 µg/L, respectively. The relative standard deviations for six replicate measurements are 3.82%.

Highly selective and sensitive method for Cu2+ detection based on chiroptical activity of L-Cysteine mediated Au nanorod assemblies.

Herein, we demonstrated a simple and efficient method to detect Cu2+ based on amplified optical activity in the chiral nanoassemblies of gold nanorods (Au NRs). L-Cysteine can induce side-by-side or end-to-end assembly of Au NRs with an evident plasmonic circular dichroism (PCD) response due to coupling between surface plasmon resonances (SPR) of Au NRs and the chiral signal of L-Cys. Because of the obvious stronger plasmonic circular dichrosim (CD) response of the side-by-side assembly compared with the end-to-end assemblies, SS assembled Au NRs was selected as a sensitive platform and used for Cu2+ detection. In the presence of Cu2+, Cu2+ can catalyze O2 oxidation of cysteine to cystine. With an increase in Cu2+ concentration, the L-Cysteine-mediated assembly of Au NRs decreased because of decrease in the free cysteine thiol groups, and the PCD signal decreased. Taking advantage of this method, Cu2+ could be detected in the concentration range of 20pM-5nM. Under optimal conditions, the calculated detection limit was found to be 7pM.

New strategy for the biosorption of atrazine after magnetic solid-phase extraction from water followed by high-performance liquid chromatography analysis.

We describe a rapid and simple microextraction of atrazine from water samples. This method is based on the use of magnetic nanoparticles as sorbents and bioaggregates that are applied to the extraction and preconcentration of atrazine. The resulting magnetic nanoparticles possess a fast adsorption kinetics and high adsorption capacity. Bioaggregates made up of rhaminolipid biosurfactant were assessed as a new strategy for the sample treatment. The extractant was obtained from magnetic nanoparticles using the magnetic solid-phase extraction method. Then the target analyte was rapidly transferred from the sorbent surface to bioaggregates, which have a low toxicity and are green and ecofriendly. Finally, the extract is centrifuged and transferred to micro-syringe for analysis by high-performance liquid chromatography. Experimental parameters affecting the extraction efficiency were studied and optimized. Under optimum conditions the enrichment factor was 268. The linear dynamic range and limit of detection were 0.1-50 and 0.033 µg/L, respectively. The relative standard deviation for six replicate measurements was 5.3%. The results demonstrate good applicability of biosorption-assisted magnetic solid-phase extraction method for the determination of atrazine from water samples.

Synthesis and application of ion-imprinted polymer nanoparticles for the extraction and preconcentration of mercury in water and food samples employing cold vapor atomic absorption spectrometry.

We describe a nanosized Hg(II)-imprinted polymer that was prepared from methacrylic acid as functional monomer, ethyleneglycol dimethacrylate as cross-linker, 2,2'-azobisisobutyronitrile (AIBN) as radical initiator, 2, 2'-di pyrydyl amine as a specific ligand, and Hg (II) as the template ions by precipitation polymerization method in methanol as the progeny solvent. Batch adsorption experiments were carried out as a function of pH, Hg (II) imprinted polymer amount, adsorption and desorption time, volume, and concentration of eluent. The synthesized polymer particles were characterized physically and morphologically by using infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopic techniques. The maximum adsorption capacity of the ion-imprinted and non-imprinted sorbent was 27.96 and 7.89 mg g(-1), respectively. Under optimal conditions, the detection limit for mercury was 0.01 µg L(-1) and the relative standard deviation was 3.2 % (n = 6) at the 1.00 µg L(-1). The procedure was applied to determination of mercury in fish and water samples with satisfactory results.

Synthesis and application of ion-imprinted polymer nanoparticles for the extraction and preconcentration of copper ions in environmental water samples.

Novel Cu(II) ion-imprinted polymers (Cu-IIP) nanoparticles were prepared by using Cu(II) ion-thiosemicarbazide complex as the template molecule and methacrylic acid, ethylene glycol dimethacrylate (EGDMA), and 2,2'azobisisobutyronitrile (AIBN) as the functional monomer, cross-linker, and the radical initiator, respectively. The synthesized polymer nanoparticles were characterized by using infrared spectroscopy (IR), thermo gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopic (SEM) techniques. Some parameters such as pH, weight of the polymer, adsorption time, elution time, eluent type, and eluent volume which affect the extraction efficiency of the polymer were studied. In the proposed method, the maximum sorbent capacity of the ion-imprinted polymer was calculated to be 38.8 mg g(-1). The preconcentration factor, relative standard deviation, and limit of detection of the method were found to be 80, 1.7%, and 0.003 µg mL(-1), respectively. The prepared ion-imprinted polymer nanoparticles have an increased selectivity toward Cu(II) ions over a range of competing metal ions with the same charge and similar ionic radius. The method was applied to the determination of ultra trace levels of Cu2+ in environmental water samples with satisfactory results.

Synthesis and application of ion-imprinted polymer nanoparticles for the determination of nickel ions.

Novel Ni(II) ion-imprinted polymers (Ni-IIP) nanoparticles were prepared by using Ni(II) ion-1,5-diphenyl carbazide (DPC) complex as the template molecule and methacrylic acid, ethylene glycol dimethacrylate (EGDMA) and 2,2'-azobisisobutyronitrile (AIBN) as the functional monomer, cross-linker and the radical initiator, respectively. The synthesized polymer particles were characterized physically and morphologically by using infrared spectroscopy (IR), thermo gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopic (SEM) techniques. Some parameters such as pH, weight of the polymer, adsorption time, elution time, eluent type and eluent volume which affects the efficiency of the polymer were studied. The preconcentration factor, relative standard deviation, and limit of detection of the method were found to be 100, 1.9%, and 0.002 µg mL(-1), respectively. The prepared ion-imprinted polymer particles have an increased selectivity toward Ni(II) ions over a range of competing metal ions with the same charge and similar ionic radius. The method was applied to the determination of nickel in tomato and some water samples.

Synthesis and application of ion-imprinted polymer nanoparticles for the extraction and preconcentration of zinc ions.

A new Zinc (II) ion-imprinted polymer (IIPs) nanoparticles was synthesised for the separation and recovery of trace Zn (II) ion from food and water sample. Zn (II) IIP was prepared by copolymerisation of methyl methacrylate (monomer) and ethylene glycol dimethacrylate (cross-linker) in the presence of Zn (II)-N,N'-o-phenylene bis (salicylideneimine) ternary complex wherein Zn (II) ion is the imprint ion and is used to form the imprinted polymer. Moreover, control polymer (NIP) particles were similarly prepared without the zinc (II) ions. The unleached and leached IIP particles were characterised by X-ray diffraction, Fourier transform infra-red spectroscopy and scanning electron microscopy. The preconcentration of Zn(2+) from aqueous solution was studied during rebinding with the leached IIP particles as a function of pH, the weight of the polymer material, the uptake and desorption times, the aqueous phase and the desorption volumes. Flame atomic absorption spectrometry was employed for determination of zinc in aqueous solution.

Sensitive quantification of trace zinc in water samples by adsorptive stripping voltammetry.

A simple and sensitive adsorptive stripping voltammetry method was developed for determination of Zn using N-nitrozo-N-phenylhydroxylamine (cupferron) as a selective complexing agent. This complex absorbed on the hanging mercury drop electrode and created a sensitive peak current. The peak current and concentration of zinc accorded with a linear relationship in the range of 0.85-320 ng mL(-1). The influence of pH and the nature of supporting electrolytes, concentration of ligand, preconcentration time and applied potential were investigated. The relative standard deviation at a concentration level of 50 ng mL(-1) was 1.8%. The method was applied to the determination of zinc in city, river and mineral water samples, with satisfactory results.

Ultra-sensitive quantification of copper in food and water samples by electrochemical adsorptive stripping voltammetry.

A new electrochemical adsorptive stripping voltammetry method was developed for the determination of trace amounts of copper in food and water samples. The study of electrochemical behavior of Cu ion indicated that Cu(II) and Schiff base formed a complex in H3BO4-NaOH buffer solution (pH = 7.25). An accumulation potential of -100 mV (vs Ag/AgCl) was applied while the solution was stirred for 60 s. The response curve was recorded by scanning the potential, and the peak current of -0.31 V (vs Ag/AgCl) was recorded. The peak current and concentration of copper accorded with linear relationship in the range of 0.04-120 ng mL(-1). The relative standard deviation (for 12 ng mL(-1) of copper) was 1.73%, and the detection limit was 0.007 ng mL(-1). The possible interference of some common ions was studied. The proposed method was applied to the determination of copper in water, rice, wheat, tea, milk, and tomato with satisfactory results.

A highly sensitive method for simultaneous determination of ultra trace levels of copper and cadmium in food and water samples with luminol as a chelating agent by adsorptive stripping voltammetry.

In the present study a selective method is presented for the simultaneous determination of copper and cadmium in food samples by adsorptive stripping voltammetry. In preliminary studies, it has been proven that the copper and cadmium react with 3-aminophthalhydrazide (luminol), giving rise to the formation of these complexes. These complexes have adsorptive characteristics on hanging mercury drop electrode (HMDE) and can be reduced in a reduction step. In this study the optimum reaction parameters and conditions studies are investigated. The calibration graphs were linear in the concentration range of 0.5-105.0 and 0.8-70.0ng/ml for copper and cadmium, respectively. The limit of detection of the method was 0.04ng/ml for Cu(2+) and 0.02ng/ml for Cd(2+). The interference of some common ions was studied and it was concluded that application of this method for the determination of copper (II) and cadmium in food and water samples led to satisfactory results.

Simultaneous determination of ultra trace amounts of lead and cadmium in food samples by adsorptive stripping voltammetry.

A selective and sensitive method for simultaneous determination of lead and cadmium by adsorptive differential pulse cathodic stripping voltammetry is presented. The method is based on adsorptive accumulation of the complexes of Pb (II) and Cd (II) ions with 2-mercaptobenzothiazole onto hanging mercury drop electrode (HMDE), followed by the reduction of the adsorbed species by differential pulse cathodic stripping voltammetry. Optimal conditions were obtained at pH 8.0, 2-mercaptobenzothiazole concentration of 1.0×10(-4)M, the accumulation potential of -0.4V (vs. Ag/AgCl), the accumulation time of 160s, and the scan rate of 100mV/s. Under optimised conditions, linear calibration curves were established for the concentration of Pb (II) and Cd (II) in the range of 0.5-70 and 0.2-30ng/ml, respectively, with detection limit of 0.017ng/ml for Pb (II) and 0.01ng/ml for Cd (II). The procedure was successfully applied to the simultaneous determination of both ions in food samples (rice, soya and sugar).

A novel kinetic spectrophotometric method for the determination of ultra trace amount of cyanide.

A kinetic spectrophotometric method is described for the determination of trace levels of cyanide based on its catalytic effect on the oxidation of Janus green by ammonium peroxodisulfate in nitric acid media. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of the Janus green at 612 nm after 4 min. The effect of reaction variables on the reaction sensitivity was investigated. Under the optimized conditions, a calibration graph from 10.0 to 500.0 ng/ml of cyanide with a detection limit of 7.0 ng/m was obtained. The proposed method is simple, sensitive and inexpensive and it was applied to directly the determination of cyanide in drinking and ground waters with the satisfactory results.