TEM Particle Size Research Articles

Fabrication of nanozeolite-Y/chitosan composite based on rice husks for efficient adsorption of methylene blue dye: kinetic and thermodynamic studies

In this work, three solid adsorbents were synthesized, namely, nanozeolite-Y prepared from rice husks ash by a sol-gel method as a green biosource (ZN), chitosan as a cationic biopolymer (CS), and nanozeolite-Y/chitosan composite (CSZ). An eco-friendly composite that consists of chitosan and nanozeolite-Y was used to combine the advantages of nanoparticles with biopolymers two materials to increase the removal % of methylene blue dye. All the synthetized solid adsorbents were investigated using TGA, nitrogen adsorption, SEM, TEM, FTIR, XRD, and zeta potential. The results showed that CSZ particles had a high specific surface area (432.3 m2/g), mesoporosity (with an average pore diameter of 2.59 nm), a smaller TEM particle size (between 28.6 and 60.7 nm), a lot of chemical functional groups, and high thermal stability. CSZ exhibited the maximum adsorption capacity (141.04 mg/g) towards methylene blue. The adsorption nature of methylene blue onto CS and CSZ is endothermic, spontaneous, and a physical adsorption process, while it is exothermic, nonspontaneous, physical adsorption process in the case of ZN, as confirmed by thermodynamic results. Pseudo-second order, Elovich, Dubinin-Radushkevich, Freundlich, Langmuir, Temkin, and adsorption models all fit the MB adsorption well, with correlation coefficients reaching about 0.9997. Nitric acid was found to be the best desorbing agent, with a desorption efficiency of about 99%.

Effect of solubilization with surfactant on the antioxidant activity of ellagic acid

Abstract Ellagic acid (EA) is a natural antioxidant found in many fruits and vegetables. However, its solubility in water is poor, which limits its application. To overcome this limitation, the surfactants Span 20 and Tween 60 are used to increase its solubility in water. FTIR, TEM and laser particle size and zeta potential analysis were used to characterize the morphology and structure of ellagic acid emulsions. The antioxidant activity of surfactant-compatible ellagic acid was determined using various antioxidant evaluation methods such as DPPH and ABTS radical scavenging, reducing power and total antioxidant activity. The results indicate that the solubility of ellagic acid in water was improved by the addition of Span 20 and Tween 60, and ellagic acid formed complex particles in combination with Span 20 and Tween 60. Compared to pure ellagic acid, the antioxidant activity of ellagic acid lotion was significantly enhanced.

Study of Structural and Optical Behaviour of Silver -Copper Bimetallic Nanoparticles

Silver-based nanomaterials have proven interesting and promising material for numerous applications such as biosensor, antimicrobial, anticancer agent, catalyst, food and water treatment, energy storage devices etc.In this study, nanoparticles of Silver and Copper were prepared by chemical reduction method, using hydrazine hydrate and Sodium borohydride as reducing agent. Fine powder of Ag-Cu nanoparticles (NPs)was obtained. The structural analysis of the sample wasdone using Powder XRD, SEM and TEM images and particle size analysis by DLS.The chemical purity and the elemental compositions of synthesized NPs were studied using SEM-EDX. Optical properties of the Ag-Cu NPs were analyzed using UV-DRS spectrum and FTIR spectrum. PXRD reveals that the NPs are highly crystalline in nature.The average crystallite size is30 nm. SEM and TEM images confirm the spherical morphology and the particle size is in nm. The DLS-particle size analyzer shows the size distribution of most of the NPs ranging from 9 nm to 100 nm. The EDX analysis reveals the percentage of elemental composition as 14.71, 9.06 and 76.23 for silver, copper and oxygen respectively. UV-DRS spectrum shows the absorption maximum occur at 371 nm. Due to the synergistic effect of silver and copper, there is blue shift in the absorption maximum. The IR spectrum discloses the metal oxide bond in the synthesized NPs.

Fabrication of silica/calcium alginate nanocomposite based on rice husk ash for efficient adsorption of phenol from water.

The current work discusses the synthesis of three different solid adsorbents: silica nanoparticles derived from rice husk (RS), calcium alginate beads (AG), and silica/alginate nanocomposite (RSG). The fabricated solid adsorbents were characterized by using different physicochemical techniques such as TGA, XRD, nitrogen adsorption/desorption analysis, ATR-FTIR, pHPZC, SEM, and TEM. The adsorption efficiencies of the prepared solid adsorbents were considered for the removal of phenol as a selected hazardous pollutant. Because of its improved adsorption capacity and environmentally friendly character, a composite made of biosilica nanoparticles and naturally occurring alginate biopolymer by click chemistry is significant in environmental treatment. Adding silica nanoparticles to the alginate biopolymer hydrogel has many advantages, including increased surface area, easier recovery of the solid adsorbent, and additional surface chemical functional groups. The silica/alginate nanocomposite showed surface heterogeneity with many chemical functional groups present, whereas silica nanoparticles had the highest surface area (893.1 m2 g-1). It has been found that the average TEM particle size of RS, AG, and RSG was between 18 and 82 nm. RSG displayed the maximum adsorption capacity of phenol (100.55 mg g-1) at pH 7 and 120 min as equilibrium adsorption time. Adsorption of phenol onto the solid adsorbents fit well with a nonlinear Langmuir isotherm with favorable adsorption. Kinetic and thermodynamic studies prove that the adsorption process follows a pseudo-second-order kinetic model, endothermic process, physical, and spontaneous adsorption. Sodium hydroxide is effective in desorbing 94% of the loaded phenols, according to desorption investigations. Solid reusability tests showed that, after seven cycles of phenol adsorption/desorption, RSG lost only 8.8% of its adsorption activity.

Improved photocatalytic decolorization of reactive black 5 dye through synthesis of graphene quantum dots-nitrogen-doped TiO2.

Graphene quantum dots (GQDs), a new solid-state electron transfer material was anchored to nitrogen-doped TiO2 via sol gel method. The introduction of GQDs effectively extended light absorption of TiO2 from UV to visible region. GQD-N-TiO2 demonstrated lower PL intensity at excitation wavelengths of 320 to 450nm confirming enhanced exciton lifespan. GQD-N-TiO2-300 revealed higher surface area (191.91m2g-1), pore diameter (1.94nm), TEM particle size distribution (4.88 ± 1.26nm) with lattice spacing of 0.45nm and bandgap (2.91eV). In addition, GQDs incorporation shifted XPS spectrum of Ti 2p to lower binding energy level (458.36eV), while substitution of oxygen sites in TiO2 lattice by carbon were confirmed through deconvolution of C 1s spectrum. Photocatalytic reaction followed the pseudo first order reaction and continuous reductions in apparent rate constant (Kapp) with incremental increase in RB5 concentration. Langmuir-Hinshelwood model showed surface reaction rate constants KC = 1.95mg L-1min-1 and KLH = 0.76 L mg-1. The active species trapping, and mechanism studies indicated the photocatalytic decolorization of RB5 through GQD-N-TiO2 was governed by type II heterojunction. Overall, the photodecolorization reactions were triggered by the formation of holes and reactive oxygen species. The presence of •OH, 1O2, and O2• during the photocatalytic process were confirmed through EPR analysis. The excellent photocatalytic decolorization of the synthesized nanocomposite against RB5 can be ascribed to the presence of GQDs in the TiO2 lattice that acted as excellent electron transporter and photosensitizer. This study provides a basis for using nonmetal, abundant, and benign materials like graphene quantum dots to enhance the TiO2 photocatalytic efficiency, opening new possibilities for environmental applications.

Green Synthesis of Silver Nanoparticles Using Salvadora persica and Caccinia macranthera Extracts: Cytotoxicity Analysis and Antimicrobial Activity Against Antibiotic-Resistant Bacteria.

Silver nanoparticles (AgNPs) have gained great interest because of their specific and distinct properties. Chemically synthesized AgNPs (cAgNPs) are often unsuitable for medical applications due to requiring toxic and hazardous solvents. Thus, green synthesis of AgNPs (gAgNPs) using safe and nontoxic substances has attracted particular focus. The current study investigated the potential of Salvadora persica and Caccinia macranthera extracts in the synthesis of CmNPs and SpNPs, respectively. Aqueous extracts of Salvadora persica and Caccinia macranthera were prepared and taken as reducing and stabilizing agents through gAgNPs synthesis. The antimicrobial effects of gAgNPs against susceptible and antibiotic-resistant bacterial strains and their toxicity effects on L929 fibroblast normal cells were evaluated. TEM images and particle size distribution analysis showed that the CmNPs and SpNPs have average sizes of 14.8nm and 39.4nm, respectively. The XRD confirms the crystalline nature and purity of both CmNPs and SpNPs. FTIR results demonstrate the involvement of the biologically active substances of both plant extracts in the green synthesis of AgNPs. According to MIC and MBC results, higher antimicrobial effects were seen for CmNPs with a smaller size than SpNPs. In addition, CmNPs and SpNPs were much less cytotoxic when examined against a normal cell relative to cAgNPs. Based on high efficacy in controlling antibiotic-resistant pathogens without detrimental adverse effects, CmNPs may have the capacity to be used in medicine as imaging, drug carrier, and antibacterial and anticancer agents.

Efficient adsorption of methylene blue on novel triple-nanocomposites of potassium Kappa-carrageenan, calcium alginate and nanohydroxyapatite obtained from sea scallop shells

In this work, four nano-solid adsorbents were synthesized namely: nanohydroxyapatite based on sea scallop shells (NHAP), potassium kappa-carrageenan (KG), potassium kappa-carrageenan/nanohydroxyapatite (KPC), and potassium kappa-carrageenan/calcium alginate/nanohydroxyapatite as triple biocomposite (TBC) beads. These fabricated materials were used as solid adsorbents for methylene blue removal from wastewater under different conditions. Based on our experimental results, TBC particles were characterized by higher specific surface area (722.62 m2/g), mesoporosity (pore radius, 3.77 nm), smaller particle size (TEM particle size, 26 nm), the presence of abundant chemical functional groups, thermal stability, and lower swelling ratio (0.3%). TBC exhibited the maximum adsorption capacity (529.1 mg/g) towards methylene blue (MB) with endothermic, spontaneous, favorable, and physical adsorption process as reported by thermodynamic studies. Adsorption of MB fits well Freundlich, Langmuir, Dubinin-Radushkevich, and Temkin adsorption models with correlation coefficients reached about 0.9999. MB adsorption onto all the solid adsorbents shows the good suitability of Elovich and pseudo-second order kinetic models. Desorption investigation proves that hydrochloric acid (1 mol/L) is the most suitable desorbing agent with desorption efficiency that reached about 86%.

Design, preparation and properties of new polyacrylamide based composite nano-microspheres with like “ball in ball” structure

Recently, polymer gel nano-microspheres as a new kind of depth profile control agent have achieved preliminary effects in enhancing oil recovery (EOR), especially, for some low-permeability reservoirs that are difficult to enter by conventional polymer flooding. To synergistically improve the water-oil mobility ratio on the basis of blocking pore throat and adjusting water flooding profile by microgel, a new polyacrylamide composite nano-microspheres with like "ball in ball" structure are designed and prepared via inverse microemulsion polymerization in the case of pre-introducing hyperbranched polyacrylamide (HBPAM) in the water phase. Like-spheroid (HBPAM) with high rheological properties are gradually released from microspheres to achieve the synergistic effects of plugging pore throat of reservoir and viscosity improvement of the dispersion. This article uses FTIR, SEM, TEM, TGA and laser particle size analyzer to characterize the structure, morphology, thermo-stability and particle size distribution of composite microspheres. The swelling dynamics, temperature, and salt resistance of the composite microspheres are then analyzed. More importantly, the rheological properties, dispersion stability, thickening ability, emulsifying property, and oil displacement mechanism of microspheres are systematically studied. The plugging rate and oil displacement efficiency are analyzed by simulated core experiments to evaluate the application effect of microspheres. The composite microspheres designed in this paper are expected to solve the challenge that conventional polyacrylamide used in EOR is difficult to be injected in low permeability reservoirs and synergistically enhance the profile control and EOR effect of nanospheres.

Synthesis and characterization of ferric@nanocellulose/nanohydroxyapatite bio-composite based on sea scallop shells and cotton stalks: adsorption of Safranin-O dye

In the present study, four solid adsorbents were prepared via green synthesis sources, namely, nanohydroxyapatite (NHAP), nanocellulose (NC), nanocellulose/nanohydroxyapatite composite (NPC), and ferric@nanocellulose/nanohydroxyapatite composite (FNPC). Synthesis procedures were based on natural sources such as sea scallop shells and cotton stalks. All the prepared solid adsorbents were characterized by TGA, XRD, nitrogen adsorption/desorption isotherm, FTIR, pHPZC, SEM, and TEM. FNPC exhibited a higher surface area (358.32 m2/g), mesoporous surface (pore diameter, 12.29 nm), TEM particle size of 45 nm, and the availability of various surface functional groups. Static adsorption of Safranin-O (SO) dye was investigated for all the prepared solid adsorbents under different application conditions. Maximum adsorption capacity (239.23 mg/g) was achieved by FNPC after 24 h of equilibrium time, at pH 7, 2 g/L as adsorbent dosage, and 40 ℃. Adsorption of Safranin-O onto all the samples well-fitted Langmuir, Temkin, Freundlich, Dubinin–Radushkevich, pseudo-second-order, and Elovich models. Thermodynamic and kinetic parameters proved that Safranin-O adsorption is favorable, spontaneous, endothermic, and physisorption. Desorption studies confirmed that hydrochloric acid (0.03 mol/L) achieved the maximum desorption efficiency (92.8%). Reusability of FNPC showed a decrease in the adsorption capacity after five cycles of adsorption and desorption by only 7.8%.

Biocompatible thermoresponsive N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide-based random copolymer: synthesis and studies of its composition dependent properties and anticancer drug delivery efficiency.

A new acrylamide monomer, N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide (M3i), consisting of both isopropyl and isopropylamidopropyl moieties, has been synthesized from isopropylamine and N-isopropylacrylamide via an aza-Michael addition reaction followed by amidation with acryloyl chloride. The homopolymer of M3i (polyM3i) and a series of random copolymers of M3i and poly(ethylene glycol)methyl ether acrylate (PEGA: CH2CHCO2(CH2CH2O)nMe, Mn = 480, n = 9 on average) with varying compositions have been synthesized via reversible addition-fragmentation chain transfer polymerization using 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) as well as 1-phenylethyl phenyl dithioacetate (PEPD) as a RAFT agent. These polymers have been characterized by 1H NMR, FTIR, GPC, UV-Vis, fluorescence, TGDTA, DSC, DLS, and TEM techniques. A lower critical solution temperature (LCST) and glass transition temperature (Tg) for polyM3i prepared using DDMAT were observed at 17 and 133 °C, respectively, while for a polymer formed using PEPD, no LCST was observed until 0 °C and its observed Tg was found at 127.3 °C. The polymers are thermally stable up to 300 °C. Upon an increase in the M3i content in the copolymers, LCST decreases, Tg increases, and the apparent hydrodynamic diameter decreases. Moreover, the effects of concentration and the addition of urea and sodium chloride on the LCST of the copolymer with an LCST close to body temperature were studied. Owing to the incorporation of PEGA, a higher critical micellar concentration and larger TEM particle size of this copolymer were observed with respect to those of polyM3i. The usefulness of the micelles of the copolymers as nano-carriers for the drug doxorubicin was explored. The in vitro tumoricidal activity of the micelles of the doxorubicin-loaded copolymers was also assessed against Dalton's lymphoma cells.

Protective prospects of eco-friendly synthesized selenium nanoparticles using Moringa oleifera or Moringa oleifera leaf extract against melamine induced nephrotoxicity in male rats

Nanotechnology is used in a wide range of applications, including medical therapies that precisely target disease prevention and treatment. The current study aimed firstly, to synthesize selenium nanoparticles (SeNPs) in an eco-friendly manner using Moringa oleifera leaf extract (MOLE). Secondly, to compare the protective effects of green-synthesized MOLE-SeNPs conjugate and MOLE ethanolic extract as remedies for melamine (MEL) induced nephrotoxicity in male rats. One hundred and five male Sprague Dawley rats were divided into seven groups (n = 15), including 1st control, 2nd MOLE (800 mg/kg BW), 3rd SeNPs (0.5 mg/kg BW), 4th MOLE-SeNPs (200 μg/kg BW), 5th MEL (700 mg/kg BW), 6th MEL+MOLE, and 7th MEL+MOLE SeNPs. All groups were orally gavaged day after day for 28 days. SeNPs and the colloidal SeNPs were characterized by TEM, SEM, and DLS particle size. SeNPs showed an absorption peak at a wavelength of 530 nm, spherical shape, and an average size between 3.2 and 20 nm. Colloidal SeNPs absorption spectra were recorded between 400 and 700 nm with an average size of 3.3−17 nm. MEL-induced nephropathic alterations represented by a significant increase in serum creatinine, urea, blood urea nitrogen (BUN), renal TNFα, oxidative stress-related indices, and altered the relative mRNA expression of apoptosis-related genes Bax, Caspase-3, Bcl2, Fas, and FasL. MEL-induced array of nephrotoxic morphological changes, and up-regulated immune-expression of proliferating cell nuclear antigen (PCNA) and proliferation-associated nuclear antigen Ki–67. Administration of MOLE or MOLE-SeNPs significantly reversed MEL-induced renal function impairments, oxidative stress, histological alterations, modulation in the relative mRNA expression of apoptosis-related genes, and the immune-expression of renal PCNA and Ki-67. Conclusively, the green-synthesized MOLE-SeNPs and MOLE display nephron-protective properties against MEL-induced murine nephropathy. This study is the first to report these effects which were more pronounced in the MOLE group than the green biosynthesized MOLE-SeNPs conjugate group.

Preparation of submicron-sized ZnFe2-xCrxO4 (x = 0.4, 0.8) via a two-step method and evaluation of the corresponding ceramic inks

In this work, submicron-sized ZnFe2-xCrxO4 (x = 0.4, 0.8) pigments were synthesized by a combustion assisted two-step method. The samples and corresponding ceramic inks are investigated by XRD, SEM, TEM, colorimeter, and laser particle size analyzer. The grindability of the pigments and the printing performance (rheological properties, surface tension, filterability and storage stability) of the inks are evaluated. Our research reveals that although the calcination temperature in the present method is 300 °C lower than the conventional solid-state reaction route, the as-prepared samples belong to a pure spinel phase and present highly saturated reddish-brown tone. Compared to the samples prepared from solid-state reaction route, the synthesized submicron-sized pigments exhibit superior grindability. The corresponding ceramic inks present excellent coloring ability, filterability and storage stability. Our work confirms that the submicron-sized ZnFe2-xCrxO4 pigments synthesized by the combustion assisted two-step method are quite suitable for ZnFe2-xCrxO4-based reddish-brown ceramic inks.

TEM Observation and Particle Size Evaluation of Cu Nanoparticles Synthesized by Cavitation Bubble Plasma

TEM Observation and Particle Size Evaluation of Cu Nanoparticles Synthesized by Cavitation Bubble Plasma

Oxytetracycline Sorption onto Synthetized Materials from Hydroxyapatite and Aluminosilicates

Oxytetracycline (OTC) is listed as an emerging contaminant due to the adverse effects that it has on human health and the environment. Being a broad spectrum antibiotic, OTC is widely used and is found in large concentrations in wastewater. Advanced wastewater treatment is an effective method for the removal of this pollutant; however, these tertiary treatments are expensive and generally not applied in nondeveloped countries. In this work, the removal of OTC by adsorption using sustainable materials synthesized from hydroxyapatite (HA) and aluminosilicates by chemical precipitation method was performed. Four different adsorbent materials were obtained: mixing hydroxyapatite and kaolin (HA-K), hydroxyapatite with natural clay (HA-NC), hydroxyapatite with synthetic zeolite (HA-SZ), and hydroxyapatite with natural aluminosilicates (HA-NA). The adsorbent materials were characterized by FT-IR, pHpzc, cation exchange capacity (CEC), SEM/EDX, TEM (particle size), and XRD. Kinetic tests and adsorption isotherms of OTC were carried out by varying conditions of the aqueous media as pH value, temperature, and the presence of ionic strength. Different kinetic and isothermal models were applied to the obtained data. All the synthesized materials showed an acceptable sorption capacity for OTC removal. The elimination of this antibiotic was greater than 50% in the four synthesized materials. Experimental data showed a better fit to the Elovich kinetic model, indicative of a heterogeneous chemical sorption process. Kinetic and thermodynamic parameters showed that the synthetized materials from HA and aluminosilicates are potential and alternative adsorbent materials for OTC removal from water.

Green synthesis of copper nanoparticles using leaf extract of Ageratum houstonianum Mill. and study of their photocatalytic and antibacterial activities

The novel copper nanoparticles (CuNPs) were synthesized using aqueous leaf extract of Ageratum houstonianum Mill. (AHLE). The green synthesized AH-CuNPs have a useful dye degradation property in the existence of daylight. The photocatalytic activity of AH-CuNPs was evaluated against an azo dye congo red (CR), whereas, same NPs displayed no effect on other dyes. The CR was completely degraded within 2 h, and the reaction rate was followed by pseudo-first-order kinetics, and the rate constant was recorded 3.1 × 10−4 s−1, (R2 = 0.9359). Antibacterial activity of green synthesized AH-CuNPs was studied against gram-negative bacterium Escherichia coli (MTCC no. 40), and a significant growth inhibition was recorded with 12.43 ± 0.233 mm zone of inhibition. The AH-CuNPs were characterized through UV-visible spectroscopy, XRD, SEM, FT-IR, TEM, and zeta particle size analyzer. Ageratum houstonianum mediated green synthesized copper nanoparticles (AH-CuNPs) were cubic, hexagonal, and rectangular in shape, with average size of ∼80 nm. The optical band gap was 4.5 eV, which was investigated using UV-visible spectroscopy, and the band gap value revealed that AH-CuNPs were semiconductor materials.

Disperse dye/poly (styrene-methacrylic acid) nanospheres with high coloration performance for textiles

Dye/polymer nanosphere is a novel kind of colorant that can significantly enhance the dye utilization efficiency on textile. In order to improve the coloration ability of colored nanospheres, disperse dye/P(St-MAA) nanospheres with rough surface were successfully prepared through alkali pretreatment at pH 12 and coloration of disperse dyes. TEM image and particle size analysis indicate that the colored nanospheres had rough surfaces with the average particle size of 158.1 nm. The dye content of colored rough nanospheres was 63.7 mg/g, higher than the un-alkali-treated ones. The reason for the change of morphology, particle size and dye content was due to the swelling of nanospheres at alkali condition. The XRD, TGA and DSC diagrams show that the disperse dye molecules formed strong interaction with the macromolecular chains and aggregated to form crystals in the rough nanospheres. The printed cotton fabric shows higher color performance using the colored rough nanospheres because of the lower visible light reflectance. The printed fabric also exhibits satisfactory color fastness for practical application.

Metal organic precursor derived Ba1-xCaxZrO3 (0.05 ≤ x ≤ 0.20) nanoceramics for excellent capacitor applications

Monophasic nanoceramics of calcium doped barium zirconate (BCZ) Ba1-xCaxZrO3 (x = 0.0, 0.05, 0.10, 0.15 and 0.20) have been manufactured via easy and cost effective metal organic precursor route at 1000 °C. The structural elucidations of the BCZ nanoparticles were confirmed by different analytical techniques i.e. SEM, TEM, XRD etc. Moreover, the elemental composition and detailed surface area were estimated through EDS/EDX and BET analysis. TEM particle sizes of Ba1-xCaxZrO3 (x = 0.0, 0.05, 0.10, 0.15 and 0.20) were found in the range of 75–42 nm. Mixed (spherical, hexagonal and cubic) morphology and shapes of the nanoceramics were established by SEM and TEM studies. The incorporation of calcium to BaZrO3 host lattice confirmed by EDS/EDX studies. Very high specific surface area was achieved (233–271 m2 g−1) for Ba1-xCaxZrO3 (x = 0.0, 0.05, 0.10, 0.15 and 0.20) nanoceramics which is corroborated well with TEM particle size and pore (BJH and DA) size studies. Excellent dielectric properties of BCZ were found at room temperature in the frequency range of 20 kHz to 1 MHz. As the concentration of Ca2+ ion increased the values of dielectric constant were found to increase (48.1–284.7). High surface area and excellent porosity with high dielectric constant of BCZ could make it as an ideal material for energy devices.

Synthesis of polyacrylonitrile nanoflowers and their controlled pH-sensitive drug release behavior.

A novel controlled drug release system based on pH sensitive polyacrylonitrile (PAN) nanoflowers in different kinds of solvents was successfully prepared with azobisisobutyronitrile (AIBN) as the initiator and without any emulsifier or stabilizer by a one step static polymerization method. The composition and structure of the PAN nanoflowers were analyzed by FTIR, XRD, SEM, TEM, and laser particle size analysis. The polymer particles consisted of a number of lamellae, with a sheet thickness of about 10 nm, and were similar to the shape of flowers with a particle diameter of about 350 nm. The mechanism of the polymerization reaction and the formation were studied. Moreover, the effects of monomer ratio, initiator concentration, reaction time, dispersion medium and co-monomer on the morphology and particle size of the nanoflowers were also discussed. A relatively large specific surface area was formed during the formation of the nanoflowers, which favored drug adsorption. The results of the in vitro experiments revealed that PAN(TBP) nanoflowers, containing BSA in buffer solution of pH 7.4, demonstrated good sustained-release and the cumulative release rate was about 83% after 260 h. The results also showed that the sustained-release from the PAN(TBP) nanoflowers best fitted the Riger-Peppas model. This study indicated that PAN(TBP) nanoflowers provided a theoretical base for the development of carriers for sustainable drug-release.

Antioxidant and Antibacterial Activities of Biosynthesized Silver Nanoparticles using Aqueous Terminalia catappa Leaf Extracts as Novel Reducing Agent

In this study, silver nanoparticles (AgNPs) were successfully synthesized from aqueous Terminalia catappa leaf extract that acts as a novel reducing agent. Various parameters, including pH, temperature and reaction time, were determined. The UV-visible spectra showed the main peak at 416 nm, which was the characteristic surface plasmon resonance of AgNPs. The spherical shape and particle size of 49 ± 0.01 nm were observed from SEM, TEM and laser particle size analysis (LPSA). FTIR spectra of the leaf extract exhibited the characteristic functional groups that should be responsible for Ag+ ion reduction. The EDX spectrum proved that the obtained sample is silver. The antioxidant activity of AgNPs treated with the leaf extract as determined by the DPPH assay was higher compared to that of Terminalia catappa leaf extract, and the treated AgNP sample exhibited high antibacterial potential against both Gram-positive and Gram-negative bacteria.

Magnetic evolution from the superparamagnetism in nanospinel chromites Cd1−xCoxCr2O4 (0 ≤ x ≤ 1.0)

Magnetic properties of the spinel-type Cd1−xCoxCr2O4 (0 ≤ x ≤ 1.0) nanocrystals are systematically studied. Complementary results of the inductively coupled plasma optical emission spectroscopy (ICP-OES) and the dispersive X-ray spectroscopy (EDX) indicate cations redistribution with increased Cr concentration from the nanoparticle core to the surface. Powder X-ray diffraction (XRD) reveals an obtained single spinel phase of average crystallite size of 7–10 nm that is in consistence with TEM particle size. The lattice constant exhibits a general decrease by incorporating the smaller Co atoms, however its behavior violates Vegard’s law. An observed kink anomaly in the lattice constant behavior at x ~ 0.4 is attributed to the cations redistribution and further preferred site occupations. Static magnetization and AC susceptibility measurements reveal competitive magnetic phases in the solid solution nanocrystals. A superparamagnetic state of the noninteracting and single domain CdCr2O4 nanoparticles expands first to higher blocking temperatures at x < 0.4 before it evolves to a core collinear ferrimagnetic (FIM) state with coexisting surface spin-glass freezing. The low-temperature core spiral spin orders survive in the FIM phase. A tentative magnetic phase diagram is presented and discussed in a frame of effects of the type and redistribution of cations as well as emergent uncompensated surface spins on the nearest and next nearest neighbor exchanges in chromite nanospinels.