Biomedical applications of electrospun polycaprolactone-based carbohydrate polymers: A review.

Carbohydrate used in biomedical applications is influenced by numerous factors. One of the most appealing characteristic of carbohydrates is their ability to reproduce from natural resources which makes them ecologically friendly. Due to their abundance, biocompatibility, and no contamination by residual initiators, the desire for polysaccharides in medical uses is growing. Research on fiber-based materials, with a variety of medical applications including bio-functional scaffolds, continues to yield novel and intriguing findings. Almost all biopolymers of diverse structural compositions are electrospun to fulfill biomedical usage criteria, and the electrospinning technique is widely employed in biomedical technologies for both in-vivo and in-vitro therapies. Due to its biocompatibility and biodegradability, polycaprolactone (PCL) is employed in medical applications like tissue engineering and drug delivery. Although PCL nanofibers have established effects in vitro, more research is needed before their potential therapeutic application in the clinic. Here we tried to focus mainly on the carbohydrate incorporated PCL-based nanofibers production techniques, structures, morphology, and physicochemical properties along with their usage in biomedicine.

Efficient CuO/Ag2WO4 photoelectrodes for photoelectrochemical water splitting using solar visible radiation.

Water splitting energy production relies heavily on the development of high-performance photoelectrochemical cells (PECs). Among the most highly regarded semiconductor materials, cupric oxide (CuO) is an excellent photocathode material. Pristine CuO does not perform well as a photocathode due to its tendency to recombine electrons and holes rapidly. Photocathodes with high efficiency can be produced by developing CuO-based composite systems. The aim of our research is to develop an Ag2WO4/CuO composite by incorporating silver tungstate (Ag2WO4) nanoparticles onto hydrothermally grown CuO nanoleaves (NLs) by successive ionic layer adsorption and reaction (SILAR). To prepare CuO/Ag2WO4 composites, SILAR was used in conjunction with different Ag2WO4 nanoparticle deposition cycles. Physicochemical characterization reveals well-defined nanoleaves morphologies with tailored surface compositions. Composite CuO/Ag2WO4 crystal structures are governed by the monoclinic phase of CuO and the hexagonal phase of Ag2WO4. It has been demonstrated that the CuO/Ag2WO4 composite has outstanding performance in the PEC water splitting process when used with five cycles. In the CuO/Ag2WO4 photocathode, water splitting activity is observed at low overpotential and high photocurrent density, indicating that the reaction takes place at low energy barriers. Several factors contribute to PEC performance in composites. These factors include the high density of surface active sites, the high charge separation rate, the presence of favourable surface defects, and the synergy of CuO and Ag2WO4 photoreaction. By using SILAR, silver tungstate can be deposited onto semiconducting materials with strong visible absorption, enabling the development of energy-efficient photocathodes.

Plasmon-Enhanced Light Absorption in (p-i-n) Junction GaAs Nanowire Solar Cells: An FDTD Simulation Method Study.

A finite-difference time-domain method is developed for studying the plasmon enhancement of light absorption from vertically aligned GaAs nanowire arrays decorated with Au nanoparticles. Vertically aligned GaAs nanowires with a length of 1 µm, a diameter of 100 nm and a periodicity of 165-500 nm are functionalized with Au nanoparticles with a diameter between 30 and 60 nm decorated in the sidewall of the nanowires. The results show that the metal nanoparticles can improve the absorption efficiency through their plasmonic resonances, most significantly within the near-bandgap edge of GaAs. By optimizing the nanoparticle parameters, an absorption enhancement of almost 35% at 800 nm wavelength is achieved. The latter increases the chance of generating more electron-hole pairs, which leads to an increase in the overall efficiency of the solar cell. The proposed structure emerges as a promising material combination for high-efficiency solar cells.

Anisotropic deformation of NiO nanoparticles embedded in silica under swift heavy ion irradiation.

We report on the ion-induced anisotropic deformation in nickel oxide nanoparticles prepared by conventional sol-gel technique. Colloidal-like NiO nanoparticles with an average diameter of about 40-50 nm embedded in a SiO2 layer change their shape dramatically under swift heavy ion irradiation with 32 MeV Cu+5 ions at room temperature and normal incidence. Transmission electron microscopy analysis show irradiation induced shape transformation from nearly spherical nanoparticles into oblate nanorods at a rate that increases with ion fluence. For low nanoparticle density, the apparent nanoparticle size aspect ratio increases gradually with increasing irradiation fluence to 5 × 1014 ions cm-2 while no significant volume change is observed upon irradiation. For higher density of the nanoparticles, Rutherford backscattering spectrometry analysis indicates collective growth of nanoparticles under irradiation with fluence above 5 × 1014 ions cm-2. Magnetization experiments of the NiO nanoparticles show that the film consisting the pristine NiO nanoaprticles has a small magnetic anisotropy with axis in the direction parallel to ion beam. However, after 32 MeV Cu+5 ion irradiation, the change in magnetic anisotropy is much larger, which can be correlated with the elongation of nanoparticles in the beam direction. Furthermore, a threshold fluence, under which no deformation takes place is observed.

Ion-induced elongation of gold nanoparticles in silica by irradiation with Ag and Cu swift heavy ions: track radius and energy loss threshold.

Systematic investigations of the energy loss threshold above which the irradiation-induced elongation of spherical Au nanoparticles occurs are reported. Silica films containing Au nanoparticles with average diameters of 15-80 nm embedded within a single plane were irradiated with 12-54 MeV Ag and 10-45 MeV Cu ions at 300 K and at normal incidence. We demonstrate that the efficiency of the ion-induced nanoparticle elongation increases linearly with the electronic energy transferred per ion track length unit from the energetic ions to the silica film. Ion beam shaping occurs above a threshold value of the specific electronic energy transfer. Three relevant regions are identified with respect to the original size of the Au nanoparticles. For 15 and 30 nm diameter particles, elongation occurs for electronic stopping power larger than 3.5 keV nm(-1). For Au nanoparticles with 40-50 nm diameter an electronic stopping power above 5.5 keV nm(-1) is required for elongation to be observed. Elongation of Au nanoparticles with 80 nm diameter is observed for electronic stopping between ∼ 7-8 keV nm(-1). For all combinations of ions and energies, the ion track temperature profiles are calculated within the framework of the thermal spike model. The correlation between experimental results and simulated data indicates a thermal origin of the increase in the elongation rate with increasing the track diameter.