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1.
The physical interaction between plasma-membrane lipids and the epidermal growth factor (EGF)-receptor was investigated on single A431 human epidermoid carcinoma cells by monitoring fluorescence resonance energy transfer (FRET) between exogeneously added fluorescein-EGF (donor) and 2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine (Bodipy-PC, acceptor) using donor-photobleaching FRET-microscopy. The measured mean FRET-efficiency of 13% is indicative of such a physical interaction and exemplifies the great potential and sensitivity of time-resolved imaging fluorescence microscopy techniques for the study of lipid-receptor interactions on single cells. 相似文献
2.
Molecular Diversity - Epidermal growth factor receptor (EGFR) has received widespread attention because it is an important target for anticancer drug design. Mutations in the EGFR, especially the... 相似文献
3.
R.Y. Hong T.T. Pan Y.P. Han H.Z. Li J. Ding Sijin Han 《Journal of magnetism and magnetic materials》2007
Methods to synthesize magnetic Fe3O4 nanoparticles and to modify the nanoparticle surface are presented in this paper. In these methods, Fe3O4 nanoparticles were prepared by co-precipitation, and the aging of nanoparticles was improved by applied magnetic field. The obtained nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). Thereafter, to enhance the compatibility between nanoparticles and water, an effective surface modification method was developed by grafting acrylic acid onto the nanoparticle surface. FT-IR, XRD, transmission electron microscopy (TEM), and thermogravimetry (TG) were used to characterize the resultant sample. The testing results indicated that the polyacrylic acid chains have been covalently bonded to the surface of magnetic Fe3O4 nanoparticles. The effects of initiator dosage, monomer concentration, and reaction temperature on the characteristics of surface-modified Fe3O4 nanoparticles were investigated. Moreover, the Fe3O4-g-PAA hybrid nanoparticles were dispersed in water to form ferrofluids (FFs). The obtained FFs were characterized by UV–vis spectrophotometer, Gouy magnetic balance and laser particle-size analyzer. The testing results showed that the high-concentration FF had excellent stability, with high susceptibility and high saturation magnetization. The rheological properties of the FFs were also investigated using a rotating rheometer. 相似文献
4.
为了直观、准确地定量分析表面拉曼增强散射基底结构的拉曼增强,利用磁控溅射和高温退火的方法制备了银纳米粒子修饰垂直排列的碳纳米管阵列三维复合结构样品;实验采用罗丹明6G(R6G)溶剂作为探针分子,结合共聚焦显微拉曼系统,开展了表面增强拉曼增强因子(EF)分析计算的相关实验。SEM结果表明:在有序碳纳米管阵列的表面和外壁均匀地负载了大量银纳米粒子。对退火温度为450 ℃,退火时间为30 min的样品进行了EF计算,得到其增强因子约为2.2×103,并分析了EF值低的原因主要是:在碳纳米管上溅射的银膜膜厚不均匀,导致退火后银颗粒分布不均,使得样品粗糙度值偏大,EF值较低;实验中所用的激励光源并非银纳米颗粒的优化光源。 相似文献
5.
Fine grain growth of nickel electrodeposit: effect of applied magnetic field during deposition 总被引:1,自引:0,他引:1
The electrodeposition of nickel from a nickel sulphamate bath in the presence of a magnetic field applied at an angle of 45° to the cathode surface produces a nickel deposit with a fine grain structure. The sizes of grains vary from 17 to 25 nm. We have used scanning electron microscopy (SEM), scanning tunneling microscopy (STM) and X-ray diffraction (XRD) to characterize the surface morphology of the deposit. The SEM pictures show the formation of domain growth of nickel in which the nickel nanoparticles are mostly concentrated at domain boundaries while STM and XRD analysis show the existence of individual nanoparticles. From the chronopotentiometry studies during magnetoelectrolysis of nickel, we find a significant lowering of overpotential with time and large negative shift in electrode potential in the presence of a magnetic field. We believe from these results that magnetic field induced convection increases the mass transfer rate, reduces the concentration polarisation and leads to the growth of fine grain deposit. The large shift in electrode potential on the application of magnetic field is attributed to the field-induced shift in chemical potential of the ferromagnetic nickel electrode. We have used cyclic voltammetry (CV) to determine the roughness factor and steady state current-potential plots to study the hydrogen evolution reaction on the nickel-electrodeposited surface. 相似文献
6.
Very promising nanoparticles for biomedical applications or in medical drug targeting are superparamagnetic nanoparticles based on a core consisting of iron oxides (SPION) that can be targeted through external magnets. Polyvinyl alcohol (PVA) is a unique synthetic biocompatible polymer that can be chemically cross-linked to form a gel. Biotechnology applications of magnetic gels include biosensors, targeted drug delivery, artificial muscles and magnetic buckles. These gels are produced by incorporating magnetic materials in the polymer composites. In this paper we report the synthesis of an aqueous ferrofluid and the preparation of a biocompatible magnetic gel with polyvinyl alcohol and glutharaldehyde (GTA). HClO4 was used to induce the peptization since this kind of ferrofluid does not have surfactant. The magnetic gel was dried to generate a biocompatible film. 相似文献
7.
The chitosan-coated magnetic nanoparticles (CS MNPs) were in situ synthesized by cross-linking method. In this method; during the adsorption of cationic chitosan molecules onto the surface of anionic magnetic nanoparticles (MNPs) with electrostatic interactions, tripolyphosphate (TPP) is added for ionic cross-linking of the chitosan molecules with each other. The characterization of synthesized nanoparticles was performed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS/ESCA), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), dynamic light scattering (DLS), thermal gravimetric analysis (TGA), and vibrating sample magnetometry (VSM) analyses. The XRD and XPS analyses proved that the synthesized iron oxide was magnetite (Fe3O4). The layer of chitosan on the magnetite surface was confirmed by FTIR. TEM results demonstrated a spherical morphology. In the synthesis, at higher NH4OH concentrations, smaller sized nanoparticles were obtained. The average diameters were generally between 2 and 8?nm for CS MNPs in TEM and between 58 and 103?nm in DLS. The average diameters of bare MNPs were found as around 18?nm both in TEM and DLS. TGA results indicated that the chitosan content of CS MNPs were between 15 and 23?% by weight. Bare and CS MNPs were superparamagnetic. These nanoparticles were found non-cytotoxic on cancer cell lines (SiHa, HeLa). The synthesized MNPs have many potential applications in biomedicine including targeted drug delivery, magnetic resonance imaging?(MRI), and magnetic hyperthermia. 相似文献
8.
9.
Sun‐Woong Kang Jong‐Jin Choi Ha‐Na Kim Joseph Seo Soon‐Jung Park Eun‐Young Kim Se‐Pil Park Kang Moo Huh Hyung‐Min Chung Ho Yun Chung Sung‐Hwan Moon 《Particle & Particle Systems Characterization》2017,34(5)
Epidermal growth factor (EGF) is widely recognized to be involved in the regenerative process, but only a few studies document its effect on acute wounds when EGF release is sustained over a period of time by encapsulation in an emulsion‐based hydrogel. Among hydrogels, hyaluronic acid (HA) is a promising carrier because it is biodegradable and known to bind to the components of the Extracellular Matrix (ECM) which undergoes remodeling during regeneration. Coupled with EGF in microparticulates, it may serve to directly deliver the cytokine to the impaired ECM to stimulate cells for ECM remodeling. In this study, a very simple and effective way is demonstrated to produce EGF‐conjugated HA microspheres for the purpose of targeted and sustained EGF delivery to damaged ECM in acute wounds. This approach is advantageous due to its simplicity which may serve to accelerate research in wound regeneration and relevant drug discovery. 相似文献
10.
Nesreen Alzoghoul Alsmadi Aniket S. Wadajkar Weina Cui Kytai T. Nguyen 《Journal of nanoparticle research》2011,13(12):7177-7186
The objective of this research was to compare the effects of two different surfactants on the physicochemical properties of
thermo-responsive poly(N-isopropylacrylamide-acrylamide-allylamine) (PNIPAAm-AAm-AH)-coated magnetic nanoparticles (MNPs). Sodium dodecyl sulfate
(SDS) as a commonly used surfactant in nanoparticle formulation process and Pluronic F127 as an FDA approved material were
used as surfactants to synthesize PNIPAAm-AAm-AH-coated MNPs (PMNPs). The properties of PMNPs synthesized using SDS (PMNPs-SDS)
and PF127 (PMNPs-PF127) were compared in terms of size, polydispersity, surface charge, drug loading efficiency, drug release
profile, biocompatibility, cellular uptake, and ligand conjugation efficiency. These nanoparticles had a stable core–shell
structure with about a 100-nm diameter and were superparamagnetic in behavior with no difference in the magnetic properties
in both types of nanoparticles. In vitro cell studies showed that PMNPs-PF127 were more cytocompatible and taken up more by
prostate cancer cells than that of PMNPs-SDS. Cells internalized with these nanoparticles generated a dark negative contrast
in agarose phantoms for magnetic resonance imaging. Furthermore, a higher doxorubicin release at 40 °C was observed from PMNPs-PF127,
and the released drugs were pharmacologically active in killing cancer cells. Finally, surfactant type did not affect the
conjugation efficiency to the nanoparticles when folic acid was used as a targeting ligand model. These results indicate that
PF127 might be a better surfactant to form polymer-coated magnetic nanoparticles for targeted and controlled drug delivery. 相似文献
11.
In this paper, we report a method for recognizing human ovarian tumor(HOT) cells using fluorescent biological label based
on core-shell nanoparticles. The luminescent nanoparticles were synthesized with a water-in-oil(W/O)micromulsion technique.
The fluorescent silica core-shell nanoparticles modified with anti-HER2 antibody using bifunctional cross-linker glutaraldedhyde
targeted the corresponding tumor antigen in the cell surface of the SKOV3 ovarian cancer cells. The specific immunoreactivity
of antibody-nanoparticles with cells was characterized by laser scanning microscopy (LSM) and scanning electron microscope
(SEM). The results showed that the method offered potential advantages of sensitivity and simplicity due to high binding efficiency
between nanoparticles and cells and provided an alternative method for the detection of HOT. 相似文献
12.
Producing ultra-thin silica coatings on iron-oxide nanoparticles to improve their surface reactivity
Slavko Kralj Darko Makovec Miha Drofenik 《Journal of magnetism and magnetic materials》2010,322(13):1847-89
The reactivity of the relatively inert surfaces of iron-oxide magnetic nanoparticles can be significantly improved by coating the surfaces with silica. Unfortunately, however, this nonmagnetic silica layer tends to dilute the magnetic properties of the nanoparticles. Therefore, the silica layer should be as continuous, homogeneous, and as thin as possible.In this investigation we coated superparamagnetic maghemite nanoparticles by hydrolysis and the polycondensation of tetraethyl orthosilicate (TEOS), with the ethanol solution of TEOS being added to a stable suspension of citric acid-coated nanoparticles. The influences of the various parameters of the procedure on the quality of the coatings were systematically evaluated. The quality of the silica layer was characterized using electron microscopy and by performing leaching of the nanoparticles in HCl, while the surface reactivity was tested by grafting (3-aminopropyl) triethoxysilane (APS) onto the nanoparticles. We observed that the surface concentration of the grafted APS strongly increased when the nanoparticles were coated with a silica layer. The choice of experimental conditions for the coating procedure that favors the heterogeneous nucleation of silica on the surfaces of the nanoparticles enabled the preparation of very thin silica layers, less than 2 nm thick. By decreasing the amount of added TEOS to correspond to a monolayer of -Si-OH at the nanoparticles' surfaces, their surface reactivity could be very much improved, and with a reduction in their magnetization of only ∼10%. 相似文献
13.
Small-angle neutron scattering study on the stability of oxide nanoparticles in long-term thermally aged 9Cr-oxide dispersion strengthened steel 下载免费PDF全文
Peng-Lin Gao 《中国物理 B》2022,31(5):56102-056102
A 9Cr-oxide dispersion strengthened (ODS) steel was thermally aged at 873 K for up to 5000 h. The size distribution and chemical composition of the dispersed oxide nanoparticles were analyzed by small-angle neutron scattering under a magnetic field. Combined with transmission electron microscopy, Vickers micro-hardness tests and electron backscattered diffraction measurements, all the results showed that the thermal treatment had little or no effect on the size distributions and volume fractions of the oxide nanoparticles in the ferromagnetic matrix, which suggested excellent thermal stability of the 9Cr-ODS steel. 相似文献
14.
Laser ablation (LA) of a Au foil immersed in chloroform and/or in diluted 5,10,15,20-tetrakis-4-pyridylporphine (TPyP) chloroform solutions was carried out using 1064 nm nanosecond laser pulses. The products were characterized by UV-visible-NIR optical extinction and IR absorption measurements, Raman spectroscopy and transmission electron microscopy (TEM). They were found to be strongly influenced by the convergence of the incident laser beam and delivered energy per pulse. Our results show that with highly focused laser beam chloroform underwent photochemical reactions and no nanoparticles with observable surface plasmon extinction (SPE) band were formed whereas at particular focusing conditions Au nanoparticles with the SPE band typical for Au organosols were created. Au organosols in pure chloroform showed a limited stability, the SPE band disappeared in a few hours after the preparation. When a small amount of TPyP was present in the course of LA both the efficiency of Au nanoparticles formation and the stability of the resulting organosols were improved. A possible mechanism of LA of the Au target in chloroform and in diluted TPyP chloroform solutions is discussed. 相似文献
15.
Dipsikha Bhattacharya Sumanta K. Sahu Indranil Banerjee Manasmita Das Debashish Mishra Tapas K. Maiti Panchanan Pramanik 《Journal of nanoparticle research》2011,13(9):4173-4188
In this article, we report the design and synthesis of a series of well-dispersed superparamagnetic iron oxide nanoparticles
(SPIONs) using chitosan as a surface modifying agent to develop a potential T
2 contrast probe for magnetic resonance imaging (MRI). The amine, carboxyl, hydroxyl, and thiol functionalities were introduced
on chitosan-coated magnetic probe via simple reactions with small reactive organic molecules to afford a series of biofunctionalized
nanoparticles. Physico-chemical characterizations of these functionalized nanoparticles were performed by TEM, XRD, DLS, FTIR,
and VSM. The colloidal stability of these functionalized iron oxide nanoparticles was investigated in presence of phosphate
buffer saline, high salt concentrations and different cell media for 1 week. MRI analysis of human cervical carcinoma (HeLa)
cell lines treated with nanoparticles elucidated that the amine-functionalized nanoparticles exhibited higher amount of signal
darkening and lower T
2 relaxation in comparison to the others. The cellular internalization efficacy of these functionalized SPIONs was also investigated
with HeLa cancer cell line by magnetically activated cell sorting (MACS) and fluorescence microscopy and results established
selectively higher internalization efficacy of amine-functionalized nanoparticles to cancer cells. These positive attributes
demonstrated that these nanoconjugates can be used as a promising platform for further in vitro and in vivo biological evaluations. 相似文献
16.
Rivière C Wilhelm C Cousin F Dupuis V Gazeau F Perzynski R 《The European physical journal. E, Soft matter》2007,22(1):1-10
The internal structure of biological vesicles filled with magnetic
nanoparticles is investigated using the following complementary analyses:
electronic transmission microscopy, dynamic probing by magneto-optical
birefringence and structural probing by Small Angle Neutron Scattering
(SANS). These magnetic vesicles are magnetic endosomes obtained via a
non-specific interaction between cells and anionic magnetic iron oxide
nanoparticles. Thanks to a magnetic purification process, they are probed at
two different stages of their formation within HeLa cells: (i) adsorption of
nanoparticles onto the cellular membrane and (ii) their subsequent
internalisation within endosomes. Differences in the microenvironment of the
magnetic nanoparticles at those two different stages are highlighted here.
The dynamics of magnetic nanoparticles adsorbed onto cellular membranes and
confined within endosomes is respectively 3 and 5 orders of magnitude slower
than for isolated magnetic nanoparticles in aqueous media. Interestingly,
SANS experiments show that magnetic endosomes have an internal structure
close to decorated vesicles, with magnetic nanoparticles locally decorating
the endosome membrane, inside their inner-sphere. These results, important
for future biomedical applications, suggest that multiple fusions of
decorated vesicles are the biological processes underlying the endocytosis
of that kind of nanometric materials. 相似文献
17.
Leanne J. Lucas Claudio Tellez Maiara L. Castilho Christopher L. D. Lee Michael A. Hupman Lais S. Vieira Isabelle Ferreira Leandro Raniero Kevin C. Hewitt 《Journal of Raman spectroscopy : JRS》2015,46(5):434-446
We created and studied a novel nanoprobe for spectroscopic molecular imaging of the epidermal growth factor (EGF) receptor, whose over‐expression is a hallmark of a wide range of cancers. Silver nanoparticles (AgNPs) of 45 nm diameter were synthesized and coupled to EGF by α‐lipoic acid, a short ligand that exhibits excellent silver binding affinity. Time‐of‐flight mass spectroscopy demonstrates formation of the protein complex. Enzyme‐linked immunosorbent assay verifies the protein complex is 100% active for the EGF receptor, alone and, following conjugation to silver nanoparticles. Compared with its monosulfide analog, 6‐mercaptohexanoic acid, α‐lipoic acid is stabilized by binding to silver with a total energy that is lower by 1.38 eV, as found from Density Functional Theory (DFT)/natural bond analysis calculations. A Highest Occupied Molecular Orbital (HOMO)‐Lowest Unoccupied Molecular Orbital (LUMO) gap energy of 5.25 (spin‐up electrons) and 5.74 eV (spin‐down electrons) was obtained for the silver‐α‐lipoic acid complex. This is the first report of silver nanoparticles being attached to EGF, and the first theoretical and experimental report on the surface enhanced Raman spectroscopy spectral interpretation of α‐lipoic acid bound to silver. These nanoprobes exhibit surface enhanced Raman spectroscopy, when aggregated in solution, at picomolar concentrations and have the necessary properties – specificity, sensitivity and stability – to serve as molecular imaging agents. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
18.
Laser ablation of iron in an organic solvent (pentane, hexane, or decane) was performed using an air-tight cell to produce iron carbide nanoparticles. M?ssbauer spectra of the nanoparticles were obtained at room temperature. They revealed that the nanoparticles consisted of two paramagnetic components and magnetic components. The two paramagnetic components were a high-spin Fe(II) species and an amorphous iron carbide containing a large amount of carbon. Whereas the magnetic components measured at room temperature exhibited superparamagnetism, those measured at low temperature were fitted by a combination of four sextets, which were assigned to Fe7 C 3. The Fe7 C 3 yield was higher in higher molecular weight solvents. Transmission electron microscopy (TEM) images of the samples showed that the nanoparticles were spherical with diameters in the range 10–100?nm. 相似文献
19.
Reynolds A. Frimpong Michael Pechan 《Journal of magnetism and magnetic materials》2010,322(3):326-4180
Citric acid coated magnetite nanoparticles were synthesized using a one-step and two-step co-precipitation method at different temperatures. The stability of the nanoparticles in aqueous media was compared. The magnetic heating characteristics in an alternating magnetic field were examined and specific absorption rates were determined. The nanoparticles were characterized by various techniques (Fourier transform infrared, UV spectrophotometry, thermogravimetric analysis, dynamic light scattering, transmission electron microscopy, X-ray diffraction and vibrating sample magnetometry). The temperature of synthesis and mode of functionalizing the particles affected their physical and magnetic properties. Higher temperatures led to increased specific absorption rates for both methods but more stable hydrophilic superparamagnetic nanoparticles were obtained in the one-step method. 相似文献
20.
Undoped and Cr (2 and 4 at.%) doped CdS nanoparticles were synthesized in aqueous solution by simple chemical co-precipitation method using polyvinylpyrrolidone (PVP) as stabilizer. The prepared nanoparticles were examined using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR). XRD pattern of the nanoparticles showed cubic zincblende phase with the particle size of the order of 3-4 nm, which was in good agreement with the results obtained from TEM studies. The EDAX analysis confirmed that Cd, Cr and S elements were present in the samples and the variations between the target and actual compositions were microscopic. UV-vis DRS spectra of the samples exhibited decrease in the band gap which further attests the incorporation of Cr into CdS nanoparticles. FTIR studies revealed that the undoped as well as Cr doped CdS nanoparticles were capped by polyvinylpyrrolidone. 相似文献