Green synthesis and characterizations of gold nanoparticles using Thyme and survey cytotoxic effect, antibacterial and antioxidant potential.

Nowadays, green chemistry methods are noticeable for synthesis metal nanoparticles due to affordable, easy and high reaction rate. In the present study gold nanoparticles (Au NPs) were eco-friendly synthesized using Thyme extract at the room temperature for 30 min to provide non-toxic, which can be used for different applications. Identifying properties of synthesized gold nanoparticles was done by various analytical technique including UV-Vis absorption spectroscopy approved presence of Au NPs in the solution, the functional groups of Thyme extract in the reduction and capping process of Au NPs are determined by FT-IR, Crystalline with the fcc plane approved by X-ray diffraction (XRD) pattern, energy dispersive spectroscopy (EDS) determined existence of elements in the sample, surface morphology, diverse shapes and size of present Au NPs were showed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Transmission electron microscopy (TEM). Beginning and end destroy temperature of the gold nanoparticles were determined by thermal gravimetric spectroscopy (TGA). In addition, antibacterial, antioxidant, and cytotoxicity properties of Au NPs were studied. Antibacterial activity of Au NPs was investigated on gram-positive (Bacillus) and gram-negative (Escherichia coli) by disk diffusion; also MIC (Minimum Inhibitory Concentration) and MBC (Minimum Bactericidal Concentration) were determined. DPPH free radical scavenging assay was used for antioxidant property and compared to butylated hydroxy toluene (BHT) as a standard antioxidant that showed high antioxidant activity. Synthesized Au NPs have great cell viability in a dose-depended manner and demonstrate that this method provided nontoxic for synthesis gold nanoparticles. The average diameter of synthesized Au NPs was about 35 nm.

Intellectual modifying a bare glassy carbon electrode to fabricate a novel and ultrasensitive electrochemical biosensor: Application to determination of acrylamide in food samples.

Acrylamide (AA) is a neurotoxin and carcinogen which is mainly formed in foods containing large quantities of starch processed at high temperatures and its determination is very important to control the quality of foods. In this work, a novel electrochemical biosensor based on hemoglobin-dimethyldioctadecylammonium bromide (HG-DDAB)/platinum-gold-palladium three metallic alloy nanoparticles (PtAuPd NPs)/chitosan-1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (Ch-IL)/multiwalled carbon nanotubes-IL (MWCNTs-IL)/glassy carbon electrode (GCE) is proposed for ultrasensitive determination of AA in food samples. Development of the biosensor is based on forming an adduct by the reaction of AA with α-NH2 group of N-terminal valine of HG which decreases the peak current of HG-Fe+3 reduction. The modifications were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), energy dispersive X-ray spectroscopic (EDS) and scanning electron microscopy (SEM). Under optimized conditions, the biosensor detected AA by square wave voltammetry (SWV) in two linear concentration ranges of 0.03-39.0nM and 39.0-150.0nM with a limit of detection (LOD) of 0.01nM. The biosensor was able to selective detection of AA even in the presence of high concentrations of common interferents which confirmed that the biosensor is highly selective. Also, the results obtained from further studies confirmed that the proposed biosensor has a short response time (less than 8s), good sensitivity, long term stability, repeatability, and reproducibility. Finally, the proposed biosensor was successfully applied to determine AA in potato chips and its results were comparable to those obtained by gas chromatography-mass spectrometry (GC-MS) as reference method.