Oxygen saturation and blood volume analysis by photoacoustic imaging to identify pre and post-PDT vascular changes.

In this study, the blood volume and oxygen saturation of tumors were measured after photoacoustic imaging (PAI) under conditions of pre-photodynamic therapy (PDT), post-PDT, and 4 hrs, and 24 hrs post-PDT. PDTs with aminolevulinic acid (ALA) and low and high doses of benzoporphyrin derivative (BPD) were conducted to observe oxygen saturation changes, and the rapid oxygen consumption in the blood detected due to the action of BPD at the vascular level resulted in the recovery of PDT completion. Likewise, blood volume changes followed by ALA-PDT and BPD-PDT at low and high doses depicted a fast expansion of the blood volume after treatment. The tumor subjected to a high dose of ALA-PDT showed a partial alteration of Hb-pO2 in the first 24 hrs, as did the tumors treated with two ALA- and BPD-mediated PDTs. The Hb-pO2 started reducing immediately post-PDT and was less than 30% after 4 hrs until 24 hrs post-PDT. Reduced vascular demand was possibly due to tumor necrosis, as shown by the permanent damage in the cancer cells' bioluminescence signal. The ALA-mediated PDT-subjected tumor showed a 50% drop in BV at 24 hrs post-PDT, which is suggestive of vascular pruning. The studied data of blood volume against BLI showed the blood volume and oxygenation variations validating the cells' metabolic activity, including cell death.

Structural and optical characterization of alpha-irradiated and chemically etched PM-355 solid state nuclear track detectors before and after solar exposure.

PM-355 polymeric solid state nuclear track detectors were studied. Samples were irradiated with alpha particles before and after exposure to sunlight under various seasonal conditions. Track formation and optical characteristics of chemically etched samples were investigated. X-ray diffraction (XRD) analysis showed that the dominant structure of the PM-355 detectors is of an amorphous nature with some degree of crystallinity. Micro strain, distortion density and distortion parameter were calculated from the XRD data, and indicate that the structure was modified after alpha irradiation and solar exposure. There was a tendency in the structure towards crystallinity. Some optical properties of PM-355 detectors were studied using Ultraviolet-Visible absorption spectroscopy. The absorption edge was detectable in all samples. The direct band gap decreased first and then subsequently increased again. The fluorescence spectra of alpha irradiated and solar exposed PM-355 polymer detectors after chemical etching showed three dominant peaks at wavelengths 327, 418 and 465 nm, respectively. The changes in the optical properties can be used to detect the effect of alpha and ultraviolet irradiations. The variation of the optical band gap, fluorescence spectra and/or track diameters can be used as a detection of nuclear radiation.

Tuning Photophysical Properties of Donor/Acceptor Hybrid Thin- Film via Addition of SiO2/TiO2 Nanocomposites.

The influence of SiO2/TiO2 nanocomposites (STNCs) content on non-radiative energy transfer (Förster-type) from poly (9,9'-dioctylfluorene-2,7-diyl) (PFO) to poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) using steady-state and time-resolved photoluminescence spectroscopies was investigated at room temperature. The improved energy transfer from PFO to MEH-PPV upon an increment of the STNCs was achieved by examining absorbance, emission (PL) and photoluminescence excitation (PLE) spectra. The shorter values of the quantum yield (φDA) and lifetime (τDA) of the PFO in the hybrid thin films compared with the pure PFO, indicating efficient energy transfer from PFO to MEH-PPV with the increment of STNCs in the hybrid. The energy transfer parameters can be tuned by increment of the STNCs in the hybrid of PFO/MEH-PPV. The Stern-Volmer value (kSV), quenching rate value (kq), Förster radius (R0), distance between the molecules of PFO and MEH-PPV (RDA), energy transfer lifetime (τET), energy transfer rate (kET), total decay rate of the donor (TDR), critical concentration (Ao), and conjugation length (Aπ) were calculated. The gradually increasing donor lifetime and decreasing acceptor lifetime, upon increasing the STNCs content, prove the increase in conjugation length and meanwhile enhance in the energy transfer.

Delving into the properties of polymer nanocomposites with distinctive nano-particle quantities, for the enhancement of optoelectronic devices.

The study focusses on synthesis and modification of structural, optical and electrical characteristics of nanostructured titanium dioxide anatase embedded Poly(methyl methacrylate) (PMMA) nanocomposite with different weight percentages (0.03, 0.06, 0.12, 0.18 and 0.24%) by the solvent casting method. Modification in the morphology of PMMA nanocomposites with an increasing amount of titanium dioxide anatase is studied by using a field emission scanning electron microscope (FE-SEM). Micrograms of FE-SEM show spherical shaped nanoparticles distribution in PMMA nanocomposites thin films. In optical characterization, transmission, optical band gaps, the real and imaginary part of dielectric constant, linear susceptibility, optical conductivity, refractive index and extinction coefficient are calculated using experimental data. It is observed that the optical band gap has an overall decreasing trend with increasing the weight percentage of TiO2 (anatase) in PMMA nanocomposites. It is also found that values of all electrical parameters decrease with increasing the weight percentage of TiO2 (anatase) in PMMA nanocomposites. All wavelength depending parameters are investigated in the wavelength range from 190 nm to 2700 nm. Single oscillator model is used to analyze the refractive index dispersion and estimation of the oscillator energy and dispersion energy of the films. The study is applicable to optical sensors and other optoelectronic devices.

An experimental and algorithm-based study of the spectral features of breast cancer patients by a photodiagnosis approach.

In the present study, the spectral diagnosis of blood plasma samples of breast cancer patients and an equal number of normal controls was investigated. A set of ratio parameters was acquired by employing SXS and FES. The samples were also analyzed statistically by employing Welch two-sample t-tests, and the effects of three ratio parameters, R1, R2, and R3, were also studied by plotting them against the subject numbers. A linear discriminant was also applied to verify the exact classification of normal control and breast cancer patients. It was observed that the levels of biofluorophores such as porphyrin, NADH, tryptophan and flavins were elevated 2- to 3-fold for breast cancer patients compared to normal controls, with an accuracy of approximately 100 %. We have also confirmed the validity of the obtained experimental results by using an advanced robust diagnostic algorithm. The experimental results of the current study may have a vital and substantial impact on the detection and screening protocols used for future breast cancer patients. The spectral analysis of body fluid could be of great value to add to and enhance the current procedures with an accuracy of approximately 100 % with limited number of samples. The results and objectives of this preliminary study were encouraging and useful for the discrimination of the features of breast cancer patients compared to those of normal controls.

Optical and structural properties of CsPbBr3 perovskite quantum dots/PFO polymer composite thin films.

The aim of this study is to investigate the optical and structural properties of polymer/perovskite quantum dots (QDs) composite thin films and estimate the applicability of using these blends as active materials in photonic devices. A solution has been utilized, which is processed based on conjugated polymer and perovskite QDs composite films. The incorporation of CsPbBr3 QDs, with various weight ratios, influences the structure of the thin films, as proven by several techniques. The results of the study showed that the surface of the poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO)/CsPbBr3 thin films improved, when compared to that of the pristine CsPbBr3 thin film. The increase in the steepness parameter and decrease in both the energy gaps and Urbach tail, upon the increment of CsPbBr3 QDs, can be attributed to the decrease in the localized density of electronic states within the forbidden band gap of the hybrids. The overlap between the absorption spectrum of PFO and emission spectrum of CsPbBr3 QDs, and the enhancement in the emission peak of CsPbBr3 in the blends, confirmed the efficient non-radiative energy transfer between them.

Spectral Properties of PMMA Films Doped by Perylene Dyestuffs for Photoselective Greenhouse Cladding Applications.

Luminescent polymethylmethacrylate (PMMA) films were prepared by the solvent-casting technique from polymer solution doped with different concentrations of red perylene dyestuffs (KREMER 94720 and KREMER 94739). The effect of the dye concentration on the structure and spectroscopic properties was studied using X-ray diffraction (XRD), transmission electron microscope (TEM) optical absorption, and fluorescence spectroscopy. The optimum dye concentration of photoselective PMMA films was determined by the fluorescence spectroscopy measurements and showed the best emission properties for the doping concentration 10-3 wt % of the investigated dyes. The accelerated photostability tests showed promising stability of the prepared films towards terrestrial solar ultraviolet radiation (UVA). The results endorsed a promising application of the investigated films in photoselective greenhouse cladding applications as the optimized film fluoresces at the action spectra of special chlorophyll a.

A study for the detection of kidney cancer using fluorescence emission spectra and synchronous fluorescence excitation spectra of blood and urine.

In this study, we compared different types of biomolecular markers in kidney cancer patients and in normal healthy controls, using fluorescence emission spectra and synchronous fluorescence excitation spectra. We were able to provide an accurate classification of the spectral features of kidney cancer patients relative to that of normal controls, in terms of the concentration ratios of biomolecules (viz., tryptophan, NADH, FAD, basic porphyrin, and acidic porphyrin) based on the intensity of their spectral peaks. The specificity and sensitivity of the method were 90%. The rationale of our current approach is to evolve an innovative protocol for the spectral characterization of in vitro optical analyses suitable for both small clinics and hospitals.

Photodynamic Effect of Ni Nanotubes on an HeLa Cell Line.

Nickel nanomaterials are promising in the biomedical field, especially in cancer diagnostics and targeted therapy, due to their distinctive chemical and physical properties. In this experiment, the toxicity of nickel nanotubes (Ni NTs) were tested in an in vitro cervical cancer model (HeLa cell line) to optimize the parameters of photodynamic therapy (PDT) for their greatest effectiveness. Ni NTs were synthesized by electrodeposition. Morphological analysis and magnetic behavior were examined using a Scanning electron microscope (SEM), an energy dispersive X-ray analysis (EDAX) and a vibrating sample magnetometer (VSM) analysis. Phototoxic and cytotoxic effects of nanomaterials were studied using the Ni NTs alone as well as in conjugation with aminolevulinic acid (5-ALA); this was performed both in the dark and under laser exposure. Toxic effects on the HeLa cell model were evaluated by a neutral red assay (NRA) and by detection of intracellular reactive oxygen species (ROS) production. Furthermore, 10-200 nM of Ni NTs was prepared in solution form and applied to HeLa cells in 96-well plates. Maximum toxicity of Ni NTs complexed with 5-ALA was observed at 100 J/cm2 and 200 nM. Up to 65-68% loss in cell viability was observed. Statistical analysis was performed on the experimental results to confirm the worth and clarity of results, with p-values = 0.003 and 0.000, respectively. Current results pave the way for a more rational strategy to overcome the problem of drug bioavailability in nanoparticulate targeted cancer therapy, which plays a dynamic role in clinical practice.

Laser from Optically Pumped Quantum Dot CdSe/ZnS in a Colloidal Liquid.

In this study, we had investigated the amplified spontaneous emission (ASE) characteristics of CdSe/ZnS quantum dot (QDs) in a colloidal liquid. A third harmonic of Nd:YAG laser (355 nm) was used to produce laser-induced fluorescence (LIF) at 605 nm with a spectral width of 0 nm [full width at half maximum (FWHM)]. When the pump power and focusing were carefully optimized, an ASE at 610 nm with a spectral width of Δλ = 8 nm (FWHM) could be obtained. The beam was directional with a divergence of 10 milli radians (mrad); but the conversion efficiency was about 0.05%.

Spectral detection of thalassemia: a preliminary study.

BACKGROUND: Thalassemias (Thal) are forms of inherited autosomal recessive blood disorders arising out of mutations in the chromosomes 11 or 16. These disorders lead to poor oxygen delivery to blood vessels and consequent splenomegaly, bone deformities, and shorter life spans. The most common detection methods for Thal are complete blood count (CBC) followed by electrophoresis and molecular diagnosis methods, such as high-performance liquid chromatography (HPLC) and polymerase chain reaction (PCR) genotyping. These methods involve sophisticated instrumentations and are cumbersome and expensive. RESULTS: In this study an innovative spectral detection method, based on the fluorescence spectra of a set of biomolecules (tyrosine, tryptophan, nicotinamide adenine dinucleotide, and flavin adenine dinucleotide and porphyrins) found in blood components is presented. An algorithm based on the spectral features of such biomolecules of blood components of 20 Thal patients (10 female and 10 male) and 18 age adjusted normal controls (4 female and 14 male) demonstrate reasonable level of classification with sensitivity and specificity values exceeding 90%. CONCLUSION: This new technique could be of significant value for Thal detection, diagnosis, and subsequent genetic counselling and could be adapted for use in small primary health centres.

A parallelism between spectral grading and Gleason grading of malignant prostate tissues.

Gleason score is the most common method of grading the virulence of prostate malignancy and is based on the pathological assessment of morphology of cellular matrix. Since this involves the excision of the tissue, we are working on a new, minimally invasive, non-contact, procedure of spectral diagnosis of prostate malignancy. In this preliminary in vitro study reported here, we have analyzed 27 tissue samples (normal control=7: benign=8: malignant=12) by Stokes' shift spectra (SSS) to establish a one-to-one correspondence between spectral grading and Gleason grading.

Detection of lead in paint samples synthesized locally using-laser-induced breakdown spectroscopy.

A laser-induced breakdown spectroscopy (LIBS) setup was developed to detect lead and other toxic contaminants such as chromium in paint emulsion samples manufactured in Saudi Arabia. The lead concentration detected in these samples was in the 327.2-755.3 ppm range, which is much higher than the safe permissible limit set by Saudi regulatory agencies. Similarly, chromium concentration (98.1-149.5 ppm) was found in high concentrations as well. The results obtained with our LIBS setup are comparable with the sample analysis utilizing a standard technique such as ICP, and our LIBS results are comparable to ICP with in an accuracy limit of 2-4 %.