Papers by Keyword: Nanofilm

Abstract: Conventional drug delivery systems face challenges like low bioavailability, rapid degradation and limited effectiveness in drug delivery, especially for persistent infections. Our research focus to develop nanofiber drug delivery systems (NDDSs) using biopolymers like starch and gelatine. In this study, nanofilm was produced using polylactic acid (PLA), Nanocrystalline Cellulose (NCC), gelatine/starch, and paracetamol (acetaminophen) as the drug at different ratios. From SEM, the best ratio for gelatine-based nanofilm was 6% PLA: 0.5% gelatine : 0.15% NCC : 0.02% drug while starch-based nanofilm the best ratio was 8% PLA: 0.2% starch: 0.15% NCC: 0.02% drug. In drug release kinetics study, the results were compared using mathematical models such as zero order, first order, and Higuchi models for both types of bio-based nanofilm. The drug release kinetics results indicate that the starch-based nanofilm was superior to the gelatin-based nanofilm in drug delivery, fitting both the Higuchi and Zero-order models.

Abstract: Multilayer sheets or films have many potential applications in micro-nanoelectromechanical systems. When surface and scale effects are not considered, the bending of multilayer film systems can theoretically be discussed by the classical Stoney formula or Timoshenko formula. When the system has anisotropic surface stress or mismatch strain, the four-parameter bending model proposed by Narsu et al. can be used. However, if the thickness of the film is several nanometers and the bending radius of curvature is less than 1micron, the existing theoretical model is no longer applicable. For this reason, a bending formulation for the nanomulti-layer film system is derived and the structure of the multilayer film is optimized in this paper.

Abstract: Cellulose based nanofilms have large applications in biomedical and related fields due to their antimicrobial properties. Their applicability depends upon purity of cellulose, composition, and structural properties of films. The nanofilms of cellulose extracted from Water Hyacinth (Eichhornia crassipes) and Roselle (Hibiscus Sabdariffa) plant possesses excellent properties for biomedical applications due to their biological origin and ZnO or other metal loading properties. Microwave assisted physical separation of cellulose provided excellent films formation properties and ZnO loading compared without any chemical traces. The presence of chemical impurities to affects structural, morphological properties and contact angle. It affects the biomedical applicability of cellulose based films. The microwave-based extraction was further assisted by use of polyethylene glycol with molecular weight 600, which increases the solubility and extractability of cellulose to 90 %. Formed films showed higher contact angle and hydrophobicity. This increased hydrophobicity of cellulosic nanofilms showed enhanced antimicrobial activities towards gram-negative and gram-positive bacteria by water hyacinth nanofilms. Thus, microwave-based synthesis of cellulose nanofilms resulted into enhanced microbial activities.

Abstract: The structure, phase composition, and morphology of FeSi and FeSi₂ nanofilms grown by three alternations of Fe (with a wedge-shaped thickness in the range 0 ‒ 2 ml) and Si (with a thickness 1 ML) depositions on a Si (001) 2×1 substrate heated to 400 °C were studied. According to Auger electron spectroscopy and electron energy loss, FeSi and FeSi₂ films were formed before and after the third deposition of Si, respectively. With this, a FeSi₂ film had ~1.5 ML of Si, which segregated on its surface. Both films consisted of a wetting coating (WL) and bulk phase forming at 2‒3 ML and after 3 ML of Fe, respectively. According to data of low electron energy diffraction, these films had a nanocrystalline structure. Moreover, according atomic force microscopy, deep square pores were formed in FeSi₂ films. They had a depth of 18‒10 nm, which was decreased and then increased before and, respectively, after Fe thickness ~ 3 ML.

Abstract: The structural-phase state of two-dimensional (d = 1 - 3 ML) coatings before and after annealing and that of Fe nanolayers (d = 4 - 10 ML) were investigated on Si (001)2×1 by electron spectroscopy methods of Auger-electrons and energy losses. The room (30 °С) and lowed (≤ 1250 °С) temperatures of the Si (001) substrate and Fe vapor, respectively, were used during Fe deposition. This study showed the following. An ordered two-dimensional 1×1 phase of Fe stable up to 600 °C and then a Fe₂Si wetting coating stable at 250 °C form near the thickness 1 ML and 3 ML, respectively. Fe deposition on this Fe₂Si coating leads to the one-after-another formation of the Fe₃Si, the Si-in-Fe solution, and then a stable up to 250 °C Fe nanofilm with segregated Si.

Abstract: Dye-sensitized solar cells have better development prospects than silicon cells, and their main structural composition of nanoporous semiconductor films is particularly important. It is the tin dioxide film, and the effect of preparing tin oxide film on dye-sensitized solar cells under different conditions is studied. In this paper, the SnO₂ powder was prepared by hydrothermal method, and the experiment was studied by controlled variable method. The properties of the obtained tin dioxide powder were characterized by SEM and three-dimensional ultra-depth microscope and XRD. The XRD diffraction peak is shown as tetragonal phase rutile type SnO₂, With the increase of the concentration of tin tetrachloride solution, the coarser the particle size of the tin oxide crystal in the film, the more complicated the surface morphology, so that the specific surface area of the film is larger. At 0.1 mol/L, the surface of the film is a porous structure in the form of a loose sheet is presented. After analyzing the surface microstructure and flatness of the tin dioxide film, it can be concluded that the effect of salt concentration on the specific surface area of the film is extremely large. When the salt concentration is higher or lower, the obtained two the surface of the tin oxide film is relatively flat and has poor performance. When the salt concentration is 0.1mol/L, the surface of the obtained film has a large undulation and a large specific surface area, and the ability to adsorb the dye molecules can be predicted to be the greatest, and the photoelectric conversion efficiency is optimal in the photocatalytic process.

Abstract: Dye-sensitized solar cells have better development prospects than silicon cells, and the main structural components of nanoporous semiconductor films are particularly important. In this experimental study, we used tin dioxide film and investigated the effect of preparing this film on dye-sensitized solar cells under different conditions. Furthermore, SnO₂ powder was prepared through hydrothermal method, and an experiment was conducted through a controlled variable method. The properties of the obtained tin dioxide powder were characterized by SEM, 3D ultradepth microscopy, and XRD. An XRD peak is displayed as tetragonal-phase rutile-type SnO₂, and the SEM indicates that the powder grain size is several nanometers. With the increase in reaction time, the film gradually became flat and uniform from only a small amount of powder coating. At the reaction time of 8 days, the integrity and flatness of the film were optimal, and the pore size was uniform. Moreover, the specific surface area was large. In summary, the reaction time of 8 days is suitable for membrane growth.

Abstract: In this research, anatase TiO₂ nanoparticles were electrophoretically deposited on the FTO glass. This investigation was focused on the self-cleaning property of TiO₂ coatings and the effects of different parameters on this characteristic such as: applied voltages during electrophoretic depositions and durations of UV irradiation. Electrophoretic depositions of suspensions were performed in different voltages of 10, 30 and 60 V (for 10 s) at room temperature. TiO₂ coatings were sintered in 450°C for 1 hr. The phase transformation of TiO₂ films was considered using XRD. Morphology, average particle size and the thickness of TiO₂ films was analyzed using FESEM microscope. The photocatalytic activity of TiO₂ films was evaluated by the degradation of aqueous methyl orange (MO) under UV irradiation. The ultraviolet-visible spectrophotometer was used to record the changes of the adsorbancy of the MO solution. Hydrophilicity of TiO₂ films was determined by measuring contact angle of water droplet with the surface of TiO₂ films. Results represented that decomposition rate of MO solution by TiO₂ films enhances from 6.5% to 31% by increasing applied voltage of deposition from 10 to 60V and from 5% to 40% by increasing UV illumination duration from 1 to 5 hours. It was also observed that the contact angles of water droplet with the surface of TiO₂ films decrease from 34^o to 6.6^o by increasing applied voltage from 10 to 60V.

Abstract: Surface plasmon resonance (SPR) biochemical analysis system began to be developed from the detection and analysis of molecular interactions to the ligand/cell interactions, cell/cell contacts, or cellular reactions. Cells needed be immobilized on the SPR chips based on the penetration depth of surface plasma waves. However it is not easily to fix suspension cells on the bare gold chips. In this paper, an effective method has been developed to immobilize yeast cells on the SPR chip based on a nanoSiO₂ film which was chemically modified. The sensitivity of the SPR chip with a nanoSiO₂ film is 6×10^-7 refractive index unit (RIU), which could meet different applications including cell detection. The whole procedure of cell immobilization has been measured in a lab-free and real-time mode by using our home-made SPR instrument. From the experimental results, the change of the SPR signal of the SPR chip with a modified nanoSiO₂ film is 2.83 times of the bare SPR chip. That means the cell immobilization capability of the modified SiO₂-coating SPR chip is much stronger than that of the bare gold SPR chip, which was also proved by using a microscope. Yeast cells can be effectively fixed on the SPR chip and their immobilization process could be monitored, which hold great potential for the immobilization, detection and further analysis of other suspension cells, such as blood cells.

Abstract: In this paper, electrochemical polymerization method was used to prepare electrochromic PANI films with different thicknesses via changing the polymerization time. It is found that the obtained PANI films are uniform and have good adherence with the ITO bases. Scanning electron microscope (SEM) images further show that the obtained films exhibited the tremella like lamellar structures with the diameter of each leaf about 100nm and the thickness of about 20nm at polymerization time of 8min. Optical electronic tests indicated that the films showed a gradient color variation from pale yellow, light yellow to green, blue-green, blue and dark blue among -0.2V and 1.0V. Furthermore, the color saturation increased and the hues became more abundant as polymerization time extended. The optical contrast ratios (ΔT) firstly increased to the maximum of 35% and then decreased, while the response time became longer. The results illustrate that the different shades of color are probably obtained through electrochemical polymerization method, which is important for the preparation of RGB full color system.