Fabrication of magnetite/GO/potassium copper hexacyanoferrate nanocomposite for removal of radioactive cesium ions.

Metal hexacyanoferrates (MHCF) are a class of inorganic adsorbents used for wastewater management due to the presence of interstitial sites for capturing heavy metal ions. In present work, we are reporting the synthesis of magnetic nanocomposite of Fe3O4/graphene oxide/potassium copper hexacyanoferrate via wet chemical and coprecipitation approach. Potassium copper hexacyanoferrate (KCuHCF) and Graphene oxide (GO) both are marvelous adsorbents but their nano-size becomes a major obstacle in their separation process after the adsorption of the radionuclides. Thus, our synthesized nanocomposite Fe3O4/GO/KCuHCF enhances the recovery of KCuHCF even after radioactive Cs+ adsorption with adsorption capacity of 18 mg g-1 coinciding well with the Langmuir adsorption isotherm mechanism. The synthesized adsorbent is characterized thoroughly using UV-Visible spectroscopy, FT-IR, TGA, XPS, Raman spectroscopy, TEM-EDAX and XRD. This synthesized nanocomposite is used for the batch extraction of radioactive Cs+ from low level radioactive waste (LLW). The extraction kinetics followed pseudo-second-order kinetics mechanism.

Modified hydrophobic and oleophilic polyurethane sponge for oil absorption with MIL-53.

A hydrophobic composite sponge (HPCS) is developed for the first time using the dip coating and drying method in an effort to remove organic contaminants like toluene and various oils from water. We employed a polyurethane (PU) sponge, which is reasonably priced, easily accessible, high mechanical strength and a suitable porous substrate on which the hydrophobic composite of MIL-53(Al) along with PDMS was anchored. A crystalline metal organic framework (MOF), MIL-53(Al), with adjustable porosity, functionality, and hydrophobicity is used for oil absorption. Polydimethylsiloxane (PDMS) is utilized to increase the hydrophobicity of MIL-53(Al). The MIL-53(Al)@PDMS composite was used to the produce a sponge having high hydrophobicity and oleophilicity. In contrast to PU sponge, which has a low water contact angle (79.64°), the hydrophobic composite sponge showed a wide range of oil absorption capacity (12-50.5 g/g), a very low amount of water absorption (0.84 g/g), and water contact angle of 128.13°. This hydrophobic composite performed phenomenally by separating out various oils and solvents from water even in varying ionic strengths. Moreover, the recyclability of the formed composite was also performed resulting into 6-20 cycles for different oils and solvents. The synthesized hydrophobic composite sponge was characterized using FT-IR, XRD, TEM, surface area analysis, FESEM, XPS, TG analysis and contact angle measurement. Furthermore, the materials used in the synthesis of composite are non-toxic and do not harm the environment, resulting in no greenhouse gas emissions making our composite environmentally friendly.

Interdigitated electrodes-based Au-MoS2hybrid gas sensor for sensing toxic CO and NH3gases at room temperature.

In the quest to create effective sensors that operate at room temperature, consume less power and maintain their stability over time for detecting toxic gases in the environment, molybdenum disulfide (MoS2) and MoS2-based hybrids have emerged as potent materials. In this context, the current work describes the fabrication of Au-MoS2hybrid gas sensor fabricated on gold interdigitated electrodes (GIEs) for sensing harmful CO and NH3gases at room temperature. The GIEs-based Au-MoS2hybrid sensors are fabricated by decorating MoS2nanoflowers (MNF) with varying size of Au nanoparticles using an inert gas evaporation technique. It is observed that by varying the size of Au nanoparticles, the crystallinity gets modified, as confirmed by x-ray diffraction and Micro-Raman spectroscopy (µRS). The gas sensing measurements revealed that the best sensing response is found from the Au-MoS2hybrid (with an average particle size of 10 nm). This particular hybrid shows a 79% response to CO exposure and a 69% response to NH3exposure. The measurements are about 3.5 and 5 times higher than the bare MoS2when exposed to CO and NH3at room temperature, respectively. This enhancement in sensing response is attributed to the modified interfacial interaction between the Au nanoparticles and MNF gets improved, which leads to the formation of a Schottky barrier, as confirmed using x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy analysis. This enables the development of efficient gas sensors that respond quickly to changes in the gas around them.

Synergistic C-TiO2/ZIF-8 type II heterojunction photocatalyst for enhanced photocatalytic degradation of methylene blue.

Zinc imidazolate framework (ZIF-8) and titanium dioxide (TiO2) have been extensively studied as photocatalysts and have shown remarkable potential. In this study, we report the synthesis of a type II heterojunction photocatalyst based on carbon-doped TiO2 (C-TiO2) and ZIF-8 as a potentially improved material for solar light-harvested methylene blue (MB) degradation. Pure ZIF-8 has a wide band gap of 4.9 eV, due to which the application of this material to visible light-assisted photocatalytic performance is a challenging task. Therefore, C-TiO2 has been chosen as a composite material with ZIF-8 owing to its narrow band gap compared to TiO2. This enables the free radical-initiated photocatalytic reaction to shift into the visible region instead of the ultraviolet region. To construct the C-TiO2/ZIF-8 heterostructure, the zinc-based ZIF matrix has been built upon the exterior of C-TiO2 nanoparticles. UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS) corroborated the decrease in the band gap of ZIF-8 after the fabrication of C-TiO2/ZIF-8, while X-ray diffraction (XRD) analysis demonstrated a decrease in average d-spacing and average crystallite size of the synthesized photocatalyst. Raman spectra and X-ray photoelectron spectroscopy (XPS) analysis of the synthesized samples were also performed to further understand their chemical structure and elemental content. Ultraviolet photoelectron spectroscopy (UPS) and high-resolution transmission electron microscopy (HRTEM) analyses were performed to understand the valence band (VB) states and the morphology of C-TiO2/ZIF-8. The comparison between pure ZIF-8 and C-TiO2/ZIF-8 in the photocatalytic degradation of MB under visible light has also been drawn. A possible charge-transfer mechanism for the same has also been proposed. It is concluded that the synergistic effect of C-TiO2 and ZIF-8 in C-TiO2/ZIF-8 produces an effective material for photocatalytic dye degradation.

Antimicrobial activity of synthesized graphene oxide-selenium nanocomposites: A mechanistic insight.

Nanoparticles have recently gained interest as an anti-bacterial agent due to their large surface area/volume ratio and potential to compromise the integrity of bacterial cell membranes. Due to its versatility and anti-bacterial activity, graphene-based materials have drawn significant interest in biomedical applications. One of the greatest threats to life in the modern technological era is the pervasiveness of infectious diseases since bacteria cells are constantly updating themselves to resist antibiotics. In this presented study, GO-Se nanocomposite has been synthesized using polymer solution via a simple dispersion method. The structural and physicochemical properties of nanocomposite were investigated in detail. Staphylococcus aureus, Proteus vulgaris, and Bacillus subtilis bacterial strains were employed to study the anti-bacterial activity of GO-Se nanocomposite. The results show that the synthesized nanocomposites have good efficacy as an anti-bacterial agent. UV-vis spectroscopy, FTIR spectroscopy, HRTEM, XPS, and Raman spectroscopy were used to analyze the as-prepared GO and GO-Se nanocomposite.

Enhanced interfacial charge transfer on strain-induced 2D-1D/MoS2-TiO2heterostructures for electrochemical and photocatalytic applications.

Two-dimensional (2D)/one dimensionsal (1D)-MoS2/TiO2heterostructures have proven to be potent for photocatalytic applications. Enhancement of a heterostructure's photocatalytic activity may be influenced by the accumulation of strain at the interface, which affects the interfacial interaction. Keeping this in mind, the present paper reports strain-accumulated interfacial modification of 2D/1D-MoS2/TiO2heterostructures for the enhancement of photocatalytic activity. Two different synthesis methods, namely the hydrothermal and chemical vapor deposition (CVD) methods, are used for the growth of MoS2on TiO2nanostructures. Micro-Raman spectroscopy reveals that strain is accumulated at the interface of the growth of the MoS2over the TiO2nanostructures. It is further revealed that the MoS2/TiO2heterostructure synthesized by the CVD method induces compressive strain. Also, the heterostructure synthesized by the hydrothermal method induces tensile strain that modifies the charge separation at the interface, which is further confirmed by x-ray photoelectron spectroscopy (XPS). Moreover, ultraviolet photoelectron spectroscopy (UPS) reveals upward band-bending in the MoS2/TiO2heterostructure synthesized by the hydrothermal method. Similarly, the heterostructure synthesized by the CVD method shows downward band-bending that leads to improved charge separation at the interface. The modified interfaces of the heterostructures are further studied for electrochemical measurements using cyclic voltammetry (CV) and photocatalytic activity by degradation of a model compound.

In Vivo Biocompatibility of Electrospun Biodegradable Dual Carrier (Antibiotic + Growth Factor) in a Mouse Model-Implications for Rapid Wound Healing.

Tissue engineering technologies involving growth factors have produced one of the most advanced generations of diabetic wound healing solutions. Using this approach, a nanocomposite carrier was designed using Poly(d,l-lactide-co-glycolide) (PLGA)/Gelatin polymer solutions for the simultaneous release of recombinant human epidermal growth factor (rhEGF) and gentamicin sulfate at the wound site to hasten the process of diabetic wound healing and inactivation of bacterial growth. The physicochemical characterization of the fabricated scaffolds was carried out using scanning electron microscopy (SEM) and X-ay diffraction (XRD). The scaffolds were analyzed for thermal stability using thermogravimetric analysis and differential scanning calorimetry. The porosity, biodegradability, and swelling behavior of the scaffolds was also evaluated. Encapsulation efficiency, drug loading capacity, and in vitro drug release were also investigated. Further, the bacterial inhibition percentage and detailed in vivo biocompatibility for wound healing efficiency was performed on diabetic C57BL6 mice with dorsal wounds. The scaffolds exhibited excellent wound healing and continuous proliferation of cells for 12 days. These results support the applicability of such systems in rapid healing of diabetic wounds and ulcers.

In vivo diabetic wound healing with nanofibrous scaffolds modified with gentamicin and recombinant human epidermal growth factor.

Diabetic wounds are susceptible to microbial infection. The treatment of these wounds requires a higher payload of growth factors. With this in mind, the strategy for this study was to utilize a novel payload comprising of Eudragit RL/RS 100 nanofibers carrying the bacterial inhibitor gentamicin sulfate (GS) in concert with recombinant human epidermal growth factor (rhEGF); an accelerator of wound healing. GS containing Eudragit was electrospun to yield nanofiber scaffolds, which were further modified by covalent immobilization of rhEGF to their surface. This novel fabricated nanoscaffold was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The thermal behavior of the nanoscaffold was determined using thermogravimetric analysis and differential scanning calorimetry. In the in vitro antibacterial assays, the nanoscaffolds exhibited comparable antibacterial activity to pure gentemicin powder. In vivo work using female C57/BL6 mice, the nanoscaffolds induced faster wound healing activity in dorsal wounds compared to the control. The paradigm in this study presents a robust in vivo model to enhance the applicability of drug delivery systems in wound healing applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 641-651, 2018.

Nanofibre Based Smart Pharmaceutical Scaffolds for Wound Repair and Regenerations.

Chronic wounds and ulcers are posing a devastating manifestation on the socioeconomic status across the globe along with the patient compliance. It reinforces a need for the development of successful alternative treatments for the chronic wound care and ulcer management practices. This review explores the progressive developments being made in the fabrication of electrospun nanofibrous scaffolds towards elimination of microbial infection from chronic wounds to accelerate the wound healing process. Functional three dimensional nanofibrous scaffolds produced by electrospinning have great potential in a wide spectrum of biomedical practices, such as tissue engineering, drug/gene delivery and wound dressing. Moreover, this review also highlights the materials and post modification methods, such as the functionaliation of electrospun nanofibrous scaffolds using growth factors, so that such smart and bioactive nanofibrous scaffolds could be made suitable for wound healing applications.

Nitrogen-doped, thiol-functionalized carbon dots for ultrasensitive Hg(II) detection.

Nitrogen-doped, PEGylated carbon dots (C-dots) have been synthesized for the detection of mercury ions (Hg(2+)). The detection limit was found to be 6.8 nM. However, upon functionalization with dithiothreitol (DTT), it reached to as low as 18 pM. The C-dots-Hg(2+) system was also able to efficiently detect biothiols.

Direct visualization of lead corona and its nanomolar colorimetric detection using anisotropic gold nanoparticles.

The study presents dithiothreitol (DTT) functionalized anisotropic gold nanoparticles (GNP) based colorimetric sensor for detection of toxic lead ions in water. Our results demonstrate the selectivity and sensitivity of the developed sensor over various heavy metal ions with detection limit of ∼9 nM. The mechanism of sensing is explained on the basis of unique corona formation around the DTT functionalized anisotropic GNP.

Silver nanoparticle-loaded PVA/gum acacia hydrogel: synthesis, characterization and antibacterial study.

A simple one-pot method for in situ synthesis of silver nanoparticles (AgNPs), within polyvinyl alcohol/gum acacia (PVA-GA) hydrogel matrix, by gamma radiation-induced cross-linking is reported here. The synthesized hydrogels were characterized by FT-IR, thermogravimetry, dynamic light scattering and inductively coupled mass spectrometry method. The thermal stability was found to be more for the hydrogel loaded with silver nanoparticles and also the percentage silver loading was found to increase with increase in cross-linking density. The influence of gum acacia (GA) concentration on the equilibrium degree of swelling of the synthesized hydrogels, and also on the silver release from hydrogel matrix, was investigated. The size of the silver nanoparticles formed in the hydrogel matrix was in the range of 10-40 nm. The rheological gel point was found to be at 25.34 kGy of radiation dose, for a typical hydrogel synthesized, using 5% GA, 3% PVA and 1mM AgNO3. The antibacterial studies of the synthesized nanosilver-containing hydrogels showed good antibacterial activity against gram-negative bacterium, Escherichia coli.