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1.
Silk fibroin film (SFF) has been widely used in biomaterials. SFF is usually prepared from a regenerated silk aqueous solution and its properties depend remarkably on the preparation conditions. However, the effect of the silk fibroin concentration (C0) on the SFF surface properties as well as the cytocompatibility has rarely been investigated. In this work we prepared a series of Bombyx mori SFFs by casting SF aqueous solutions with the concentration from 100 to 102mg/mL on TCPS substrate at 60°C. The test results of atomic force microscopy, attenuated total reflection Fourier transform infrared and contact angles analysis showed that the film surface roughness and β-sheet structure increased with the increase of C0, whereas the surface hydrophilicity increased with the decrease of C0. The in vitro clotting time measurement results revealed that the SFFs prepared from the thinner solution showed a longer APTT (activated partial thromboplastin time) and TT (thrombin time). The results of microscopy and MTT assay also revealed that cell adhesion and growth were enhanced on the SFF cast from lower C0 for fibroblasts. In contrast, endothelial cells showed a similar behavior on all those films that were prepared from the solution in different concentrations. 相似文献
2.
By using electrospinning technique, beaded, cylinder shaped and ribbon like ultra-fine silk fibroin (SF) fibers were obtained
from its concentrated aqueous solution under different processing conditions. These fibers had an average diameter of 700
nm and were characterized by scanning electron microscopy (SEM), Wide-angle X-ray diffraction (WAXD) and Raman spectroscopy.
It was found that the morphology and the secondary structure of the as-spun SF fibers were strongly influenced by the solution
concentration, as well as the processing voltage. By adjusting these technological parameters, β-sheet conformation and silk
II crystal structure of the SF fibers can be formed without any post-treatment. 相似文献
3.
Luciana Gaffo Márcia R. Cordeiro Adonilson R. Freitas Wania C. Moreira Emerson M. Girotto Valtencir Zucolotto 《Journal of Materials Science》2010,45(5):1366-1370
Phthalocyanine compounds have been widely investigated as candidate materials for technological applications, which is mainly
due to their thermal stability and possibility of processing in the form of thin films. In most applications, the controlled
growth of thin films with high crystalline quality is essential. In this study, zinc phthalocyanine (ZnPc) thin films were
prepared by evaporation on glass and Au-coated glass substrates with subsequent annealing at different temperatures in ambient
atmosphere. The morphological and structural features of 80 nm thick zinc phthalocyanine films were investigated, evidencing
an α → β phase transformation after annealing the films at 200 °C, as indicated by UV–Vis spectroscopy and FTIR analyses.
A better uniformity of the annealed films was also evidenced via AFM analysis, which may be of importance for applications
where film homogeneity and excellent optical quality are required. 相似文献
4.
Florence Teulé William A. Furin Alyssa R. Cooper Joshua R. Duncan Randolph V. Lewis 《Journal of Materials Science》2007,42(21):8974-8985
Bacteria were genetically engineered to produce two spider silk protein variants composed of basic repeat units combining
a flagelliform elastic motif ([GPGGX]4) and a major ampullate silk strength motif ([linker/poly-alanine]. The secondary structures of the pure recombinant proteins
in solution were determined by circular dichroism. The data presented suggest that the nature of the 5th and 10th amino acid
(X) in the [GPGGX]2 elastic motif and temperature have an impact on the amount of β-sheet structures present in the proteins. More specifically,
increasing temperatures seem to be positively correlated with β-sheet formation for both proteins and this state is irreversible
or reversible when both X (5th and 10th) in the elastic motif are hydrophilic or hydrophobic respectively. Moreover, each pure silk-like protein was
able to spontaneously self-assemble into films from aqueous solutions. Two kinds of synthetic fibers were made by pulling
fibers from these preassembled films as well as spinning fibers from each protein resolubilized in HFIP. The mechanical data
show that the pulled fibers are far tougher than the spun fibers suggesting a better fiber organization.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Zhen Gao Song Wang He-sun Zhu Dong-xu Zhao Jia-chao Xu 《Frontiers of Materials Science in China》2008,2(2):221-227
Fucoidan (FC), an effective anticoagulant constituent extracted from brown algae, was introduced into silk fibroin (SF) for
improving its blood compatibility. The SF and SF/FC blend films were characterized by attenuated total reflectance Fourier-transform
infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and dynamic contact angle
determinator (CA). The in vitro anticoagulant activities of the films were evaluated by activated partial thromboplastin time (APTT), thrombin time (TT)
and prothrombin time (PT) measurements. The endothelial cell attachment and proliferation viability on the film were assessed
by micropipette aspiration technique and MTT assay, respectively. The testing results indicated that the introduction of FC
increased the roughness, hydrophilicity and sulfate component of the film surface without impeding the formation of β-sheet
conformation in SF. More important, FC brought excellent anticoagulant activity and better endothelial cell affinity to SF.
The SF/FC blend film was hopeful to be used as blood-contacting biomaterials. 相似文献
6.
The dielectric properties of melt compounded hot-pressed nanocomposite films consisting of a poly(ethylene oxide) (PEO) and
organophilic montmorillonite (OMMT) clay surface modified with trimethyl stearyl ammonium as filler with increasing amount
up to 20 wt.% OMMT were investigated in a frequency range of 20 Hz–1 MHz at 30 °C. The predominance of OMMT exfoliated structures
in PEO–OMMT nanocomposites were recognized by a decrease of the real part of complex dielectric function. OMMT concentration
dependent dielectric and electric modulus relaxation times have revealed that the interactions compatibility between PEO molecules
and dispersed OMMT nano-platelets in PEO matrix governs the PEO segmental dynamics. A.C. conductivity of these nanocomposites
increases by two orders of magnitude in the experimental frequency range. 相似文献
7.
M. Kilani B. Yahmadi N. Kamoun Turki M. Castagné 《Journal of Materials Science》2011,46(19):6293-6300
β-In2−x
Al
x
S3 thin films have been grown on glass substrate by chemical bath deposition for different value of Al concentration y = (([Al])/([In]))sol (0 ≤ y ≤ 5 at.%). Samples have been characterized using X-ray diffraction, atomic force microscopy and by spectrophotometric measurements.
The influence of the increase of y ratio in the structural and optical properties are described and discussed in terms of crystallinity improvement. In order
to increase film thickness of β-In2−x
Al
x
S3, we have been realized multi-deposition system. The structural, the surface morphology as well as the optical properties
seem to be improved as the film thickness is of about 1200 nm. 相似文献
8.
AFM observation of silk fibroin on mica substrates: morphologies reflecting the secondary structures
Bombyx mori silk fibroin was fixed on mica substrates by cast of aqueous fibroin solutions, and the microscopic morphologies of the samples were revealed by means of atomic force microscopy. By adjusting the method used to prepare the solution, we succeeded in forming quasi-2-dimensional thin films in which a network of fibroin molecules developed over the substrate. The film network consisted of fibroin in a random coil structure. The morphology of the network changed after thermal or methanol treatments, which are known to convert the secondary structure of fibroin from the random coil to the β-sheet type. In both of these cases, the network morphology disappeared and characteristic island-like morphologies appeared. On the other hand, temporally evolving gelation occurred in a fibroin solution due to the formation of β-sheet crystals. Such islands were also observable in a specimen prepared by the cast of the gel-containing solution. Based on these results, it was concluded that the islands consist of β-sheet crystals. Of particular interest is the observation that all of the islands had a common thickness value of 1.3 nm. These morphologies are discussed in terms of the secondary structure of fibroin. 相似文献
9.
The nanocrystalline cerium dioxide (CeO2) thin films were deposited on soda lime (SLG) and Corning glass by pulsed e-beam deposition (PED) method at room temperature.
The structure of the produced CeO2 thin films was investigated by X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and micro Raman
spectroscopy. The surface topography of the films was examined by atomic force microscopy (AFM). Film thickness and growth
morphologies were determined with FEG-SEM from the fracture cross sections. XPS studies gave a film composition composed of
+4 and +3 valent cerium typical to nanocrystalline ceria structures deficient in oxygen. The ceria films were polycrystalline
in nature with a lattice parameter (a) of 0.542 nm. The Raman characteristics of the source material and the films deposited were very similar in character. Raman
lines for thin film and bulk CeO2 was observed at 465 cm−1. The optical properties of the CeO2 films were deduced from reflectance and transmittance measurements at room temperature. From the optical model, the refractive
index was determined as 1.8–2.7 in the photon energy interval from 3.5 to 1.25 eV. The optical indirect band gap (E
g) of CeO2 nanocrystalline films was calculated as 2.58 eV. 相似文献
10.
Hailin Zhu Na Liu Xinxing Feng Jianyong Chen 《Materials science & engineering. C, Materials for biological applications》2012,32(4):822-829
Composite films of silk fibroin (SF) with nano bioactive glass (NBG) were prepared by the solvent casting method, and the structures and properties of the composite films were characterized. Fourier transform infrared (FT-IR) spectroscopy analysis shows that the random coil and β-sheet structure co-exist in the SF films. Results of field emission scanning electron microscope (FESEM) indicate that the NBG particles are uniformly dispersed in the SF films. The measurements of the water contact angles suggest that the incorporation of NBG into SF can improve the hydrophilicity of the composites. The bioactivity of the composite films was evaluated by soaking in 1.5 times simulated body fluid (1.5 × SBF), and formation of a hydroxycarbonate apatite (HCA) layer was determined by XRD and FESEM. The results show that the SF/NBG composite film is bioactive as it induces the formation of HCA on the surface of the composite film after soaking in 1.5 × SBF for 7 days. In vitro osteoblasts attachment and proliferation tests show that the composite film is a good matrix for the growth of osteoblasts. Consequently, the incorporation of NBG into the SF film can enhance both the bioactivity and biocompatibility of the film, which suggests that the SF/NBG composite film may be a potential biomaterial for bone tissue engineering. 相似文献
11.
Sumanth Joishy B. V. Rajendra 《Journal of Materials Science: Materials in Electronics》2018,29(15):12603-12614
Cd1?xZnxO nanocrystallite films with doping concentrations varied from x?=?0.00–0.90 were synthesized through a simple chemical route of the spray pyrolysis process using 0.05M precursor solution. The suitable optimized temperatures for different compositions films were obtained by adjusting deposition temperatures from 693 to 723 K. It was found that structures, surface morphology, optical and electrical properties of the films can be altered by changing Zn contents in CdO deposits. The film composition from x?=?0 to 0.50 have shown cubic phase with (1 1 1) prominent plane and the composition x?=?0.90 shown wurtzite structure with (1 0 1) prominent plane. However, the composition varied from x?=?0.60 to 0.80, in the deposits which showed mixed structure of cubic and wurtzite. The crystallite size, dislocation density and microstrain have been evaluated using XRD data. Scanning electron microscope images have shown different surface morphologies for different Zn doped CdO films. The absorption edge was found to be a blue shift with the increase of Zn content, confirming that there is an increase in the optical band gap. Other optical parameters such as extinction coefficient, Urbach energy, and optical conductivity have estimated using absorption spectra. All films show n-type conductivity, and it decreases with increasing Zn content due to decreasing carrier concentration. 相似文献
12.
Ahmed M. El-Naggar 《Journal of Materials Science: Materials in Electronics》2012,23(4):972-976
GaN films with different thicknesses were grown on Si(111) substrates by Plasma—Assisted Molecular Beam Epitaxy (PA-MBE).
The optical properties of the films were investigated using spectrophotometric measurements of the reflectance in the wavelength
range 200–3,300 nm. With increasing film thickness, the refractive index (n) increased slightly, while the optical energy
gap (Eg) changed with no specific trend. The structural properties of the grown films were studied at (002) reflections using two
types of rocking curve measurements; normal rocking curve (ω-scan) and triple axis rocking curve (ω/2θ-scan). The Full Width
at Half Maximum (FWHM) of rocking curve decreased with increasing film thickness. Hall effect measurements showed that all
the samples were n-type with carrier concentrations decreasing from 8.025 × 1018 to 5.65 × 1017 cm−3, and mobility increasing from 14 to 110 cm2 V−1 s−1 as increasing the film thickness from 590 to 1,420 nm, respectively. Photoluminescence (PL) spectra for the grown GaN films
with different thicknesses were measured at room temperature. PL spectra for all the samples exhibited band edge (BE) emissions
at peak energies of 3.24 eV, with peak intensities increased with increasing the film thickness. 相似文献
13.
ZnO thin films were prepared on quartz glass, Si (100), and sapphire (001) substrates by a chemical vapour transport (CVT) technique. During the growing processes, the source and substrate temperatures were maintained at 1000 °C and 600 °C, respectively. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements showed that the crystalline qualities of ZnO thin films were sensitively dependent on substrates. ZnO thin film deposited on sapphire substrate exhibited the best morphology with the largest crystallite size of more than 20 μm. Meanwhile, the XRD patterns showed that ZnO thin film deposited on sapphire substrate was strongly c-axis preferred-oriented with high crystalline quality. The optical properties of ZnO thin films were investigated by photoluminescence (PL) spectroscopy at room temperature (RT). The results suggested that the optical properties of ZnO thin films were highly influenced by their crystalline qualities and surface morphologies. 相似文献
14.
《Materials Chemistry and Physics》2013,140(1):365-372
Indium gallium zinc oxide (IGZO) transparent semiconductor thin films were prepared by KrF excimer laser annealing of sol–gel derived precursor films. Each as-coated film was dried at 150 °C in air and then annealed using excimer laser irradiation. The influence of laser irradiation energy density on surface conditions, optical transmittances, and electrical properties of laser annealed IGZO thin films were investigated, and the physical properties of the excimer laser annealed (ELA) and the thermally annealed (TA) thin films were compared. Experimental results showed that two kinds of surface morphology resulted from excimer laser annealing. Irradiation with a lower energy density (≤250 mJ cm−2) produced wavy and irregular surfaces, while irradiation with a higher energy density (≥350 mJ cm−2) produced flat and dense surfaces consisting of uniform nano-sized amorphous particles. The explanation for the differences in surface features and film quality is that using laser irradiation energy to form IGZO thin films improves the film density and removes organic constituents. The dried IGZO sol–gel films irradiated with a laser energy density of 350 mJ/cm2 had the best physical properties of all the ELA IGZO thin films. The mean resistivity of the ELA 350 thin films (4.48 × 103 Ω cm) was lower than that of TA thin films (1.39 × 104 Ω cm), and the average optical transmittance in the visible range (90.2%) of the ELA 350 thin films was slightly higher than that of TA thin films (89.7%). 相似文献
15.
V. Dhanasekaran T. Mahalingam R. Chandramohan J. P. Chu Jin-Koo Rhee 《Journal of Materials Science: Materials in Electronics》2012,23(2):645-651
The effects of deposition potentials on the electrochemical, structural, morphological and optical properties of the CdSnSe
films are studied. X-ray diffraction patterns revealed a mix of cubic and orthogonal phases for the grown CdSnSe thin films.
The refractive index, extinction coefficient, dielectric constant and thereby the optical band gap of the films are calculated
from transmittance spectral data recorded in the range 400–1,200 nm by UV–Vis–NIR Spectrometer. The optical band gap energy
of CdSnSe thin films is found to be in the range of 1.23–1.25 eV. Morphological studies revealed nano-rod shaped grains occupied
over the entire surface of the film with average grain size of 150 nm. The influence of deposition potential on the microstructural
properties of CdSnSe is also explained in the paper. 相似文献
16.
Synthesis and characterizations of CdS nanorods by SILAR method: effect of film thickness 总被引:1,自引:0,他引:1
D. S. Dhawale D. P. Dubal M. R. Phadatare J. S. Patil C. D. Lokhande 《Journal of Materials Science》2011,46(14):5009-5015
In this investigation, we have successfully synthesized CdS nanorods by simple and inexpensive successive ionic layer adsorption
and reaction (SILAR) method. The effect of film thickness on the physico-chemical properties such as structural, morphological,
wettability, optical, and electrical properties of CdS nanorods has been investigated. The XRD pattern revealed that CdS films
are polycrystalline with hexagonal crystal structure. SEM and TEM images showed that CdS film surface are composed of spherical
grains along with some spongy cluster and an increase in film thickness up to 1.23 μm causes the formation of matured nanorods
having diameter 150–200 nm. The increases in water contact angle form 105° to 130° have been observed as film thickness increases
from 0.13 to 1.23 μm indicating hydrophobic nature. The optical band gap was found to be increased from 2.02 to 2.2 eV with
increase in film thickness. The films showed the semiconducting behavior with room temperature electrical resistivity in the
range of 104–106 Ω cm and have n-type electrical conductivity. 相似文献
17.
K. Vijayakumar C. Sanjeeviraja M. Jayachandran L. Amalraj 《Journal of Materials Science: Materials in Electronics》2011,22(8):929-935
Thin films of tin disulphide on glass substrates were prepared by spray pyrolysis technique using precursor solutions of SnCl2·2H2O and n–n dimethyl thiourea at different substrate temperatures varied in the range 348–423 K. Using the hot probe technique
the type of conductivity is found to be n type. X ray diffraction analysis revealed the polycrystalline nature with increasing
crystallinity with respect to substrate temperature. The preferential orientation growth of SnS2 compound having hexagonal structure along (002) plane increased with the substrate temperature. The size of the tin disulphide
crystallites with nano dimension were determined using the Full Width Half Maximum values of the Bragg peaks and found to
increase with the substrate temperature. The surface morphology had been observed on the surface of these films using scanning
electron microscope. The optical absorption and transmittance spectra have been recorded for these films in the wavelength
range 400–800 nm. Thickness of these films was found using surface roughness profilometer. The absorption coefficient (α) was determined for all the films. Direct band gap values were found to exist in all the films deposited at different substrate
temperatures. The value of room temperature resistivity in dark decreased from 5.95 × 103 Ω cm for the amorphous film deposited at low temperature (348 K) to 2.22 × 103 Ω cm for the polycrystalline film deposited at high temperature (423 K) whereas the resistivity values in light decreased
from 1.48 × 103 to 0.55 × 103 Ω cm respectively, which is determined using the four probe method. Activation energy of these thin films was determined
by Arrhenius plot. 相似文献
18.
I. K. El Zawawi N. Rabie Khalil Manal A. Mahdy 《Journal of Materials Science: Materials in Electronics》2012,23(2):520-527
ZnSe thin films were prepared by thermal evaporation technique under high vacuum (10−6 Torr) at 300 K and different film thickness. The structure of thin films was measured using grazing incident in-plane X-ray
diffraction (GIIXD) and shows single phase zinc blende structure. The particle sizes of the deposited films were estimated
for low film thickness by TEM and high film thickness by GIIXD. The particle size of ZnSe films was decreased from ~8.53 to
3.93 nm as film thickness lowered from 200 to 20 nm which ensures the nanocrystalline structure. The optical transmission
(T) and reflection (R) in the wavelength range 190–2,500 nm for irradiated and unirradiated ZnSe thin films under investigation
were measured. The effect of irradiation of different energies in range (0.1–1.25 MeV) from X-ray, 137Cs and 60Co irradiation sources were studied for ZnSe thin films of 100 and 200 nm thicknesses. The dependence of the absorption spectra
and refractive index were investigated for different energies irradiation sources. The ZnSe films show direct allowed interband
transition. The effect of particle size of nanocrystalline ZnSe thin films for unirradiated and irradiated by gamma (γ) doses
from 137Cs on the optical properties was studied. Both the optical energy bandwidth and absorption coefficient (α) were found to be
(γ) dose dependent. 相似文献
19.
Jianxin He Yongrui Qin Shizhong Cui Yaying Gao Shanyuan Wang 《Journal of Materials Science》2011,46(9):2938-2946
The tussah silk fibroin (TSF)/poly(lactic acid) (PLA) composite nanofibers with different composition ratios were prepared
by electrospinning with 1,1,1,3,3,3-Hexafluoro-2-propanol as the solvent. The morphology and secondary structure of the fibers
were characterized by Scanning electronic microscope, Fourier transform infrared (FTIR), and X-ray diffraction (XRD). The
thermal and mechanical tests were also performed. The spinnability of TSF solution was improved significantly through adding
10% PLA, and the average diameter of the fibers decreased from 583 nm to 178 nm with an obvious improvement in fiber diameter
uniformity. In addition, the mechanical properties of electrospun nanofibers increased evidently after blending 10% PLA, whereas
the thermal properties kept stable. FTIR and XRD analysis indicated the addition of 5% PLA could induce a conformation transformation
of TSF from random coil and α-helix to β-sheet, however, when PLA content was more than 10%, the β-sheet structure of TSF
in composite nanofibers decreased, and the phase separation of two compositions occurred. Therefore, when PLA content exceeded
15%, the average diameters of TSF/PLA composite nanofibers increased and appeared to be polarized, moreover, the mechanical
properties of the fibers decreased with the increase of PLA content, and the fibers displayed the mechanical behavior of PLA
component more. 相似文献
20.
In order to fabricate fiber-optic temperature sensors based on ZnO film, it is important to study the temperature-dependent optical properties of this material. In this work, we deposited ZnO films on c-plane (0001) sapphire substrate at 250 °C. Atomic force microscope and X-ray diffraction measurements show the smooth surface and high orientation along [0001] of ZnO film, respectively. The high-temperature-dependent optical properties of ZnO film were measured by ultraviolet-visible transmission with temperatures ranging from room-temperature to 300 °C and analyzed by theoretically fitting the optical absorption edge curve. It is observed that the band gap energy red shifts nonlinearly from 3.345 to 3.153 eV with increasing temperature. The sharp absorption edge of ZnO films after annealing at 300 °C is almost consistent with that of the as-deposited sample, indicating an excellent thermal stability and the potential application in fiber-optic temperature sensors. 相似文献