Mansour Ghaffari-Moghaddam

Green synthesis of silver nanoparticles using plant extracts

The strategy for design of new nanometals was developed due to their wide applications in many fields. One of the most important nanometals is silver nanoparticles (AgNPs) because of their extensive applications in biotechnology and biomedical fields. AgNPs were usually synthesized by using chemical and physical methods. In the chemical methods, various toxic chemicals are used, which are harmful to the health of living organisms. Therefore, the AgNPs were synthesized by using biological methods based on green chemistry for reducing the toxic chemicals. There are various resources for green synthesis of AgNPs, such as bacteria, fungi, enzyme and plant extracts. The green synthesis of AgNPs involves three main steps: the selection of the solvent medium, the selection of environmentally reducing agents, and the selection of non-toxic substances for the stability of AgNPs. The biosynthesis of AgNPs using plant extracts is more favorable than other biological methods because of removing the elaborate process of maintaining cell cultures. It can be also suitably scaled up for large scale production of AgNPs. This review focuses on green synthesis of AgNPs using various plant extracts.

Magnetic molecularly imprinted polymers–silver nanoparticle based micro-solid phase extraction for the determination of polycyclic aromatic hydrocarbons in water samples

In this study, an efficient and sensitive magnetic molecularly imprinted polymer–silver nanoparticle (MMIPS) system was successfully synthesized. The MMIPS-based micro-solid phase extraction, followed by gas chromatography-flame ionization detection, was employed for the extraction and analysis of polycyclic aromatic hydrocarbons such as naphthalene, anthracene and pyrene. The adsorbent was analyzed with Fourier transform-infrared spectrometry (FT-IR) and scanning electron microscopy (SEM). The equilibrium data of the adsorbent were investigated by Scatchard analysis. In the optimized conditions, the limits of detection were achieved in the range of 0.01 to 0.09 μg L−1. Precisions were obtained from 1.1 to 6.2% for intra-day and 5.9 to 10.2% for inter-day.

Mechanism and behavior of silver nanoparticles in aqueous medium as adsorbent.

In recent years there has been a rising interest in the application of nanomaterial such as silver nanoparticles (AgNps) in many areas of scientific research. The most active areas of investigation are related to the study and application of optical, biomedical, and newly applied adsorption properties of AgNps. The recent evaluation of adsorptive properties of AgNPs has added new areas to their wide range of applications in analytical separations and pre-concentrating steps. They have also been used for removal of several environmental organic pollutants and uptake of heavy metals. The main objective of this review is to describe the characteristics, mechanisms, and behavior of AgNPs as adsorbent in aquatic systems and sample solutions.

Maghemite nanoparticle‐decorated hollow fiber electromembrane extraction combined with dispersive liquid–liquid microextraction for determination of thymol from Carum copticum

BACKGROUND A novel technique using maghemite nanoparticle-decorated hollow fibers to assist electromembrane extraction is proposed. Electromembrane extraction combined with dispersive liquid-liquid microextraction (EME-DLLME) was applied for the extraction of thymol from Carum copticum, followed by gas chromatography with flame ionization detection (GC-FID). RESULTS The use of maghemite nanoparticle-decorated hollow fibers was found to improve the extraction efficiency of thymol significantly. Important operational parameters, including pH of acceptor phase, extraction time, voltage and temperature, were investigated and optimized. At the optimal conditions, linearity in the range 4-1800 µg L-1 with a determination coefficient of 0.9996 was obtained. The limit of detection was 0.11 µg L-1 (S/N = 3) and the pre-concentration factor was 200. The intra- and inter-day precision was 5.9 and 2.2% respectively. The intra- and inter-day accuracy was higher than 93.6%. CONCLUSION The results indicated that EME-DLLME/GC-FID is a useful technique for the extraction and determination of thymol in C copticum.

Flotation-Assisted Homogenous Liquid–Liquid Microextraction for Determination of Cadmium in Vegetables

ABSTRACT Cadmium (Cd) is a toxic element that can damage human organs. Determination of Cd in vegetables is often difficult because of low concentration and matrix effects. A simple, fast, flotation-assisted homogenous liquid–liquid microextraction (FA-HLLME) was developed for determination of Cd in vegetables prior to flame atomic absorption spectrometry (FAAS), in which 1-(2-pyridylazo)-2-naphthol (PAN) was used as a complexing agent. The process was carried out based on fast extraction of Cd from an acetic acid sample solution in which cyclohexane was the extracting solvent. Effects of pH, type and volume of extraction and homogeneous solvents, concentration of PAN, extraction time, and ionic strength on the extraction method were optimized. Under optimum conditions, the limit of detection and preconcentration factor were 0.6 µg·L−1 and 38, respectively. The relative standard deviation was less than 3.1%. Extraction recovery was 94.3%–100.9%.

Application of response surface methodology in enzymatic synthesis: A review

There are very chemical reactions with very slow rates which can be catalyzed by enzymes. These biocatalysts need to moderate conditions for their catalytic activity and are stable in low temperature (between 15–50°C), average pH (5–10) and aqueous media. One of important things in enzymatic synthesis which has been recently noticed is the yield of reactions. Nowadays wide application of response surface methodology (RSM) was observed in organic chemistry. In one-variable-at-a-time technique only one parameter is changed and other parameters are kept at a constant level. It does not study the interactive effects among the variables, and does not illustrate the complete effects of the parameters on the process. Increasing the yield of product without increase in casts is carried out by modeling and optimization of reaction variables through statistical techniques such as RSM. In this paper, we reviewed some articles that used the RSM for optimization in the enzymatic synthesis.

The role of acetoacetate in Amadori product formation of human serum albumin.

Amadori product is an important and stable intermediate, which is produced during glycation process. It is a marker of hyperglycemia in diabetes mellitus, and its accumulation in the body contributes to microvascular complication of diabetes including diabetic nephropathy and retinopathy. In this study, the effect of acetoacetate on the formation of Amadori products and biophysical properties of human serum albumin (HSA), after incubation with glucose, was investigated using various methods. These included circular dichroism (CD), Fourier transform infrared (FTIR) spectroscopy, and UV-visible and fluorescence spectroscopy. Our results indicated that the production of Amadori products in HSA incubated with glucose (GHSA) was increased in the presence of acetoacetate. We also detected alterations in the secondary and tertiary structure of GHSA, which was increased in the presence of acetoacetate. These changes were attributed to the formation of covalent bonds between the carbonyl group of acetoacetate and the nucleophilic groups (lysine residues) of HSA. Thus, acetoacetate can enhance the production of Amadori products through formation of covalent bonds with biomaterials.

Acetoacetate promotes the formation of fluorescent advanced glycation end products (AGEs)

Acetoacetate (AA) is an important ketone body, which produces reactive oxygen species (ROS). Advanced glycation end products (AGEs) are defined as final products of glycation process whose production is influenced by the levels of ROS. The accumulation of AGEs in the body contributes to pathogenesis of many diseases including complications of diabetes, and Alzheimer’s and Parkinson’s disease. Here, we evaluated the impact of AA on production of AGEs upon incubation of human serum albumin (HSA) with glucose. The effect of AA on the AGEs formation of HSA was studied under physiological conditions after incubation with glucose for 35 days. The physical techniques including circular dichroism (CD) and fluorescence spectroscopy were used to assess the impact of AA on formation and structural changes of glycated HSA (GHSA). Our results indicated that the secondary and tertiary structural changes of GHSA were increased in the presence of AA. The fluorescence intensity measurements of AGEs also showed an increase in AGEs formation. Acetoacetate has an activator effect in formation of AGEs through ROS production. The presence of AA may result in enhanced glycation in the presence of glucose and severity of complications associated with accumulation of AGEs.

A rapid synthesis of silver nanoparticles using a radical initiator under UV light and evaluation of their antibacterial activities

In this study the silver nanoparticles (AgNPs) were synthesized by reduction of silver ions using benzoin as a radical initiator under UV light. Polyvinyl alcohol (PVA) was used as a stabilizing agent. The AgNPs were characterized with UV-Vis spectrophotometry, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and FT-IR. The results exhibited the spherical shape of nanoparticles with size of 20–30 nm. The synthesized AgNPs were evaluated for their antibacterial activities against the Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Two types of bacteria were effectively inhibited by synthesized AgNPs.

Determination of Gold in Water Samples Using Electromembrane Extraction

ABSTRACT In this work, an electromembrane extraction (EME) technique was used for the extraction and determination of gold from water samples prior to UV-Vis spectrophotometry. An artificial neural network (ANN) combined with imperialist competitive algorithm (ICA) has been applied to optimize the EME. The effective parameters including pH of acceptor phase, extraction time (t), volume of sample solution (V), stirring rate (S), and voltage (E) were chosen as input variables and the extraction recovery of gold was considered as output variable. The mean of squared error (i.e., 0.0009) and determination coefficient (i.e., 0.9821) were applied to estimate the performance of the ANN model. The limit of detection was 4.5 µg L−1 (S/N = 3) on the optimized variables. The intra- and interday precisions (%) were found to be 6.7% and 2.6%, respectively. This technique was then applied for analysis of gold from environment water samples. GRAPHICAL ABSTRACT