Sorption of brilliant green dye using soybean straw-derived biochar: characterization, kinetics, thermodynamics and toxicity studies.

The present study was aimed to investigate brilliant green (BG) dye sorption onto soybean straw biochar (SSB) prepared at 800 °C and further understanding the sorption mechanism. Sorption kinetic models such as pseudo-first and pseudo-second order were executed for demonstrating sorption mechanism between the dye and biochar. Results of kinetics study were fitted well to pseudo-second-order kinetic model (R2 0.997) indicating that the reaction followed chemisorption mechanism. Furthermore, the effect of various parameters like sorbent dose, dye concentration, incubation time, pH and temperature on dye sorption was also studied. The maximum dye removal percentage and sorption capacity for SSB (800 °C) within 60 min were found to be 99.73% and 73.50 mg g- 1, respectively, at pH 8 and 60 °C temperature, whereas adsorption isotherm studies showed a higher correlation coefficient values for Freundlich model (R2 0.990-0.996) followed by Langmuir model suggesting that sorption process was multilayer. The characterization of biomass and biochar was performed with the aid of analytical techniques like scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) theory, X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA). FTIR analysis showed active groups on biochar surface. BET study revealed higher surface area of biochar (194.7 m2/g) than the biomass (12.84 m2/g). Besides, phyto- and cytogenotoxic studies revealed significant decrease in the toxicity of dye containing water after treating with SSB. Therefore, this study has proved the sorption potential of soybean straw biochar for BG dye and could be further considered as sustainable cost-effective strategy for treating the textile dye-contaminated wastewater.

Comparative evaluation of MAX, MXene, NanoMAX, and NanoMAX-derived-MXene for microwave absorption and Li ion battery anode applications.

MAX and MXene phases possess unique physical properties, encompassing the realms of both ceramics and metals. Their nanolaminated layered configuration, high anisotropic electrical conductivity, and ability to scatter electromagnetic radiation are beneficial in multiple applications. Herein, detailed applications of MAX and MXene are studied in the fields of microwave absorption and Li ion batteries (LIB). In particular, coatings based on MAX, MXene, ball-milled NanoMAX, and NanoMAX-derived-MXene (MXene-N) and their composites are examined in terms of their comparative efficacy for the aforesaid applications. NanoMAX and MXene-N based composites with graphite exhibit superior performance with specific reflection loss values (representing absorbance when measured with metal-backing) of -21.4 and -19 dB cm3 g-1, respectively, as compared to their bulk counterparts, that too with a low density (0.63 g cm-3) and very small thickness (0.03 mm). These performance improvements in absorbance in only 30 µm coatings can be attributed to reflective losses compounded with multiple internal reflections within the nanocomposite intensified by dielectric losses, arising from high interface density. The pristine samples were also studied for their performance as Li ion battery anodes. Herein, MXene-N exhibits the best performance with a specific capacity of 330 mA h g-1 at 100 mA g-1 and excellent cycling stability tested up to 1000 cycles.

Correction to: A review on nanomaterial-modified optical fiber sensors for gases, vapors and ions.

The published version of this article, unfortunately, contains error. Corrections in Figs. 1, 3 and 5 were incorrectly carried out. Given in this article are the correct figures. The original article has been corrected.

A review on nanomaterial-modified optical fiber sensors for gases, vapors and ions.

The mesmerizing properties of nanomaterials and the features offered by optical fibers can be combined to result in an attractive new platform for chemical sensing. This review (with 230 refs.) summarizes the progress made in the past five years in the field of fiber-optic sensors: The first group comprises metals and metal oxides and their composites, and the second group comprises graphene, graphene oxides and CNTs, and its composites. By combining these nanocomposites with various optical fiber geometries, numerous sensors have been realized. Following an introduction, first section summarizes fiber-optic configuration for chemical sensing (including Fabry-Perot and Mach-Zehnder interferometry, surface plasmon resonance, and optical fiber gratings of the FBG and LPG type). The second section covers typical nanomaterials used in such sensors, with a first subsection on metals, metal oxides, their composites and nanostructured modifications, and a second subsection on graphenes, graphene oxides, carbon nanotubes, and their derivatives. Section 3 summarizes sensors (i) for various gaseous species (NH3, H2, CH4, H2S, CO2, NO2, O2), (ii) for volatile organic compounds (such as ethanol, methanol, acetone, toluene, and formaldehyde), and (iii) for heavy metal ions (such as Hg2+, Pb2+, Mg2+, Cd2+, Ni2+, and Mn2+). The merits and limitations of these nanomaterials and numerous examples for nanomaterial-based sensors are discussed and presented in the form of tables. A concluding section addresses technological challenges and future trends. Graphical Abstract Schematic presentation of an optical fiber modified with various nanomaterials such as metal oxides (MOXs), metals, carbon-nanotubes (CNTs) and graphene. Such sensors are based on several fiber-optic configurations like Fabry-Perot interferometers (FPI), Mach-Zehnder interferometer (MZI) (includes an in-line MZI), surface plasmon resonance (SPR) (includes coating on cladding and unclad part of an optical fiber) and fiber gratings (FGs) (includes fiber Bragg gratings (FBGs) and long-period gratings (LPGs), these are explored for detection of various gases (NH3, H2, H2S, CH4, O2, CO2), vapors (VOCs), and ions.

Microneedles of chitosan-porous carbon nanocomposites: Stimuli (pH and electric field)-initiated drug delivery and toxicological studies.

An array of microneedles (MNs) of chitosan-graphene assembled in porous carbon (CS-GAPC) nanocomposites has been synthesized and evaluated. The safety of the formulated system has been ensured using detailed in vivo toxicological studies and efficacy has been ensured by evaluating the stimuli (pH and electric field) initiated drug delivery properties. Drug cephalexin has been incorporated in these MNs. In vivo toxicological studies of CS-GAPC nanocomposite were performed on Sprague rats, using acute dermal and subacute dermal (ADT& SADT) test, histopathological studies, biochemical studies, and AMES tests. ADT and SADT studies showed that median lethal dose (LD50 ) was found greater than 2000 mg/kg body weight; with no abnormal weight gain and food consumption, during the study period of 28 days. This study showed that administration of CS-GAPC did not cause any substantial alterations in hematological and biochemical parameters of the animals. Histopathological studies showed no significant changes in the control and CS-GAPC administered groups. AMES tests reveal that CS-GAPC nanocomposite is nonmutagenic against the Salmonella thyphimurium strains. No abnormalities were observed in the animal's chromosomal aberrations and clastogenic values when the animals were treated with CS-GAPC. At acidic pH of 4, the encapsulated drug was completely released, indicating that the drug release from the prepared nanocomposite is pH dependent. An electric field of 5 V showed optimum drug release, as a function of applied electric pulses. A biologically safe drug encapsulation model system is hence projected for smart drug delivery (pH dependent and electric field triggered) using the microneedle approach. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1582-1596, 2019.

Sprayed zinc oxide films: Ultra-violet light-induced reversible surface wettability and platinum-sensitization-assisted improved liquefied petroleum gas response.

We report the rapid (superhydrophobic to superhydrophilic) transition property and improvement in the liquefied petroleum gas (LPG) sensing response of zinc oxide (ZnO) nanorods (NRs) on UV-irradiation and platinum (Pt) surface sensitization, respectively. The morphological evolution of ZnO NRs is evidenced from the field emission scanning electron microscope and atomic force microscope digital images and for the structural elucidation X-ray diffraction pattern is used. Elemental survey mapping is obtained from energy dispersive X-ray analysis spectrum. The optical properties have been studied by UV-Visible and photoluminescence spectroscopy measurements. The rapid (120sec) conversion of superhydrophobic (154°) ZnO NRs film to superhydrophilic (7°) is obtained under UV light illumination and the superhydrophobicity is regained by storing sample in dark. The mechanism for switching wettability behavior of ZnO NRs has thoroughly been discussed. In second phase, Pt-sensitized ZnO NRs film has demonstrated considerable gas sensitivity at 260ppm concentration of LPG. At 623K operating temperature, the maximum LPG response of 58% and the response time of 49sec for 1040ppm LPG concentration of Pt- sensitized ZnO NRs film are obtained. This higher LPG response of Pt-sensitized ZnO NRs film over pristine is primarily due to electronic effect and catalytic effect (spill-over effect) caused by an additional of Pt on ZnO NRs film surface.

Diosgenin Functionalized Iron Oxide Nanoparticles as Novel Nanomaterial Against Breast Cancer.

Iron oxide nanoparticles (IONPs) have gained immense importance recently as drug nanocarriers due to easy multifunctionalization, simultaneous targeting, imaging and cancer hyperthermia. Herein, we report a novel nanomedicine comprising of IONPs core functionalized with a potent anticancer bioactive principle, diosgenin from medicinal plant Dioscorea bulbifera via citric acid linker molecule. IONPs were synthesized by reverse co-precipitation and characterized using field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS). Diosgenin functionalization was confirmed using fourier transform infrared spectroscopy (FTIR) and biochemical methods. Synthesized IONPs, citrate linked IONPs (IONPs-CA), diosgenin functionalized IONPs (IONPs-D) along with free citric acid and diosgenin were checked for anticancer activity against MCF7 breast cancer cells by MTT assay, wound migration assay, confocal microscopy and protein expression by western blotting. Size of IONPs, IONPs-CA and IONPs-D gradually increased ranging from 12 to 21 nm as confirmed by FESEM and HRTEM. Signature peaks of diosgenin at 2914, 1166 and 1444 cm-1 IONPs-D, revealed in FTIR indicated the presence of functionalized diosgenin. IONPs-D exhibited 51.08 ± 0.37% antiproliferative activity against MCF7 cells, which was found to be superior to free citric acid (17.71 ± 0.58%) and diosgenin (33.31 ± 0.37%). Treatment with IONPs-D exhibited reduced wound migration upto 40.83 ± 2.91% compared to bare IONPs (89.03 ± 2.58%) and IONPs-CA (50.35 ± 0.48%). IONPs-D and diosgenin exhibited apoptosis induction, confirmed by Alexa Fluor 488 annexin V/PI double-stained cells indicating extensive cell membrane damage coupled with PI influx leading to nuclear staining in treated cells. IONPs-D mediated selective PARP cleavage strongly rationalized it as superior apoptotic inducers. Based on these findings, IONPs-D can be considered as first diosgenin functionalized novel magnetic nanomedicine with antiproliferative, migration inhibiting and apoptosis inducing properties against breast cancer.

Novel platinum-palladium bimetallic nanoparticles synthesized by Dioscorea bulbifera: anticancer and antioxidant activities.

Medicinal plants serve as rich sources of diverse bioactive phytochemicals that might even take part in bioreduction and stabilization of phytogenic nanoparticles with immense therapeutic properties. Herein, we report for the first time the rapid efficient synthesis of novel platinum-palladium bimetallic nanoparticles (Pt-PdNPs) along with individual platinum (PtNPs) and palladium (PdNPs) nanoparticles using a medicinal plant, Dioscorea bulbifera tuber extract (DBTE). High-resolution transmission electron microscopy revealed monodispersed PtNPs of size 2-5 nm, while PdNPs and Pt-PdNPs between 10 and 25 nm. Energy dispersive spectroscopy analysis confirmed 30.88% ± 1.73% elemental Pt and 68.96% ± 1.48% elemental Pd in the bimetallic nanoparticles. Fourier transform infrared spectra indicated strong peaks at 3,373 cm(-1), attributed to hydroxyl group of polyphenolic compounds in DBTE that might play a key role in bioreduction in addition to the sharp peaks at 2,937, 1,647, 1,518, and 1,024 cm(-1), associated with C-H stretching, N-H bending in primary amines, N-O stretching in nitro group, and C-C stretch, respectively. Anticancer activity against HeLa cells showed that Pt-PdNPs exhibited more pronounced cell death of 74.25% compared to individual PtNPs (12.6%) or PdNPs (33.15%). Further, Pt-PdNPs showed an enhanced scavenging activity against 2,2-diphenyl-1-picrylhydrazyl, superoxide, nitric oxide, and hydroxyl radicals.

Citrate milling of oxides: from poly-dispersed micron scale to nearly mono-dispersed nanoscale.

Complex (multivalent/mixed valent) oxides involving two or more cations (e.g. ABO3, AB2O4 and A2B2O7) exhibit the most fascinating range of physical and chemical properties amongst the family of materials systems. There is growing interest in nanoscale forms of such oxides which emanates from the novel changes in their properties with size. To obtain nanomaterials with a high degree of crystallinity it is desirable to first make crystalline oxide powders by high temperature processing and then mill them down to nanometer size. In this paper we show that simple citric acid treatment of BiFeO3 and Bi2O3 powders leads to the desired micron-scale to nanoscale transformation, yielding nearly monodispersed nanoparticles. Importantly, these are highly dispersible and stable in water. By performing similar experiments on Fe3O4 and Fe2O3 we have elucidated the possible mechanism, which hinges on valence-controlled dissolution and ripening phenomena.

Gnidia glauca flower extract mediated synthesis of gold nanoparticles and evaluation of its chemocatalytic potential.

BACKGROUND: Novel approaches for synthesis of gold nanoparticles (AuNPs) are of utmost importance owing to its immense applications in diverse fields including catalysis, optics, medical diagnostics and therapeutics. We report on synthesis of AuNPs using Gnidia glauca flower extract (GGFE), its detailed characterization and evaluation of its chemocatalytic potential. RESULTS: Synthesis of AuNPs using GGFE was monitored by UV-Vis spectroscopy and was found to be rapid that completed within 20 min. The concentration of chloroauric acid and temperature was optimized to be 0.7 mM and 50°C respectively. Bioreduced nanoparticles varied in morphology from nanotriangles to nanohexagons majority being spherical. AuNPs were characterized employing transmission electron microscopy, high resolution transmission electron microscopy. Confirmation of elemental gold was carried out by elemental mapping in scanning transmission electron microscopic mode, energy dispersive spectroscopy and X-ray diffraction studies. Spherical particles of size ~10 nm were found in majority. However, particles of larger dimensions were in range between 50-150 nm. The bioreduced AuNPs exhibited remarkable catalytic properties in a reduction reaction of 4-nitrophenol to 4-aminophenol by NaBH4 in aqueous phase. CONCLUSION: The elaborate experimental evidences support that GGFE can provide an environmentally benign rapid route for synthesis of AuNPs that can be applied for various purposes. Biogenic AuNPs synthesized using GGFE exhibited excellent chemocatalytic potential.

Synthesis of silver nanoparticles using Dioscorea bulbifera tuber extract and evaluation of its synergistic potential in combination with antimicrobial agents.

BACKGROUND: Development of an environmentally benign process for the synthesis of silver nanomaterials is an important aspect of current nanotechnology research. Among the 600 species of the genus Dioscorea, Dioscorea bulbifera has profound therapeutic applications due to its unique phytochemistry. In this paper, we report on the rapid synthesis of silver nanoparticles by reduction of aqueous Ag(+) ions using D. bulbifera tuber extract. METHODS AND RESULTS: Phytochemical analysis revealed that D. bulbifera tuber extract is rich in flavonoid, phenolics, reducing sugars, starch, diosgenin, ascorbic acid, and citric acid. The biosynthesis process was quite fast, and silver nanoparticles were formed within 5 hours. Ultraviolet-visible absorption spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, and x-ray diffraction confirmed reduction of the Ag(+) ions. Varied morphology of the bioreduced silver nanoparticles included spheres, triangles, and hexagons. Optimization studies revealed that the maximum rate of synthesis could be achieved with 0.7 mM AgNO(3) solution at 50°C in 5 hours. The resulting silver nanoparticles were found to possess potent antibacterial activity against both Gram-negative and Gram-positive bacteria. Beta-lactam (piperacillin) and macrolide (eryth-romycin) antibiotics showed a 3.6-fold and 3-fold increase, respectively, in combination with silver nanoparticles selectively against multidrug-resistant Acinetobacter baumannii. Notable synergy was seen between silver nanoparticles and chloramphenicol or vancomycin against Pseudomonas aeruginosa, and was supported by a 4.9-fold and 4.2-fold increase in zone diameter, respectively. Similarly, we found a maximum 11.8-fold increase in zone diameter of streptomycin when combined with silver nanoparticles against E. coli, providing strong evidence for the synergistic action of a combination of antibiotics and silver nanoparticles. CONCLUSION: This is the first report on the synthesis of silver nanoparticles using D. bulbifera tuber extract followed by an estimation of its synergistic potential for enhancement of the antibacterial activity of broad spectrum antimicrobial agents.

Characterization of biocompatible NiCo2O4 nanoparticles for applications in hyperthermia and drug delivery.

Monodispersed, superparamagnetic nickel cobaltite (NCO) nanoparticles were functionalized using mercaptopropionic acid (MPA). MPA conjugates with NCO forming a metal-carboxylate linkage, with the MPA-MPA interaction occurring via formation of disulfide bonds, leaving another carboxyl end free for additional conjugation. The cytotoxicity studies on NCO-MPA show cell viability of ∼100% up to a dosage of 40 µg/mL on SiHa, MCF7, and B16F10 cell lines, and on mouse primary fibroblasts. Time-dependent cell viability studies done for a duration of 72 hours showed the cell lines' viability up to 80% for dosages as high as 80 µg/mL. Negligible leaching (<5 ppm) of ionic Co or Ni was noted into the delivery medium. Upon subjecting the NCO-MPA dispersion (0.1 mg/mL) to radiofrequency absorption, the nanoparticles were heated to 75°C within 2 minutes, suggesting its promise as a magnetic hyperthermia agent. Furthermore, the amino acid lysine and the drug cephalexin were successfully adducted to the NCO system, suggesting its potential for drug delivery. FROM THE CLINICAL EDITOR: NCO-MPA nanopartciles were found to be promising magnetic hyperthermia agents, suggesting potential future clinical applications.

Cerium doping and stoichiometry control for biomedical use of La0.7Sr0.3MnO3 nanoparticles: microwave absorption and cytotoxicity study.

La0.7Sr0.3MnO3 nanoparticles doped with cerium (La0.7-xCe(x)Sr0.3MnO3 where 0 < or = x < or = 0.7) as well as the La(1-y)Sr(y)MnO3 nanoparticles with different values of y (La/Sr ratio) are evaluated for cytotoxicity and heating application. Considering hyperthermia as one of the possible application domains of such materials, the cytotoxicity studies were done on human skin carcinoma and human fibrosarcoma cell lines. All the samples showed the desired heating effect when subjected to high-frequency exposure at 2.45 GHz. Cytotoxicity studies revealed extremely low cytotoxicity in Ce-doped samples as well as in samples with a reduced La/Sr ratio. A maximum percentage cell viability on exposure to these nanoparticles was 95% and 85% for the two groups of samples, respectively, with a dose of 20 microg/mL for the x = 0.4 sample. The issues of dopant solubility and nonstoichiometry are discussed.