Creation of highly stable selenium nanoparticles capped with hyperbranched polysaccharide in water

Water-dispersible selenium nanoparticles (SeNPs) were created by using natural hyperbranched polysaccharide (HBP) as the stabilizer and capping agent under extremely safe conditions. The structure, morphology, size, and stability of the nanocomposites were investigated by transmission electron microscopy (TEM), atomic force microscopy (AFM), and static and dynamic light scattering (DLS) measurements. The results revealed that the spherical selenium nanoparticles (mean particle size of about 24 nm) were ligated with HBP to form nanocomposites (Se-HBP) in aqueous solution and were stable for over one month. In our findings, supported by the results of FTIR, TEM, AFM, and DLS, SeNPs were capped with the HBP macromolecules, as a result of strong physical adsorption of OH groups on Se surfaces, leading to a highly stable structure of Se nanoparticles in water. This work provided reaction sites for the complexation between HBP and Se to fabricate well-dispersed Se nanoparticles in aqueous system with potential bioapplications.     

Highly Stable Amorphous Calcium Phosphate Porous Nanospheres: Microwave‐Assisted Rapid Synthesis Using ATP as Phosphorus Source and Stabilizer,and Their Application in Anticancer Drug Delivery

Highly stable amorphous calcium phosphate (ACP) porous nanospheres with a relatively uniform size and an average pore diameter of about 10 nm have been synthesized by using a microwave‐assisted hydrothermal method with adenosine 5′‐triphosphate disodium salt (ATP) as the phosphorus source and stabilizer. The as‐prepared ACP porous nanospheres have a high stability in the phosphate buffer saline (PBS) solution for more than 150 h without phase transformation to hydroxyapatite, and the morphology and size were essentially not changed. The important role of ATP and effects of experimental conditions on the formation of ACP porous nanospheres were also investigated. The ACP porous nanospheres were characterized by X‐ray powder diffraction (XRD), Fourier‐transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). This method is facile, rapid, surfactant‐free and environmentally friendly. The as‐prepared ACP porous nanospheres are efficient for anticancer drug (docetaxel) loading and release. The ACP porous nanosphere drug‐delivery system with docetaxel shows a high ability to damage tumor cells, thus, is promising for the application in anticancer treatment.     

Synthesis,Characterization of Copper-Loaded Carboxymethyl-Chitosan Nanoparticles with Effective Antibacterial Activity

Summary: Copper-loaded carboxymethyl-chitosan (CMCS-Cu) nanoparticles were successfully prepared by chelation under aqueous conditions. The effect of degree of deacetylation and substitution, the molecular weight of CMCS, CMCS concentration, Cu(II) ions concentration, pH value of the solution, as well as temperature, on the morphology of the yielded particles were systematically investigated. The physicochemical properties of the particles were determined by size and zeta potential analysis, FTIR analysis, DLS, TEM, SEM and XRD pattern. FTIR and XRD revealed that Cu (II) ions and CMCS formed a chelate complex. The size of CMCS-Cu particles shows a good consistency by DLS, TEM, and SEM. The nanoparticles with the size of about 70 nm have been prepared at 0.13 wt% CMCS, 16 mmol/L Cu(II) ions, pH value 4.56 at 25 °C. The antibacterial activity of CMCS, CMCS-Cu normal particles with the size of about 1000 nm and CMCS-Cu nanoparticles with the size of less than 100 nm against Staphylococcus aureus was evaluated by vibration method. Results show that the antibacterial efficiency of nanoparticles reached 99%, which is much more efficient than 68.9% of the normal one and 6.1% of CMCS. CMCS-Cu nanoparticles were proved to be a good novel antibacterial material.     

Amphiphilic polyethylenes leading to surfactant-free thermoresponsive nanoparticles

Linear copolymers of ethylene and acrylic acid (PEAA) were prepared by catalytic polymerization of ethylene and tert-butyl acrylate followed by hydrolysis of the ester groups. The copolymers contained COOH groups inserted into the crystalline unit cell with formation of intramolecular hydrogen-bonds, as established on the basis of differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) studies. A solvent-exchange protocol, with no added surfactant, converted a solution in tetrahydrofuran of a PEAA sample containing 12 mol % of acrylic acid (AA) into a colloidally stable aqueous suspension of nanoparticles. Transmission electron microscopy (TEM), dynamic light scattering (DLS), and high sensitivity differential scanning calorimetry (HS-DSC) were used to characterize the nanoparticles. They are single crystals of elongated shape with a polar radius of 49 nm (σ = 15 nm) and an equatorial radius of 9 nm (σ = 3 nm) stabilized in aqueous media via carboxylate groups located preferentially on the particle/water interface. The PEAA (AA: 12 mol %) nanoparticles dispersed in aqueous media exhibited a remarkable reversible thermoresponsive behavior upon heating/cooling from 25 to 80 °C.     

肝靶向甘草次酸修饰的壳聚糖纳米粒子的合成和表征

合成了修饰甘草次酸的壳聚糖(GA-CTS), 采用离子交联法制备了GA-CTS纳米粒子. 该材料可能具有肝细胞主动靶向作用, 为进一步的肝靶向药物控释的研究奠定了基础.     

Fructose 1,6‐Bisphosphate Trisodium Salt as A New Phosphorus Source for the Rapid Microwave Synthesis of Porous Calcium–Phosphate Microspheres and their Application in Drug Delivery

Calcium phosphates (CPs), as the major inorganic component of biological hard tissues, have been investigated for applications as biomaterials owing to their excellent biocompatibility. However, the traditional synthetic CPs are usually prepared from inorganic phosphorus and calcium sources. Herein, we report a new strategy for the synthesis of a variety of calcium–phosphate nanostructures, including porous amorphous calcium phosphate (ACP) microspheres, hydroxyapatite (HAP) nanorods, and ACP/HAP composite microspheres, by using fructose 1,6‐bisphosphate trisodium salt (FBP) as an organic phosphorus source in aqueous solution in a rapid microwave‐assisted hydrothermal reaction. The important role of FBP and the effect of the experimental conditions on the formation and evolution of the CPs nanostructures were investigated. The crystal phase and composition of the as‐prepared products were characterized by powder X‐ray diffraction (XRD), FTIR spectroscopy, and thermogravimetric (TGA) analysis and the morphologies of the products were characterized by SEM and TEM. This method is facile, rapid, surfactant‐free, and environmentally friendly. The as‐prepared porous ACP microspheres have a relatively high drug‐loading capacity and good sustained drug‐release behavior; thus, they are promising for applications in drug delivery.     

NaYF_4:Yb~(3+),Er~(3+)上转换发光纳米晶在三元混合溶剂体系中的配体交换修饰及发光性质

选用2-胺乙基膦酸双官能团小分子作为配体交换剂,采用氯仿/乙醇/水三元混合溶剂体系下的配体交换修饰方法,解决了疏水纳米晶与亲水配体的有效接触反应问题,实现了上转换纳米晶的水溶性以及表面胺基功能化修饰.通过傅里叶变转换红外光谱和热重分析证实了表面配体分子的替换.透射电子显微镜和激光粒度分析结果显示,所得水溶性纳米晶具有粒径均一,水力直径小和分散稳定的特点.样品的发射光谱结果表明,配体交换过程对纳米晶的发光无明显影响,保持了良好的发光性能.通过荧光共聚焦成像技术实现了胺基修饰上转换发光纳米晶对HeLa细胞的光学成像,证实所得纳米晶适合于潜在的生物学应用.     

Biosynthesis of Highly Dispersed Palladium Nanoparticles Using Astraglmanna Aqueous Extract

Biosynthesis of nanoparticles has received increased attention due to a growing need to develop environmentally benign technologies in material synthesis and employment of secondary metabolites from plant extract that has emerged as a novel technology for this purpose. In this study, a rapid and biogenic process for fabrication of palladium nanoparticles (PdNPs) is reported. Highly dispersed palladium nanoparticles were successfully prepared by using aqueous extract of Astraglmanna, a non‐toxic and eco‐friendly material, without extra surfactant, capping agent, and template. The PdNPs were characterized by using UV—Visible spectroscopy, scanning electron microscope ‐ energy dispersive spectra (SEM‐EDX), Fourier transform infra red spectroscopy (FTIR), dynamic light scattering (DLS) and X‐ray diffraction (XRD) analysis. Transmission electron microscopic (TEM) images of the PdNPs were recorded and mean size of the biosynthesized nanoparticles was found to be approximately 15 nm.     

CdS/石墨烯复合材料的制备及其可见光催化分解水产氢性能

以氧化石墨烯和CdS为原料, 在乙醇水溶液中采用CdS光催化还原法制备了CdS/石墨烯复合光催化材料, 并用透射电子显微镜(TEM)、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、X射线光电子能谱(XPS)和瞬态光电流等技术对复合材料的结构和光电性能进行了表征. 可见光照射下(λ≥420 nm), 研究了该复合材料光催化分解水产氢的性能. 结果表明, 可见光照射下CdS的光生电子可有效地还原氧化石墨烯, 得到CdS与石墨烯之间具有强相互作用力的CdS/石墨烯复合材料. 与CdS相比, 复合材料中石墨烯作为良好的电子受体和传递介质, 可明显加快CdS光生电子的迁移速率, 提高光生载流子的分离效率, 从而增强复合材料的光电性能和光催化分解水产氢的活性.     

Sucrose ester micellar-mediated synthesis of Ag nanoparticles and the antibacterial properties

Ag nanoparticles with diameter in the range of 10–25 nm had been synthesized using a simple sucrose ester micellar-mediated method. Ag nanoparticles were formed by adding AgNO₃ solution into the sucrose ester micellar solution containing sodium hydroxide at atmospheric condition after 24 h of aging time. Trace amount of dimethyl formamide (DMF) in the sucrose ester solution served as a reducing agent while NaOH acted as a catalyst. The produced Ag nanoparticles were highly stable in the sucrose ester micellar system as there was no precipitation after 6 months of storage. The as-synthesized Ag nanoparticles were characterized using transmission electron microscope (TEM), X-ray diffractometer (XRD), dynamic light scattering (DLS) and UV–vis spectroscopy (UV–vis). Formation mechanism of Ag nanoparticles in the micellar-mediated synthesis is postulated. The antibacterial properties of the Ag nanoparticles were tested against Methicillin-resistant Staphylococcus aureus (MRSA) (Gram-positive) and Aeromonas hydrophila (Gram-negative) bacteria. This work provides a simple and “green” method for the synthesis of highly stable Ag nanoparticles in aqueous solution with promising antibacterial property.     

Study on facile designing,swelling properties and structural relationship of gelatin nanoparticles

In the present work glutaraldehyde crosslinked gelatin (Type-A and Type-B) nanoparticles were fabricated following a microemulsion crosslinking technique. The structural, morphological, and stability features of nanoparticles were investigated using the techniques like FTIR, TEM, XRD, DLS, and surface charge measurements. The spectral peaks appeared in the FTIR spectra of gelatin nanoparticles confirmed the crosslinking of gelatin molecules with glutaraldehyde. The SEM analysis of the nanoparticles suggested that the size of gelatin nanoparticles was nearly 300 nm whereas the TEM analysis revealed their size around 200?nm. The size of nanoparticles was found to increase with increasing amounts of gelatin while it showed a decrease when the concentration of crosslinker was increased. An increase in percent crystallinity was observed when gelatin was crosslinked with glutaraldehyde. The water uptake capacity of the gelatin nanoparticles was evaluated under varying experimental conditions like, pH, temperature, presence of simulated physiological fluids and varying composition of the gelatin nanoparticles. To study the cytotoxic behavior of gelatin nanoparticles in vitro cytotoxicity analysis were performed. The gelatin nanoparticles demonstrated good stability and biocompatibility which suggested that these particles can be used as drug carrier in fabricating a swelling controlled drug delivery system.     

Temperature-responsive magnetite/PEO-PPO-PEO block copolymer nanoparticles for controlled drug targeting delivery

In this study, temperature-responsive magnetite/polymer nanoparticles were developed from iron oxide nanoparticles and poly(ethyleneimine)-modified poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymer. The particles were characterized by TEM, XRD, DLS, VSM, FTIR, and TGA. A typical product has an approximately 20 nm magnetite core and an approximately 40 nm hydrodynamic diameter with a narrow size distribution and is superparamagnetic with large saturation magnetization (51.34 emu/g) at room temperature. The most attractive feature of the nanoparticles is their temperature-responsive volume-transition property. DLS results indicated that their average hydrodynamic diameter underwent a sharp decrease from 45 to 25 nm while evaluating the temperature from 20 to 35 degrees C. The temperature-dependent evolution of the C-O stretching band in the FTIR spectra of the aqueous nanoparticles solution revealed that thermo-induced self-assembly of the immobilized block copolymers occurred on the magnetite solid surfaces, which is accompanied by a conformational change from a fully extended state to a highly coiled state of the copolymer. Consequently, the copolymer shell could act as a temperature-controlled "gate" for the transit of guest substance. The uptake and release of both hydrophobic and hydrophilic model drugs were well controlled by switching the transient opening and closing of the polymer shell at different temperatures. A sustained release of about 3 days was achieved in simulated human body conditions. In primary mouse experiments, drug-entrapped magnetic nanoparticles showed good biocompatibility and effective therapy for spinal cord damage. Such intelligent magnetic nanoparticles are attractive candidates for widespread biomedical applications, particularly in controlled drug-targeting delivery.     

Self-aggregated nanoparticles of cholesterol-modified glycol chitosan conjugate: Preparation, characterization, and preliminary assessment as a new drug delivery carrier

Cholesterol-modified glycol chitosan (CHGC) conjugate was synthesized and characterized by FTIR and ¹H NMR. The degree of substitution (DS) was 6.7 cholesterol groups per 100 sugar residues of glycol chitosan. CHGC formed self-aggregated nanoparticles with a roughly spherical shape and a mean diameter of 228 nm by probe sonication in aqueous medium. The physicochemical properties of the self-aggregated nanoparticles were studied using dynamic light scattering (DLS), transmission electron microscopy (TEM) and fluorescence spectroscopy. The critical aggregation concentration (CAC) of self-aggregated nanoparticles in aqueous solution was 0.1223 mg/mL. Indomethacin (IND), as a model drug, was physically entrapped into the CHGC nanoparticles by dialysis method. The characteristics of IND-loaded CHGC (IND-CHGC) nanoparticles was analyzed using DLS, TEM and high performance liquid chromatography (HPLC). The IND-CHGC nanoparticles were almost spherical in shape and their size increased from 275 to 384 nm with the IND-loading content increasing from 7.14% to 16.2%. The in vitro release behavior of IND from CHGC nanoparticles was studied by a dialysis method in phosphate buffered saline (PBS, pH 7.4). IND was released in a biphasic way. The initial rapid release in 2 h and slower release for up to 12 h were observed. The results indicated that CHGC nanoparticles had a potential as a drug delivery carrier.     

A facile synthesis and characterization of Ag, Au and Pt nanoparticles using a natural hydrocolloid gum kondagogu (Cochlospermum gossypium)

An environmentally benign method for the synthesis of noble metal nanoparticles has been reported using aqueous solution of gum kondagogu (Cochlospermum gossypium). Both the synthesis, as well as stabilization of colloidal Ag, Au and Pt nanoparticles has been accomplished in an aqueous medium containing gum kondagogu. The colloidal suspensions so obtained were found to be highly stable for prolonged period, without undergoing any oxidation. SEM-EDXA, UV-vis spectroscopy, XRD, FTIR and TEM techniques were used to characterize the Ag, Au and Pt nanoparticles. FTIR analysis indicates that -OH groups present in the gum matrix were responsible for the reduction of metal cations into nanoparticles. UV-vis studies showed a distinct surface plasmon resonance at 412 and 525 nm due to the formation of Au and Ag nanoparticles, respectively, within the gum network. XRD studies indicated that the nanoparticles were crystalline in nature with face centered cubic geometry. The noble metal nanoparticles prepared in the present study appears to be homogeneous with the particle size ranging between 2 and 10 nm, as evidenced by TEM analysis. The Ag and Au nanoparticles formed were in the average size range of 5.5±2.5 nm and 7.8±2.3 nm; while Pt nanoparticles were in the size range of 2.4±0.7 nm, which were considerably smaller than Ag and Au nanoparticles. The present approach exemplifies a totally green synthesis using the plant derived natural product (gum kondagogu) for the production of noble metal nanoparticles and the process can also be extended to the synthesis of other metal oxide nanoparticles.     

Synthesis and Characterization of Polyaniline/Partially Phosphorylated Poly（vinyl alcohol） Nanoparticles

The polyaniline/partially phosphorylated poly（vinyl alcohol）（PANI/P-PVA） nanoparticles were prepared by the chemical oxidative dispersion polymerization of aniline monomer in 0.5 mol/L HC1 aqueous media with the partially phosphorylated poly（vinyl alcohol） （P-PVA） as the stabilizer and co-dopant. The PANI/P-PVA nanoparticles were characterized by transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR）, thermal gravimetric analysis （TGA）, X-ray diffraction （XRD）, electrical conductivity measurements and re-dispersion stability testing. All the results were compared with the properties of the conventional polyaniline in the emeraldine salt form （PANI ES）. It was found that the feeding ratio of P-PVA obviously affected the morphology, re-dispersion stability and electrical conductivity of the PANI/P-PVA nanoparticles. When the feeding ratio of P-PVA ranged from 40 wt% to 50 wt%, the PANI/P-PVA nanoparticles showed spherical shape with good uniformity, significant re-dispersion stability in aqueous media and good electrical conductivity.     

Catalytic Reduction of p‐Nitrophenol and Hexacyanoferrate (III) by Borohydride Using Green Synthesized Gold Nanoparticles

A simple and green approach for the synthesis of well‐stabilized gold nanoparticles (AuNPs) using gum Acacia (GA) is presented here. The gum acacia acts as the reductant and stabilizer. The synthesized gold nanoparticles were characterized by using ultraviolet visible (UV‐Vis), fourier transform infrared spectroscopy (FTIR), x‐ray diffraction (XRD), dynamic light scattering (DLS) and transmission electron microscopy (TEM) techniques. The UV‐Vis study revealed a distinct surface plasmon resonance at 520 – 550 nm, due to the formation of AuNPs. FTIR analysis showed the evidence that –OH groups present in the gum matrix were responsible in reducing the tetra chloroauric acid into AuNPs. XRD studies confirmed the formation of well crystalline nanoparticles with fcc structure and the particle size ranges from 4 – 29 nm, as indicated by TEM analysis. The synthesized gold nanoparticles exhibited homogeneous catalytic activity. The two model reactions studied were the reduction of p‐nitro phenol and the reduction of hexacyanoferrate (III) by borohydride ions. Both the reactions were monitored by UV‐Vis spectroscopy. The kinetic investigations were carried out for the AuNPs‐catalyzed reactions at different temperatures and different amount of catalyst.     

Role of phenol derivatives in the formation of silver nanoparticles

We demonstrate that dihydroxy benzenes are excellent reducing agents and may be used to reduce silver ions to synthesize stable silver nanoparticles in air-saturated aqueous solutions. The formation of Ag nanoparticles in deaerated aqueous solution at high pH values suggests that the reduction of silver ions occurs due to oxidation of dihydroxy benzenes and probably on the surface of Ag2O. Pulse radiolysis studies show that the semi-quinone radical does not participate in the reduction of silver ions at short time scales. Nevertheless, results show that primary intermediates undergo slower transformation in the presence of dihydroxy benzenes than in their absence. This slow transformation eventually leads to the formation of silver nanoparticles. The Ag nanoparticles were characterized by UV-vis absorption spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). XRD and TEM techniques showed the presence of Ag nanoparticles with an average size of 30 nm.     

Fluorescent organic nanoparticles self-assembled from hexa[p-(carbonyl glycin methyl ester) phenoxy] cyclotriphosphazene in solution

Novel organic nanoparticles self-assembled from the hexa[p-(carbonyl glycin methyl ester) phenoxy] cyclotriphosphazene (HGPCP) were prepared by a simple solution method. The as-prepared nanoparticles were extensively characterized by SEM, TEM, XRD, TGA, and fluorescence spectrum. The size of nanoparticles was increased with increasing the HGPCP concentration in solution. The effect of reaction conditions on the particle size and stability was further investigated. Based upon the experimental results, a growth mechanism was proposed for the formation of the nanoparticles. The obtained nanoparticles were highly thermal stable and exhibited strong fluorescent emission, which could be potential candidates for drug-loading carriers and tracer drug delivery.     

Green synthesis of silver nanoparticles using Macrotyloma uniflorum

Green synthesis of noble metal nanoparticles is a vast developing area of research. In this paper we report the green synthesis of silver nanoparticles using aqueous seed extract of Macrotyloma uniflorum. The effect of experimental parameters such as amount of extract, temperature and pH on the formation of silver nanoparticles was studied. The as prepared samples are characterized using XRD, TEM, UV-Visible and FTIR techniques. The formation of silver nanoparticles is evidenced by the appearance of signatory brown colour of the solution and UV-vis spectra. The XRD analysis shows that the silver nanoparticles are of face centered cubic structure. Well-dispersed silver nanoparticles with anisotropic morphology having size ～12 nm are seen in TEM images. FTIR spectrum indicates the presence of different functional groups in capping the nanoparticles. The possible mechanism leading to the formation of silver nanoparticles is suggested.     

Synthesis of Metallic Silver Nanoparticles by Fluconazole Drug and Gamma Rays to Inhibit the Growth of Multidrug-Resistant Microbes

Here we tailored a methodology, including green synthesis of silver nanoparticles (AgNPs) in aqueous solution using Fluconazole (Fluc.), a broad-spectrum antifungal agent under the influence of gamma rays. AgNPs were characterized by UV–Vis., FTIR, XRD, DLS, and TEM image. Antimicrobial activities of AgNPs, Fluc., and Ag⁺ were investigated against multidrug-resistant (MDR) bacteria and unicellular fungi. From our results, AgNPs production was found to be dependent on the concentration of Ag⁺, Fluc. and gamma doses. DLS with TEM image explained the size and shape of AgNPs and were found to be spherical with diameter of 11.65 nm. FTIR analysis indicates that, the hydroxyl, nitrogen and fluoride moiety in Fluc. were responsible for the reduction and binding process. AgNPs possesses antimicrobial activity against all tested microbes more than Ag⁺. It produced high efficacy against Acinetobacter baumannii (20.0 mm ZOI). AgNPs are synergistically active towards Candida albicans (17.0 mm ZOI). Investigated action mechanisms for AgNPs activity had been discussed. Thereby, owing to its unique features as cost-effective with continued-term stabilization, it can discover potential targets in biomedical applications and infectious diseases control.