Souad A. Elfeky

Solid-State Structures and Solution Analyses of a Phenylpropylpyridine N-Oxide and an N-Methyl Phenylpropylpyridine

The crystal structures of phenylpropylpyridine-N-oxide and N-methyl-phenylpropylpyridinium iodide are compared, revealing that hydrogen bonding with the solvent molecule plays an important role in the N-oxide compound, whilst electrostatic interactions are predominant in controlling the solid-state orientation of the N-methylated compound. Fluorescence spectroscopy and NOESY indicate that in contrast to the previously reported pyridinium iodide, the N-oxide is not subject to intramolecular pi-stacking, as judged by excimer emission and a lack of corresponding cross peaks, respectively.

Diol Appended Quenchers for Fluorescein Boronic Acid

Fluorescein isothiocyanate is treated with 3-aminophenylboronic acid to provide a fluorescently tagged boronic acid derivative which is used to assess Förster resonance energy transfer (FRET) quenching upon boronate ester formation with a series of bespoke diol appended quenchers. Fluorescence spectroscopy comparison of quenching efficiency between treatment of fluorescein and its boronic acid appended congener with quencher appended diol reveals boronate ester formation (covalently linked) to be the more efficient regime and from the panel of quenchers which also included nucleosides.

Biotinylated boronic acid fluorophore conjugates: Quencher elimination strategy for imaging and saccharide detection

A biotinylated boronic acid fluorophore conjugate bound to a diol-quencher via a boronic ester linkage demonstrated a fluorescence increase upon exposure to model saccharides. The sensing motif was attached to SuperAvidin microspheres where the sensing regime was imaged by fluorescence microscopy.

Photocatalytic Decomposition of Trypan Blue Over Nanocomposite Thin Films

The photocatalytic activity of titanium dioxide and gold modified TiO2 (Au/TiO2), supported on polymethylmethacrylate (PMMA) thin film, was evaluated in the photodegradation of Trypan Blue (TB) under sunlight irradiation. The effect of parameters such as the photocatalyst amount and pH on TiO2 photocatalytic activity is investigated. Oxygen flow stream was applied to enhance the decomposition process of TB. The maximum photoactivity was attained using Au/TiO2-PMMA thin film at pH 2.

Photo-oxidation of rhodamine-6-G via TiO 2 and Au/TiO 2 -bound polythene beads

It is very important to improve the efficiency of water detoxification techniques. In this study, TiO2 or gold-TiO2 (Au/TiO2) nanocomposite-bound polythene beads were used for the photo-oxidation of rhodamine 6G (R6G) as a model of water organic pollutants. Simple thermal procedures were employed for anchoring TiO2 or Au/TiO2 nanocomposites to polythene beads. The results revealed that the synthesized Au/TiO2 composites exhibited both considerably higher absorption capability of organic pollutants and better photocatalytic activity for the photo-oxidation of R-6G than pure titania. The better photocatalytic activity of the synthesized Au/TiO2 composites film than that of the pure titania film was attributed to high capacity of light absorption intensity and easy diffusion of absorbed pollutants on the absorption sites to photogenerated oxidizing radicals on the photoactive sites.

Fluorescent sensor for bacterial recognition

Boronic acid-based fluorescent sensor is one of the non-enzymatic methods used for the recognition of saccharides. Since bacterial membrane has polysaccharides with diol groups, boronic acids probe could be applied for rapid bacterial recognition. Escherichia coli (XL-1 blue) were recognized by applying (3-(5-(dimethylamino) naphthalene-1-sulfonamide) phenyl) boronic acid (DNSBA) as a sensor and the fluorescence recorded by fluorometer micro-plate reader. Results showed that, fluorescence records of DNSBA increase in a dose dependent manner upon increasing the bacterial cell numbers. Moreover, the increase in the number of bacterial cells induces a shift in the spectra due to the formation of the anionic form of boronic acid complex. Therefore, DNSBA is an efficient sensor for monitoring bacterial cells.

Applications of CTAB modified magnetic nanoparticles for removal of chromium (VI) from contaminated water

Graphical abstract

A new biocompatible nanocomposite as a promising constituent of sunscreens

Skin naturally uses antioxidants to protect itself from the damaging effects of sunlight. If this is not sufficient, other measures have to be taken. Like this, hydroxyapatite has the potential to be applied as an active constituent of sunscreens since calcium phosphate absorbs in the ultraviolet region (UV). The objective of the present work was to synthesize a hydroxyapatite-ascorbic acid nanocomposite (HAp/AA-NC) as a new biocompatible constituent of sunscreens and to test its efficiency with skin cell models. The synthesized HAp/AA-NC was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, absorption spectrophotometry and X-ray diffraction analysis. The protective effect of the construct was tested with respect to viability and intracellular reactive oxygen species (ROS) generation of primary human dermal fibroblasts (SKIN) and human epidermal keratinocytes (HaCaT). Both cell lines were irradiated with UV light, λmax=254 nm with a fluence of 25 mJ cm(-2) to mimic the effect of UV radiation of sunlight on the skin. Results showed that HAp/AA-NC had a stimulating effect on the cell viability of both, HaCaT and SKIN cells, relative to the irradiated control. Intracellular ROS significantly decreased in UV irradiated cells when treated with HAp/AA-NC. We conclude that the synthesized HAp/AA-NC have been validated in vitro as a skin protector against the harmful effect of UV-induced ROS.

Fluorescence-based CdTe nanosensor for sensitive detection of cytochrome C

Cytochrome c (Cyt c) is commonly used as intrinsic biomarker for several characteristics of the cell such as respiration, energy level and apoptosis. In the present study a simple colorimetric sensor should be developed and tested for the real-time detection of Cyt c in living cells. We synthesized cadmium telluride quantum dots (CdTe QDs) capped with thioglycolic acid (TGA) as a fluorometric Cyt c nanosensor. The synthesized TGA/CdTe QDs nanosensor was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and absorption as well as fluorescence spectrophotometry. We investigated the developed TGA/CdTe QDs sensor with regard to its applicability in the fluorometric detection of Cyt c. Results showed that the TGA/CdTe QDs could be used as a sensitive fluorescence probe for the quantification of different concentrations of Cyt c ranging from 0.5 - 2.5μM. Increased binding of QDs to Cyt c results in decreasing fluorescence. The fluorescence of the QDs is inversely correlated to the Cyt c concentration. Based on these data, a standard curve up to 2.5μM Cyt c was established. Moreover, the developed nanosensor was applied in different concentrations on primary human dermal fibroblasts. Results showed that TGA/CdTe QDs were taken up by cells and could be visualized by fluorescence microscopy. Quantification of Cyt c within living cells via QDs is, however, influenced by various factors such as cell damage, QD aggregation or the level of reactive oxygen species, which have to be taken into account.

Production of Well-Dispersed Aqueous Cross-Linked Chitosan-Based Nanomaterials as Alternative Antimicrobial Approach

In the current study, chitosan was extracted by deacetylation of chitin, which is extracted from shrimp shell. chitosan nanoparticles (CSNPs) were prepared by ionotropic gelation technique. chitosan/tripolyphosphate ratio (CS:TPP) was kept at 3:1 to prepare CSNPs. chitosan/silver nanocomposite (CS/AgNCs) were prepared by incorporating silver nanoparticles into CSNPs. The quality of the prepared nanocomposite was evaluated by infrared spectroscopy, UV–Vis spectroscopy, transmission electron microscopy, and antibacterial activity. Results showed that chitosan/silver nanocomposite in which, both chitosan and silver are in nanoscale was successfully prepared for the first time in a well-dispersed aqueous form. Whereas CSNPs act as a host material to form the nanocomposite unlike the previously prepared forms of chitosan–silver nanocomposites, that used chitosan bulk as host materials and the dispersion medium was slightly acidic. Moreover, results revealed that the antibacterial activity of CSNPs was significantly enhanced after incorporating trace amount of silver nanoparticles (0.535% w/w AgNPs/CSNPs).