纳米固体碱催化酯交换反应动力学

尿素为沉淀剂制备纳米Mg-Al水滑石,对其高温煅烧物进行X射线衍射、傅里叶变换红外光谱和扫描电子显微镜表征,以其煅烧物为催化剂催化制备生物柴油,并系统研究酯交换反应动力学。研究结果表明:纳米Mg-Al水滑石500℃煅烧6 h,水滑石特征衍射峰d(003)部分消失,柱撑阴离子碳酸根离子对称性降低,晶粒团聚成层状结构。纳米固体碱催化酯交换反应的表观反应级数为1.5,表观活化能Ea=25.92 kJ/mol,在最优条件下,生物柴油转化率高达95.4%。     

Studies on the synthesis of ether-, substituted alkyl-, or aryl-linked C-disaccharide derivatives

A series of ether-, substituted alkyl-, or aryl-linked disaccharide derivatives have been synthesized in relatively good yield and characterized using different spectral techniques including single-crystal X-ray diffraction (XRD). β-Anomeric forms of sugar moiety in these derivatives were identified from ¹H NMR studies. The existence of inter- and intramolecular hydrogen bonding interactions were identified from single-crystal XRD studies.     

Structural and optical properties of dysprosium-doped hydroxyapatite nanoparticles and the use as a bioimaging probe in human cells

In this work, the hydroxyapatite nanoparticles doped with trivalent dysprosium ions were synthesized by a co-precipitation method. The characterization techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) were carried out to determine the crystalline and structural properties. The Rietveld structural refinement of the XRD patterns confirmed the purity of the phase formation of the synthesized nanoparticles. The photoluminescence emission spectra exhibited intense emissions in the blue region at 450 nm and 476 nm along with less intense yellow emission at 573 nm which can be attributed to the magnetic dipole and electric dipole transitions of dysprosium respectively. In order to evaluate the colour tunability of the emitted light CIE chromaticity coordinate values were calculated. The intense blue emissions from the synthesized sample were found to be favourable for bioimaging. The images obtained from the fluorescence microscopy revealed that the dysprosium-doped hydroxyapatite nanoparticles are potential bioimaging probes in human cells.     

Green synthesis of silver nanoparticles from aqueous extract of Scutellaria barbata and coating on the cotton fabric for antimicrobial applications and wound healing activity in fibroblast cells (L929)

Scutellaria barbata is a perennial herb which was vastly prescribed in Chinese medicine to treat inflammations, infections and it is also used a detoxifying agent. We synthesized silver nanoparticles with Scutellaria barbata extract and characterized the nanoparticles with UV–Vis spectroscopic analysis, TEM, AFM, FTIR and XRD. The biofilm inhibiting property of synthesized silver nanoparticles were examined with XTT reduction assay and the antimicrobial property was examined with well diffusion method. The silver nanoparticles were also coated with cotton fabrics and their efficacy against antimicrobials was analyzed to prove its application. The cytotoxic property of synthesized silver nanoparticles was examined with L929 fibroblast cells using MTT assay. Finally we analyzed the wound healing property of synthesized silver nanoparticles with wound scratch assay. The result of our UV–Vis spectroscopic analysis confirms Scutellaria barbata aqueous extract reduced silver ions and synthesized silver nanoparticles. The characterization studies TEM, AFM, FTIR and XRD confirms the synthesized silver nanoparticles are in ideal shape and size to be utilized as a drug. The XTT reduction assay proves silver nanoparticles effectively inhibits the biofilm formation in both resistant and sensitive strains. Antimicrobial sensitivity tests confirms synthesized silver nanoparticles and cotton coated synthesized silver nanoparticles both are effective against gram positive, gram negative and fungal species. Further the results of MTT assay confirms the synthesized silver nanoparticles are non toxic and finally the wound healing potency of the nanoparticles was confirmed with wound scratch assay. Over all our results authentically confirms the silver nanoparticles synthesized with Scutellaria barbata aqueous extract is potent wound healing drug.     

Rapid biosynthesis of PVP coated silver nanoparticles by <Emphasis Type="Italic">Kocuria rosea</Emphasis> and their antimicrobial activity

The need for more effective antimicrobial agent and propitious application of nanotechnology in therapeutics and diagnostics has prompted the research on ecofriendly synthesis of silver nanoparticles. The objective of present study was to investigate the antibacterial and antifungal activity of biologically synthesized silver nanoparticles. The silver nanoparticles were synthesized by extracellular method, using soil bacteria Kocuria rosea. The synthesized silver nanoparticles were characterized by UV-Visible spectroscopy, X-ray diffractometry (XRD), transmission electron microscopy (TEM) and fourier transformation infrared spectroscopy (FTIR). On the basis of TEM analysis, the synthesized nanoparticles were found to be spherical with an average size of 30–50 nm. The biologically synthesized silver nanoparticles showed significant antimicrobial activity against pathogens.     

Evaluation of plant-mediated Silver nanoparticles synthesis and its application in postharvest Physiology of cut Flowers

Today the use of silver nanoparticles is becoming increasingly widespread due to their wide applications as antimicrobial agent. Green synthesis of silver nanoparticles (SNPs) using the petal extract of saffron (Crocus sativus) as a reducing agent from 5 mM AgNO₃ has been investigated in this work. Diverse petal extracts quantities and reaction times were used for the synthesis of SNPs. The resulting SNPs were characterized by means of UV–Vis, XRD and FTIR techniques. SNPs were synthesized rapidly within 30 min of incubation period and synthesized SNPs showed an absorption peak at 380-400 nm in the UV-Vis spectrum. XRD spectrum confirmed the formation of metallic silver, too. Green synthesized SNPs were used as antimicrobial agent against three bacterial genera of Bacillus, Pseudomonas and Acinetobacter which contaminate preservative solution of cut-flowers, too. According to the results biosynthesized SNPs using saffron petals successfully controlled these bacteria and have made them promising candidates as new generation of antimicrobials. This route is rapid, simple without any hazardous chemicals and economical to synthesized SNPs.     

Mycocrystallization of gold ions by the fungus Cylindrocladium floridanum

The size and morphology determines the thermodynamic, physical and electronic properties of metal nanoparticles. The extracellular synthesis of gold nanoparticles by fungus, Cylindrocladium floridanum, which acts as a source of reducing and stabilizing agent has been described. The synthesized nanoparticles were characterized using techniques such as UV–Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, energy dispersive X-ray analysis (EDAX), and high-resolution transmission electron microscopy (HR-TEM). Based on the evidence of HR-TEM, the synthesized particles were found to be spherical with an average size of 19.05 nm. Powder XRD pattern proved the formation of (111)-oriented face-centered cubic crystals of metallic gold. This microbial approach by fungus for the green synthesis of spherical gold nanoparticles has many advantages such as economic viability, scaling up and environment friendliness.     

Synthesize and characterization of organic-soluble acylated chitosan

Acylated chitosan was synthesized by reaction of chitosan and stearoyl chloride. The chemical structures and physical properties of the prepared compounds were confirmed by Fourier transform infrared (FT-IR), ¹H Nuclear Magnetic Resonance (¹H NMR) spectroscopy, X-ray diffraction (XRD) and Thermogravimetric (TG) techniques. The degree of substitution (DS) was calculated by ¹H NMR and ranged from 1.8 to 3.8. The synthesized compounds exhibited an excellent solubility in organic solvents. XRD analysis showed that they had high crystalline structure. TG results demonstrated that thermal stability of the prepared compounds was lower than that of chitosan, the weight loss decreased with increase of DS. This procedure could be a facile method to prepare organic-soluble chitosan derivatives.     

Green synthesis of silver nanoparticles using Ocimum canum and their anti-bacterial activity

Green synthesis of nanoparticles is an important area in the field of nanotechnology, which has cost effective and environment friendly benefit over physical and chemical methods. The present study aims at preparation of silver nanoparticles through green route using leaves of Ocimum canum Sims, a widely distributed medicinal herb. The synthesized silver nanoparticles were characterized by SEM and XRD. The spherical and rod like morphological shapes were proven by SEM techniques. Crystallographic structure was confirmed by XRD and average particle size of synthesized silver nanoparticles was calculated which was found to be of 15.72 nm. The antibacterial activity of these prepared silver nanoparticles against pathogenic bacterium Escherichia coli (E. coli) has shown the highest ZOI of 2.45 cm at 30 ppm.     

Effect of synthesis method and chemical reagents on the structural parameters,particle size,and optical and photoluminescence properties of ZnS nanostructures

In this experimental study, ZnS nanostructures were synthesized using two hydrothermal and co‐precipitation methods with different precursors. Different reagents and precursors were changed to obtain the best product size and morphology. The structure and crystal phase of the products were studied using X‐ray diffraction (XRD) patterns. Some structural parameters were calculated using the XRD results and a product composition was obtained by energy dispersive X‐ray (EDX) analysis and Fourier transform infrared (FT‐IR) spectra to study the chemical composition. The size and morphology of ZnS nanostructures were obtained by scanning electron microscopy (SEM). The optical properties of the synthesized ZnS nanostructures were examined using ultraviolet–visible (UV–Vis) spectra to estimate the optical band gap. Band gap energies were higher than those in the ZnS bulk sample, mainly due to quantum size effects. The photoluminescence (PL) properties of the products were investigated using PL spectra. The results showed the effect of two factors, namely synthesis method and chemical reagents, on the structure parameters, crystallite size, product size and morphology, and optical and PL properties.     

Biologically synthesized fluorescent CdS NPs encapsulated by PHB

Here an attempt was made to biologically synthesize fluorescent cadmium sulfide nanoparticles and to immobilize the synthesized nanoparticles in PHB nanoparticles. The present study uses Brevibacterium casei SRKP2 as a potential producer for the green synthesis of CdS nanoparticles. Biologically synthesized nanoparticles were characterized and confirmed using electron microscopy and XRD. The size distribution of the nanoparticles was found to be 10-30 nm followed by which the consequence of time, growth of the organism, pH, concentration of CdCl(2) and Na(2)S on the synthesis of nanoparticles were checked. Enhanced synthesis and fluorescence emission of CdS nanoparticles were achieved at pH 9. The synthesized CdS NPs were immobilized with PHB and were characterized. The fluorescent intensity of the CdS nanoparticles remained unaffected even after immobilization within PHB nanoparticles.     

The effect of synthesis media on the properties of substituted polyaniline/chitosan composites

Substituted polyaniline/chitosan (sPANI/Ch) composites were chemically synthesized in H₂SO₄ and CH₃COOH synthesis media. Structural and physical properties of the composites were characterized by using FTIR, SEM, TGA, UV–vis, XRD techniques, and conductivity measurements. The effect of synthesis media on morphology, thermal stability, conductivity, and crystalline properties was investigated. Chemical interactions between substituted polyanilines and chitosan were explained using FTIR spectra results. The different morphological surfaces were observed in SEM images of the composites. The size of the substituted polyaniline/chitosan (sPANI/Ch) composites was in nanoscale, and the composites synthesized in acetic acid media showed smaller structures than those of H₂SO₄ media and pure chitosan. It was interpreted from XRD results that the composites have amorphous structure and the PNEANI/Ch–CH₃COOH composite has the highest crystallinity.     

季磷盐壳聚糖的合成及其水溶性研究

目的:对壳聚糖进行化学改性,提高其水溶性并扩大其在医药领域的应用范围。方法:在均相体系中HOBt和EDC的催化下,采用酰化缩合反应将小分子磷盐连接到壳聚糖主链上,合成不同取代度的壳聚糖季磷盐,并用核磁共振氢谱、红外光谱、X-射线衍射谱表征产物的结构以及结晶性能。测定壳聚糖季磷盐的水溶解度及溶液的pH稳定性。结果:合成得到12.1%和21.5%两种不同取代度的壳聚糖季磷盐。与壳聚糖相比,两种不同取代度的壳聚糖季磷盐的结晶性能均有所下降,水溶性有很大的提高,并且溶液的pH稳定性显著增强。结论:使用小分子磷盐对壳聚糖进行化学改性得到水溶性良好且具有一定pH稳定性的壳聚糖衍生物,在用作药物输送载体及抗菌材料等领域内必将具有广阔的应用前景。     

Novel microbial route to synthesize silver nanoparticles using spore crystal mixture of Bacillus thuringiensis

Metallic nanoparticles are traditionally synthesized by wet chemical techniques, where the chemicals used are often toxic and flammable. In the present study, the spore crystal mixture of Bacillus thuringiensis was used for the synthesis of silver nanoparticles. Nanoparticles were characterized using UV-Vis absorption spectroscopy, XRD and TEM. X-ray diffraction and TEM analysis showed the average particle size of 15 nm and mixed (cubic and hexagonal) structure. This is for the first time that any bacterial spore crystal mixture was used for the synthesis of nanoparticles. Further, these biologically synthesized nanoparticles were found to be highly toxic against different multi drug resistant human pathogenic bacteria.     

<Emphasis Type="Italic">Caulerpa racemosa</Emphasis>: a marine green alga for eco-friendly synthesis of silver nanoparticles and its catalytic degradation of methylene blue

In this study, a simple and green method has been demonstrated for the synthesis of highly stable silver nanoparticles (AgNPs) using aqueous extract of Caulerpa racemosa (C. racemosa) as a reducing and capping agent. The formation and stability of AgNPs were studied using visual observation and UV–Visible (UV–Vis) spectroscopy. The stable AgNPs were further characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and high resolution transmission electron microscopy (HR-TEM) with energy dispersive spectroscopic (EDS) methods. The biosynthesized AgNPs showed a sharp surface plasmon resonance peak at 441 nm in the visible region and they have extended stability which has been confirmed by the UV–Vis spectroscopic results. XRD result revealed the crystalline nature of synthesized AgNPs and they are mainly oriented in (111) plane. FT-IR studies proved that the phytoconstituents of C. racemosa protect the AgNPs from aggregation and also which are responsible for the high stability. The size of synthesized AgNPs was approximately 25 nm with distorted spherical shape, identified from the HR-TEM images. The synthesized AgNPs showed excellent catalytic activity towards degradation of methylene blue.     

A new insight into the recycling of hyperaccumulator: synthesis of the mixed Cu and Zn oxide nanoparticles using Brassica juncea L

The mixed Cu and Zn oxide (Cu/ZnO) nanoparticles have been synthesized using Brassica juncea L. plants. The synthesized Cu/ZnO nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectrum (EDS). It was found that the synthesized Cu/ZnO nanoparticles were corresponding to the Cu(0.05)Zn(0.95)O structure. The shapes of the synthesized ZnO nanoparticles were nonuniform, but the CuO nanoparticles showed a spherical shape. The CuO nanoparticles entered in the structures of ZnO nanoparticles. An average size of 97 nm was obtained for Cu(0.05)Zn(0.95)O. The Cu(0.05)Zn(0.95)O nanoparticles were pure. The method for synthesis of Cu(0.05)Zn(0.95)O nanoparticles using Cu hyperaccumulator (B. juncea) plants constitutes a new insight into the recycling of hyperaccumulator and provides a novel route for further development of green nanostructure syntheses.     

季磷盐壳聚糖的合成及其水溶性研究

目的：对壳聚糖进行化学改性,提高其水溶性并扩大其在医药领域的应用范围。方法：在均相体系中HOBt和EDC的催化下,采用酰化缩合反应将小分子磷盐连接到壳聚糖主链上,合成不同取代度的壳聚糖季磷盐,并用核磁共振氢谱、红外光谱、x一射线衍射谱表征产物的结构以及结晶性能。测定壳聚糖季磷盐的水溶解度及溶液的pH稳定性。结果：合成得到12．1％和21．5％两种不同取代度的壳聚糖季磷盐。与壳聚糖相比,两种不同取代度的壳聚糖季磷盐的结晶性能均有所下降,水溶性有很大的提高,并且溶液的pH稳定性显著增强。结论：使用小分子磷盐对壳聚糖进行化学改性得到水溶性良好且具有一定pH稳定性的壳聚糖衍生物,在用作药物输送栽体及抗茵材料等领域内必将具有广阔的应用前景。     

Luminescence study of monodispersed ZnS nanoparticles

Monodispersed ZnS nanoparticles have been successfully synthesized by a chemical precipitation method in an air atmosphere using polyvinylpyrrolidone (PVP) and sodium hexametaphosphate (SHMP) as surfactants. The synthesized nanoparticles were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT‐IR), UV–Vis optical absorption and photoluminescence (PL) spectra. Prepared surfactants capped ZnS nanoparticles are highly homogeneous and well dispersed. Optical absorption spectra showed a strong blue shift from the uncapped particles due to the quantum confinement effect. The capped ZnS emission intensity is enhanced than more the uncapped particles. The size of the synthesized particles is around 4–6.5 nm range. Copyright © 2012 John Wiley & Sons, Ltd.     

Optical studies of CdS:Mn nanoparticles

Cadmium sulphide nanoparticles were grown using a wet chemical method, by dissolving the reactants, cadmium chloride and sodium sulphide in water, in the presence of mercaptoethanol (ME), which was used as a capping agent. Manganese chloride was used to dope the nanoparticles. It was found that the particle size varied with different concentrations of ME. At higher concentrations of ME, smaller sized nanoparticles were synthesized. This method also reveals the high stability of nanoparticles in water. Nanoparticle properties were investigated using UV–vis absorption, photoluminescence spectroscopy, X‐ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The particle sizes were measured by the XRD technique, SEM and optical absorption spectra and were in the range 2–6 nm. Copyright © 2011 John Wiley & Sons, Ltd.     

Stereocontrolled facile synthesis and antimicrobial activity of oximes and oxime ethers of diversely substituted bispidines

A small library of diversely substituted 2,4,6,8-tetraaryl-3,7-diazabicyco[3.3.1]nonan-9-ones, their oximes and O-methyloximes were achieved in a stereocontrolled manner by an easiest synthetic strategy as single isomers with high yields. Stereochemistry of all the synthesized compounds was established by their 1D/2D NMR spectral studies, further, witnessed by single-crystal XRD analysis. Accordingly, the compounds exist in a chair-boat conformation with equatorial orientation of the substituents in the chair part and boat-axial orientation in the boat part. Finally, all the synthesized oximes and oxime ethers were evaluated for their in vitro antimicrobial activity against a panel of pathogenic bacteria and fungi, and as a result of the structure-activity correlations, some lead molecules were known for further optimization.