TiO2 nanowire bundle microelectrode based impedance immunosensor for rapid and sensitive detection of Listeria monocytogenes

A novel TiO 2 nanowire bundle microelectrode based immunosensor was demonstrated as a more sensitive, specific, and rapid technology for detection of Listeria monocytogenes. TiO 2 nanowire bundle was prepared through a hydrothermal reaction of alkali with TiO 2 powder and connected to gold microelectrodes with mask welding. Monoclonal antibodies were immobilized on the surface of a TiO 2 nanowire bundle to specifically capture L. monocytogenes. Impedance change caused by the nanowire-antibody-bacteria complex was measured and correlated to bacterial number. This nanowire bundle based immunosensor could detect as low as 10 (2) cfu/ml of L. monocytogenes in 1 h without significant interference from other foodborne pathogens.     

用于制备优质单壁碳纳米管管束的MgO负载Fe3O4纳米粒子的合成

采用沉淀方法制备了直径分布狭窄的均匀Fe3O4纳米颗粒.Fe3O4纳粒形体几近一致,平均粒径为10.33 nm±2.99 nm(平均粒径±标准偏差).在超声作用下将MgO纳米颗粒分散在一定量Fe3O4纳米颗粒的水溶液中获得MgO负载Fe3O4的纳米颗粒.以甲烷为碳源,Fe3O4/MgO为催化剂,经化学气相沉积,在Fe3O4纳粒上制得了大量直径近乎均匀的单壁碳纳米管(SWCNTs)束.TEM显示:SWCNTs的平均直径1.22rm.热重分析显示:样品在400℃～600℃温度区间失重量约19％.拉曼光谱显示:SWCNTs的ID/IG的强度比为0.03,表明采用Fe3O4/MgO催化剂可制得高石墨化程度的单壁碳纳米管.     

Synthesis of size-controlled Fe3O4@SiO2 magnetic nanoparticles for nucleic acid analysis

We present a systematic study on the preparation, characteration and potential application of Fe3O4 and Fe3O4@SiO2 nanoparticles. Fe3O4 nanoparticles of controllable diameters were successfully synthesized by solvothermal system with tuning pH. The magnetic properties of nanoparticles were measured by vibration sample magnetometer. Fe3O4@ SiO2 nanoparticles were obtained via classic St?ber process. Streptavidin coated Fe3O4@SiO2 nanoparticles were prepared by covalent interaction. The quantity of streptavidin bound to nanoparticles was determined by UV-Vis spectrometer. To evaluate the binding efficiency and capacity of nucleic acid on nanoparticles, the capture of biotinylated oligonucleotide on streptavidin coated Fe3O4@SiO2 nanoparticles at different concentration was estimated by fluorescence detection. Both Fe3O4 and Fe3O4@SiO2 nanoparticles exhibited well crystallization and magnetic properties. The maximal amount of streptavidin immobilized onto the Fe3O4@SiO2 nanoparticles was 29.3 microg/mg. The saturation ratio of biotinylated oligonucleotides captured on streptavidin coated Fe3O4@SiO2 nanoparticles was 5 microM/mg within 20 minutes, indicating that FeO4@SiO2 nanoparticles immobilized by streptavidin were excellent carriers in nucleic acid analysis due to their convenient magnetic-separation property. Therefore, the synthesized Fe3O4 and Fe3O4@SiO2 nanoparticles with controllable size and high magnetic saturation have shown great application potentials in nucleic acid research.     

接枝聚阳离子磁性微球的合成及抗菌活性

共沉淀法合成Fe3O4纳米颗粒,经硅烷偶联剂3-(异丁烯酰氧)丙基三甲氧基硅烷(MPS)表面双键功能化,与季铵盐化(苄基溴化或溴己烷化)甲基丙烯酸二甲基氨基乙酯(DMAEMA)单体自由基共聚,获得可循环利用的聚阳离子接枝的磁性抗菌微球(pQAC-Fe3O4)。颗粒形貌及表面性质通过X射线衍射(XRD)、红外(FT-IR)、动态光散射粒径分析(DLS)、透射电镜(TEM)、热重分析(TGA)等表征。测试pQAC-Fe3O4微球对革兰氏阳性、革兰氏阴性菌及真菌的抗菌活性,结果表明两种具有外磁场响应性的pQAC-Fe3O4颗粒均具有高效广谱杀菌性,且经磁分离回收循环利用10次后对大肠杆菌的杀菌率仍可达95%以上。颗粒杀菌效果不仅与接枝季铵盐基团的多少有关还与季铵盐取代基团有关。     

纳米金磁颗粒的组装法制备及其核酸分离性能

以丙烯酰胺为单体,采用原位聚合法制备了Fe3O4/聚丙烯酰胺纳米磁粒(Fe3O4/PAM);利用胺基与金的相互作用,借助自组装法在Fe3O4/PAM表面组装金胶体制备了草莓型纳米金磁颗粒(Fe3O4/PAM/Au);用TEM、VSM、UV-vis对其进行了表征,并考察了表面修饰核酸探针的金磁颗粒对核酸靶分子的分离能力。结果表明,Fe3O4/PAM/Au粒子的粒径为36～56nm,具有超顺磁性,饱和磁化强度为31.2emu/g,分散在磷酸盐缓冲液中的Fe3O4/PAM/Au完全磁分离的时间为6min。修饰核酸探针的Fe3O4/PAM/Au粒子可以借助核酸杂交作用分离核酸靶分子,分离能力为118pmol/mg。     

Fe_3O_4-ODA/GO/PANI复合材料的制备及其电容性能

在当今能源紧缺的情况下,超级电容器由于具有功率密度高、充放电时间短、循环寿命长等优点而被广泛应用于工业自动化控制、电力、国防以及新能源汽车等众多领域。本文以十八胺修饰的四氧化三铁纳米粒子(Fe_3O_4-ODA),氧化石墨烯(GO)以及苯胺单体为原料,通过原位聚合成功制备了Fe_3O_4-ODA/GO/PANI三元复合电极材料,其比电容高达516F/g,远高于二元复合材料GO/PANI和Fe_3O_4-ODA/PANI的比电容(分别为224F/g和345F/g)。并且,在1000次循环充放电之后,其容量仍可维持86.5%。此外,利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线粉末衍射(XRD)和傅立叶变换红外光谱仪(FT-IR)等手段对该复合材料的形貌和结构进行了表征。     

Magnetic controllable biorecognition process of doxorubicin detected by electrochemical contact angle measurement

Fe3O4 nanoparticles are the most commonly used magnetic materials with promising applications in biomedical and biochemical engineering. In this study, a novel application of the tetraheptylammonium capped Fe3O4 nanoparticles in controllable biorecognition process of anticancer drug doxorubicin through combination with external static magnetic field has been demonstrated. Our AFM and electrochemical studies illustrate that the presence of the tetraheptylammonium capped Fe3O4 nanoparticles could promote the binding behavior of doxorubicin to DNA. And the results of the electrochemical contact angle measurements indicate that the controllable biomolecular recognition of doxorubicin could be readily achieved by combining these functionalized Fe3O4 nanoparticles with changing the positions of external magnetic field.     

功能化超顺磁性Fe3O4纳米微粒的制备及在β-银环蛇毒素检测中的应用

采用微波共沉淀法制备超顺磁性Fe3O4纳米粒子并对其进行功能化修饰,探讨了制备功能化β—BGT磁性纳米微粒的最佳工作条件,建立了双抗体夹心磁分离酶免疫分析法检测β-BGT,结果表明,制备的功能化β—BGT磁性纳米微粒具有良好的活性,每mg磁微粒固定的生物素标记β—BGT多抗最大量为925μg。双抗体夹心磁分离酶免疫分析法检测β-BGT线性范围为0．062～125μg／L,线性回归方程为Y=0．705X＋1．017（R^2=0．991,n=12,P〈0．0001）,检测限为O．062μg／L,具有较好的重现性。不同浓度的蓖麻毒素、相思子毒素、葡萄球菌肠毒素B对检测结果基本无干扰。     

Ag3PO4/BigFe4O9复合催化剂的制备及其光催化性能

利用水热法成功地制备得到具有高效光催化活性的Ag3PO4/Bi2Fe4O9复合型光催化剂.使用X-射线多晶粉末衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)对样品进行表征,并以罗丹明B为目标降解物对其光催化性能进行研究.结果表明:样品是由纳米Ag3 PO4颗粒负载在片状四边形的Bi2Fe4O9表面组成的,当Ag3PO4的负载量为4wt％时,复合材料的光催化效果最好,在可见光(波长＞420nm)照射下,1.5h内对100mL浓度为10-5mol.L-1罗丹明B溶液的脱色率可达98.7％.     

Synthesis and characterization of SiO2/(PMMA/Fe3O4) magnetic nanocomposites

Magnetic silica nanocomposites (magnetic nanoparticles core coated by silica shell) have the wide promising applications in the biomedical field and usually been prepared based on the famous St?ber process. However, the flocculation of Fe3O4 nanoparticles easily occurs during the silica coating, which limits the amount of magnetic silica particles produced in the St?ber process. In this paper, PMMA/Fe3O4 nanoparticles were used in the St?ber process instead of the "nude" Fe3O4 nanoparticles. And coating Fe3O4 with PMMA polymer beforehand can prevent magnetic nanoparticles from the aggregation that usually comes from the increasing of ionic strength during the hydrolyzation of tetraethoxysilane (TEOS) by the steric hindrance. The results show that the critical concentration of magnetic nanoparticles can increase from 12 mg/L for "nude" Fe3O4 nanoparticles to 3 g/L for PMMA/Fe3O4 nanoparticles during the St?ber process. And before the deposition of silica shell, the surface of PMMA/FeO4 nanoparticles had to be further modified by hydrolyzing them in CH3OH/NH3 x H2O mixture solution, which provides the carboxyl groups on their surface to react further with the silanol groups of silicic acid.     

Controlled synthetic conditions of FePt nanoparticles with high magnetization for biomedical applications

Monodispersed FePt nanoparticles with hydrophobic ligand were chemically synthesized and with controllable surface-functional properties. In order to enhance the saturation magnetization of FePt nanoparticles, the initial mole ratio of Fe to Pt precursors and reaction times were controlled to effectively increase magnetization due to the increased particle size and formation of FePt-Fe3O4 nanocomposites. The surface modification of FePt nanoparticles by using mercaptoacetic acid (C2H4O2S) as a phase transfer reagent through ligand exchange turned the nanoparticles hydrophilic, and the nanoparticles could water-dispersible. The streptavidin-biotin binding pair was used to conjugate with carboxylic acid (COOH) functional group on the surface of FePt nanoparticles that could be further functionalized to provide a biotin moiety for specific interactions with streptavidin protein.     

Synthesis of core/shell spinel ferrite/carbon nanoparticles with enhanced cycling stability for lithium ion battery anodes

Monodispersed core/shell spinel ferrite/carbon nanoparticles are formed by thermolysis of metal (Fe3+, Co2+) oleates followed by carbon coating. The phase and morphology of nanoparticles are characterized by x-ray diffraction and transmission electron microscopy. Pure Fe3O4 and CoFe2O4 nanoparticles are initially prepared through thermal decomposition of metal–oleate precursors at 310 degrees C and they are found to exhibit poor electrochemical performance because of the easy aggregation of nanoparticles and the resulting increase in the interparticle contact resistance. In contrast, uniform carbon coating of Fe3O4 and CoFe2O4 nanoparticles by low-temperature (180 degrees C) decomposition of malic acid allowed each nanoparticle to be electrically wired to a current collector through a conducting percolative path. Core/shell Fe3O4/C and CoFe2O4/C nanocomposite electrodes show a high specific capacity that can exceed 700 mAh g(-1) after 200 cycles, along with enhanced cycling stability.     

Flexible coatings with microphase separation structure attained by copolymers and ultra-fine nanoparticles for endurable antifouling

Incorporating antibacterial agent into biomimetic coating inspired by natural organisms with micro-nano structure surface has generated more interest for antifouling applications.In this work,poly(dimethylsiloxane)(PDMS)-based triblock copolymers and sub-20 nm nanoparticles Ag and het-erogeneous Fe3O4-coated Ag(Fe3O4@Ag)were used to construct microphase separation topography with oriented copolymer blocks structure.The artificial surface was verified by atomic force microscopy and scanning electron microscopy images.Meanwhile,the surface exhibited relative stable hydrophobic property,which was demonstrated by the water contact angle and dynamic air-bubble contact angle measurements.Consequently,after immersed in BSA solution 24 h and 720 h,the actual BSA absorp-tion amount of the surface with Fe3O4@Ag nanoparticles was as low as 10％and 27％that of the initial BSA amount,respectively.Moreover,the surface also showed remarkable antibacterial performance,which effectively suppressed the growth rate of Escherichia coli.The strategy of constructing the flexi-ble microphase separation structure by introducing heterogeneous inorganic antibacterial nanoparticles into a block copolymer substrate opens up a new way to create an antifouling surface coating.     

Fe3O4/CdTe磁性荧光纳米复合物的逐步杂凝聚法合成及其表征

采用逐步杂凝聚法合成了Fe3O4/CdTe磁性荧光纳米复合物.以化学共沉淀法制备Fe3O4纳米颗粒,经油酸修饰后分散在表面活性剂中形成磁流体.CdTe量子点以巯基乙酸为稳定剂制得.最后以聚乙烯亚胺(PEI)为联接剂,成功制备了Fe3 O4 /CdTe磁性荧光双功能纳米复合物颗粒.该复合物颗粒平均尺寸为(30±5)nm,荧光产率为0.186,饱和磁化强度为15.745emu/g,该纳米粒子既具有优异的荧光特性,也具有较强的超顺磁性.     

Iridium-complex-functionalized Fe3O4/SiO2 core/shell nanoparticles: a facile three-in-one system in magnetic resonance imaging, luminescence imaging, and photodynamic therapy

Highly uniform Fe3O4/SiO2 core/shell nanoparticles functionalized by phosphorescent iridium complexes (Ir) have been strategically designed and synthesized. The Fe3O4/SiO2(Ir) nanocomposite demonstrates its versatility in various applications: the magnetic core provides the capability for magnetic resonance imaging and the great enhancement of the spin-orbit coupling in the iridium complex makes it well suited for phosphorescent labeling and simultaneous singlet oxygen generation to induce apoptosis.     

Synthesis and characterization of environment friendly and multifunctional Fe3O4 magnetic nanoparticles

In this study, the size-uniform (5-6 nm), nearly spherical, and well-dispersed aqueous Fe3o4 magnetic nanoparticles were prepared by an improved chemical coprecipitation method. The DDAT-terminated (S-1-Dodecyl-S'-(alpha,alpha'-dimethyl-alpha"-acetic acid) trithiocarbonate) polymethacrylic (PMA-DDAT) was chosen as the apt surfactant, and the terminal DDAT can be used as a high efficient RAFT chain-transfer agent for further functionalization. Then, the functionalized Fe3O4 reacted with 4-amino-2,2,6,6-tetramethyl-piperidine-oxyl (4-NH2-TEMPO) to give the spin labeling magnetic nanoparticles. Finally, the multifunctional MNPs was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR), Fourier transform infrared spectrometer (FT-IR), and vibrating-sample magnetometer (VSM). The obtained highly water-soluble, superparamagnetic, and multifunctional magnetic nanoparticles should find potential applications in biomedical research.     

Reduced graphene oxide supersonically sprayed on wearable fabric and decorated with iron oxide for supercapacitor applications

We demonstrate the fabrication of wearable supercapacitor electrodes.The electrodes were applied to wearable fabric by supersonically spraying the fabric with reduced graphene oxide(rGO)followed by decoration with iron oxide(Fe2O3)nanoparticles via a hydrothermal process.The integration of iron oxide with rGO flakes on wearable fabric demonstrates immense potential for applications in high-energy-storage devices.The synergetic impact of the intermingled rGO flakes and Fe2O3 nanoparticles enhances the charge transport within the composite electrode,ultimately improving the overall electrochemical performance.Taking advantage of the porous nature of the fabric,electrolyte diffusion into the active rGO and Fe2O3 materials was significantly enhanced and subsequently increased the electrochemical interfacial activities.The effect of the Fe2O3 concentration on the overall electrochemical performance was investigated.The optimal composition yields a specific capacitance of 360 F g-1 at a current density of 1A g-1 with a capacitance retention rate of 89％after 8500 galvanostatic cycles,confirming the long-term stability of the Fe2O3/rGO fabric electrode.     

Synthesis of superparamagnetic CaCO3 mesocrystals for multistage delivery in cancer therapy

To develop a new system for site-specific targeting, superparamagnetic CaCO(3) mesocrystals with the properties of biocompatibility and biodegradability are designed and synthesized. They serve as carriers for the co-delivery of drug and gene nanoparticles via a multistage method for cancer therapy. With a porous structure, the mesocrystalline CaCO(3) particles encapsulate doxorubicin (DOX), Au-DNA, and Fe(3)O(4)@silica nanoparticles for magnetic control and therapy. As stage 1 microparticles (S1MPs), the nanoparticles-CaCO(3) system is designed to protect functional sections from degradation and phagocytosis in blood circulation. After the particle margination in vascular walls, the Au-DNA nanoparticles (stage 2 nanoparticles, S2NPs) and DOX are gradually released from S1MPs by degradation towards targeted tissues for biomedical therapy. The nanoparticles-CaCO(3) system exhibits high efficiency of intracellular delivery, especially in nuclear invasion. The successful expression of reporter gene and intracellular transport of DOX in vitro suggest potential as a co-delivery system for drug and gene therapy. In a mouse tumor model, the system with particle margination and two-step strategy affords the protection of functional nanoparticles and drug from clearance and inactivation by enzymes and proteins in vivo. The targeted delivery of S2NPs into tumors by this system is tenfold more efficient than that of the nanoparticles themselves. The drug is observed to be widely distributed in tumor slices. Thus, this platform exhibits an efficient approach in the targeted delivery of therapeutic nanoparticles and molecules via a multistage strategy, and can be used as a potential system in co-delivery of multiple agents for biomedical imaging and therapy.     

A Hydrangea‐Like Superstructure of Open Carbon Cages with Hierarchical Porosity and Highly Active Metal Sites

Carbon micro‐/nanocages have attracted great attention owing to their wide potential applications. Herein, a self‐templated strategy is presented for the synthesis of a hydrangea‐like superstructure of open carbon cages through morphology‐controlled thermal transformation of core@shell metal–organic frameworks (MOFs). Direct pyrolysis of core@shell zinc (Zn)@cobalt (Co)‐MOFs produces well‐defined open‐wall nitrogen‐doped carbon cages. By introducing guest iron (Fe) ions into the core@shell MOF precursor, the open carbon cages are self‐assembled into a hydrangea‐like 3D superstructure interconnected by carbon nanotubes, which are grown in situ on the Fe–Co alloy nanoparticles formed during the pyrolysis of Fe‐introduced Zn@Co‐MOFs. Taking advantage of such hierarchically porous superstructures with excellent accessibility, synergetic effects between the Fe and the Co, and the presence of catalytically active sites of both metal nanoparticles and metal–N_x species, this superstructure of open carbon cages exhibits efficient bifunctional catalysis for both oxygen evolution reaction and oxygen reduction reaction, achieving a great performance in Zn–air batteries.     

Preparation of guanidine group functionalized magnetic nanoparticles and the application in preconcentration and separation of acidic protein

Guanidine group (Gnd) functionalized magnetic nanoparticles (Fe3O4@SiO2@NH2-Gnd) were synthesized and characterized in this work for the first time. The characterization of Fe3O4@SiO2@ NH2-Gnd nanoparticles was demonstrated by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectra, vibration sample magnetometer, and zeta potential analyzer. The novel multifunctional nanoparticles were served as a solid-phase extraction sorbent for easy isolation and preconcentration of acidic protein from aqueous solution only using a magnet. Bovine serum albumin (BSA) was selected as a model protein and the main experimental parameters influencing the adsorption and desorption efficiency were investigated and optimized. Under the optimum conditions, the particles reached saturated adsorption within 20 min and exhibited significant specific recognition for the acidic proteins. Fifteen fold enrichment efficiency was achieved and the detection limits was 45 ng x mL(-1) for BSA by capillary electrophoresis (CE). The practical application of the novel nanoparticles as a sorbent for the isolation and preconcentration of acidic proteins from basic proteins was demonstrated by effective separation and enrichment of bovine serum albumin from lysozyme and cytochrome C mixture, which was assayed by CE.