A. S. Aldwayyan

Prospects of Nanotechnology in Clinical Immunodiagnostics

Nanostructured materials are promising compounds that offer new opportunities as sensing platforms for the detection of biomolecules. Having micrometer-scale length and nanometer-scale diameters, nanomaterials can be manipulated with current nanofabrication methods, as well as self-assembly techniques, to fabricate nanoscale bio-sensing devices. Nanostructured materials possess extraordinary physical, mechanical, electrical, thermal and multifunctional properties. Such unique properties advocate their use as biomimetic membranes to immobilize and modify biomolecules on the surface of nanoparticles. Alignment, uniform dispersion, selective growth and diameter control are general parameters which play critical roles in the successful integration of nanostructures for the fabrication of bioelectronic sensing devices. In this review, we focus on different types and aspects of nanomaterials, including their synthesis, properties, conjugation with biomolecules and their application in the construction of immunosensing devices. Some key results from each cited article are summarized by relating the concept and mechanism behind each sensor, experimental conditions and the behavior of the sensor under different conditions, etc. The variety of nanomaterial-based bioelectronic devices exhibiting novel functions proves the unique properties of nanomaterials in such sensing devices, which will surely continue to expand in the future. Such nanomaterial based devices are expected to have a major impact in clinical immunodiagnostics, environmental monitoring, security surveillance and for ensuring food safety.

One Step Synthesis of NiO Nanoparticles via Solid-State Thermal Decomposition at Low-Temperature of Novel Aqua(2,9-dimethyl-1,10-phenanthroline)NiCl2 Complex

[NiCl2(C14H12N2)(H2O)] complex has been synthesized from nickel chloride hexahydrate (NiCl2·6H2O) and 2,9-dimethyl-1,10-phenanthroline (dmphen) as N,N-bidentate ligand. The synthesized complex was characterized by elemental analysis, infrared (IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential thermal/thermogravimetric analysis (TG/DTA). The complex was further confirmed by single crystal X-ray diffraction (XRD) as triclinic with space group P-1. The desired complex, subjected to thermal decomposition at low temperature of 400 ºC in an open atmosphere, revealed a novel and facile synthesis of pure NiO nanoparticles with uniform spherical particle; the structure of the NiO nanoparticles product was elucidated on the basis of Fourier transform infrared (FT-IR), UV-vis spectroscopy, TG/DTA, XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS) and transmission electron microscopy (TEM).

Fluorescence spectra of blood and urine for cervical cancer detection

Abstract. In the current study, the fluorescence emission spectra (FES) and Stokes shift spectra (SSS) of blood and urine samples of cervical cancer patients were obtained and compared to those of normal controls. Both spectra showed that the relative intensity of biomolecules such as porphyrin, collagen, Nicotinamide adenine dinucleotide, and flavin were quite out of proportion in cervical cancer patients. The biochemical mechanism for the elevation of these fluorophores is not yet definitive; nevertheless, these biomolecules could serve as tumor markers for diagnosis, screening, and follow-up of cervical cancers. To the best of our knowledge, this is the first report on FES and SSS of blood and urine of cervical cancer patients to give a sensitivity of 80% and specificity of 78%.

Optical probing of laser-induced shock waves in air

Shock Waves (SW) were produced in air by focusing the (0.25 J, 6 ns) second-harmonic (λ = 532 nm) Nd : YAG laser light into a stainless-steel cylindrical cell at a pressure from 200 to 760 Torr. The laser fluence at the focal point is > 5 GW/cm2. The spatial variation and consequently the time evolution of the radial propagation velocityU of the generated shock waves were measured via a simple optical system utilizing a HeNe laser beam triply intersecting the propagating shock wave at three successive positions. Using a reflector, we were able to probe the traveling SW in six consecutive positions during its round trip. Good agreement was obtained between the experimental results and the predictions of the point strong explosion theory. It is shown that this method is simple with a fairly good precision. It therefore appears to be useful for the determination of the SW dynamic parameters, namely its Mach number, the pressure at the SW front, the thickness of the compressed air layer and the energy consumed in producing this layer.

Amplified spontaneous emission spectra from the superexciplex of coumarin 138

In this report the dual amplified spontaneous emission (ASE) characteristics of coumarin 138 (C(138)) had been studied, under different solvent environments. The results obtained were compared with coumarin 461 (C(461)) and coumarin 450 (C(450)), which have closely related structure. The results showed that all these dyes could produce ASE from superexciplex - a new molecular species - formed only under high inversion densities, obtainable by pulsed laser excitation. We have strong indication that a superexciplex with TICT conformation is capable of producing strong ASE.

Elemental analysis of fertilizer using laser induced breakdown spectroscopy

In recent years, the use of fertilizers has increased to achieve high growth rate of agriculture products. With this increase the chemical impact of agricultural activities on the environment has also been enhanced. In order to keep the environment healthy, and clean, it is necessary to identify contaminants and characterize the sources of contamination. In this study, a comprehensive chemical characterization of a DAP fertilizer has been carried out using laser induced breakdown spectroscopy. Phosphorous, manganese, magnesium, iron, titanium, molybdenum, nickel, cobalt, aluminum, chromium, lead, and uranium traces are detected. Relative abundances of Phosphorous, manganese, magnesium, molybdenum, iron, titanium, nickel, vanadium, calcium, cobalt, cadmium, tin are 26.64, 17.75, 13 97, 8.25, 7.97, 7.11, 5.07, 3.15, 2.94, 1.94, 1,55, 1.73 percent, respectively, whereas relative abundances of sulfur, aluminum, chromium, lead, and uranium are less than 1% and their sum is 1.93% of the total sample.

Photoluminescence spectra of CdSe/ZnS quantum dots in solution

The spectral properties of CdSe/ZnS core-shell quantum dots (QDs) of 3 nm size have been studied under different organic solvents, concentrations and temperatures. Our results showed that the absorption spectra of CdSe/ZnS in benzene have two humps; one around 420 nm and another at 525 nm, with a steady increase in absorption along UV region, and the absorption spectral profile under a wide range of concentrations did not change. On the other hand, the photoluminescence (PL) spectra of CdSe/ZnS in benzene showed two bands one around 375 nm and the other around 550 nm. It could be seen that the band at 375 nm is due to the interaction between the shell (ZnS) with the solvent species in high excited state, and the band at 550 nm is due to core alone (CdSe).

Facile synthesis of water-soluble luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres

Luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres were synthesized through W/O microemulsion process at ambient temperature. The negatively charged silica favors a coating of the positively charged Tb3+ composite. Thus, silicon layer was adsorbed on the surface of Tb(OH)3 groups to form Tb-O-Si through electrostatic interaction. X-ray diffraction, field emission transmission electron microscopy (FE-TEM), energy-dispersive X-ray spectrometry, and Fourier transform infrared, UV/Visible, and photoluminescence spectroscopies were applied to examine the phase purity, crystallinity, surface morphology, and optical properties of the core-shell nanospheres. The FE-TEM results have revealed typically ordered mesoporous characteristics of the material with monodisperse spherical morphology in a narrow size distribution. The luminescent mesoporous core-shell nanospheres exposed remarkable splitting with broadening in the emission transition 5D4 → 7F5 (543 nm). In addition, the luminescent mesoporous core-shell nanospheres emit strong green fluorescence (from Tb3+) in the middle of the visible region under 325 nm (3.8) excitation. The luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres can therefore be exploited as fluorescent probes in biomarkers or biolabeling, optical sensing, and drug delivery system. Further, these nanospheres could have potential use as scattering layers in dye-sensitized solar cells.

Photodynamic damage study of HeLa cell line using ALA

The present study evaluates the photodynamic damage with 5-aminolevulinic acid (5-ALA) using HeLa as experimental model. HeLa cell line was irradiated with red light (He-Ne laser, λ = 632.8 CW nm). The influence of different incubation times and concentrations of 5-ALA, different irradiation doses and various combinations of photosensitizer and light doses on the cellular viability of HeLa cells were studied. The optimal uptake of photosensitizer ALA in HeLa cells was investigated by means of PpIX fluorescence intensity by exciting the HeLa cell suspension at 450 nm and a detection wavelength set at 690 nm. Cells viability was determined by means of trypan blue solution. The spectrometric measurements showed that the maximal cellular uptake of 5-ALA occurred after 4 h in vitro incubation. We found that the combination with 5-ALA and laser irradiation leads to time/concentration-dependent increase of cells death and also energy doses-dependent enlarge the cells death. The fluorescence intensity after PDD of carcinoma cells reduce when compared with the control group. The fluorescence emission spectral profiles after PDD of carcinoma cells showed a dip around 425–525 nm when compared with the control group. This may be due to the damage of mitochondria component of cells. The percentage of HeLa cells after PDD shows that the percentage of cells survival rate as function of laser dose (power). Hence it is clear that at 200 μg/ml ALA and 20 mW laser irradiation, more than 70% of HeLa cells were dead after 15 min.

Influence of 190 MeV Ag+15 ion irradiation on electrical transport and magnetic properties of LaFe1―xNixO3 (x=0.3 and 0.4) thin films

In the present work we have studied the effect of 190 MeV Ag ion irradiation on the structural, electrical, and magnetic properties of LaFe1−xNixO3 (x=0.3 and 0.4) thin films. The films were grown on LaAlO3 ⟨001⟩ oriented substrates using pulsed laser deposition technique. The pristine and irradiated samples were investigated using x-ray diffraction, temperature dependent resistivity, and magnetic measurements. The x-ray diffraction patterns of the irradiated films show that the lattice of the composition strain relaxed with enhanced c-axis orientation. The temperature dependence of the resistivity indicates that all the films (pristine and irradiated) exhibit semiconducting behavior for entire studied temperature range (80–300 K). The pristine and irradiated samples show the activated variable range hopping behavior throughout the studied temperature range. The magnetization hysteresis measurements show ferromagnetic behavior at 300 K for all samples. The results are explained on the basis of the close i...