Detection of Interleukin-6 Protein Using Graphene Field-Effect Transistor.

Universal platforms to analyze biomolecules using sensor devices can address critical diagnostic challenges. Sensor devices like electrical-based field-effect transistors play an essential role in sensing biomolecules by charge probing. Graphene-based devices are more suitable for these applications. It has been previously reported that Graphene Field-Effect Transistor (GFET) devices detect DNA hybridization, pH sensors, and protein molecules. Graphene became a promising material for electrical-based field-effect transistor devices in sensing biomarkers, including biomolecules and proteins. In the last decade, FET devices have detected biomolecules such as DNA molecules, pH, glucose, and protein. These studies have suggested that the reference electrode is placed externally and measures the transfer characteristics. However, the external probing method damages the samples, requiring safety measurements and a substantial amount of time. To control this problem, the graphene field-effect transistor (GFET) device is fabricated with an inbuilt gate that acts as a reference electrode to measure the biomolecules. Herein, the monolayer graphene is exfoliated, and the GFET is designed with an in-built gate to detect the Interleukin-6 (IL-6) protein. IL-6 is a multifunctional cytokine which plays a significant role in immune regulation and metabolism. Additionally, IL-6 subsidizes a variability of disease states, including many types of cancer development, and metastasis, progression, and increased levels of IL-6 are associated with a higher risk of cancer and can also serve as a prognostic marker for cancer. Here, the protein is desiccated on the GFET device and measured, and Dirac point shifting in the transfer characteristics systematically evaluates the device's performance. Our work yielded a conductive and electrical response with the IL-6 protein. This graphene-based transducer with an inbuilt gate gives a promising platform to enable low-cost, compact, facile, real-time, and sensitive amperometric sensors to detect IL-6. Targeting this pathway may help develop treatments for several other symptoms, such as neuromyelitis optica, uveitis, and, more recently, COVID-19 pneumonia.

Enhanced electrochemical performance of the MoS2/Bi2S3 nanocomposite-based electrode material prepared by a hydrothermal method for supercapacitor applications.

Supercapacitors are widely used energy storage systems in the modern world due to their excellent electrochemical performance, fast charging capability, easy handling, and high power density. In the present work, pure MoS2 and MoS2/Bi2S3 nanocomposites with different compositions of bismuth were synthesized by the hydrothermal method. The structural properties of the electrode materials were studied using the XRD technique, which confirmed the formation of MoS2 and the secondary phase of Bi2S3 while increasing Bi substitution. The morphological studies of the synthesized electrode materials were performed using SEM, TEM, and HRTEM techniques, which indicated the 3D layered hierarchical structure of MoS2 nanospheres and the nanosheet-like structure of Bi2S3. The electrochemical properties of pristine MoS2 and MoS2/Bi2S3 nanocomposites were analysed by CV, CP, and EIS techniques using a 2 M KOH electrolyte in a three-electrode system. The CV curves show evidence of significant improvement in the electrochemical performance of MoS2/Bi2S3 composites compared to that of pure MoS2. The calculated specific capacitances of MoS2/Bi2S3 nanocomposites were relatively higher than those of pristine MoS2. The 20 mol% Bi added sample showed a maximum specific capacitance of 371 F g-1, compared to pristine MoS2 and other samples at a current density of 1 A g-1. The kinetics of the electrochemical process was studied. The Nyquist plots indicated that the Bi-added nanocomposites had lower Resr and RCT values, which resulted in high electrochemical performance. The experimental results revealed that Bi-substitution can further enhance the electrochemical energy storage performance of MoS2 for supercapacitor applications.

Facile route of heterostructure CeO2-CuO nanocomposite as an efficient electron transport material for perovskite solar cells.

Cerium copper metal nanostructures have received extensive attention as promising electrode materials for energy storage applications due to its attractive structure, and good conductivity. Herein, CeO2-CuO nanocomposite was prepared via chemical method. The crystal structure, dielectric, and magnetic properties of the samples were characterized using by different techniques. The morphological properties of samples were inspected by field emission scanning electron microscopy (FE‒SEM) and high-resolution transmission electron microcopy (HR‒TEM) analysis implied an agglomerated with nanorod structure. The sample surface roughness and morphology were inspected using atomic force microscopy (AFM). Electron paramagnetic resonance (EPR) spectroscopy result reveals the oxygen insufficiency in the material. The variation of oxygen vacancies concentration is consistent with the changes of the saturation magnetization for the sample. Dielectric constant and dielectric losses were studied with respect to the temperature from range from 150 to 350 °C. The electrochemical study of CeO2-CuO nanocomposite shows clear oxidation and reduction peaks with covering wide potential range. In this present paper, first time we have demonstrated that the CeO2-CuO composite as an electron transport material (ETM) with copper (I) thiocyanate (CuSCN) as hole transport material (HTM) for the perovskite solar cells device fabrication. To understand the properties of perovskite like structural, optical, and morphological extensive characterizations such as XRD, UV-visible spectroscopy, and FE-SEM, was performed. For the first time, the CeO2-CuO was used as anode material for preparation low-temperature processing perovskite solar cells, results the power conversion efficiency (PCE) of 10.58% was achieved. The improvement in the device performance for the nanocomposite compared to the pure CeO2, due to unique properties of CeO2-CuO, including high hole mobility, good energy level alignment with CH3NH3PbI3 and longer life time of photo-excited carriers for facilitating the developments of industrial-scale perovskite solar cells.

The Anticancer Efficacy of Thiourea-Mediated Reduced Graphene Oxide Nanosheets against Human Colon Cancer Cells (HT-29).

The current research focuses on the fabrication of water-soluble, reduced graphene oxide (rGO) employing thiourea (T) using a simple cost-effective method, and subsequently examining its anticancer characteristics. The cytotoxicity caused by graphene oxide (GO) and T-rGO is investigated in detail. Biological results reveal a concentration-dependent toxicity of GO and T-rGO in human colon cancer cells HT-29. A decrease in cell viability alongside DNA fragmentation is observed. Flow cytometry analysis confirms the cytotoxic effects. The novelty in this work is the use of raw graphite powder, and oxidants such as KMNO4, NaNO3, and 98 percent H2SO4 to produce graphene oxide by a modified Hummers method. This study demonstrates a simple and affordable procedure for utilising thiourea to fabricate a water-soluble reduced graphene oxide, which will be useful in a variety of biomedical applications.

A novel visible light active rare earth doped CdS nanoparticles decorated reduced graphene oxide sheets for the degradation of cationic dye from wastewater.

A variety of rare earth metals (La, Sm, Nd, Ce, Gd) doped cadmium sulfide (RE-CdS) grafted reduced graphene oxide (G) sheet nanocomposites estimated imperative attention due to their visible light-driven, tunable band gap and high surface to volume ratio were investigated for the photocatalytic degradation of cationic dye from aqueous solution. The formation of wurtzite (hexagonal) crystal structures of cadmium sulfide nanoparticles (NPs) was confirmed by Powder X-ray diffraction spectra and the average crystallite size was determined to be 10 ± 2 nm. HRTEM analysis confirmed the homogeneous distribution of RE-CdS NPs over the G sheets. The photocatalytic behaviour of the RE-CdS decorated G sheets was studied using a textile dye methylene blue (MB) under sunlight. The result indicates that among the various RE-CdS nanocomposites studied, Cerium-cadmium sulfide-reduced graphene oxide (Ce-CdS-G) shows highest MB degradation of 99.0 ± 0.4% within 90 min under sunlight. The result confirms that RE-CdS-G nanocatalyst efficiently accelerates the separation and slows down the recombination rate in photo excited charge carriers. The catalytic activity was retained over 80% of its original value even after four successive runs and the present method can be employed for the large-scale synthesis of RE-CdS-G nanocatalyst.

The Cytotoxic Effectiveness of Thiourea-Reduced Graphene Oxide on Human Lung Cancer Cells and Fungi.

This study demonstrated the effective reduction of graphene oxide (GO) by employing thiourea as a reducing and stabilizing agent. Two fungi (Aspergillus flavus and Aspergillus fumigatus) were used for anti-fungal assay. Cell viability, cell cycle analysis, DNA fragmentation, and cell morphology were assessed to determine the toxicity of thiourea-reduced graphene oxide (T-rGO) on human lung cancer cells. The results revealed that GO and T-rGO were hazardous to cells in a dose-dependent trend. The viability of both A. fumigatus and A. flavus was affected by GO and T-rGO. The reactive oxygen species produced by T-rGO caused the death of A. flavus and A. fumigatus cells. This study highlighted the effectiveness of T-rGO as an antifungal agent. In addition, T-rGO was found to be more harmful to cancer cells than GO. Thus, T-rGO manifested great potential in biological and biomedical applications.

A Compact Sensory Platform Based pH Sensor Using Graphene Field Effect Transistor.

A compact sensory platform has been fabricated using a graphene field effect transistor (GFET) to identify the biomolecules by pH sensing. The monolayer GFET is driven by an in-built top-gate for detecting the pH of the contacting buffer solution. The GFET device detects the effect of hydroxide ions on a graphite surface. Electrical characteristics of the device were measured after desiccating the buffer solution on the surface of the monolayer graphene. Electrically, the VDirac point shifted toward the positive direction when the pH value of the buffer solution is varied. The transfer curve of the device also moved in the positive direction with increasing pH values, indicating charge transfer from dopant molecules to the surface of graphene. The sensitivity of the device was estimated to be ~48.5 mV/pH. The fabrication of the compact GFET device with an in-built gate provides a platform for effective pH sensing with a user-friendly interface for biosensing applications.

High Electrochemical Performance and Enhanced Electrocatalytic Behavior of a Hydrothermally Synthesized Highly Crystalline Heterostructure CeO2@NiO Nanocomposite.

A CeO2-based heterostructure nanocomposite has been attractive as an electrode material for energy storage and as an electrochemical sensor. In the present work, a CeO2@NiO nanocomposite was prepared by a simple hydrothermal method. The structural and morphological information on the heterostructure CeO2@NiO nanocomposite were obtained by using different characterization methods like X-ray diffraction, UV-visible, Fourier transform infrared, electron paramagnetic resonance, Raman, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray elemental color mapping, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Compared with pristine CeO2, the heterostructure CeO2@NiO nanocomposite exhibits a higher electrochemical performance with a specific capacitance of 317 F g-1 at a current density of 1 A g-1 in a 1 M KOH electrolyte. This device demonstrates a high energy density and a power density of 11 Wh kg-1 and 750 W kg-1, respectively. Besides, it was found that CeO2@NiO/glassy carbon electrode (GCE) shows appreciable electrocatalytic activity toward NO2- oxidation. The CeO2@NiO-modified electrode displays a linear response for NO2- oxidation between 0.001 × 10-6 and 4 × 10-3 M. Apart from high sensitivity (2260 µA mM-1 cm-2), the CeO2@NiO-modified electrode also exhibits good selectivity and long-term stability for nitrite (NO2-) detection in a water real sample, and the obtained results showed excellent recovery. The encouraging electrochemical performance of the CeO2@NiO nanocomposite provides a promising approach for the development of multifunctional electrode materials for future energy storage devices and sensors.

Superior Photocatalytic Performance of CeO2 Nanoparticles and Reduced Graphene Oxide Nanocomposite Prepared by Low Cost Co-Precipitation Method.

In this article, cerium oxide nanoparticles (CeO2 NPs) and reduced graphene oxide nanocomposite have been fabricated through simple, easy and cost effective co-precipitation method. The structural, optical and morphological characterization provides the evidence of successful synthesis of CeO2 NPs and nanocomposite. X-ray photoelectron spectroscopic characterization provides useful information about the concentrations and proportions of Ce3+ and Ce4+ ions in nanoparticles as well as in nanocomposite. These studies provide an insight to understand enhanced photocatalytic activity of nanocomposite. The nanocomposite produces 81% photocatalytic degradation of methyl orange compared to only 45% degradation by CeO2 NPs alone.

Fabrication of Hybrid Collagen Aerogels Reinforced with Wheat Grass Bioactives as Instructive Scaffolds for Collagen Turnover and Angiogenesis for Wound Healing Applications.

The present study illustrates the progress of the wheat grass bioactive-reinforced collagen-based aerogel system as an instructive scaffold for collagen turnover and angiogenesis for wound healing applications. The reinforcement of wheat grass bioactives in collagen resulted in the design and development of aerogels with enhanced physicochemical and biomechanical properties due to the intermolecular interaction between the active growth factors of wheat grass and collagen fibril. Differential scanning calorimetry analysis revealed an enhanced denaturation temperature when compared to those of native collagen aerogels. Fourier transform infrared spectroscopy analysis confirmed that the reinforcement of bioactives in the wheat grass did not affect the structural integrity of the collagen molecule. Additionally, the reinforced biomaterial with a systematic absorptive morphology resulted in a three-dimensional (3D) sponge-like aerogel exhibiting a potent highly oriented 3D structural assembly that showed increased water retention ability and substance permeability that would enable the passage of nutrients and gaseous components for cellular growth. Furthermore, the cumulative effect of the growth factors in wheat grass and the collagen molecule augments the angiogenic ability and collagen production of the aerogel by restoration of the damaged tissue thereby making it a potential 3D wound dressing scaffold. The results were confirmed by in vivo wound healing assays. This study shows the possibility for progress of a biocompatible, biodegradable, and nonadhesive nutraceutical-reinforced collagen aerogel as an instructive scaffold with good antimicrobial properties for collagen turnover and angiogenic response for wound healing applications.

Simplified detection of the hybridized DNA using a graphene field effect transistor.

Detection of disease-related gene expression by DNA hybridization is a useful diagnostic method. In this study a monolayer graphene field effect transistor (GFET) was fabricated for the detection of a particular single-stranded DNA (target DNA). The probe DNA, which is a single-stranded DNA with a complementary nucleotide sequence, was directly immobilized onto the graphene surface without any linker. The VDirac was shifted to the negative direction in the probe DNA immobilization. A further shift of VDirac in the negative direction was observed when the target DNA was applied to GFET, but no shift was observed upon the application of non-complementary mismatched DNA. Direct immobilization of double-stranded DNA onto the graphene surface also shifted the VDirac in the negative direction to the same extent as that of the shift induced by the immobilization of probe DNA and following target DNA application. These results suggest that the further shift of VDirac after application of the target DNA to the GFET was caused by the hybridization between the probe DNA and target DNA.

In-situ microwave synthesis of graphene-TiO2 nanocomposites with enhanced photocatalytic properties for the degradation of organic pollutants.

Graphene-titanium oxide (G-TiO2) nanocomposites were synthesized by a novel surfactant free, environmentally friendly one-port in-situ microwave method. The structure of the nanocomposite was characterized by the X-ray diffraction analysis and the morphology by using scanning electron microscopic and transmission electron microscopic images. The functional groups and carbon band structures were identified using FTIR and Raman spectral analysis. TiO2 nanoparticles in the size range of 5-10nm were distributed on the graphene sheets. The surface area of pure TiO2 and G-TiO2 nanocomposite was measured to be 20.11 and 173.76m(2)/g respectively. The pore volume and pore size of TiO2 were 0.018cm(3)/g and 1.5266nm respectively. G-TiO2 composite possesses higher pore volume (0.259cm(3)/g) and pore size 3.2075nm. The binding states of C, O and Ti of nanocomposite were analyzed by X-ray photoelectron spectroscopy, which confirmed the chemical bonding between graphene-TiO2. The photocatalytic activity of pure TiO2 and G-TiO2 nanocomposite was studied under UV and visible light irradiation sources with methylene blue dye. It has been observed that the degradation was faster in G-TiO2 nanocomposite than pure TiO2 nanoparticles. The rate constant and half life time were calculated from the kinetic studies of the degradation. The highest degradation efficiency of 97% was achieved in UV light and 96% for visible light irradiation with G-TiO2 as a catalyst. The studies reveal that G-TiO2 nanocomposite can be an effective catalyst for industrial waste water treatment.

Synthesis, Optical and Electrochemical Properties of Y2O3 Nanoparticles Prepared by Co-Precipitation Method.

Y2O3 nanoparticles were synthesized by co-precipitation route using yttrium nitrate hexahydrate and ammonium hydroxide as precursors. The prepared sample was calcined at 500 degrees C and subjected to various characterization studies like thermal analysis (TG/DTA), X-ray diffraction (XRD), transmission electron microscope (TEM), UV-visible (UV-Vis) and photoluminescence (PL) spectroscopy. The XRD pattern showed the cubic fluorite structure of Y2O3 without any impurity peaks, revealing high purity of the prepared sample. TEM images revealed that the calcined Y2O3 nanoparticles consist of spherical-like morphology with an average particle size of 12 nm. The absorption spectrum of calcined samples shows blue-shift compared to the as-prepared sample, which was further confirmed by PL studies. The possible formation mechanism of Y2O3 nanoparticles has been discussed based on the experimental results. Electrochemical behavior of Y2O3 nanoparticles was studied by cyclic voltammetry to assess their suitability for supercapacitor applications.

Photoscopic characterization of green synthesized silver nanoparticles from Trichosanthes tricuspidata and its antibacterial potential.

The present study focused on the finding of reducing agents for the formation of silver nanoparticles (AgNPs) from the plant, Trichosanthes tricuspidata. The synthesized AgNPs were characterized using UV-Visible spectroscopy, particle size analyzer (PSA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses. The UV-Visible spectrum resulted a sharp peak (at 430nm) represents the strong plasmon resonance of silver. The average size distributions of AgNPs were found to be 78.49nm, through (PSA), and the silver ion with its crystalline nature was confirmed using intensity (2θ) peak value of 38.22°, 44.66°, 64.61°, and 77.49°. The SEM micrograph revealed that the synthesized AgNPs have a spherical morphology with the size ranges from 20 to 28nm. AFM showed the presence of polydispersed AgNPs with its size (20 to 60nm in height). The gas chromatography-mass spectroscopy (GC-MS) study analyzed the responsible compounds present in the methanolic extracts for the bio-reduction of AgNPs and their antibacterial effect was studied. AgNPs exhibited preponderant activity than the methanolic extracts on clinical pathogens. Thus, the synthesized AgNPs might act as an effective antibacterial agent. Further studies are required to isolate the specific compound responsible for the reduction capability and its their inhibitory mechanisms for target bacterial strains.

Enhanced Photocatalytic Performance of the Graphene-V2O5 Nanocomposite in the Degradation of Methylene Blue Dye under Direct Sunlight.

A simple and efficient solution mixing method has been developed for the synthesis of the G-V2O5 nanocomposite. By this method, one-dimensional V2O5 rods are decorated onto the two-dimensional graphene sheets. The synthesized nanocomposites are characterized by XRD, SEM with elemental mapping, TEM, FT-IR, Raman, BET, and XPS analyses. The photocatalytic activity of the G-V2O5 nanocomposite studied with methylene blue dye shows strong degradation efficiency with direct sunlight irradiation compared to UV and visible light sources. The mechanism of methylene blue dye degradation by the G-V2O5 nanocomposite has been elucidated through the kinetics of the degradation process by calculating the rate constant and half-life time of the degradation process.

Mesoporous carbon encapsulated with SrO nanoparticles for the transesterification of ethyl acetoacetate.

Highly basic active sites were introduced by the encapsulation of SrO nanoparticles inside the porous channels of highly ordered mesoporous carbon using wet-impregnation method. The samples prepared were thoroughly investigated employing various physico-chemical characterization techniques such as X-ray diffraction (XRD), N2 adsorption, high resolution transmission electron microscope (HRTEM) and elemental mapping. The basic sites located inside the nanochannels were quantified by the temperature programmed desorption (TPD) of CO2. XRD, N2 adsorption and HRTEM results revealed that the structural order of the parent CMK-3 support is retained even after higher loading of SrO nanoparticles. TPD of CO2 profiles confirmed that the number of basic active sites can be controlled by varying the SrO loading and the pore diameter of the CMK-3 support. The catalytic potential of the prepared samples was investigated on the transesterification of ethyl acetoacetate (EAA) as a probe reaction. Among the catalysts studied, CMK-3-150 loaded with 30 wt% of SrO nanoparticles exhibited the highest catalytic activity. The effect of various alcohols such as aryl (benzyl alcohol), aliphatic (1-butanol and 1-octanol) and cyclic alcohols (cyclohexanol and furfuryl alcohol) affecting the activity of the catalyst was also investigated. It was found that the catalyst offers maximum conversion when linear aliphatic alcohols especially, 1-butanol with shorter chain length are used. The amount of SrO loading, pore diameter of the CMK-3 support and the weight of the catalyst affecting the catalytic performance of the samples were investigated and discussed in accordance with the physico-chemical characterization data of the catalysts.

Synthesis and morphological control of europium doped cadmium sulphide nanocrystals.

Europium doped cadmium sulphide (Cd(0.98)Eu(0.2)S) nanostructures were synthesised by chemical co-precipitation method using ethylene glycol (EG) and deionized water (Eu:CdS-1), and isopropyl alcohol (IPA) and deionized water (Eu:CdS-2) as mixed solvents. It has been found that the nanostructure of the europium doped CdS can be controlled by simply varying the mixed solvent system. Powder XRD pattern reveals the formation of hexagonal (wurtzite) and cubic (zinc blende) structure for Eu:CdS-1, and Eu:CdS-2, respectively. The crystallite size of the sample prepared using IPA and deionized water was measured to be 2.64 nm which is much smaller than that of the sample prepared using EG and deionized water as mixed solvent (3.65 nm). Morphology of the materials can also be changed from flower shaped crystals to paddy like structures by varying the mixed solvents. Band gap values of Eu3+ doped CdS nanocrystals synthesized from two different solvents were estimated using UV-reflectance spectra. The size and crystallinity of the samples were confirmed by HRTEM and SAED analysis. A significant change in the PL emission of the CdS nanocrystals was observed for the europium doped CdS which is mainly due to the presence of EU3+ ions which also play a significant role in the energy transfer process. It was also observed that the shift in the emission and efficiency depends on size and shape of the synthesised nanoparticles.

Fabrication and interfacial electronic structure studies on polypyrrole/TiO2 nano hybrid systems for photovoltaic aspects.

The progress in studying the interfacial electronic structures of the developing new class of hybrid organic/inorganic material systems have envisaged a new dimension into the field of photovoltaics, which could be of great help in understanding the nature of charge transfer in them. In this regard, electropolymerization of pyrrole monomers have been carried out at room temperature on the surface of TiO2 working electrodes (assisted by UV radiations) and their interfacial electronic structure has been studied as a function of the applied photo anodic potentials. The formation of polypyrrole deposits has been ensured using FT-IR and Raman spectroscopy. Surface analysis of the hybrid matrix revealed the tendency of polymer molecules to cover up the spherical surface of TiO2 nanoparticles that could help in improving the light absorption rate. Signals (bands) corresponding to pyrrole molecules observed in the ultraviolet photoelectron spectroscopy measurements have been correlated with the polaronic states formed and identified to shift as a function of the applied photo anodic potentials, revealing the decrease in work function of the hybrid system to take place (confirmed using cyclic voltammetry measurements). The decreasing trend in the work function elucidates the adjustment in electronic structure of the system (hybrid materials possessing smaller work functions are generally preferred for photovoltaic studies). The aforementioned behavioural aspects have been reasoned with the increase in overpotential values for polarization, from the decrease in up-take rate of the anionic dopant, which increases the current density values, thereby modifying the conductivity of the systems.

Ultrafast microwave assisted synthesis of mesoporous SnO2 and its characterization.

Mesoporous SnO2 was prepared by a high temperature microwave assisted process using a low cost polymeric surfactant, poly(ethylene glycol). The obtained material has been characterized by several sophisticated techniques such as XRD, nitrogen adsorption, HRTEM, UV-Vis DRS, HRSEM and photoluminescence. The characterization results reveal that the obtained material exhibits a high surface area with a spherical morphology, crystalline walls and narrow mesopores. In addition, microwave process requires only a short time for the formation of mesoporous SnO2. SnO2 with no porous structure was obtained when hydrothermal technique was used. We also found that the band gap of the mesoporous SnO2 is much smaller than that of the nonporous bulk SnO2 and showed excellent photoluminescent properties.