Novel biosynthesis of gold nanoparticles for multifunctional applications: Electrochemical detection of hydrazine and treatment of gastric cancer.

In this work, an environmentally friendly strategy was used to synthesize gold nanoparticles (Au NPs) using Olea europaea (olive) fruit. Transmission electron microscopy (TEM), UV-Vis spectroscopy, X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) were used to characterize the physicochemical properties of the synthesized NPs. An Au NPs modified glassy carbon electrode was used to investigate the direct electrochemical oxidation of hydrazine. The suggested hydrazine sensor has good performance, such as a wide linear range (2.5-275 µM), low limit of detection (0.09 µM), notable selectivity and excellent reproducibility (RSD = 2.2%). The in-vitro cytotoxicity of three human cancer cell lines (KATOIII, NCI-N87, and SNU-16) was also explored with various concentrations of Au NPs prepared from olive fruit extract. Bio-synthesized Au NPs were found to have cytotoxic properties against gastric cancer in humans based on MTT assay protocol. The obtained results show that green synthesized Au NPs can be successfully employed in electrochemical sensing and cancer treatment applications.

A strategy for As(III) determination based on ultrafine gold nanoparticles decorated on magnetic graphene oxide.

In this work, a new dendrimer modified magnetic graphene oxide (GO) was used as a substrate for electrodeposition of Au nanoparticles. The modified magnetic electrode was employed for sensitive measuring of As(III) ion as a well-established human carcinogen. The prepared electrochemical device exhibits excellent activity towards As(III) detection using the square wave anodic stripping voltammetry (SWASV) protocol. At optimum conditions (deposition potential at -0.5 V for 100 s in 0.1 M acetate buffer with pH 5.0), a linear range from 1.0 to 125.0 µgL-1 with a low detection limit (calculated by S/N = 3) of 0.47 µg L-1 was obtained. In addition to the simplicity and sensitivity of the proposed sensor, its high selectivity against some major interfering agents, such as Cu(II) and Hg(II) makes it an appreciable sensing tool for the screening of As(III). In addition, the sensor revealed satisfactory results for detection of As(III) in different water samples, and the accuracy of obtained data were confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) setup. Accounting for the high sensitivity, remarkable selectivity and good reproducibility, the established electrochemical strategy has great potential for analysis of As(III) in environmental matrices.

Application of BiNPs/MWCNTs-PDA/GC sensor to measurement of Tl (1) and Pb (II) using stripping voltammetry.

Herein, simultaneous determination of Tl (1) and Pb (II) has been carried out at the surface of a modified glassy carbon electrode with polydopamine functionalized multi-walled carbon nanotubes- BiNPs nanocomposite (BiNPs/MWCNTs-PDA/GC) using square-wave anodic stripping voltammetry (SWASV) technique. The morphologies, composition and, electrochemical properties of the BiNPs/MWCNTs-PDA/GC were characterized by scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray energy dispersive spectroscopy (EDX), electrochemical impedance spectroscopy (EIS) and, SWASV. The parameters affecting the stripping current response were investigated and optimized. The large specific area of MWCNTs and good electro-conductibility of BiNPs causes the BiNPs/MWCNTs-PDA/GC electrode to exhibit an excellent electro-catalytic effect with good separation peaks for Tl and Pb oxidation compared to bare GCE under the optimal conditions. The proposed sensor showed wide leaner ranges from 0.4-100 ppb and 100-400 ppb for Tl (I) and Pb (II). Low detection limits of 0.04 ppb for Tl (I) and 0.07 ppb for Pb (II) were achieved. The efficiency of the electrode after thirty days of storage in ambient conditions without using it and also with the ability to reuse for 16 days did not decrease significantly. In addition, the modified electrode with simple preparation method showed good reproducibility, and high selectivity for measuring target ions. The method was successfully implemented for the simultaneous determination of Tl (I) and Pb (II) in tap, mineral and waste water samples with acceptable recovery (from 99.1-103.2 for Tl (I) and 98.4-100.4 for Pb (II)).

Mutations of rpob Gene Associated with Rifampin Resistance among Mycobacterium Tuberculosis Isolated in Tuberculosis Regional Reference Laboratory in Northeast of Iran during 2015-2016.

BACKGROUND: Drug resistance is a leading concern in control of TB. Resistance against rifampin as one of the most important drugs in the treatment of Mycobacterium tuberculosis is caused by mutations in the 81-base pair region of the rpoB gene encoding the ß-subunit of RNA polymerase. This study aimed to characterize the mutations in the rpoB gene associated with rifampin resistance among M. tuberculosis. METHODS: This study was conducted on referred samples of patients who did not respond to anti-TB treatment, in Tuberculosis Regional Reference Laboratory at Shariati Hospital. Drug susceptibility of M. tuberculosis isolates was surveyed using a proportional method on LJ medium. The isolates with resistant to rifampin were reconfirmed and then the rpoB gene was amplified and sequenced. RESULTS: Among 27 resistant cases, 8, 11 and 8 people were from Iran, Afghanistan, and Turkmenistan, respectively. In 26 out of 27 isolates, rpoB gene mutations were observed. The most prevalent mutations belonged to the codon 53. The most prevalent mutations belonged to the TCG (Ser) 531TTG (leu) with prevalence 51.8% (n=14), and GAC (Asp)516TAC (Tyr), CAC (His) 526GAC (Asp) and CAC (His) 526TAC(Tyr) mutations with prevalence 14.8%(n=4). Twenty-three isolates had just one mutation. CONCLUSION: The use of rpoB gene sequencing led to the lack of the need for growth of the organism in the culture medium, the direct use of clinical samples, reduction of biological risks and a detection about 96.3% of MDR TB cases lowering the cost of the treatment.