M. Atif

Hydrothermal Growth of Vertically Aligned ZnO Nanorods Using a Biocomposite Seed Layer of ZnO Nanoparticles

Well aligned ZnO nanorods have been prepared by a low temperature aqueous chemical growth method, using a biocomposite seed layer of ZnO nanoparticles prepared in starch and cellulose bio polymers. The effect of different concentrations of biocomposite seed layer on the alignment of ZnO nanorods has been investigated. ZnO nanorods grown on a gold-coated glass substrate have been characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. These techniques have shown that the ZnO nanorods are well aligned and perpendicular to the substrate, and grown with a high density and uniformity on the substrate. Moreover, ZnO nanorods can be grown with an orientation along the c-axis of the substrate and exhibit a wurtzite crystal structure with a dominant (002) peak in an XRD spectrum and possessed a high crystal quality. A photoluminescence (PL) spectroscopy study of the ZnO nanorods has revealed a conventional near band edge ultraviolet emission, along with emission in the visible part of the electromagnetic spectrum due to defect emission. This study provides an alternative method for the fabrication of well aligned ZnO nanorods. This method can be helpful in improving the performance of devices where alignment plays a significant role.

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%.

Two-photon excitation studies of m-THPC photosensitizer and photodynamic activity in an epithelial cell line.

A femtosecond laser delivering pulses of wavelength 800nm and 124fs duration at rates of 1kHz has been used to investigate the two-photon excited fluorescence in the photosensitizer m-THPC. The scaling of fluorescence amplitude with laser power and fluorescence sidelight imaging are found to support a predominantly two-photon excitation mechanism. A value for the two-photon cross-section of δ=1.8×10(-57)m(4)s is derived by comparing the fluorescence signals excited by wavelengths of 800 and 400nm. Preliminary results demonstrating the two-photon induced PDT activity of m-THPC in an epithelial cell line are also reported.

Study of the efficacy of 5 ALA-mediated photodynamic therapy on human larynx squamous cell carcinoma (Hep2c) cell line

Abstract5-aminolevulanic acid (ALA), a precursor of Protoporphyrin IX, was evaluated as an inducer of photodamage on Hep2c, human larynx squamous cell carcinoma, cell line. Porphyrins are used as active cytotoxic antitumor agents in photodynamic therapy (PDT). The present study evaluates the effects of photodynamic therapy (PDT) with 5-aminolevulinic acid (5-ALA) using human larynx cells as experimental model. Hep2c cell line was irradiated with red light (a diode laser, λ = 635 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 Hep2c cells were studied. The optimal uptake of photosensitizer ALA in Hep-2c cells was investigated by means of spectrometric measurement. Cells viability was determined by means of neutral red assay (NR). It was observed that sensitizer or light doses have no significant effect on cells viability when studied independently. The spectrometric measurements showed that the maximal cellular uptake of 5-ALA occurred after 7 h in vitro incubation. The photocytotoxic assay showed that light dose of 85 J/cm2 gives effective PDT outcome for Hep2c cell line incubated with 55 μg/ml of 5-ALA with a conclusion that Hep2c cell line is sensitive to ALA-mediated PDT.

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.

Optical Properties of Normal and Thermally Coagulated Chicken Liver Tissue Measured ex vivo with Diffuse Reflectance

The purpose of the present study is to determine the optical properties of normal and thermally coagulated chicken liver at 720, 740, 770, 810, 825 and 840 nm wavelengths of laser irradiation. So, we were able to evaluate these optical properties (absorption and scattering coefficients) with ex-vivo study using Kubelka Munk Model (KMM) from the radial dependence of the diffuse reflectance with femtosecond pulsed laser in near IR region. These coefficients were significantly increased with coagulation. The penetration depths of the diffused light have been reported to a maximum value of 8.12 ± 0.36 mm in normal liver and 2.49 ± 0.17 mm in coagulated liver at 840 nm showing increasing behavior towards IR region. The Monte Carlo simulation was used to check the theoretical validation of measured optical properties of the tissue that showed a good match with our experimental results. We believe that these differences in optical properties will be helpful for the understanding arid optimal use of laser applications in medicine and differential diagnosis of tissues by using different optical methods. Especially for the investigation of biological tissue for photodynamic therapy (PDT), the knowledge of the specific optical properties and their thermo-induced changes is important.

Photodynamic therapy of non-melanoma skin cancers

In this prospective study duly approved from Institutional Ethics Review Committee for research in medicine, PAEC General Hospital Islamabad, Pakistan, we investigate the efficacy, safety and tolerability along with cosmetic outcome of topical 5-aminolaevulinic acid photodynamic therapy for superficial nonmelanoma skin cancers (NMSCs) and their precursors. Patients with Histological diagnosis of NMSCs and their precursors were assessed for PDT, after photographic documentation of the lesions and written consent, underwent two (2) sessions of PDT in one month (4 weeks) according to standard protocol. A freshly prepared 20% 5-ALA in Unguentum base was applied under occlusive dressing for 4–6 h as Drug Light Interval (DLI) and irradiated with light of 630 nm wavelength from a diode laser at standard dose of 90 J/cm2. Approximately 11% patients reported pain during treatment which was managed in different simple ways. In our study we regularly followed up the patients for gross as well as histopathological response and recurrence free periods during median follow-up of 24 months. Regarding Basal cell carcinomas complete response was observed in 86.2% (25/29), partial response in 10.3% (3/29) and recurrence during first year in 3.5% (1/29) lesions. All the lesions which showed partial response or recurrence were nBCCs. Regarding Actinic Keratosis complete response was observed in 95.3% (20/21), partial response in 4.7% (1/21) while Bowen’s disease showed 100% (2/2) results. 81.8% (9/11) Squamous Cell Carcinomas showed complete, 9% (1/11) partial response and 9% (1/11) presented with recurrence after 3 months. We observed excellent and good cosmetic results along with tumor clearance in our study. Treatment sessions were well tolerated with high level of patient’s satisfaction and only minor side effects of pain during treatment sessions and inflammatory changes post photodynamic therapy were observed. We concluded that 5-ALA PDT is an effective and safe emerging treatment modality for management of superficial non-melanoma skin cancers and their precursors with better cosmetic outcome and minor side effects.

Fabrication of Well-Aligned ZnO Nanorods Using a Composite Seed Layer of ZnO Nanoparticles and Chitosan Polymer

In this study, by taking the advantage of both inorganic ZnO nanoparticles and the organic material chitosan as a composite seed layer, we have fabricated well-aligned ZnO nanorods on a gold-coated glass substrate using the hydrothermal growth method. The ZnO nanoparticles were characterized by the Raman spectroscopic techniques, which showed the nanocrystalline phase of the ZnO nanoparticles. Different composites of ZnO nanoparticles and chitosan were prepared and used as a seed layer for the fabrication of well-aligned ZnO nanorods. Field emission scanning electron microscopy, energy dispersive X-ray, high-resolution transmission electron microscopy, X-ray diffraction, and infrared reflection absorption spectroscopic techniques were utilized for the structural characterization of the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods on a gold-coated glass substrate. This study has shown that the ZnO nanorods are well-aligned, uniform, and dense, exhibit the wurtzite hexagonal structure, and are perpendicularly oriented to the substrate. Moreover, the ZnO nanorods are only composed of Zn and O atoms. An optical study was also carried out for the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods, and the obtained results have shown that the fabricated ZnO nanorods exhibit good crystal quality. This study has provided a cheap fabrication method for the controlled morphology and good alignment of ZnO nanorods, which is of high demand for enhancing the working performance of optoelectronic devices.

The influence of intracellular mTHPC concentration upon photobleaching dynamics

In this study, we report the effect of the local photosensitizer concentration upon the dynamics of the singlet oxygen-mediated photobleaching, within formalin-fixed keratinocytes. Although the cells were incubated at a single mTHPC dose, cell-to-cell variations in concentration were defined within the perinuclear region by differences in the initial amplitude of the laser-induced fluorescence emission, located around 652nm. At a fixed laser fluence-rate, it was found that the photobleaching, when plotted as a function of delivered light dose, proceeded more rapidly at higher drug concentration. The mTHPC spectral emission profile is shown to be approximately Lorentzian and remains unchanged as the photobleaching proceeds. This indicates that there is no perturbation of the detected signal due to the inner-filter effect.

ZnO nanoparticles as drug delivery agent for photodynamic therapy

Multidrug resistance (MDR) limits the success of many tumoricidal drugs. Non-significant accumulation of the drug into the target site is one major problem in photodynamic therapy. Nanoparticles are extensively used as efficient drug carriers in various local infectious and premalignant biological tissues. Due to their unique physical and chemical properties, PEGylated zinc oxide nanoparticles (ZnO NPs) exhibit high drug loading capacities, sustained drug release profiles and long-term anticancer efficacy. (Polyethylene glycol) PEG-zinc oxide nanoparticles were synthesized using the aquis chemical technique. Morphology/structural analysis of the said nanoparticles was confirmed by applying many techniques, e.g. scanning electron microscopy (SEM) and XRD. Average grain size of the nanoparticles, which was ≈100 nm, was calculated by applying the Scherrer formula. The PEGylated ZnO NPs were loaded with protoporphyrin IX (PpIX) to enhance the capability of drug carrying potency. Current work focused on the comparison of the cell killing effect (apoptosis/necrosis) by functionalizing different nanostructures via PEGylated ZnO NPs and bare ZnO NPs using the free-standing drug delivery procedure. ZnO NPs were used as anticancer drug vehicles because of their biocompatibility and bio-safety profile. The apoptotic effect of PEGylated tumoricidal drugs has been studied in human muscle carcinoma (RD cell line) in the dark as well as under laser exposure. It was concluded that PpIX localization was a significant time greater using encapsulation as compared to a conventional drug delivery system. This new technique may find excellent opportunities in the field of nanomedicine, especially in a multidrug delivery system.