This study used a hydrothermal method to synthesize MoS2 nanosheets (NSs). The study also utilized various analytical procedures to characterize the MoS2 NSs. It has been found that XRD, in particular, gave information on the crystal structure of the MoS2 NSs. These NSs have been visible with SEM. In addition, EDX has been used to scrutinize MoS2 NSs formation. Moreover, MoS2 NSs modified graphite screen printed electrode (MoS2 NSS/GSPE) has been built by dropping the MoS2 NSS onto GSPE for making a voltammetric sensor as well as the evaluation of the morphine voltammetric behavior. Findings showed stronger electro-catalytic oxidation of MoS2 NSS for morphine with a more negative potential. Consequently, the modified electrode enabled the simultaneous detection of diclofenac and morphine with the peak potential at 0.47 V and 0.27 V. Results indicated linear response in a concentration range between 0.05 and 600.0 μM (morphine) with 0.03 μM limit of detection (LOD). Finally, the modified electrode has been substantially utilized for analyzing diclofenac and morphine in the samples of diclophenac tablet, urine, and morphine ampoule with acceptable recovery and accuracy.

In this study, new chemiluminescence (CL) method was proposed to determine the amount of remifentanil in pharmaceuticals. We found that the weak CL intensity in the reaction between acidic cerium(IV) and Ru(phen)32+ complex increases significantly in the presence of remifentanil. Effect of remifentanil was investigated in some other CL systems such as luminol-IO4-, direct oxidation using acidic cerium(IV) or acidic KMnO4. Moreover, the effect of different dyes as a sensitizer was investigated in the KMnO4-Dye CL system. The dyes used in this study were crystal violet, amido black, naphthol green, amaranth, rhodamine 6G, safranin, orange G, fluorescein, and chromotrope 2R. The results showed that remifentanil has the highest CL intensity and S/B ratio in the acidic cerium(IV)- Ru(phen)32+ CL system. The reaction mechanism was evaluated by studying the CL reaction kinetics in the presence and absence of remifentanil and spectrophotometric spectra. The results indicate that remifentanil can convert Ru(phen)33+ complex rapidly to Ru(phen)32+* complex, which emits light when it returns to its ground-state. The method's linear dynamic range, detection limit, and reproducibility for four repetitive measurements of 109.39 μg mL-1 were 1.75-145.85, 1.41 μg mL-1, and 2.3%, respectively. The method proposed in this study was used to determine the content of remifentanil in pharmaceutical preparations.

A cloud point extraction/solvation method (CPE-SM) based on the use of vitamin C as a chelating agent was developed for the separation and determination of silver in environmental samples. TritonX-100 was used to extract silver ions in aqueous solutions after forming solvation species with vitamin C in the presence of salting-out (0.5 mol L-1 KNO3) at 90 C for 10 minutes. This study evaluated the main parameters affecting the CPE-SM method, such as the kind and concentration of the salting-out, organic reagents, silver ion, temperature, heating time, and volume of surfactant. Under the optimized experimental factors, the calibration curve was linear in the range (0.1 -10 μg/L). The relative standard deviation (RSD) was 1.1-2.9% for n:5 at 1,4,9 μg L-1, a low limit of detection (LOD), and a limit of quantification (LOQ) of 0.035, 0.116 μg L-1 respectively. The accuracy of the method was evaluated by two independent techniques (flame atomic absorption spectrometry – FAAS, and spectrophotometry - using dithizone as a complexing agent). The CPE-SM technique was used to preconcentrate and determine the silver ions in river water, tap water, and soil samples, and the results were favorable and good.

The main objective of this work was to evaluate the feasibility of the application of GO/Na2SiO3 nanocomposite as highly efficient adsorbent for the removal of malachite green as a cationic dye from aqueous solutions. To do so, first the synthesized nanosorbent was characterized via FTIR, SEM, TEM and XRD techniques. Surface area and pore mean size of above mentioned nanocomposite were determined using BET technique. Also, some important parameters affecting the efficiency of the absorption of malachite green, such as pH, adsorbent dosage, contact time, primary concentration of dye and salt effect were optimized. The malachite green (water-soluble) dye was analyzed at a maximum wavelength of 618 nm. The optimal conditions for removal of malachite green from aqueous solution included a 20 mg l-1 initial concentration with 25 mg adsorbent at pH 7, and adsorption equilibrium was achieved within 5 min. Kinetic studies confirmed that dye adsorption process followed pseudo-second order kinetic models (R2 = 0.9999) and adsorption equilibrium data showed good correlation with Freundlich isotherm (R2=0.9982 at 298 K). Thermodynamic analysis indicates that the adsorption process is spontaneous and exothermic in nature. In addition, the experimental data obtained from reusability studies showed that the prepared adsorbent could be used in up to six adsorption-desorption cycles without significant decrease in removal efficiency.

In this article, polycaprolactone (PCL) polymer nanofibers has been used in the presence of curcumin (Cur) to control the corrosion rate of temporary magnesium (alloy AZ31) implants. PCL, PCL-Cur, and sodium alginate (SA)-polyvinyl alcohol (PVA)/PCL-Cur polymer coating were produced. The mentioned nanofibers were produced using a simple and cost-effective electrospinning technique. We used different techniques to examine the properties of the produced fibers, and it was demonstrated that the hydrophobic produced nanofibers with contact angle of 135.2 degrees have continuous strands and a diameter of 171.57 nm. The presence of Cur inside PCL nanofiber not only did not have any effect on the PCL nanofiber morphology, but also it increased adhesion of the coating, and 74.59% of Cur was released after 7 days. To investigate the effects of different polymeric coatings on the surface of Mg metal in the simulated body fluid (SBF), SEM, weight measurement tests, pH measurement, Polarization, and Electrochemical Impedance Spectroscopy (EIS) has been used. During the study period there was no degradation in any part of the PCL-Cur hydrophobic polymer coating. For this coating, the percentage of weight loss, pH value, corrosion potential (Ecorr) and corrosion rate (CR) were 0.19%, 8.39, -1.388 V and 0.198 mm/y, respectively, where these values indicate the significant decrease of corrosion rate while using PCL-Cur coating.

Bacterial infection is a global problem, and detection of bacteria is the first step for solving such a problem. Herein, we developed an electrochemical biosensor for the detection of the bacteria Chlamydia Trachomatis. The hybridization-based biosensor was made by modifying the screen-printed gold electrode (SPGE) with the thiolated specific detection probes, which were complementary sequences to the target DNA molecule of the bacteria. The Oracet blue was used as an electrochemical label which was intercalated between two DNA sequences, and its reduction peak current was recorded by DPV method as an output signal of the biosensor. Conventional electrochemical characterization techniques, including cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS), were used to confirm the fabrication of the modified electrode. In addition, the Atomic Force Microscopy (AFM) imaging was performed to assess the electrode surface. The dynamic range of the biosensor was from 4 to 3000 pM with a detection limit of 1.3 pM. The simplicity and performance mentioned above of the biosensor, alongside the low cost and repeatability of the production, make it a great candidate for clinical applications for Chlamydia Trachomatis detection. Plus, it can be used for another species of bacteria with just a change of the thiolated probe.

In recent years, biosensors are used in various applications ranging from biomedical and pharmaceutical to food and chemical products. As an example, biosensors can be used for glucose assessment in blood and regulation of insulin usage in diabetic patients. In this regard, it is anticipated that many diseases could be diagnosed in the near future at an early stage regarding further progress in nanotechnology. The advancement in nanotechnology meets the technological requirements for the increased demand for sensors in biomedical applications. Enzymes play a significant role among various biologic elements exerted in the design of biosensors. Glucose oxidase is an enzyme and biocatalysts that accelerate the process of turning glucose to oxygenated water. Recent surveys have reported the novel qualitative and quantitative approaches used to enhance the sensitivity, detection limit, and biocompatibility of biosensors. Furthermore, they have confirmed the enhanced performance of glucose-based biosensors in both response and detection limits in their implementation. This review aims to summarize recent progress in sensitivity, selectivity, response time, and stability of the enzymatic biosensor based on the versatile fabrication of glucose by semi-permeable membranes.

Melia azedarach fruit extract is used to synthesize iron-polyphenol nanohydrogel and its capability as a flocculant in coagulation and removal of Disperse Yellow 211 dye from the aqueous solution is examined. The structure of iron-polyphenol nanohydrogel is studied by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller analysis, and zeta potential. The field emission scanning electron microscopy analysis indicates that in situ-cross-linking of polyphenols of Melia azedarach extract by ferric ions resulted in the formation of nanohydrogel containing particles in the range of 23-35 nm. Experiments confirmed that the prepared iron-polyphenol nanohydrogel has the excellent ability as the flocculant for coagulation and removal of the Disperse Yellow 211 dye in the pH range of 4.0-8.0, at room temperature. The required time for obtaining equilibrium at different concentrations of dye is ~ 50 minutes, and in this period, 200 mg L-1 of dye solution is 92% decolorized. The best-fitted model for experimental data is found to be the second-order kinetics and Langmuir thermodynamic indicating the sorption occurs in a monolayer and is governed by chemisorption. The maximum capacity of the sorbent is 1111.1 mg g-1.

A mesoporous silica SBA-15/iron oxide (Fe3O4-SBA-15) nanocomposite was fabricated and employed as a magnetic solid-phase extraction (MSPE) sorbent to determine three types of organophosphorus pesticides (OPPs) in fruit samples. The fabricated nanocomposite was analysed using high-performance liquid chromatography with an ultraviolet detector (HPLC-UV). Meanwhile, the optimisation of extraction efficiency on three OPPs analyses used three different parameters, viz. desorption conditions, extraction time, and sorbent amount. The experimental results showed that the Fe3O4-SBA-15 nanocomposite achieved high analyte recoveries ranging from 89 to 118% with a relative deviation of less than 8.0%. By combining the optimised MSPE conditions with HPLC-UV, a suitable method for determining three OPPs was developed. This study revealed that the proposed method exhibits good coefficients of determination varying from 0.9942 to 0.9980, with low limit detection (LODs) ranging from 0.03 - 0.08 mgL-1 and low limit quantifications (LOQs) of 0.10 - 0.24 mgL-1. Based on these findings, the fabricated Fe3O4-SBA-15 nanocomposite is a suitable sorbent with excellent adsorption capacity for the selected OPPs from fruit matrices.

Due to vital essence of medicine dosage monitoring within therapeutic range, a simple, rapid, high performance, sensitive and environmentally friendly electrochemical sensor was designed and used to diagnosis low concentrations of famotidine, a histamine-2 blocker, at pharmaceutical products and biological fluids. In this work, a simple, fast response and efficient voltammetic sensor was designed by using the functionalized dendrite-like gold nanostructures with 3-mercapto-propanioc acid (3-MPA/Au-DNSs). Electrochemical studies confirmed well the efficiency of the surface modified glassy carbon electrode (GCE) with 3-MPA/Au-DNSs on amplification of response signal in presence of famotidine in an applicable linear concentration range of 3.0 × 10−7–1.0 × 10−5 M. The limit of detection was evaluated to be 3.33 × 10−8 M (for S/N=3) under the optimum conditions. The modified GCE with 3-MPA/Au-DNSs was successfully applied in determination of famotidine in real samples such as human serum and pharmaceuticals with recoveries of 104.8 % and 100.90%, respectively.