Bio-therapeutic Potential and Cytotoxicity Assessment of Pectin-Mediated Synthesized Nanostructured Cerium Oxide

In the present studies, renewable and nontoxic biopolymer, pectin, was extracted from Indian red pomelo fruit peels and used for the synthesis of cerium oxide nanoparticles (CeO₂-NPs) having bio-therapeutic potential. The structural information of extracted pectin was investigated by FTIR and NMR spectroscopic techniques. Physicochemical characteristics of this pectin suggested its application in the synthesis of metal oxide nanoparticles. Using this pectin as a template, CeO₂-NPs were synthesized by simple, one step and eco-friendly approach. The UV–Vis spectrum of synthesized CeO₂-NPs exhibited a characteristic absorption peak at wavelength 345 nm, which can be assigned to its intrinsic band gap (3.59 eV) absorption. Photoluminescence measurements of CeO₂-NPs revealed that the broad emission was composed of seven different bands. FTIR analysis ensured involvement of pectin in the formation and stabilization of CeO₂-NPs. FT-Raman spectra showed a sharp Raman active mode peak at 461.8 cm^?1 due to a symmetrical stretching mode of Ce–O vibration. DLS, FESEM, EDX, and XRD analysis showed that the CeO₂-NPs prepared were polydispersed, spherical shaped with a cubic fluorite structure and average particle size ≤40 nm. These CeO₂-NPs displayed broad spectrum antimicrobial activity, antioxidant potential, and non-cytotoxic nature.     

Synthesis, Characterization, Photoluminescence and Photocatalytic Properties of CeO2 Nanoparticles by the Sonochemical Method

Uniform CeO₂ nanoparticles were synthesized via a facile sonochemical reaction between ceric ammonium nitrate and ammonia. Nanoparticles were synthesized via a surfactant free reaction at room temperature in solvent of water. Products were characterized using X-ray diffraction, scanning electron microscopy, photoluminescence (PL) spectroscopy, and energy dispersive X-ray analysis. The effect of different parameters such as precursor, power of pulsation, surfactant and reaction time on the morphology of the products was investigated. It was found that the as-obtained CeO₂ nanoparticles exhibit a strong PL peak at 381 nm at room temperature that can be ascribed to the high level transition in the CeO₂ semiconductor. The photocatalytic behavior of CeO₂ nanoparticles was evaluated using the degradation of a methyl orange aqueous solution under ultraviolet light irradiation. The results show that CeO₂ nanoparticles are promising materials with excellent performance in photocatalytic applications.     

Sol–gel synthesis and optical behavior of Mg–Ce–O nano-crystallites

The Mg–Ce–O powder are shown to contain periclase-type MgO and/or fluoride-type cerium oxide (CeO₂) depending upon the composition (x) defined by Ce/(Ce + Mg) atomic ratio. Lattice contraction of pariclase phase of MgO (average crystallite size ~8.8 nm) at Ce content of ‘x’ = 0.20 in comparison to pure MgO (crystallite size ~9.5 nm) has been realized due to oxygen vacancy formation. The optical band gap values of CeO₂ varies (3.0–3.2 eV) due to oxygen vacancy formation in CeO₂ phase, crystallite size and/or Ce³⁺/Ce⁴⁺ ratio. Further, the addition of Ce has shown to reduce the physisorption and chemisorption of water significantly as reflected by (1) suppression of related absorption peaks and (2) absence of magnesium hydroxide, Mg(OH)₂, bands in Fourier transform infrared spectra.     

Synthesis of VO2 Nanopowders. Part II. Hydrolysis of Vanadium Alkoxide/Citric Acid Premixes: VO2 Nanostructures of Controlled Shape

Reaction of VO(OiPr)₃/citric acid premixes with excess water produces stable, blue dispersions of V_xO_y gel nanoparticles (5–100 nm in diameter) that can be isolated via acetone precipitation. Annealing under reducing conditions transforms these gel particles into crystalline, faceted VO₂ nanoparticles of similar size. Larger V_xO_y gel particles (75–200 nm in diameter) form when V_xO_y nanogel dispersions are aged with aqueous ammonia. Upon annealing, these larger gel particles transform into crystalline VO₂ rods of 50 nm–10 μm in length. Hysteresis loops confirming a semiconductor-to-metal phase transition near 68 °C expected for crystalline VO₂ particles are recorded by variable-temperature electrical resistance and powder X-ray diffraction measurements.     

Synthesis of ZnS Nanospheres in Microemulsion Containing Cationic Gemini Surfactant

The reverse microemulsion containing cationic gemini surfactant trimethylene‐1,3‐bis(dodecyldimethyl ammonium bromide) (12‐3‐12, 2Br^?) is applied to synthesize ZnS nanospheres. Narrow size distributed ZnS nanospheres with controllable size and uniform morphology are successfully fabricated by direct reaction of ZnCl₂ and Na₂S in the reverse microemulsion systems. Except for the appearance of large aggregates owing to quantum size effects when the incubation time is 2 h, with increasing the incubation time from 12 to 48 h, the diameter of the ZnS nanosphere can be controlled as 20–25 nm and 140 nm, respectively. X‐ray diffraction (XRD), transmission electron microscopy (TEM), and UV‐visible absorption spectroscopy are applied to characterize the resulting ZnS nanoparticles. In the system used in the present study uniform nanosphere morphology can be synthesized, with the incubation time as an important factor in controlling the size of as‐prepared products.     

Biosynthesis of cerium oxide nanoparticles and its cytotoxicity survey against colon cancer cell line

Nanoparticles of cerium oxide (CeO₂-NPs), as a metal oxide of rare earth, have found an important role in improving technologies such as polishing, the degradation of harmful industrial dyes and even the treatment of some diseases. Therefore, the development of quick and inexpensive production methods for CeO₂-NPs is sought by researchers. In the present study, we report the biosynthesis of CeO₂-NPs using aqueous extract of Salvadora persica. Synthesized nanoparticles were investigated through powder X-ray diffraction (PXRD), ultraviolet–visible (UV–vis), Fourier transform infrared, transmission electron microscope (TEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray and Raman techniques. The UV–vis result shows an absorption peak at 325 nm, which confirms the formation of CeO₂-NPs. The band-gap of synthesized nanoparticles (4.1 eV) is higher than in its bulk state. PXRD and Raman show a crystalline fluorite cubic structure for synthesized nanoparticles. The morphology of synthesized nanoparticles shows a uniform and almost spherical shape via TEM and FESEM images. The particles size was estimated in the range of 10–15 nm. Cytotoxic activity of synthesized nanoparticles was determined through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay against a colon (HT-29) cancer cell line. The results did not show any significant cytotoxic effect for synthesized samples even for concentration higher than 800 μg/mL. Hence, CeO₂-NPs were synthesized using a natural source; the procedure was rapid with good productivity and biosynthesized nanoparticles were non-toxic.     

Double-Layer TiO2 Electrodes with Controlled Phase Composition and Morphology for Efficient Light Management in Dye-Sensitized Solar Cells

The light-scattering effect in the dye-sensitized solar cells (DSCs) was studied by controlling TiO₂ phase composition and morphology by fabrication of double-layer cells with different arrangement modes. The starting material for preparation of TiO₂ cells was synthesized by an aqueous sol–gel process. X-ray diffraction and field emission scanning electron microscopic analyses revealed that TiO₂ nanoparticles had particle size ranging between 18 and 44 nm. The optical property and band gap energy of TiO₂ nanoparticles were studied through UV–Vis absorption. The indirect optical band gap energy of anatase and rutile nanoparticles was found to be 3.47 and 3.41 eV, respectively. The double-layer DSC made of nanostructured TiO₂ film with phase composition of 78 % anatase and 22 % rutile as the under-layer and mixtures of anatase-nanoparticles and anatase-microparticles as the over-layer (i.e., NM solar cell) was shown the highest power conversion efficiency (PCE) of 6.04 % and open circuit voltage of 795 mV. This was achieved due to the optimal balance between the light scattering effect and dye sensitization parameters. Optimum light scattering of photoanode led to improve the PCE of NM double-layer solar cell which was demonstrated by diffuse reflectance spectroscopy.     

Preparation and nonlinear optical properties of Au nanoparticles doped TiO2 thin films

Nano-sized noble metal nanoparticles doped dielectric composite films with large third-order nonlinear susceptibility due to the confinement and the enhancement of local field were considered to be applied for optical information processing devices, such as optical switch or all optical logical gates. In this paper, sol–gel titania thin films doped with gold nanoparticles (AuNPs, ~10 nm in average size) were prepared. AuNPs were firstly synthesized from HAuCl₄ in aqueous solution at ~60 °C, using trisodium citrate as the reducing agent, polyvinylpyrrolidone as the stable agent; then the particle size and optical absorption spectra of the AuNPs in aqueous solutions were characterized by transmitting electron microscopy and UV–Vis–NIR spectrometry. Sol–gel 2AuNPs–100TiO₂ (in %mol) thin films (5 layers, ~1 μm in thickness) were deposited on silica glass slides by multilayer dip-coating. After heat-treated at 300–1,000 °C in air, the AuNPs–TiO₂ thin films were investigated by X-ray diffraction, scanning electron microscopy and atomic force microscopy. The nonlinear optical properties of the AuNPs–TiO₂ thin films were measured with the Z-scan technique, using a femtosecond laser (200 fs) at the wavelength of 800 nm. The third-order nonlinear refractive index and nonlinear absorption coefficient of 2AuNPs–100TiO₂ films were at the order of 10^?12 cm²/W, and the order of 10^?6 cm/W, respectively, and the third-order optical nonlinear susceptibility χ⁽³⁾ was ~6.88 × 10^?10 esu.     

Interpenetrating polymer networks templated on bicontinuous microemulsions containing silicone oil, methacrylic acid, and hydroxyethyl methacrylate

Polydimethylsiloxane-poly(methacrylic acid—hydroxyethyl methacrylate) interpenetrating polymer networks (PDMS-P(MAA–HEMA) IPN) were formulated and polymerized simultaneously from bicontinuous microemulsion templates. Microemulsions containing reactive silicone oils and MAA/HEMA in aqueous solution were stabilized with silicone surfactants, and were then reacted at 50 °C for 3 h under an N₂ atmosphere. The formation of bicontinuous morphology was confirmed by laser scanning confocal microscopy, reversible swelling behavior, differential scanning calorimetry, texture analysis, and permeability to vitamin B₁₂ in aqueous solution. Incorporating polymerizable surfactants into the microemulsion aided in stabilizing the initial microemulsion structure during polymerization, yielding a more uniform IPN morphology with domain sizes of <200 nm at equilibrium swelling. The process developed here demonstrates a simple, single-step polymerization approach to forming IPNs from low viscosity microemulsion templates, and could potentially be extended to a variety of hydrophilic and hydrophobic monomers.     

Biosynthesis and Photocatalytic Properties of SnO<Subscript>2</Subscript> Nanoparticles Prepared Using Aqueous Extract of Cauliflower

This work reports the biosynthesis of Sn(OH)₂ using aqueous extract of fresh cauliflower (Brassica oleracea L. var. botrytis), and the subsequent preparation of SnO₂ nanoparticles at two different annealing temperatures of 300 and 450 °C for 2 h. The obtained SnO₂ nanoparticles were denoted as S1 and S2 for the samples prepared at 300 and 450 °C, respectively. XRD analysis identified rutile tetragonal phase of SnO₂ nanoparticles and TEM results gave a quasispherical and spherical morphologies for S1 and S2 respectively of the size range 3.62–6.34 nm. The optical properties were studied with UV–vis and photoluminescence (PL) spectroscopies, and the nanoparticles showed blue shift in their absorption edges. The observed emission peak in the PL spectra found around 419 nm is attributable to oxygen vacancies and defects. Photocatalytic activities of the nanoparticles (S1 and S2) were studied using methylene blue (MB) under ultraviolet light irradiation and the results reveal 91.89 and 88.23% degradation efficiency of MB by S1 and S2 respectively over a period of 180 min.     

Synthesis of highly stable silver nanoparticles using imidazolium-based ionic liquid

Highly stable, aqueous dispersions, and hydrophilic ionic liquid-capped silver nanoparticles with positive surface charge were synthesized by in situ reduction of AgNO₃ with NaBH₄ in the presence of an imidazolium-based ionic liquid, viz., 1-dodecyl-3-methylimidazolium chloride ([C₁₂mim][Cl]) at room temperature. Prepared silver nanoparticles were characterized by UV–vis spectra, transmission electron microscopy (TEM), and zeta potential. UV–visible spectrum of the aqueous medium peaked at 407 nm corresponding to the plasmon absorbance of silver nanoparticles. TEM analysis revealed the spherical shape of the particles with sizes about 9 nm and low polydispersed. The surface charge of the synthesized silver nanoparticles was determined as +5.0 mV. The ionic liquid ([C₁₂mim][Cl]) capped silver nanoparticles were stable for at least 8 months.     

Transition from anatase to rutile phase in titanium dioxide (TiO2) nanoparticles synthesized by complexing sol–gel process: effect of kind of complexing agent and calcinating temperature

In this work, the structural and optical properties of titanium dioxide (TiO₂) nanopowders are studied. The TiO₂ nanoparticles were synthesized by complexing sol–gel process and effect of complexing agents on transition of the anatase phase to rutile phase during the heat treatment have been investigated. In addition, we have studied the grain size of TiO₂ powders and their dependence on the type of complexing agent. The analysis of the XRD patterns, FT-IR and UV–Vis spectroscopy, BET surface area and TEM images show that the synthesis of nanoparticles with acetyl acetone (AcAc) as complexing agent yielded the smallest size of nanoparticles about 22–35 nm. Our results indicate that with increasing the calcinating temperature, the size of the nanoparticles is increased and the energy gap reduced, too. Also, the optical band gap was obtained in the range of 3.4–4.1 and 3.06–3.74 eV for anatase and rutile phases, respectively.     

微乳液中球形及棒状SrTiO3纳米粒子的控制合成

以氢氧化锶和钛酸四丁酯为原料, 在水溶液/Triton X-100/环己烷/正己醇反相微乳液体系中制备了直径约为20～80 nm的钛酸锶球形纳米粒子和长约300～1200 nm、直径约为30～150 nm的钛酸锶纳米棒. 用XRD, ICP, TEM, SAED和SEM对样品的结构、成分和形貌进行了表征; 用DLS分析了样品的粒度分布. 结果显示, 水与表面活性剂的物质的量比(ω₀)、反应物浓度、陈化时间等因素都能影响钛酸锶纳米粒子的形貌和尺寸. 所得钛酸锶的锶钛物质的量比约为1.0, 粒度分布较窄, 为立方相单晶结构.     

One-Pot Green Synthesis of Hematite (α-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>) Nanoparticles by Ultrasonic Irradiation and Their In Vitro Cytotoxicity on Human Keratinocytes CRL-2310

Greener and ecofriendly approaches to the synthesis of hematite (α-Fe₂O₃) nanoparticles are important for various biomedical applications. The authors describe on a facile, one-pot method for synthesizing hematite nanoparticles (HNPs) using ultrasonic irradiation of iron(III) oxide solution containing the aqueous root extract of Arisaema amurense, which was used as both reducing and stabilizing agents. The synthesized HNPs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). FT-IR analysis indicated the presence of stabilizing groups such as hydroxyl (–OH), C–O, and amide (–NH–) on the surfaces of HNPs. TEM analysis revealed the formation of near spherical HNPs of average size 24.55 ± 6.9 nm. VSM confirmed the ferromagnetic nature of the HNPs with a saturation magnetization (Ms) at 1.25 emu/g and remanent magnetization (Mr) at 0.50 emu/g at 301 K. The electrochemical behavior of glassy carbon (GC)/HNPs electrode was studied using cyclic voltammetry (CV). MTT assays of the HNPs exhibited in vitro concentration-dependent cytotoxicity to human keratinocytes CRL-2310, which indicated the synthesized HNPs are compatible with requirements for in vivo biomedical applications at lower concentrations.     

Sol–gel synthesis of macroporous TiO2 from ionic precursors via phase separation route

Monolithic macroporous titanium dioxide (TiO₂) derived from ionic precursors has been successfully prepared via the sol–gel route accompanied by phase separation in the presence of formamide (FA) and poly(vinylpyrrolidone) (PVP). The addition of FA promotes the gelation, whereas PVP enhances the polymerization-induced phase separation. Appropriate choice of the starting compositions allows the production of cocontinuous macroporous TiO₂ monoliths in large dimensions, and controls the size of macropores. The resultant dried gel is amorphous, whereas anatase and rutile phases are precipitated at 500 and 900 °C respectively, without spoiling the macroporous morphology. Nitrogen adsorption–desorption measurements revealed that the dried gels exhibits mesostructure with a median pore size of about 3 nm and BET surface area of 228 m²/g, whereas 15 nm and 73 m²/g for the gels calcined at 600 °C.     

Deposition of silver nanoparticles into porous system of sol–gel silica monoliths and properties of silver/porous silica composites

Porous monolithic gels based on silica with pore size from 16 nm to 3–5 μm have been synthesized using sol–gel technology. Parameters of porous structure are determined by the components molar ratio in the reaction mixture. The reduction processes of silver ions by formamide in the synthesized porous gel were studied. It has been shown that at the initial stage of the reaction, silver particles with size up to 10 nm are formed in the absence of any stabilizers. The composites Ag/SiO₂ were synthesized by means of the threefold impregnation of porous monoliths using the solution of silver nitrate in the mixture of methanol and formamide. Their catalytic activity in the CO oxidation was studied. It was discovered that after activation in oxygen and hydrogen the samples display a low temperature activity, which depends on the number of Si–O-nonbridging oxygen groups on the surface of silica porous monoliths.     

Concurrent synthesis of SnO/SnO<Subscript>2</Subscript> nanocomposites and their enhanced photocatalytic activity

The SnO/SnO₂ nanocomposites were synthesized using semisolvothermal reaction technique. These nanocomposites were prepared using different combination of solvents viz., ethanol, water, and ethylene glycol at 180 °C for 24 h. The synthesized nanocomposites were analyzed with various characterization techniques. Structural analysis indicates the formation of tetragonal phase of SnO₂ for the sample prepared in ethanol, whereas for other solvent combinations, the mixture of SnO and SnO₂ having tetragonal crystal structures were observed. The optical study shows enhanced absorbance in the visible region for all the prepared SnO/SnO₂ nanocomposites. The observed band gap was found to be in the range of 3.0 to 3.25 eV. Microstructural determinations confirm the formation of nanostructures having spherical as well as rod-like morphology. The size of nanoparticles in ethanol-mediated solvent was found to be in the range of 5 to 7 nm. Thermogravimetric analysis indicate the weight gain around 1.3 wt% confirming the conversion of SnO to SnO₂ material. The photocatalytic activity of synthesized nanocomposites was evaluated by following the aqueous methylene blue (MB) degradation. The sample prepared in ethylene glycol-mediated solvent showed highest photoactivity having apparent rate constant (K_app) 0.62 × 10^?2 min^?1.     

Synthesis of VO2 Nanopowders. Part I. Sol–Gel Processing of Vanadium Alkoxide Precursor Within Inverse Micelles

Hydrolysis and condensation of VO(Oi–Pr)₃ within inverse micelles containing aqueous ammonia catalyst is conducted under different reaction conditions as a synthesis strategy for preparing VO₂ nanoparticles having average diameter <100 nm. Sol–gel processing of VO(Oi–Pr)₃ to form V_xO_y gel particles is controlled by varying NH₃(aq) concentration and using oleic acid or acetic acid pre-treatments. Isolated V_xO_y gel nanoparticles are reduced to VO₂ nanoparticles by thermal annealing, although annealing conditions must be optimized for each batch of gel particles. VO₂ nanoparticles of average diameters 24 or 70 nm prepared by this method show an expected hysteretic semiconductor-to-metal phase transition near 68 °C.     

Enhancement of catalytic degradation of perchlorate using novel stabilized Ni/Fe/Zn nanoparticles

The stabilized Ni/Fe/Zn nanoparticles (S-Ni/Fe/Zn NPs) were successfully synthesized in the presence of starch as a stabilizing agent through the borohydride reductive method. The physicochemical properties of the prepared nanoparticles were characterized by FE-SEM, XRD, and EDS. The results showed that the synthesized S-Ni/Fe/Zn NPs were spherical in shape and they have nearly uniform distribution with the particle size of 20–60 nm. In the following, the prepared nanoparticles were used for the catalytic degradation of perchlorate to chloride ion from aqueous solutions. The main factors controlling the degradation of perchlorate, such as the pH, the amount of nanoparticles, and the reaction time were optimized by using an experimental design based on the response surface methodology. Under the optimum conditions, the degradation efficiency of perchlorate was 98%. Also, the degradation data were modeled using the pseudo-first-order kinetic equations which describe best the degradation kinetic. The rate constant (k _obs) for the degradation step was 0.0353 min^?1 at 303 K, and the activation energy (E _a) was calculated to be 13.38 kJ mol^?1. However, the S-Ni/Fe/Zn NPs were successfully applied to the degradation of perchlorate in the well water and the industrial wastewater samples.     

Synthesis and Characterization of CeO2 Nanoparticles via Solution Combustion Method for Photocatalytic and Antibacterial Activity Studies

CeO₂ nanoparticles have been proven to be competent photocatalysts for environmental applications because of their strong redox ability, nontoxicity, long-term stability, and low cost. We have synthesized CeO₂ nanoparticles via solution combustion method using ceric ammonium nitrate as an oxidizer and ethylenediaminetetraacetic acid (EDTA) as fuel at 450 °C. These nanoparticles exhibit good photocatalytic degradation and antibacterial activity. The obtained product was characterized by various techniques. X-ray diffraction data confirms a cerianite structure: a cubic phase CeO₂ having crystallite size of 35 nm. The infrared spectrum shows a strong band below 700 cm⁻¹ due to the Ce−O−Ce stretching vibrations. The UV/Vis spectrum shows maximum absorption at 302 nm. The photoluminescence spectrum shows characteristic peaks of CeO₂ nanoparticles. Scanning electron microscopy (SEM) images clearly show the presence of a porous network with a lot of voids. From transmission electron microscopy (TEM) images, it is clear that the particles are almost spherical, and the average size of the nanoparticles is found to be 42 nm. CeO₂ nanoparticles exhibit photocatalytic activity against trypan blue at pH 10 in UV light, and the reaction follows pseudo first-order kinetics. Finally, CeO₂ nanoparticles also reduce Cr^VI to Cr^III and show antibacterial activity against Pseudomonas aeruginosa.