Recent Advances in Two-Dimensional Nanomaterials for Healthcare Monitoring.

The development of advanced technologies for the fabrication of functional nanomaterials, nanostructures, and devices has facilitated the development of biosensors for analyses. Two-dimensional (2D) nanomaterials, with unique hierarchical structures, a high surface area, and the ability to be functionalized for target detection at the surface, exhibit high potential for biosensing applications. The electronic properties, mechanical flexibility, and optical, electrochemical, and physical properties of 2D nanomaterials can be easily modulated, enabling the construction of biosensing platforms for the detection of various analytes with targeted recognition, sensitivity, and selectivity. This review provides an overview of the recent advances in 2D nanomaterials and nanostructures used for biosensor and wearable-sensor development for healthcare and health-monitoring applications. Finally, the advantages of 2D-nanomaterial-based devices and several challenges in their optimal operation have been discussed to facilitate the development of smart high-performance biosensors in the future.

TiO2 nanorod decorated with MoS2 nanospheres: An efficient dual-functional photocatalyst for antibiotic degradation and hydrogen production.

The design and preparation of dual-functional photocatalysts for simultaneously realizing photocatalytic wastewater purification and hydrogen energy generation pose significant challenges. This article presents the engineering of a binary heterostructured photocatalyst by combining TiO2 (nanorods) and MoS2 nanosphere using a straightforward solvothermal method and the assessment of the phase structures, morphologies, and optical properties of the resulting nanocomposites using diverse analytical techniques. The TiO2(Rod)/MoS2 composite exhibits remarkable efficacy in degrading ciprofloxacin, achieving 93% removal rate within 1 h, which is four times higher than that of bare TiO2. Moreover, the optimized TiO2(Rod)/MoS2 presents an outstanding hydrogen production rate of 7415 µmol g-1, which is ∼24 times higher than that of pristine TiO2. Under UV-visible light irradiation, the TiO2(Rod)/MoS2 heterojunction displays an exceptional photocatalytic performance in terms of both photodegradation and hydrogen production, surpassing the performance of TiO2 particle/MoS2. The study findings demonstrate that TiO2(Rod)/MoS2 nanocomposites exhibit considerably improved photocatalytic degradation and hydrogen generation activities. Based on the experimental results, a possible mechanism is proposed for the transfer and separation of charge carriers in Z-scheme heterojunctions.

Compact Flexible Planar Antennas for Biomedical Applications: Insight into Materials and Systems Design.

Planar antennas have become an integral component in modern biomedical instruments owing to their compact structure, cost effectiveness, and light weight. These antennas are crucial in realizing medical systems such as body area networks, remote health monitoring, and microwave imaging systems. Antennas intended for the above applications should be conformal and fabricated using lightweight materials that are suitable for wear on the human body. Wearable antennas are intended to be placed on the human body to examine its health conditions. Hence, the performance of the antenna, such as its radiation characteristics across the operating frequency bands, should not be affected by human body proximity. This is achieved by selecting appropriate conformal materials whose characteristics remain stable under all environmental conditions. This paper aims to highlight the effects of human body proximity on wearable antenna performance. Additionally, this paper reviews the various types of flexible antennas proposed for biomedical applications. It describes the challenges in designing wearable antennas, the selection of a flexible material that is suitable for fabricating wearable antennas, and the relevant methods of fabrication. This paper also highlights the future directions in this rapidly growing field. Flexible antennas are the keystone for implementing next-generation wireless communication devices for health monitoring and health safety applications.

Effective Visible-Light-Driven Photocatalytic Degradation of Harmful Antibiotics Using Reduced Graphene Oxide-Zinc Sulfide-Copper Sulfide Nanocomposites as a Catalyst.

In recent decades, antibiotics have been found in aquatic environments, raising severe concerns. In this study, a unique reduced graphene oxide-zinc sulfide-copper sulfide (rGO-ZnS-CuS) nanocomposite (NC) prepared by using a straightforward surfactant-free in situ microwave method was used for antibiotic degradation via photocatalysis. The structural and morphological characteristics of the produced catalysts were characterized using various techniques, confirming the successful development of nanocomposite structures of better quality than that of the pure samples. The photocatalytic degradation of antibiotics containing ofloxacin was also investigated. The results suggest that the rGO-ZCS NC outperformed the other composites in terms of photocatalytic activity toward ofloxacin degradation. Superoxide and hydroxyl radicals were the main active species during the degradation process. According to our results, the catalytic activity of rGO-ZCS NC is much better than that of the other composites.

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.

Multicomponent X-ray Shielding Using Sulfated Cerium Oxide and Bismuth Halide Composites.

Lead is the most widely used X-ray-shielding material, but it is heavy (density ≈ 11.34 g/cm3) and toxic. Therefore, the replacement of Pb with lightweight, ecofriendly materials would be beneficial, and such materials would have applications in medicine, electronics, and aerospace engineering. However, the shielding ability of Pb-free materials is significantly lower than that of Pb itself. To maximize the radiation attenuation of non-Pb-based shielding materials, a high-attenuation cross-section, normal to the incoming X-ray direction, must be achieved. In this study, we developed efficient X-ray-shielding materials composed of sulfated cerium oxide (S-CeO2) and bismuth halides. Crucially, the materials are lightweight and mechanically flexible because of the absence of heavy metals (for example, Pb and W). Further, by pre-forming the doped metal oxide as a porous sponge matrix, and then incorporating the bismuth halides into the porous matrix, uniform, compact, and intimate composites with a high-attenuation cross-section were achieved. Owing to the synergetic effect of the doped metal oxide and bismuth halides, the resultant thin (approximately 3 mm) and lightweight (0.85 g·cm-3) composite achieved an excellent X-ray-shielding rate of approximately 92% at 60 kV, one of the highest values reported for non-heavy-metal shielding materials.

Recent Advances in Molybdenum Disulfide and Its Nanocomposites for Energy Applications: Challenges and Development.

Energy storage and conversion are critical components of modern energy systems, enabling the integration of renewable energy sources and the optimization of energy use. These technologies play a key role in reducing greenhouse gas emissions and promoting sustainable development. Supercapacitors play a vital role in the development of energy storage systems due to their high power density, long life cycles, high stability, low manufacturing cost, fast charging-discharging capability and eco-friendly. Molybdenum disulfide (MoS2) has emerged as a promising material for supercapacitor electrodes due to its high surface area, excellent electrical conductivity, and good stability. Its unique layered structure also allows for efficient ion transport and storage, making it a potential candidate for high-performance energy storage devices. Additionally, research efforts have focused on improving synthesis methods and developing novel device architectures to enhance the performance of MoS2-based devices. This review article on MoS2 and MoS2-based nanocomposites provides a comprehensive overview of the recent advancements in the synthesis, properties, and applications of MoS2 and its nanocomposites in the field of supercapacitors. This article also highlights the challenges and future directions in this rapidly growing field.

Biogenic Synthesis and Characterization of Silver Nanoparticles: Evaluation of Their Larvicidal, Antibacterial, and Cytotoxic Activities.

To explore the larvicidal activity of the silver nanoparticles (AgNPs) synthesized using the ethanolic Catharanthus roseus flower extract (CRE) against the larvae of Aedes aegypti (A. aegypti), AgNPs were synthesized by an eco-friendly method and characterized by Ultraviolet-Visible (UV-Vis) spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), Particle Size Analysis, Transmission Electron Microscopy (TEM), and Energy-Dispersive X-Ray spectrometry (EDX) analysis. The resultant AgNPs showed a spherically well-defined, highly stable, and monodispersed shape with an average particle size ranging from 15 to 25 nm. The absorbance of the AgNPs was measured by using a UV-Vis spectrophotometer at a wavelength of 416 nm. The presence and binding of the phenolic functional group with the AgNPs were confirmed using FTIR analysis. Particle size analysis revealed an average particle diameter of 90 nm with 80 % distribution. XRD analysis revealed the highly crystalline nature of the CRE-AgNPs. The LC50 and LC90 values of CRE-AgNPs and the extract were calculated. The mortality percentage of the extract and synthesized CRE-AgNPs was observed after 24 h. The maximum larvicidal activity with 100 % mortality of A. aegypti was observed in AgNPs synthesized using ethanolic CRE. The LC50 and LC90 values are 8.963 and 20.515 ppm for CRE-AgNPs against A. aegypti larvae, respectively. The CRE-AgNPs revealed superior antibacterial activity against human pathogenic bacteria; the zone of inhibition (ZOI) was measured for all of the pathogens, and the results revealed that different concentrations of CRE-AgNPs showed a remarkable ZOI of about (a) 10-14 mm for Salmonella typhimurium, (b) 6-11 mm for Bacillus subtilis, (c) 11-14 mm for Enterococcus faecalis, and (d) 9-10 mm for Shigella boydii. The maximum ZOI was observed in E. faecalis. Impeccably, the cytotoxicity of CRE-AgNPs at 250 µg/mL is 82% against the HaCaT cell lines. The synthesized CRE-AgNPs showed maximum effectiveness of paradoxical activity on mosquito larvae.

Effective Chemical Vapor Deposition and Characterization of N-Doped Graphene for High Electrochemical Performance.

Here we reports an effective synthetic method for the preparation of N-graphene upon thermal annealing of prepared graphene oxide in the existence of ammonia. N-doped graphene oxide was analysed using different characterization techniques like X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The nitrogen atom showed good binding with the graphene sheets, that are analysed by the X-ray photoelectron spectroscopy. The synthesized N-graphene have shown higher thermal stability compared with GO and graphene. The elcerochemnical performance like Cyclic voltammetry as well chronopotentiometry charge-discharge calculations revealed that the N-doped graphene exhibits remarkable behaviour favors a specific capacitance value about 209 F g-1 at 5 mV s-1 and 270 F g-1 for 1 A g-1 applied current density including outsanding charge-discharge stability about 98% of the initial capacitance subsequent 1000 cycles at 5 A g-1. The N-content in the graphene material with the optimized reaction parameters potentially improved electrode active material for energy storage applications.

Facile one-pot microwave assisted synthesis of rGO-CuS-ZnS hybrid nanocomposite cathode catalysts for microbial fuel cell application.

A reduced graphene oxide-copper sulfide-zinc sulfide (rGO-CuS-ZnS) hybrid nanocomposite was synthesized using a surfactant-free in-situ microwave technique. The in-situ microwave method was used to prepare 1-D ZnS nanorods and CuS nanoparticles decorated into the rGO nanosheets. The prepared hybrid nanocomposite catalysts were analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, elemental mapping analysis, and X-ray photoelectron spectroscopy. The effectiveness of the synthesized rGO-CuS-ZnS hybrid nanocomposite (rGO-CZS HBNC) was estimated using an innovative cathode catalyst in microbial fuel cell (MFC). MFCs were fabricated differently such as SL (single-layer), DL (double-layer), and TL (triple-layer) loading. Followed using cyclic voltammetry and impedance analyses, the electrochemical evaluation of the prepared MFCs was evaluated. Among the fabricated MFCs, the DL MFCs with rGO-CuS-ZnS cathode catalyst displayed higher power density (1692 ± 15 mW/m2) and OCP (761 ± 9 mV) than the other catalysts loadings, such as SL and TL. rGO-CZS HBNC are potential cathode materials for MFC applications.

Antibacterial and photocatalytic activities of 5-nitroindole capped bimetal nanoparticles against multidrug resistant bacteria.

The emergence of antibiotic resistance to commercially- available antibiotics is becoming a major health crisis worldwide. Non-antibiotic strategies are needed to combat biofilm-associated infectious diseases caused by multidrug resistant (MDR) bacterial pathogens. In this study, MBR1 was isolated from a membrane bioreactor used in wastewater treatment plants, and the resistance profile was explored. 5-Nitroindole (5 N)-capped CuO/ZnO bimetal nanoparticles (5 NNP) were synthesized using a one pot method to improve the antibacterial and antibiofilm activities of 5 N against Gram-negative (Escherichia coli ATCC700376 and Pseudomonas aeruginosa PA01) and positive (Staphylococcus aureus ATCC6538) human pathogens. 5 NNP containing 1 mM of 5 N exhibited strong antibacterial and antibiofilm properties to most MDR bacteria. In addition, the photocatalytic activity of CuO/ZnO reduced bacterial cell growth by 1.8 log CFU/mL maximum when exposed to visible light. Scanning electron microscopy showed that 5 NNP reduced the cell density and biofilm attachment of MBR1 by >90% under static conditions. In addition to the antimicrobial and antibiofilm activities, 5 NNP inhibited the persister cell formation of MDR bacterial strains P. aeruginosa, MBR1, E. coli and S. aureus. Therefore, it is speculated that 5 NNP potentially inhibits biofilm and persister cells; hence, 5 NNP could be an alternative agent to combat MDR infectious diseases using a non-antibiotic therapeutic approach.

Antibacterial and photocatalytic activity of hydrothermally synthesized SnO2 doped GO and CNT under visible light irradiation.

Bacterial and dye pollution are major problems with wastewater treatment. An increasing number of photocatalysts are being used in industry to kill bacterial and reduce pollution. In the present study, highly stable SnO2-doped nanocomposites have been prepared successively by a hydrothermal method. The synthesized nanocomposite was characterized using a range of techniques, such as X-ray diffraction, field emission scanning electron microscopy with energy dispersive X-ray spectroscopy and electron probe micro analysis, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and high resolution transmission electron microscopy (HR-TEM). The nanocomposites showed significant dose-dependent bactericidal activity in the disc diffusion assay and cell viability test. The S-GO-SnO2 200 µg/mL produced a cell viability of 184.3 ±â€¯11.71 and 172.3 ±â€¯3.05 × 106 CFU/mL for E. coli and P. graminis, respectively. The S-GO-SnO2 showed significant photocatalytic degradation against MB in 120 min. The photocatalyst S-GO-SnO2 showed 159 and 161 × 106 CFU/mL at 150 min in E. coli and P. graminis, respectively. The cells treated with photocatalytic SnO2-doped nanocomposites showed 50% cell death. HR-TEM revealed 50% cell growth inhibition by bacterial damage. This photocatalytic SnO2-doped nanocomposite is a good candidate for treating industrial wastewater treatment contaminated with dyes and bacteria.

Enhanced cathode performance of a rGO-V2O5 nanocomposite catalyst for microbial fuel cell applications.

A reduced graphene oxide-V2O5 nanocomposite was synthesized by a low temperature surfactant free hydrothermal method and its MFC performance was assessed. The structural properties of the synthesized nanocomposite were studied by X-ray diffraction. Field emission scanning electron microscopy of the nanocomposite revealed a wrinkled paper-like structure of rGO and a nanobelt-like structure of V2O5. This study estimated the viability of the graphene-based nanocomposite rGO-V2O5 as a novel cathode catalyst in single chamber air-cathode MFCs. A series of MFCs with different catalyst loadings were produced. The electrochemical behavior of the MFCs was calculated by cyclic voltammetry. The MFCs with the rGO-V2O5 nanocomposite cathode exhibited superior maximum power densities (83%) to those with the pure V2O5 cathodes. The rGO-V2O5 with a double-loaded nanocomposite catalyst achieved an enhanced power density of 1668 ± 11 mW m-2 and an OCP of 698 ± 4 mV, which was 83% of that estimated for the Pt/C 2004 ± 15 mW m-2 nanocomposite cathode. The significant increase in power density suggests that the reduced graphene oxide-V2O5 nanocomposite is a promising material for MFC applications. The CV result showed good agreement with the MFC result. The prepared rGO-V2O5 nanocomposite cathode, particularly with a double loading catalyst, is promising as a sustainable low-cost green material for stable power generation and long-term operation of MFCs.