Characterisation of the Pulsed-laser Induced Phase Transformation and Osteogenic Properties of Photo-active Iron-Calcium Phosphate Biomineral

Personalised medicine and near patient manufacturing are two emerging concepts in tissue engineering. They are based on the design and manufacture of individual bone grafts which are dependent on the needs of individual patients. To date, the most efficient method to achieve this is through selective laser sintering (SLS), which has been one of the most developed and successfully applied techniques [2]. Various forms of calcium phosphates (CaP) have been used so far for scaffold manufacturing through SLS because of their compositional and structural similarity with the mineral within human bone and teeth. The main drawback of bone and tissue-like materials has been the lack of vascularisation which limits blood supply to essential healing areas. Recently there has been an increasing interest in Fe2+\Fe3+ doped calcium phosphates due to the essential function of iron in regulating oxygen through hemoglobin in human body [3]. In addition, it was reported that doping brushite (CaHPO4.2H2O) with Fe2+/Fe3+ ions, improved energy absorption and controlled the volume of energy absorbed region [4]. The Incorporation of Fe within CaP’s lattice resulted in the characteristic thermal phase transformation temperatures to shift to lower values, thereby promoting densification and sintering. The aim of the present work is to identify an optimum doping concentration of sintered β-CPP (Ca2P2O7) doped with Fe ions. The mechanical properties, biological response and the scaffold fabrication potential in relation to laser-matter interaction will be fully investigated. Various concentrations of iron (0 mol%, 5 mol%, 10 mol%, 20 mol% and 30 mol% by substituting ca2+) doped brushite powder were synthesised and sintered at temperature of 1000ºC for 5hrs. A femtosecond pulse laser emitting at a wavelength of 800 nm with 1 KHz repetition rate was used to create micro-channels in the surface of the samples to investigate the effect of surface properties in cell behaviour

Ag/ZnO Thin Film Nanocomposite Membrane Prepared by Laser-Assisted Method for Catalytic Degradation of 4-Nitrophenol

Zinc oxide thin film (ZnO thin film) and a silver-doped zinc oxide nanocomposite thin film (Ag/ZnO thin film) were prepared by the technique of the pulsed laser deposition at 600 °C to be applicable as a portable catalytic material for the removal of 4-nitrophenol. The nanocomposite was prepared by making the deposition of the two targets (Zn and Ag), and it was analyzed by different techniques. According to the XRD pattern, the hexagonal wurtzite crystalline form of Ag-doped ZnO NPs suggested that the samples were polycrystalline. Additionally, the shifting of the diffraction peaks to the higher angles, which denotes that doping reduces the crystallite size, illustrated the typical effect of the dopant Ag nanostructure on the ZnO thin film, which has an ionic radius less than the host cation. From SEM images, Ag-doping drastically altered the morphological characteristics and reduced the aggregation. Additionally, its energy band gap decreased when Ag was incorporated. UV spectroscopy was then used to monitor the catalysis process, and Ag/ZnO thin films had a larger first-order rate constant of the catalytic reaction K than that of ZnO thin film. According to the catalytic experiment results, the Ag/ZnO thin film has remarkable potential for use in environmentally-favorable applications

Removal of Ni(II) Ions by Poly(Vinyl Alcohol)/Al₂O₃ Nanocomposite Film via Laser Ablation in Liquid

Al2O3-poly(vinyl alcohol) nanocomposite (Al2O3-PVA nanocomposite) was generated in a single step using an eco-friendly method based on the pulsed laser ablation approach immersed in PVA solution to be applicable for the removal of Ni(II) from aqueous solution, followed by making a physicochemical characterization by SEM, XRD, FT-IR, and EDX. After that, the effect of adsorption parameters, such as pH, contact time, initial concentration of Ni(II), and medium temperature, were investigated for removal Ni(II) ions. The results showed that the adsorption was increased when pH was 5.3, and the process was initially relatively quick, with maximum adsorption detected within 90 min of contact time with the endothermic sorption process. Moreover, the pseudo-second-order rate kinetics (k2 = 9.9 × 10−4 g mg−1 min−1) exhibited greater agreement than that of the pseudo-first-order. For that, the Ni(II) was effectively collected by Al2O3-PVA nanocomposite prepared by an eco-friendly and simple method for the production of clean water to protect public health

Photodetection Properties of CdS/Si Heterojunction Prepared by Pulsed Laser Ablation in DMSO Solution for Optoelectronic Application

The high-quality n-type CdS on a p-type Si (111) photodetector device was prepared for the first time by a one-pot method based on an ns laser ablation method in a liquid medium. Cadmium target was ablated in DMSO solution, containing sulfur precursor, and stirred, assisting in 1D-growth, to create the sulfide structure as CdS nano-ropes form, followed by depositing on the Si-substrate by spin coating. The morphological, structural, and optical characteristics of the CdS structure were examined using X-ray diffraction, transmission, and scanning electron microscopy, photoluminescence, and UV-VIS spectroscopy. From X-ray diffraction analysis, the growing CdS spheres have a good crystal nature, with a high purity and desired c-axis orientation along the (002) plane, and the crystallinity was around 30 nm. According to optical characterization, high transparency was found in the visible–near-infrared areas of the electromagnetic spectrum, and the CdS spheres have a direct optical energy band gap of 3.2 eV. After that, the CdS/Si hetero-structured device was found to be improved remarkably after adding CdS. It showed that the forward current is constantly linear, while the dark current is around 4.5 µA. Up to a bias voltage of 4 V, there was no breakdown, and the reverse current of the heterojunctions somewhat increased with reverse bias voltage, while the photocurrent reached up to 580 and 690 µA for using 15 and 30 W/cm2 light power, respectively. Additionally, the ideal factors for CdS/Si heterojunction were 3.1 and 3.3 for 15 and 30 W/cm2 light power, respectively. These results exhibited high performance compared to the same heterojunction produced by other techniques. In addition, this opens the route for obtaining more enhancements of these values based on the changing use of sulfide structures in the heterojunction formation

Analysis of the osteogenic and mechanical characteristics of iron (Fe2+/Fe3+)-doped β‑calcium pyrophosphate

The calcium phosphate is the main mineral constituent of bone. Although there has been significant amount of research on finding ideal synthetic bone, no suitable scaffold material has yet been found. In this investigation, the iron doped brushite (CaHPO4·2H2O) has been investigated for osteogenic potential and mechanical properties. The synthesis of iron-oxide doping in the form of Fe2+,3+-ions were carried out using the solution based method in which the ammonium hydrogen phosphate and calcium nitrate solutions were used in stoichiometric ratio for synthesizing CaHPO4·2H2O, with doping concentrations of Fe2+,3+-ions between 5 mol% and 30 mol%. The synthesized powders were analysed using X-ray powder diffraction, FTIR, SEM and Raman spectroscopic techniques. The heat treatment of synthesized powder was carried out at 1000 °C in air for 5 h, and it was found that the dominant crystalline phase in samples with <20 mol% was β-CPP, which also formed an iron-rich solid solution phase. Increasing the concentrations of Fe2+,3+-ions enhances the phase fraction of FePO4 and amorphous phase. Amongst the Fe2+,3+-doped β-CPP minerals, it was found that the 10 mol% Fe2+,3+-doped β-CPP offers the best combination of bio-mechanical and osteogenic properties as a scaffold for bone tissue regenerative engineering