Composites of Bimetallic Platinum-Cobalt Alloy Nanoparticles and Reduced Graphene Oxide for Electrochemical Determination of Ascorbic Acid, Dopamine, and Uric Acid

Real samples sensitive dopamine sensor based on poly 1,3-benzothiazol-2-yl((4-carboxlicphenyl)hydrazono)acetonitrile on a glassy carbon electrode

Herein, a novel electrochemical sensor that was used for the first time for sensitive and selective detection of dopamine (DA) was fabricated. The new sensor is based on the decoration of the glassy carbon electrode surface (GC) with a polymer film of 1,3-Benzothiazol-2-yl((4-carboxlicphenyl)hydrazono)) acetonitrile (poly(BTCA). The prepared (poly(BTCA) was examined by using different techniques such as 1H NMR, 13C NMR, FTIR, and UV-visible spectroscopy. The electrochemical investigations of DA were assessed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results obtained showed that the modifier increased the electrocatalytic efficiency with a noticeable increase in the oxidation peak current of DA in 0.1 M phosphate buffer solution (PBS) at an optimum pH of 7.0 and scan rate of 200 mV/s when compared to unmodified GC. The new sensor displays a good performance for detecting DA with a limit of detection (LOD 3σ), and limit of quantification (LOQ 10σ) are 0.28 nM and 94 nM respectively. The peak current of DA is linearly proportional to the concentration in the range from 0.1 to 10.0 µM. Additionally, the fabricated electrode showed sufficient reproducibility, stability, and selectivity for DA detection in the presence of different interferents. The proposed poly(BTCA)/GCE sensor was effectively applied to detect DA in the biological samples.

Green synthesis of silver nanoparticles by using Allium sativum extract and evaluation of their electrical activities in bio-electrochemical cell

An electrical application of green synthesized silver nanoparticles (Ag NPs) by developing a unique bio-electrochemical cell (BEC) has been addressed in the report. Here, garlic extract (GE) has been used as a reducing agent to synthesize Ag NPs, and as a bio-electrolyte solution of BEC. Ag NPs successfully formed into face-centered cubic structures with average crystallite and particle sizes of 8.49 nm and 20.85 nm, respectively, according to characterization techniques such as the UV-vis spectrophotometer, XRD, FTIR, and FESEM. A broad absorption peak at 410 nm in the UV-visible spectra indicated that GE played a vital role as a reducing agent in the transformation of Ag+ions to Ag NPs. After that four types of BEC were developed by varying the concentration of GE, CuSO4. 5H2O, and Ag NPs electrolyte solution. The open circuit voltage and short circuit current of all cells were examined with the time duration. Moreover, different external loads (1 Ω, 2 Ω, 5 Ω, and 6 Ω) were used to investigate the load voltage and load current of BEC. The results demonstrated that the use of Ag NPs on BEC played a significant role in increasing the electrical performance of BEC. The use of GE-mediated Ag NPs integrated the power, capacity, voltage efficiency, and energy efficiency of BEC by decreasing the internal resistance and voltage regulation. These noteworthy results can take a frontier forward to the development of nanotechnology for renewable and low-cost power production applications.

Glucose and UA sensing based on Cu nanoparticle decorated Nif/GO flexible electrode

A novel, green, and facile approach has been developed to construct an ultrasensitive flexible enzyme-less electrochemical sensor on the basis of chitosan and graphene oxide composites decorated with Cu nanoparticles supported on nickel foam (Nif/Cs/GO@Cu), in which GO functions as the intermediate between Nif and Cu nanoparticles. The Nif/Cs/GO@Cu sensing platform was successfully fabricated by the drop casting method to load Cs/GO onto Nif followed by an additionally electrodeposition to support Cu nanoparticles on Nif/Cs/GO. Impressively, the Nif/Cs/GO@Cu exhibited much higher electrocatalytic activity for glucose and UA oxidation as compared to that of Nif or Nif@Cu. For glucose and UA at about 0.6 V and 0.1 V (vs. Ag/AgCl), linearity could be obtained in the concentration ranges 5 µM-4 mM and 5-345 µM; the sensitivities were 16 and 2.5 µA µM-1 cm-2, and the detection limits 83 nM and 0.3 µM, respectively. The improved performance of the composite electrode was ascribed to the synergistic effect of Cu nanoparticles, Nif and GO, in which GO provides high electron conductivity and large surface area to prevent the agglomeration of Cu nanoparticles; Cu nanoparticles and Nif offer abundant active sites towards analytes oxidation. Additionally, the method was applied to determine both analytes successfully in blood serum samples with excellent recovery and also opens up an attractive route to potential applications of the flexible nickel foam-based electrochemical sensor.

Advances on microfluidic paper-based electroanalytical devices

Since the inception of the first electrochemical devices on paper substrates, many different reports of microfluidic paper-based electroanalytical devices (μPEDs), innovative hydrophobic barriers and electrode fabrication processes have allowed the incorporation of diverse materials, resulting in different applications and a boost in performance. These advancements have led to the creation of paper-based devices with comparable performance to many standard conventional devices, with the added benefits of pumpless fluidic transport, component separation and reagent storage that can be exploited to automate and handle sample preprocessing. Herein, we review μPEDs, summarize the characteristics and functionalities of μPEDs, such as separation, fluid flow control and storage, and outline the conventional and emerging fabrication and modification approaches for μPEDs. We also examine the recent application of μPEDs in biomedicine, the environment, and food and water safety, as well as some limitations and challenges that must be addressed.

Strategies, advances, and challenges associated with the use of graphene-based nanocomposites for electrochemical biosensors

Graphene is an intriguing two-dimensional honeycomb-like carbon material with a unique basal plane structure, charge carrier mobility, thermal conductivity, wide electrochemical spectrum, and unusual physicochemical properties. Therefore, it has attracted considerable scientific interest in the field of nanoscience and bionanotechnology. The high specific surface area of graphene allows it to support high biomolecule loading for good detection sensitivity. As such, graphene, graphene oxide (GO), and reduced GO are excellent materials for the fabrication of new nanocomposites and electrochemical sensors. Graphene has been widely used as a chemical building block and/or scaffold with various materials to create highly sensitive and selective electrochemical sensing microdevices. Over the past decade, significant advancements have been made by utilizing graphene and graphene-based nanocomposites to design electrochemical sensors with enhanced analytical performance. This review focus on the synthetic strategies, as well as the structure-to-function studies of graphene, electrochemistry, novel multi nanocomposites combining graphene, limit of detection, stability, sensitivity, assay time. Finally, the review describes the challenges, strategies and outlook on the future development of graphene sensors technology that would be usable for the internet of things are also highlighted.

A Simple, Cost-Effective, and Green HPTLC Method for the Estimation of Ascorbic Acid in Solvent and Ultrasound-Assisted Extracts of Phyllanthus emblica, Capsicum annuum, and Psidium guajava

Greener analytical methodologies for the estimation of ascorbic acid (AA) are poorly reported in the literature. Furthermore, the green indexes of the literature’s analytical assays of AA estimation have not been assessed. As a consequence, the aim of this research is to invent and validate a simple, cost-effective, and green reverse-phase “high-performance thin-layer chromatography (HPTLC)” method for the estimating AA in the solvent extracts (SE) and ultrasound-assisted extracts (UAE) of Phyllanthus emblica, Psidium guajava, and Capsicum annuum. The greener mobile phase for AA estimation was a binary mixture of water and ethanol (70:30, v/v). At a wavelength of 265 nm, the detection of AA was carried out. The greener HPTLC technique was linear in the 25–1200 ng/band range. In addition, the method was simple, cost-effective, accurate, precise, robust, sensitive, and green. The amount of AA was highest in the SE and UAE of P. emblica compared to the SE and UAE of P. guajava and C. annuum. The amount of AA in the SE of P. emblica, P. guajava, and C. annuum was found to be 491.16, 168.91, and 144.30 mg/100 g, respectively. However, the amount of AA in the UAE of P. emblica, P. guajava, and C. annuum was found to be 673.02, 218.71, and 199.30 mg/100 g, respectively. Using the “analytical GREEnness (AGREE)” methodology, the greenness index for the developed method was calculated to be 0.88, showing that the developed method has an excellent green profile. When it came to extracting AA, the UAE method outperformed the SE method. These findings suggested that the developed method might be used to estimate the AA in a variety of vegetable crops, plant-based extracts, and commercial formulations. Furthermore, because of the use of greener solvent systems against the commonly utilized hazardous solvent systems for AA determination, this technique is also safe and sustainable.

Novel lanthanum vanadate-based nanocomposite for simultaneously electrochemical detection of dopamine and uric acid in fetal bovine serum

The abnormal levels of two biological molecules, dopamine (DA) and Uric acid (UA), in human body are symptoms of diseases such as Parkinson's disease and arrhythmia. A novel lanthanum vanadate and multi-walled carbon nanotubes (LaV-MWCNTs) composite modified glassy carbon electrode (GCE) was developed and utilized as an efficient electrochemical sensor for the simultaneous detection of DA and UA. LaV-MWCNTs composite was successfully fabricated by a facile ultrasonic self-assembly method and identified by means of a series of successive measurements including XPS, XRD, FT-IR and FE-SEM. The LaV-MWCNTs modified GCE shows the concentration linear ranges of DA and UA are 2-100 μΜ using DPV. The limits of detection (LODs; signal-to-noise ratio of 3, S/N = 3) of the LaV-MWCNTs modified GCE sensor for DA and UA were calculated to be 0.046 μM and 0.025 μM, respectively. The feasibility of using the LaV-MWCNTs modified GCE sensor to detect DA and UA in a typical biological fluid, fetal bovine serum, was also evaluated by the standard addition method.

Electrochemical Dopamine Biosensor Based on Poly(3-aminobenzylamine) Layer-by-Layer Self-Assembled Multilayer Thin Film

Dopamine (DA) is an important neurotransmitter which indicates the risk of several neurological diseases. The selective determination with low detection limit is necessary for early diagnosis and prevention of neurological diseases associated with abnormal concentration of DA. The purpose of this study is to fabricate a poly(3-aminobenzylamine)/poly(sodium 4-styrenesulfonate) (PABA/PSS) multilayer thin film for use as an electrochemical DA biosensor. The PABA was firstly synthesized using a chemical oxidation method of 3-aminobenzylamine (ABA) monomer with ammonium persulfate (APS) as an oxidant. For electrochemical biosensor, the PABA/PSS thin film was fabricated on fluorine doped tin oxide (FTO)-coated glass substrate using the layer-by-layer (LBL) self-assembly method. The optimized number of bilayers was achieved using SEM and cyclic voltammetry (CV) results. The electroactivity of the optimized LBL thin film toward detection of DA in neutral solution was studied by CV and amperometry. The PABA/PSS thin film showed good sensitivity for DA sensing with sensitivity of 6.922 nA·cm-2·µM-1 and linear range of 0.1-1.0 µM (R2 = 0.9934), with low detection limit of 0.0628 µM, long-term stability and good reproducibility. In addition, the selectivity of the PABA/PSS thin film for detection of DA under the common interferences (i.e., ascorbic acid, uric acid and glucose) was also presented. The prepared PABA/PSS thin film showed the powerful efficiency for future use as DA biosensor in real sample analysis.

Single-Atom Ruthenium Biomimetic Enzyme for Simultaneous Electrochemical Detection of Dopamine and Uric Acid

Single-atom catalysts have attracted numerous attention due to the high utilization of metallic atoms, abundant active sites, and highly catalytic activities. Herein, a single-atom ruthenium biomimetic enzyme (Ru-Ala-C₃N₄) is prepared by dispersing Ru atoms on a carbon nitride support for the simultaneous electrochemical detection of dopamine (DA) and uric acid (UA), which are coexisting important biological molecules involving in many physiological and pathological aspects. The morphology and elemental states of the single-atom Ru catalyst are studied by transmission electron microscopy, energy dispersive X-ray elemental mapping, high-angle annular dark field-scanning transmission electron microscopy, and high-resolution X-ray photoelectron spectroscopy. Results show that Ru atoms atomically disperse throughout the C₃N₄ support by Ru-N chemical bonds. The electrochemical characterizations indicate that the Ru-Ala-C₃N₄ biosensor can simultaneously detect the oxidation of DA and UA with a separation of peak potential of 180 mV with high sensitivity and excellent selectivity. The calibration curves for DA and UA range from 0.06 to 490 and 0.5 to 2135 μM with detection limits of 20 and 170 nM, respectively. Moreover, the biosensor was applied to detect DA and UA in real biological serum samples using the standard addition method with satisfactory results.

Hybrid carbon nanotubes modified glassy carbon electrode for selective, sensitive and simultaneous detection of dopamine and uric acid

Based on a hybrid carbon nanotube composite, a novel electrochemical sensor with high sensitivity and selectivity was designed for the simultaneous determination of dopamine (DA) and uric acid (UA). The hybrid carbon nanotube composite was prepared by ultrasonic assembly of carboxylated multi-walled carbon nanotube (MWCNT-COOH) and hydroxylated single-walled carbon nanotube (SWCNT-OH). And the hybrid (MWCNT-COOH/SWCNT-OH) composite was characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FT-IR) spectroscopy. The electrochemical performances of MWCNT-COOH/SWCNT-OH composite modified glassy carbon electrode (MWCNT-COOH/SWCNT-OH/GCE) were analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). Under the optimum experimental conditions, the as-prepared sensor showed high sensitivity and selectivity for DA and UA. The calibration curves obtained were linear for the currents versus DA and UA concentrations in the range 2-150 μM, and limits of detection (LODs) were calculated to be 0.37 μM and 0.61 μM (signal-to-noise ratio of 3, S/N = 3), respectively. The recoveries of DA and UA in bovine serum samples at MWCNT-COOH/SWCNT-OH/GCE were in the range 96.18-105.02%, and relative standard deviations (RSDs) were 3.34-7.27%. The proposed electrochemical sensor showed good anti-interference ability, excellent reproducibility and stability, as well as high selectivity, which might provide a promising platform for determination of DA and UA.

NiO/SWCNTs coupled with an ionic liquid composite for amplified carbon paste electrode; A feasible approach for improving sensing ability of adrenalone and folic acid in dosage form

Electrochemical sensors have shown great appeal for the simultaneous analysis of pharmaceutical compounds. In this way, the presence study described first electroanalytical sensor for simultaneous determination of adrenalone and folic acid. The two-amplified voltammetric sensor was developed by modifying carbon paste electrode (CPE) with NiO/SWCNTs composite and 1-butyl-3-methylimidazolium methanesulfonate (1B3MIMS) and used for simultaneous determination of adrenalone and folic acid. The NiO/SWCNTs was synthesised by a fast and low-cost precipitation strategy and then characterised by EDS, FESEM and XRD methods. The results confirmed a particle size range of ⁓ 26.93-33.87 nm for NiO nanoparticle decorated at SWCNTs. The cyclic voltammetric investigation showed that oxidation potentials of adrenalone and folic acid depend on changing the pH value. The maximum oxidation current for the simultaneous analysis of two compounds occurred at pH = 7.0. In this condition, the sensor showed linear dynamic range 0.01-400 μM and 0.3-350 μM for determination of adrenalone and folic acid, respectively. The NiO/SWCNTs/1B3MIMS/CPE was then used as an ultrasensitive electroanalytical sensor for determination of adrenalone and folic acid in injection samples with recovery ratio between 98.2-103.66 %.

Monodisperse palladium-cobalt alloy nanocatalyst supported on activated carbon (AC) as highly effective catalyst for the DMAB dehydrocoupling

In the study, activated carbon (AC) supported palladium/cobalt (Pd/Co) nanocatalyst was synthesized to achieve hydrogen release from dimethylamine boron (DMAB). Nanocatalyst were produced by the reduction of Pd2+ and Co2+ cations by the ultrasonic double reduction method. Analytical studies of the synthesized nanomaterials were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), electron energy loss spectroscopy, ultraviolet-visible spectroscopy. In this research, nanomaterials exhibited high catalytic activity and reusability, and great performance at low temperatures and concentrations. For the dehydrogenation reaction of dimethylamine borane, TOF and Ea were calculated as 379.5 h-1 and 75.86 kJ mol-1, respectively. The PdCo@AC nanocatalyst can be used as a promising catalyst for the hydrogen production reaction from DMAB.

Single-Walled Carbon Nanotube Supported PtNi Nanoparticles (PtNi@SWCNT) Catalyzed Oxidation of Benzyl Alcohols to the Benzaldehyde Derivatives in Oxygen Atmosphere

This study reports a developed process which is a general and facile method for the oxidation of benzyl alcohol (BnOH) compounds to the benzaldehyde (BA) derivatives, under mild conditions. The oxidation of BnOH species catalyzed by PtNi@SWCNT in toluene (3 ml) at 80 °C under a continuous stream of O₂. Single wall carbon nanotube supported PtNi (PtNi@SWCNT) nanoparticles were synthesized using a single-step modified reduction process. The characterization of PtNi@SWCNT nanocatalyst was performed by transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and elemental analysis by ICP-OES. A variety of BnOH compounds were oxidized by the PtNi@SWCNT catalyst and all the expected oxidation products were obtained in high efficiency in 2 hours of reaction time. TLC was used to monitoring the reaction progress, and the products were identified by ¹H/¹³C-NMR analysis.

A Novel Hydrogenation of Nitroarene Compounds with Multi Wall Carbon Nanotube Supported Palladium/Copper Nanoparticles (PdCu@MWCNT NPs) in Aqueous Medium

A novel nanocatalyst, multi-wall carbon nanotube supported palladium/copper (PdCu@MWCNT) nanoparticles, was synthesized for the reduction of nitroarene compounds. Characterization of the nanocatalyst was achieved by XRD, XPS, TEM, and Raman spectroscopy analysis. In this study, the hydrogenation of nitroarenes to primary amine compounds was achieved in aqueous medium at room temperature. The aniline derivatives were synthesized with high yields at mild conditions via novel PdCu@MWCNT nanocatalyst. The conversion of nitroarenes to amine derivatives was accomplished at 99% efficiency. In addition to its high activity, the PdCu@MWCNT catalyst was determined to be stable and reusable after the 3rd consecutive use for the reaction and provided 99% conversion of various compounds in the reduction reaction.

Monodisperse Pt-Co/GO anodes with varying Pt: Co ratios as highly active and stable electrocatalysts for methanol electrooxidation reaction

The intense demand for alternative energy has led to efforts to find highly efficient and stable electrocatalysts for the methanol oxidation reaction. For this purpose, herein, graphene oxide-based platinum-cobalt nanoparticles (Pt100-xCox@GO NPs) were synthesized in different ratios and the synthesized nanoparticles were used directly as an efficient electrocatalyst for methanol oxidation reaction (MOR). The characterizations for the determination of particle size and surface composition of nanoparticles were performed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The structure of the catalysts was detected as face-centered cubic and the dispersion of them on graphene oxide was homogenous (distributed narrowly (4.01 ± 0.51 nm)). Cyclic voltammetry (CV) and chronoamperometry (CA) was utilized for testing electrocatalytic activities of all prepared NPs for the methanol oxidation reaction. It was detected that the newly produced NPs were more active and stable than commercially existing Pt(0)/Co nanomaterial in methanol electro-oxidation in acidic media.

Palladium supported on polypyrrole/reduced graphene oxide nanoparticles for simultaneous biosensing application of ascorbic acid, dopamine, and uric acid

In this study, we report a facile and effective production process of palladium nanoparticles supported on polypyrrole/reduced graphene oxide (rGO/Pd@PPy NPs). A novel electrochemical sensor was fabricated by incorporation of the prepared NPs onto glassy carbon electrode (GCE) for the simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The electrodes modified with rGO/Pd@PPy NPs were well decorated on the GCE and exhibited superior catalytic activity and conductivity for the detection of these molecules with higher current and oxidation peak intensities. Simultaneous detection of these molecules was achieved due to the high selectivity and sensitivity of rGO/Pd@PPy NPs. For each biomolecule, well-separated voltammetric peaks were obtained at the modified electrode in cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements. Additionally, the detection of these molecules was performed in blood serum samples with satisfying results. The detection limits and calibration curves for AA, DA, and UA were found to be 4.9 × 10^-8, 5.6 × 10^-8, 4.7 × 10^-8 M (S/N = 3) and ranging from 1 × 10^-3 to 1.5 × 10^-2 M (in 0.1 M PBS, pH 3.0), respectively. Hereby, the fabricated rGO/Pd@PPy NPs can be used with high reproducibility, selectivity, and catalytic activity for the development of electrochemical applications for the simultaneous detection of these biomolecules.

One-step rapid synthesis of Ni6(C12H25S)12 nanoclusters for electrochemical sensing of ascorbic acid

Metal nanoclusters (NCs) are highly desirable as active catalysts due to their highly active surface atoms. Among the reported metal clusters, nickel nanoclusters (Ni NCs) have been less well developed than others, such as gold, silver and copper. Herein a simple method is developed to synthesize atomically precise Ni clusters with the molecular formular of Ni₆(C₁₂H₂₅S)₁₂. Moreover, the single crystal of the Ni₆(C₁₂H₂₅S)₁₂ cluster is also obtained. The composition, morphology and optical properties of the prepared Ni₆ clusters are characterized by X-ray crystallography, XPS, XRD, SEM, HRTEM, FTIR and UV-Vis spectroscopy. The Ni cluster is composed of six nickel atoms that form a hexagonal ring with an exterior 1-dodecanethiol shell, resembling a double crown. Meanwhile, the Ni₆ NCs can be self-assembled into nanosheets due to their uniform size. It was found that the Ni₆(C₁₂H₂₅S)₁₂ clusters loaded on carbon black exhibit higher electrocatalytic activity than Ni nanoparticles towards ascorbic acid (AA) oxidation. The Ni₆ clusters show high sensing performance for AA with a wide linear range (1-3212 μM) and a low detection limit of 0.1 μM (S/N = 3). The significantly enhanced catalytic activity can be ascribed to the high fraction of surface Ni atoms with low coordination in the sub-nanometer clusters. The present work not only provides a straightforward method for synthesizing atomically precise metal clusters but also indicates that ultrasmall Ni clusters can be used as highly efficient catalysts for the electrochemical detection of AA.

Ultrasensitive electroanalytical sulfisoxazole sensors amplified with Pd-doped ZnO nanoparticles and modified with 1-hexyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide

In this study, an electrochemical sensor has been introduced by incorporating Pd-doped ZnO nanoparticles (ZnO–Pd/NPs) into a carbon paste (CP) matrix amplified by a conductive binder (1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1H3MIBTMSI), in this case) to determine the concentration of the sulfisoxazole (SFX) drug in urine, tablet, and pharmaceutical wastewater samples.

Electrochemical Sensors, a Bright Future in the Fabrication of Portable Kits in Analytical Systems

Analysis of food, pharmaceutical, and environmental compounds is an inevitable issue to evaluate quality of the compounds used in human life. Quality of drinking water, food products, and pharmaceutical compounds is directly associated with human health. Presence of forbidden additives in food products, toxic compounds in water samples and drugs with low quality lead to important problems for human health. Therefore, attention to analytical strategy for investigation of quality of food, pharmaceutical, and environmental compounds and monitoring presence of forbidden compounds in materials used by humans has increased in recent years. Analytical methods help to identify and quantify both permissible and unauthorized compounds present in the materials used in human daily life. Among analytical methods, electrochemical methods have been shown to have more advantages compared to other analytical methods due to their portability and low cost. Most of big companies have applied this type of analytical methods because of their fast and selective analysis. Due to simple operation and high diversity of electroanalytical sensors, these types of sensors are expected to be the future generation of analytical systems. Therefore, many scientists and researchers have focused on designing and fabrication of electroanalytical sensors with good selectivity and high sensitivity for different types of compounds such as drugs, food, and environmental pollutants. In this paper, we described the mechanism and different examples of DNA, enzymatic and electro-catalytic methods for electroanalytical determination of drug, food and environmental compounds.

Highly monodisperse Pd-Ni nanoparticles supported on rGO as a rapid, sensitive, reusable and selective enzyme-free glucose sensor

In this work, highly monodispersed palladium-nickel (Pd-Ni) nanoparticles supported on reduced graphene oxide (rGO) were synthesized by the microwave-assisted methodology. The synthesized nanoparticles were used for modification of a glassy carbon electrode (GCE) to produce our final product as PdNi@rGO/GCE, which were utilized for non-enzymatic detecting of glucose. In the present study, electrochemical impedance spectroscopy (EIS), chronoamperometry (CA) and, cyclic voltammetry (CV) methods were implemented to investigate the sensing performance of the developed glucose electrode. The modified electrode, PdNi@rGO/GCE, exhibited very noticeable results with a linear working range of 0.05-1.1 mM. Moreover, an ultralow detection limit of 0.15 μM was achieved. According to the results of amperometric signals of the electrodes, no significant change was observed, even after 250 h of operation period. In addition, the highly monodisperse PdNi@rGO/GCE was utilized to electrochemical detection of glucose in real serum samples. In light of the results, PdNi@rGO/GCE has shown an excellent sensing performance and can be used successfully in serum samples for glucose detection and it is suitable for practical and clinical applications.

Biological synthesis of silver nanoparticles using Rheum ribes and evaluation of their anticarcinogenic and antimicrobial potential: A novel approach in phytonanotechnology

This paper reports the anticarcinogenic and antimicrobial properties of silver nanoparticles (Ag NPs) obtained by green synthesis using the extract of Rheum ribes (R. ribes), a medicinal plant. For the synthesis of Ag NPs, the ethanolic extracts of R. ribes were used as a reducing as well as the stabilizing agent. For the characterization of Ag NPs, advanced analytical methods such as transmission electron microscopy (TEM), X-Ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV-vis spectrophotometry were performed. The synthesized Ag NPs obtained from R. ribes were evaluated as a cytotoxic agent against MDA-MB-231 breast carcinoma cell line. The IC₅₀ values of the nanoparticles were ranged from 165 to 99 μg/mL against MDA-MB 231 cell line for 24 h and 48 h, respectively. The results show that the use of Ag NPs at low concentrations show the toxic effect in the cancer cells. In addition, the results of experiments on gram-positive (Staphylococcus aureus (S. aureus), Methicillin-resistant Staphylococcus aureus (MRSA) and Bacillus subtilis (B. subtilis)) and gram-negative (Escherichia coli (E. coli)) bacteria showed that the Ag NPs had high antimicrobial activity. The results suggest that Ag NPs can be developed as potential anticancer and antibacterial agents.

Synthesis and characterization of Reishi mushroom-mediated green synthesis of silver nanoparticles for the biochemical applications

In recent years, the synthesis of nanoparticles via biological processes has attracted considerable attention. The use of plants and plant extracts is one of the most preferred methods for biological synthesis due to their rich biologically active metabolites. In this study, silver nanoparticles (Ag NPs) were synthesized using reishi mushroom (Ganoderma lucidum) extract. Different analytical techniques including X-ray Photoelectron Spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy, and Fourier Transform Infrared Spectrophotometer (FTIR) were used for the characterization of Ag NPs. UV-vis spectrum exhibited a broad absorption peak between 400-460 nm which indicates the existence of Ag NPs. TEM images showed Ag NPs are spherical with a diameter range of 15-22 nm. In addition, it is shown that Ag NPs form a face-centered cubic structure according to XRD characterization technique. The antioxidant activity towards to 1-Diphenyl-2-picrylhydrazyl (DPPH) was also studied. The highest DPPH scavenging percentage was recorded as 76.45% at 250 mg/L. The DNA cleavage activity results indicated that the green Ag NPs caused single strain DNA cleavage activity for 30 and 60 min at 50 and 100 mg/L, respectively. The Ag NPs antimicrobial activity was also investigated and results recorded as minimum inhibition concentration (MIC). Ag NPs showed a strong antibacterial effect against gram-positive (S. aureus, E. hirae, B. cereus) and gram-negative (E. coli, P. aeruginosa, L. pneumophila subsp. Pneumophila) bacteria. Furthermore, Ag NPs have also been shown to have a high antifungal effect against C. albicans fungus.