Copper foam supported g-C3N4-metal-organic framework bacteria biohybrid cathode catalyst for CO2 reduction in microbial electrosynthesis.

Microbial electrosynthesis (MES) presents a versatile approach for efficiently converting carbon dioxide (CO2) into valuable products. However, poor electron uptake by the microorganisms from the cathode severely limits the performance of MES. In this study, a graphitic carbon nitride (g-C3N4)-metal-organic framework (MOF) i.e. HKUST-1 composite was newly designed and synthesized as the cathode catalyst for MES operations. The physiochemical analysis such as X-ray diffraction, scanning electron microscopy (SEM), and X-ray fluorescence spectroscopy showed the successful synthesis of g-C3N4-HKUST-1, whereas electrochemical assessments revealed its enhanced kinetics for redox reactions. The g-C3N4-HKUST-1 composite displayed excellent biocompatibility to develop electroactive biohybrid catalyst for CO2 reduction. The MES with g-C3N4-HKUST-1 biohybrid demonstrated an excellent current uptake of 1.7 mA/cm2, which was noted higher as compared to the MES using g-C3N4 biohybrid (1.1 mA/cm2). Both the MESs could convert CO2 into acetic and isobutyric acid with a significantly higher yield of 0.46 g/L.d and 0.14 g/L.d respectively in MES with g-C3N4-HKUST-1 biohybrid and 0.27 g/L.d and 0.06 g/L.d, respectively in MES with g-C3N4 biohybrid. The findings of this study suggest that g-C3N4-HKUST-1 is a highly efficient catalytic material for biocathodes in MESs to significantly enhance the CO2 conversion.

Diffusion controlled electrochemical analysis of MoS2 and MOF derived metal oxide-carbon hybrids for high performance supercapacitors.

In the context of emerging electric devices, the demand for advanced energy storage materials has intensified. These materials must encompass both surface and diffusion-driven charge storage mechanisms. While diffusion-driven reactions offer high capacitance by utilizing the bulk of the material, their effectiveness diminishes at higher discharge rates. Conversely, surface-controlled reactions provide rapid charge/discharge rates and high power density. To strike a balance between these attributes, we devised a tri-composite material, TiO2/Carbon/MoS2 (T10/MoS2). This innovative design features a highly porous carbon core for efficient diffusion and redox-active MoS2 nanosheets on the surface. Leveraging these characteristics, the T10/MoS2 composite exhibited impressive specific capacitance (436 F/g at 5 mV/s), with a significant contribution from the diffusion-controlled process (82%). Furthermore, our symmetrical device achieved a notable energy density of ~ 50 Wh/kg at a power density of 1.3 kW/kg. This concept holds promise for extending the approach to other Metal-Organic Framework (MOF) structures, enabling enhanced diffusion-controlled processes in energy storage applications.

L-cysteine/MoS2 modified robust surface plasmon resonance optical fiber sensor for sensing of Ferritin and IgG.

L-cysteine conjugated molybdenum disulphide (MoS2) nanosheets have been covalently attached to a gold coated surface plasmon resonance (SPR) optical fiber to prepare a robust and stable sensor. Owing to the multifunctionality of the deposited nanosheet conjugate, the antibodies are also covalently conjugated in the subsequent step to realize the design of a SPR optical fiber biosensor for the two important bioanalytes namely, Ferritin and Immunoglobin G (IgG). The different stages of the biosensor preparation have been characterized and verified with microscopic and spectroscopic techniques. A uniform and stable deposition of the L-cysteine/MoS2 nanosheets has allowed the biosensor to be reused for multiple times. Unlike the peeling-off of the MoS2 coatings from the gold layer reported previously in the case of physically adsorbed nanomaterial, the herein adopted strategy addresses this critical concern. It has also been possible to use the single SPR fiber for both Ferritin and IgG bioassay experiments by regenerating the sensor and immobilizing two different antibodies in separate steps. For ferritin, the biosensor has delivered a linear sensor response (SPR wavelength shifts) in the concentration range of 50-400 ng/mL, while IgG has been successfully sensed from 50 to 250 µg/mL. The limit of detection for Ferritin and IgG analysis have been estimated to be 12 ng/mL and 7.2 µg/mL, respectively. The biosensors have also been verified for their specificity for the targeted molecule only. A uniform and stable deposition of the nanomaterial conjugate, reproducibility, regeneration capacity, a good sensitivity, and the specificity can be highlighted as some of key features of the L-cysteine/MoS2 optical fiber biosensor. The system can be advocated as a useful biosensor setup for the sensitive biosensing of Ferritin and IgG.

A novel zinc sulfide impregnated carbon composite derived from zeolitic imidazolate framework-8 for sodium-ion hybrid solid-state flexible capacitors.

The pyrolysis of metal-organic frameworks (MOFs) is an easy approach to prepare metal oxides as well as nanoporous carbon with high specific surface area. In the present work, for the first time, ZIF-8 (zeolitic imidazolate framework-8) has been pyrolyzed under different conditions to derive two products, i.e., highly porous carbon (C) and zinc sulfide (ZnS) infused carbon (ZnS@C). These two materials, i.e., nanoporous C and ZnS@C, have been investigated as a negative and a positive electrode, respectively, for potential application in a hybrid asymmetrical solid-state supercapacitor device (HASD). The controlled pyrolysis approach for the preparation of ZnS@C has yielded uniformly distributed ZnS nanoparticles inside the carbon structure. A 1.8 V HASD has been assembled, which delivered an excellent energy density of 38.3 W h kg-1 (power density of 0.92 kW kg-1) along with the greatly desirable feature of cycling stability. The proposed selection of materials as electrodes is promising to develop futuristic hybrid capacitors.

Two-dimensional transition metal dichalcogenides assisted biofunctionalized optical fiber SPR biosensor for efficient and rapid detection of bovine serum albumin.

The present study reports an alternative method of functionalizing the optical fiber Surface Plasmon Resonance (SPR) sensing probe with antibodies for label-free detection of bovine serum albumin (BSA) protein. In this novel approach, the gold coated fiber was first modified with Molybdenum disulfide (MoS2) nanosheets followed by its bio-functionalization with Anti-BSA antibodies. The developed technique not only allowed the amplification of the SPR signals by synergic effects of MoS2 and gold metallic thin film but also enabled a direct and chemical-free attachment of representative antibodies through hydrophobic interactions. The sensitivity of the MoS2 modified sensing probe with detection limit of 0.29 µg/mL was improved as compared to the fiber optic SPR biosensor without MoS2 overlayer (Detection limit  for BSA was 0.45 µg/mL). The developed biosensor has good specificity, and environmental stability. Accordingly, the proposed design of the MoS2 based SPR optical biosensor can offer the development of a simplified optical device for the monitoring of various biomedical and environmental parameters.

Rapid detection of Escherichia coli using fiber optic surface plasmon resonance immunosensor based on biofunctionalized Molybdenum disulfide (MoS2) nanosheets.

The molybdenum disulfide (MoS2) nanosheets functionalized fiber optic surface plasmon resonance (SPR) immunosensor has been reported for the sensitive detection of Escherichia coli (E. coli). The MoS2 nanosheets were prepared by chemical exfoliation method. The synthesised nanostructures were characterized for their structural, morphological and optical properties. The E. coli monoclonal antibodies were successfully immobilized on the MoS2 functionalized sensing platform via hydrophobic interactions. An alternative method simplifying the antibodies immobilization process by functionalization of 2D nanomaterial (MoS2 nanosheets) for rapid (~15 mins) bacterial quantification is presented in this study. The immunosensor uses wavelength interrogation method and a strong linear relationship (R2 = 0.994) was observed between spectral response of immunosensor and different concentration of E. coli. The nonspecificity and cross-reactivity studies of the developed immunosensor were investigated with detection of Salmonella Typhimurium and Staphylococcus aureus. To demonstrate the practical application, spiked samples of water and orange juice were analysed with acceptable recovery results. The label-free immunosensor exhibits better performance, detection limit (94 CFU/mL), high sensitivity (2.9 nm/1000 CFU mL-1; 3135 nm/RIU) and profound specificity as compared to conventional fiber optic SPR sensor (detection limit: 391 CFU/mL, sensitivity: 0.6 nm/1000 CFU mL-1; 1646 nm/RIU). This sensing platform shows promising applications in regular water and food quality monitoring for various pathogenic microorganisms.

Expression of G-protein alpha subunit genes in the vestibular periphery of Rattus norvegicus and their chromosomal mapping.

OBJECTIVE: Heterotrimeric G-proteins play an important role in mediating signals transduced across the cell membrane by membrane-bound receptors. The precise role of G-proteins and their coupled receptors in the physiology of the vestibular neuroepithelium is not well understood. The purpose of this study was to better define the role of these proteins by examining their expression in the rat vestibular periphery and characterizing their chromosomal location. MATERIAL AND METHODS: To characterize G-protein alpha subunit gene expression in the target tissue of interest, we performed polymerase chain reaction (PCR) using degenerate G-protein primers corresponding to conserved regions in the G-protein alpha subunit coding sequence on a normalized rat vestibular cDNA library. PCR amplicons were cloned and 50 clones were randomly selected and sequenced. Radiation hybrid (RH) mapping was used to determine the chromosomal location of G alpha(olf) and two previously identified G-protein alpha subunits--G alpha(i2) and G alpha(i2(vest))--in the rat genome. RESULTS: The following G-protein alpha subunits were identified in the normalized cDNA library: G alpha(olf), G alpha(s), G alpha(o) and G alpha(s2). G alpha(olf) maps to chromosome 18 between markers D18Mit17b and D18Mgh2. G alpha(i2) maps to chromosome 8 between markers D8Rat65 and D8Mgh2. G alpha(i2(vest)) maps to chromosome 1 between markers D1Rat132 and D1Rat202. These chromosomal locations in the rat genome are syntenic to chromosomal regions in which the homologous G-protein alpha subunit genes have been localized in the human and mouse genomes, further validating RH mapping as an effective and accurate tool. We were unable to RH map the location of G alpha(o) due to its extensive homology with the hamster gene. CONCLUSION: The characterization of G-protein alpha subunit gene expression in the vestibular periphery and the chromosomal localization of these genes in the rat revealed that a diverse group of these second messengers are expressed.