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.

Experimental and modeling analyses of COD removal from industrial wastewater using the TiO2-chitosan nanocomposites.

In the present study, titanium oxide (TiO2) nanoparticles, chitosan, and several nanocomposites containing different mass dosages of TiO2 and chitosan have been applied as the adsorbent for COD removal from the industrial wastewater (Bouali Sina Petrochemical Company, Iran). The FESEM, XRD, and FTIR tests have been employed to characterize TiO2 nanoparticles, chitosan, and fabricated nanocomposites. Then, the effect of adsorption parameters, including TiO2-chitosan mass ratio (1:1, 1:2, and 2:1), adsorbent content (0.25-2.5 g), temperature (20-50 °C), pH (3-11), solution volume (100-500 mL), and contact time (30-180 min) on the COD reduction has also been monitored both experimentally and numerically. The Box-Behnken design of the experiment approves that TiO2-chitosan (1:1), adsorbent content of 2.5 g, temperature = 20 °C, pH 7.4, solution volume of 100 mL, and contact time = 180 min are the condition that maximizes the COD removal (i.e., 94.5%). Moreover, the Redlich-Peterson and Pseudo-second order models are the best isotherm and kinetic scenarios to describe COD removal's transient and equilibrium behaviors. The maximum monolayer COD adsorption capacity of the TiO2-chitosan nanocomposite is 89.5 mg g-1. The results revealed that the industrial wastewater COD is better to remove using the TiO2-chitosan (1:1) at temperature = 20 °C.

Highly sensitive determination of methionine by solvent-based de-emulsification dispersive liquid-liquid microextraction using bio-stabilized silver nanoparticles.

In this study, a solvent-based de-emulsification dispersive liquid-liquid microextraction method coupled with surface plasmon resonance of silver nanoparticles was developed for determination of trace levels of methionine. The stable and dispersed silver nanoparticles were synthesized by applying ascorbic acid as reducer and Stenotrophomonas sp. bacterial suspension as bio-stabilizer and then preconcentrated in organic phase according to a facile dispersive liquid-liquid microextraction procedure based on 1-octanol as extraction solvent, methyltrioctylammonium chloride (aliquat 336) as disperser and acetone as de-emulsifier. The presence of methionine influenced the intensity of plasmon resonance absorbance of silver nanoparticles, which was employed as a colorimetric probe for the determination of this amino acid. Under the optimal conditions, the linear analytical range of 5.6 to 234.5 nmol/L and a detection limit of 3.4 nmol/L were achieved for methionine. The relative standard deviation for seven replicate measurements of 33.5 and 107.2 nmol/L of methionine was 4.3 and 2.1%, respectively. The suggested method was successfully applied for the determination of methionine in biological samples.

Development and comparison of cross-linking and non-crosslinking probe-gold nanoparticle hybridization assays for direct detection of unamplified bovine viral diarrhea virus-RNA.

BACKGROUND: Bovine viral diarrhea virus (BVDV) is a major economic disease that has been spread in most countries. In addition to vaccination, one of the main ways to control the disease and prevent it from spreading is to detect and cull infected animals, especially those with persistent infection (PI). We developed and compared two colorimetric biosensor assays based on probe-modified gold nanoparticles (AuNPs) to detect BVDV. Specific probes were designed to detect the 5' untranslated region of BVDV-RNA. The thiolated probes were immobilized on the surface of the AuNPs. Two methods of cross-linking (CL) and non-crosslinking (NCL) probe-AuNPs hybridization were developed and compared. RESULTS: The hybridization of positive targets with the two probe-AuNPs formed a polymeric network between the AuNPs which led to the aggregation of nanoparticles and color change from red to blue. Alternatively, in the NCL mode, the hybridization of complementary targets with the probe-AuNPs resulted in the increased electrostatic repulsion in nanoparticles and the increased stabilization against salt-induced aggregation. The CL and NCL assays had detection limits of 6.83 and 44.36 ng/reaction, respectively. CONCLUSION: The CL assay showed a higher sensitivity and specificity; in contrast, the NCL assay did not require optimizing and controlling of hybridization temperature and showed a higher response speed. However, both the developed methods are cost-effective and easy to perform and also could be implemented on-site or in local laboratories in low-resource countries.

Determination of Tetracycline Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Droplet Followed by HPLC-UV System.

BACKGROUND: Tetracyclines (TCs) are a group of broad-spectrum antibiotics that may be used to control bacterial diseases in humans or are applied as feed additives to enhance growth in farm animals. TCs are released into the aquatic environment via different pathways. Many analytical methods combined with a preconcentration step have been introduced for the determination of TC in various environmental samples. OBJECTIVE: The objective this paper is developing reliable analytical methods for determination of TC trace in various environmental samples. METHOD: In the present work, combined ultrasound-assisted and dispersive liquid-liquid microextraction according to the solidification of floating organic drop as a sample preconcentration procedure for determining TC hydrochloride HPLC in water and serum samples was used. RESULTS: A series of parameters, including the type and volume of disperser and extraction solvents, salt effect, extraction time, and pH of solution influencing the extraction efficiency of UA-DLLME-SFO was examined. Enrichment factors were in the range of 125-137 for TC hydrochloride under optimum conditions. The linear range was calculated from 0.005 to 3 mg/L and LOD at 0.002 mg/L. RSDs were in the range of 2.7 to 3.2 (n = 5). The UA-DLLME-SFO method used in water and serum samples revealed good extraction recoveries with RSD of 2.7-4.3%. CONCLUSIONS: This method significantly decreased the organic solvent volume from 3 mL to 90 µL, also LOD and linear ranges were lower than or almost close to levels obtained in other research studies. In this procedure, an ultrasound bath enhanced the mixing and contact between the sample solution and the extraction solvent.

Dendrimer-modified magnetic nanoparticles as a sorbent in dispersive micro-solid phase extraction for preconcentration of metribuzin in a water sample.

This study was conducted to synthesize magnetic nanoparticles (MNPs) modified with generation 5 (G5) polyamidoamine (PAMAM) dendrimer and apply them as a sorbent in the dispersive-micro-solid phase extraction (D-µ-SPE) method for preconcentration of metribuzin in water samples. The characterization of synthesized nanoparticles was performed by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), and vibrating sample magnetometry (VSM). The effects of sample solution pH, the terminal group type, dendrimer generation, ionic strength, sorbent dosage, and desorption conditions on the removal efficiency were investigated. The linear range was calculated from 25-1000 µg L-1 and the LOD was 10 µg L-1. The recovery percentages for the spiked real samples ranged from 95.3% to 103.5% and relative standard deviations (RSD%) were in the range of 87.2-92.1 and 4.2 to 6.3 (n = 5) respectively. Applying the method developed in this work in water samples revealed good extraction recoveries with a RSD of 5.6-7.3%.

Electrospun chia seed mucilage/PVA encapsulated with green cardamonmum essential oils: Antioxidant and antibacterial property.

In this work, the potential of chia seed mucilage (CSM) as a new source of carbohydrate for encapsulation of green cardamonmum Essential oils (GCEOs) was evaluated. 1H NMR spectrum, FTIR spectrum and, SEM image has confirmed the existence of the GCEOs in the nanofibers. The nanofibers of CSM and polyvinyl alcohol have not antibacterial property, while nanofibers containing GCEOs show antibacterial activity against E. coli and S. aureus. Incorporating GCEOs in CSM nanofibers improved the antioxidant of the generated nanofibers. The amount of radical scavenging for the nanofibers containing 16 (mg/ml) of GCEOs was 18% and increasing the GCEOs concentration up to 64 (mg/ml) leads to grow the activity up to 41%. Thus, our studies indicate that nanofiber can be used as a novel antioxidant and antibacterial agent in the food and pharmaceutical industry.

Separation and pre-concentration of Sunset Yellow in beverages and effervescent vitamin C tablets by a new flotation technique prior to spectrophotometric determination.

A new, simple, low cost, high efficiency, and rapid floating technique was developed for the determination of Sunset Yellow in beverage and effervescent vitamin C. The method is based on two main steps: 1)- formation of dye-surfactant complex by the addition of a cationic surfactant, cetyltrimethylammonium bromide, to the solution containing an anionic dye (Sunset Yellow) and 2)- flocculation of the dye-surfactant complex with the participation of sodium perchlorate as a coagulant followed by aggregation and enlargement of the flocs while floating at the top of the solution. After the extraction, separated and preconcentrated Sunset Yellow was investigated by spectrophotometric determination. IR spectrum, scanning electron microscopy (SEM), and light microscopy were used to characterise the flocs. The effects of different parameters such as pH, concentration of surfactant, concentration of sodium perchlorate, and temperature on the extraction of dye were investigated and optimized. Under optimum conditions, a linear calibration curve was obtained in the range of 0.05-5 mg L-1. The detection limit (3Sb/m) was 0.02 mg L-1 with a preconcentration factor of 25. The relative standard deviation (RSD) for 0.1 mg L-1 of Sunset Yellow was 2.6% (n = 10). The applicability of the method was evaluated by measuring the amount of dye in beverage and effervescent vitamin C. Interferences of typical cations and anions which may participate in the matrices were also checked. The amount of Sunset Yellow found in real samples was 1.32-3.89 mgL-1.

Delivery of antisense peptide nucleic acid by gold nanoparticles for the inhibition of virus replication.

Aim: We aim to use peptide nucleic acid (PNA) for antisense therapy against bovine viral diarrhea virus (BVDV), a surrogate model of human hepatitis C virus, and introduce an optimal approach for delivering PNA into the cell. Materials & methods: PNA was designed for hybridization to the 5'-untranslated region of BVDV RNA in order to form a heteroduplex structure and inhibit the translation and replication of virus. Gold nanoparticles (AuNPs) were used as a delivery system for PNA. Results: The cellular uptake of PNA-AuNPs and inhibition of BVDV infection in the middle stage of viral replication were found. Conclusion: Further research is warranted to develop AuNPs as a potential vehicle for delivering PNA in order to remove viruses from the infected cells.

Evaluation of antioxidant bioindicators and growth responses in Malva parviflora L. exposed to cadmium.

In this study, the effect of cadmium (Cd) uptake and concentration on some growth and biochemical responses were investigated in Malva parviflora under Cd treatments including 0, 10, 50 and 100 µM. The shoots and roots were able to accumulate Cd. However, increased Cd dose led to a considerable Cd content in the roots. Cd stress decreased growth, increased lipid peroxidation and also enhanced proline and ascorbic acid contents in both shoots and roots. Chlorophyll and carotenoid contents decreased in the plants with the increasing Cd concentration. While the activities of catalase (CAT) and superoxide dismutase (SOD) increased in the shoots under different Cd doses, these activities decreased in the roots as compared to the control. Both shoots and roots demonstrated a significant increase in guaiacol peroxidase activity in response to Cd stress. Contrary to the aboveground parts, the roots subjected to Cd doses showed a rise in protein content. Despite higher Cd content in the roots, it seems that CAT and SOD do not play a key role in detoxification of Cd-induced oxidative stress. These findings confirm that reduced biomass and growth under Cd stress can be due to an increase in oxidative stress and a decrease in photosynthetic pigment content. The present study clearly indicates that the shoots and roots exploit different tolerance behaviors to alleviate Cd-induced oxidative stress in M. parviflora.

Novel magnetic hollow zein nanoparticles for preconcentration of chlorpyrifos from water and soil samples prior to analysis via high-performance liquid chromatography (HPLC).

Herein, magnetically hollow zein nanoparticles were synthesized and used as a magnetic sorbent for the preconcentration of chlorpyrifos and its analysis by high-performance liquid chromatography (HPLC). Morphology of the sorbent was characterized by transmission electron microscopy (TEM). In this study, the effects of important parameters such as pH of the solution, adsorption and desorption time, type and volume of desorption solvent, and salt addition were investigated. Under optimized experimental conditions, the linear range was from 50 to 2000 µg mL-1, and an LOD of 25 µg L-1 was calculated. The relative standard deviations (RSD) varied from 3.8 to 5.1% (n = 5). The enrichment factors for 50 and 100 µg L-1 samples were calculated as 187 and 210, respectively. The developed method was successfully applied in soil and water samples and showed good extraction 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.

Oxidative Damage and Antioxidant Response in Chenopodium murale L. Exposed to Elevated Levels of Zn

ABSTRACT Present study was carried out to investigate the effects of different Zn concentrations on growth and some antioxidant responses in Chenopodium murale L. The seeds were sown on the pots. 45-day plants were transferred to hydroponic solution containing 0.2 (control), 150, 300 and 600 µM Zn. The plants were harvested at 6 days after applying Zn treatments and some parameters were evaluated including plant length, fresh weight, photosynthetic pigments, malondialdehyde (MDA), ascorbate, proline and enzymatic antioxidants such as catalase (CAT), guaiacol peroxidase (GPX) and superoxide dismutase (SOD). Zn concentration showed a considerable increase in the shoot and root as the concentration of Zn increased in the medium, meanwhile the roots were characterized by higher Zn accumulation. At 150 µM Zn, the length and fresh weight did not show important changes compared to the control, but these parameters decreased at 300 and 600 µM Zn. With increasing Zn doses, the content of total chlorophyll declined, and also the content of carotenoids elevated. Excess Zn led to an increase in lipid peroxidation, free proline and ascorbate pool. Moreover, elevated Zn levels enhanced the activities of CAT, GPX and SOD. C. murale probably tolerates Zn concentrations up to 150 µM using the production of carotenoid, proline and ascorbate as well as enhanced activity of enzymatic antioxidants. Higher Zn treatments seem to be toxic due to a severe decline in growth.

Development of a new method based on unmodified gold nanoparticles and peptide nucleic acids for detecting bovine viral diarrhea virus-RNA.

A simple colorimetric assay is presented for detecting bovine viral diarrhea virus (BVDV)-RNA based on aggregation of gold nanoparticles (AuNPs) in the presence of charge-neutral peptide nucleic acids (PNA). Free charge-neutral PNA oligomers tended to be adsorbed onto AuNPs and act as a coagulant, whereas hybridizing complementary RNA with PNA disrupted PNA-induced AuNP aggregation, and the NPs remained stable. However, non-complementary RNA did not have this effect, and PNA induced aggregation of the AuNPs that resulted in a color change of the reaction from red to blue. The label-free colorimetric assay developed was estimated to have a 10.48 ng/reaction BVDV-RNA detection limit for the visual assay and 1.05 ng/reaction BVDV-RNA using a spectrophotometer. Diagnostic sensitivity and specificity for the assay was in accordance with real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and nested RT-PCR results were 98 and 100%, respectively. Absorption of the 520/620 nm ratio was linear, along with an increase in the target RNA concentration of 1.64-52.4 ng/reaction (R2 = 0.992), which showed a linear correlation for the quantitative assay. This study established a rapid visual label and enzyme-free diagnostic assay for detecting BVDV that is applicable in any clinical laboratory.

Enzyme-free amplification and detection of bovine viral diarrhea virus RNA using hybridization chain reaction and gold nanoparticles.

A novel bovine viral diarrheal virus (BVDV)-RNA detection method was developed using a combination of the amplification capability of hybridization chain reaction (HCR) with the sensitivity of an unmodified-gold nanoparticle (AuNP) colorimetric detection assay. Two auxiliary probes were designed to target a conserved RNA sequence among the BVDV isolates. The complementary target BVDV-RNA was used as the initiator to trigger a cascade of hybridization events to yield nicked double-helix DNA analogous to the alternating copolymers. DNA in the form of a nicked double helix did not prevent salt-induced aggregation of AuNPs. In contrast, in the absence of the complementary target BVDV-RNA, free hairpins with single-stranded sticky ends adsorbed onto the AuNPs, stabilize them, and prevent salt-induced aggregation of the AuNP. The limit of detection (LOD) for the BVDV-RNA was estimated to be 0.008 tissue culture infective dose (TCID50)/reaction. The method developed was highly selective and specific to detect BVDV isolates in clinical samples. This protocol offers a rapid, simple, and cost-effective assay for detecting BVDV.

Gold Nanoparticles Impair Foot-and-Mouth Disease Virus Replication.

In this study, we evaluated the antiviral activity of gold nanoparticles (AuNPs) against the foot-and-mouth disease virus (FMDV), that causes a contagious disease in cloven-hoofed animals. The anti-FMDV activity of AuNPs was assessed using plaque reduction assay. MTT assay was used for quantitatively measuring the cytopathic effect caused by the viral infection. The 50% cytotoxicity concentration of nanoparticles was measured and found to be 10.4 µg/ml. The virus yield reduction assay showed that AuNP have an approximately 4-fold virus titer reduction compared with controls. Plaque reduction assay showed that at non-cytotoxic concentrations, AuNPs do not show extracellular virucidal activity and inhibition of FMDV growth at the early stages of infection including attachment and penetration. Time-of-addition experiments revealed that AuNPs inhibited post-entry stages of viral replication concomitant with the onset of intracellular viral RNA synthesis; however, the mechanism of AuNPs against FMDV was unclear.

Determination of fungicide carbendazim in water and soil samples using dispersive liquid-liquid microextraction and microvolume UV-vis spectrophotometry.

This article presents a new and sensitive method for the determination of trace amounts of fungicide carbendazim by dispersive liquid-liquid microextraction (DLLME) combined with UV-vis spectrophotometry. The method is based on the reduction of Fe(III) to Fe(II) by carbendazim, its reaction with potassium ferricynide to form a blue product and extraction into CCL4 by DLLME technique using methyltrioctylammonium chloride (Aliquat 336) as a disperser agent. Under the established optimum conditions, the calibration graph was linear in the range of 5-600 ng mL(-1) of carbendazim with a limit of detection of 2.1 ng mL(-1). The relative standard deviations for eight replicate determinations of 50 and 300 ng mL(-1) of carbendazim were 3.9% and 1.0%, respectively. The proposed method was successfully applied to determination of carbendazim in soil and water samples.

Sol-gel based optical sensor for determination of Fe (II): a novel probe for iron speciation.

A highly selective optical sensor for Fe (II) ions was developed based on entrapment of a sensitive reagent, 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), in a silica sol-gel thin film coated on a glass substrate. The thin films fabricated based on tetraethoxysilane (TEOS) as precursor, sol-gel pH∼3, water:alkoxyde ratio of 4:1 and TPTZ concentration of 0.112 mol L(-1). The influence of sol-gel parameters on sensing behavior of the fabricated sensor was also investigated. The fabricated sensor can be used for determination of Fe (II) ion with an outstanding high selectivity over a dynamic range of 5-115 ng mL(-1) and a detection limit of 1.68 ng mL(-1). It also showed reproducible results with relative standard deviation of 3.5% and 1.27% for 10 and 90 ng mL(-1) of Fe (II), respectively, along with a fast response time of ∼120 s. Total iron also was determined after reduction of Fe (III) to Fe (II) using ascorbic acid as reducing agent. Then, the concentration of Fe (III) was calculated by subtracting the concentration of Fe (II) from the total iron concentration. Interference studies showed a good selectivity for Fe (II) with trapping TPTZ into sol-gel matrix and appropriately adjusting the structure of doped sol-gel. The sensor was compared with other sensors and was applied to determine iron in different water samples with good results.

A surface plasmon resonance sensing method for determining captopril based on in situ formation of silver nanoparticles using ascorbic acid.

A new method has been proposed to sensitive detection of captopril based on surface plasmon resonance band of silver nanoparticles (AgNPs). The stable and well-dispersed AgNPs with strong plasmon resonance signal were synthesized in situ using a simple and rapid procedure by applying ascorbic acid as reducer and sodium dodecyl sulfate as stabilizer, at room temperature. It was found that, the decreasing of AgNPs plasmon absorbance is proportional to the concentration of captopril which allows the spectrophotometric sensing of this compound. The presented method is capable of determining captopril over a range of 0.20-2.75 µmol L(-1) with a limit of detection 0.07 µmol L(-1). The relative standard deviation for eight replicate measurements of 1.00 and 2.50 µmol L(-1) of captopril was 2.37% and 1.02%, respectively. The method was applied to the determination of captopril in pharmaceutical formulations with satisfactory results, which were in agreement with those of the official method.

Dispersive liquid-liquid microextraction of thiram followed by microvolume UV-vis spectrophotometric determination.

A novel and simple method for the sensitive determination of trace amounts of fungicide thiram is developed by combination of dispersive liquid-liquid microextraction (DLLME) and microvolume UV-vis spectrophotometry. The method is based on the conversion of thiram to a yellow product in the presence of ethanolic potassium hydroxide and copper sulfate, and its extraction into CCL4 using DLLME technique. In this method the ethanol existing in ethanolic KOH plays as disperser solvent and a cloudy solution is formed by injection of only CCl4 as extractant solvent into sample solution. Under the optimum conditions, the calibration graph was linear over the range of 25-1000 ng mL(-1) of thiram with limit of detection of 11.5 ng mL(-1). The relative standard deviation (RSD) for 100 and 500 ng mL(-1) of thiram was 2.7 and 1.1% (n=8), respectively. The proposed method was successfully applied to determination of thiram in water and plant seed samples.