Sherif Kandil

Antibiotic-free nanotherapeutics: Hypericin nanoparticles thereof for improved in vitro and in vivo antimicrobial photodynamic therapy and wound healing

Hypericin (HY) is a naturally-occurring, potent photosensitizer. However, its lipophilicity limits its therapeutic applications. Our attempt is, thus, to develop a biodegradable nanocarrier for hypericin capable of preserving its antibacterial photoactivity. Amphiphilic block copolymers were synthesized to prepare hypericin-laden nanoparticles (HY-NPs). The antimicrobial photoactivity of HY-NPs was assessed; in vitro against biofilm and planktonic cells of methicillin resistant Staphylococcus aureus (MRSA) clinical isolates and in vivo on infected wounds in rats. Nanoparticles of 45 nm in diameter ensured higher amounts of reactive oxygen species upon irradiation. HY-NPs demonstrated superior inhibition of biofilm over planktonic cells. In vivo wound healing studies in rats revealed faster healing, better epithelialization, keratinization and development of collagen fibers when HY-NPs were applied. Determination of growth factors and inflammatory mediators in the wound area confirmed superior healing potential of nanoencapsulated hypericin suggesting that hypericin can join the era of antibiotic-free antimicrobial therapy.

Effect of temperature and ageing on the mechanical properties of dental polymeric composite materials

Evaluation of the mechanical properties of some dental composite materials, Compact, Finesse and Prisma-Fil based on bisphenol glycidyl methacrylate resin was undertaken by applying compression, tension and hardness tests. The effects of temperature and ageing times on these properties were studied. There was a marked increase in the mechanical properties (compressive strength, diametral tensile strength, compressive elastic modulus and hardness) for all the investigated composites with increase of both temperature and time. This was explained in terms of the influence of temperature on the polymerization rate of the materials. The improvement in the mechanical properties of the samples, kept at 37 degrees C, was attributed to further and continued polymerization of the polymer content of their resin system. Such mechanical improvement was verified by the regression equation of linearity versus both temperature and time.

Synthesis of carbohydrate-containing polyamides and study of their properties☆

Abstract Carbohydrate-containing polyamides were prepared using low-temperature solution polycondensation of 2,3,4,5-tetra-O-acetylgalactaroyl dichloride (3) with various aromatic and aliphatic diamines viz. p- phenylenediamine ( 4 ) ; m-phenylenediamine; benzidine; 4,4′-diaminodiphenylmethane; 1,5-diaminoanthraquinone; 2,6-diaminoanthraquinone; 4,4′-diaminodicyclohexylmethane; hexamethylenediamine; and ethylenediamine (12). The four O-acetyl groups in 3 protect the hydroxyl functions and give good solubility as a result of increasing lipophilicity. The optimum conditions for the best yield and viscosity of the polyamide were determined by study of the factors affecting the polycondensation. These conditions for reaction of 3 with 4 were reached with reactant concentrations of 0.5 mol/l at −10°. On the other hand, the optimum conditions for reaction of 3 with 12 involved concentrations of 1.0 mol/l at 0°. Polyamides containing the unacetylated carbohydrate chains were obtained by de-O-acetylation of the synthesized acetylated carbohydrate-containing polyamides. Structures of the acetylated and de-O-acetylated carbohydrate-containing polyamides were confirmed by elemental analysis, i.r. and 1H-NMR spectroscopy. Their thermal degradations were studied by differential thermal analysis and thermogravimetric analysis.

Biocompatibility of new Ti-Nb-Ta base alloys.

β-type titanium alloys are promising materials in the field of medical implants. The effect of β-phase stability on the mechanical properties, corrosion resistance and cytotoxicity of a newly designed β-type (Ti77Nb17Ta6) biocompatible alloys are studied. The β-phase stability was controlled by the addition of small quantities of Fe and O. X-ray diffraction and microstructural analysis showed that the addition of O and Fe stabilized the β-phase in the treated solution condition. The strength and hardness have increased with the increase in β-phase stability while ductility and Youngs modulus have decreased. The potentio-dynamic polarization tests showed that the corrosion resistance of the new alloys is better than Ti-6Al-4V alloy by at least ten times. Neutral red uptake assay cytotoxicity test showed cell viability of at least 95%. The new alloys are promising candidates for biomedical applications due to their high mechanical properties, corrosion resistance, and reduced cytotoxicity.

Studies on the constituents of the green alga Ulva lactuca

Phytochemical investigations on a marine green alga Ulva lactuca led to the isolation of two new compounds (E)-6-heptacosen-5-one (1) and (E)-6-octadecen-5-ol (2), along with four known compounds, (Z)-10-hexacosene (3), docosanoic acid (4), palmitic acid (5), and isofucosterol (6). Compounds 3 and 4 were isolated for the first time from this species. The structures of the compounds were deduced with the help of modern spectroscopic techniques.

Effect of contamination of cotton fabric with linseed oil on the activation energies of pyrolysis and oxidation of the fabric

The spontaneous ignition behaviour of both uncontaminated and oil contaminated cotton fabric has been investigated by using differential thermal analysis (DTA) and evolved gas analysis (EGA) techniques. The temperature, at which the onset of spontaneous ignition T i occurs, was recorded as a function of the oxygen concentration of the flowing oxygen-nitrogen atmosphere to which the fabric materials wer exposed in the DTA furnace, when heated at different heating rates. The activation energy of pyrolysis E p was obtained according to a simple kinetic model derived by Horrocks et al, as follows In(Hr/T 1 2 )=- E p/R(1/Ti)+In A p -In( E p- E ox/R= where E ox is the activation energy of gaseous product oxidation. Plotting of 1/T i vs In [O 2 ] produces true linear regions which intersect at a certain oxygen concentration and have slopes equal to (E ox -E p )/m. Taking the minimum and maximum E p value, and estimating the slopes of the two regions, the value of the molar oxygen concentration m required for the oxidation can be estimated for both untreated and oil contaminated fabrics. The results showed that E p decreased as the oil content in the fabrics was increased. It is probable that the oxidation of the oils generates free radicals, which catalyse the pyrolysis reaction of the cellulose. The movement of the point of intersection of the 1/T i vs In [O 2 ] due to oil concentration increase, and may explain the observed decrease in E ox value with increasing oil concentration. The results also showed a simultaneous increase in the number of oxygen molecules required for combustion as the oil concentration increased, reflecting the sensitivity of the combustion mechanism to oxygen concentration. The evolved gas analysis measurements indicated a diminishing of the dehydration reaction when the fabric was contaminated with oil, therefore suggesting domination of the depolymerization route of reaction.

Development and biodistribution of a theranostic aluminum phthalocyanine nanophotosensitizer

BACKGROUND Aluminum phthalocyanine (AlPc) is an efficient second generation photosensitizer (PS) with high fluorescence ability. Its use in photodynamic therapy (PDT) is hampered by hydrophobicity and poor biodistribution. METHODS AlPc was converted to a biocompatible nanostructure by incorporation into amphiphilic polyethylene glycol-polycaprolactone (PECL) copolymer nanoparticles, allowing efficient entrapment of the PS in the hydrophobic core, water dispersibility and biodistribution enhancement by PEG-induced surface characteristics. A series of synthesized PECL copolymers were used to prepare nanophotosensitizers with an average diameter of 66.5-99.1nm and encapsulation efficiency (EE%) of 66.4-78.0%. One formulation with favorable colloidal properties and relatively slow release over 7 days was selected for in vitro photophysical assessment and in vivo biodistribution studies in mice. RESULTS The photophysical properties of AlPc were improved by encapsulating AlPc into PECL-NPs, which showed intense fluorescence emission at 687nm and no AlPc aggregation has been induced after entrapment into the nanoparticles. Biodistribution of AlPc loaded NPs (AlPc-NPs) and free AlPc drug in mice was monitored by in vivo whole body fluorescence imaging and ex vivo organ imaging, with in vivo imaging system (IVIS). Compared to a AlPc solution in aqueous TWEEN 80 (2 w/v%), the developed nanophotosensitizer showed targeted drug delivery to lungs, liver and spleen as monitored by the intrinsic fluorescence of AlPc at different time points (1h, 24h and 48h) post iv. administration. CONCLUSIONS The AlPc-based copolymer nanoparticles developed offer potential as a single agent-multifunctional theranostic nanophotosensitizer for PDT coupled with imaging-guided drug delivery and biodistribution, and possibly also fluorescence diagnostics.

Spontaneous ignition of oil-contaminated cotton fabric

The purpose of this study is to evaluate the effect of different oil contaminants on the spontaneous ignition behavior of cotton fabric. A series of treated fabrics with different oil contamination percentages was investigated and compared. Measurements were designed and carried out to determine the average time-to-ignition and to study the thermal behavior of systems containing cellulose. The results showed that the time-to-ignition of the contaminated samples has notably decreased, particularly at relatively low temperatures (350-450°C). However, at higher temperatures such effects became insignificant. Differential Thermal Analysis measurements were used to explain the mechanism by which the oils affect the thermal behavior of the sample. The heat evolved due to the oxidation of the oil content is sufficient to increase the rate of cotton depolymerization at the expense of the dehydration mechanism. In other words, the heat evolved promotes the formation of volatiles which are not char precursors.

Recycling of Pharmaceutical Waste Gelatin for Controlled Release Applications II: A Tri-fluralin Based System

Abstract During the latter half of last century, the production and consumption of synthetic plastics and fibers has vastly grown. The plastics wastes have continuously increased over recent decades. Concerns over this have now resulted in mandatory recycling laws and demands for degradable polymers. Management of plastic wastes cannot be treated as an individual problem; it must be considered as an integral part of the global waste management system. The development of recycling processes leading to higher quality recycled products would help the recycling economy. In this study, recycling of pharmaceutical gelatin scraps will be conducted by incorporating them in biodegradable mulching films. The formulation and preparation of these films is described and the effect of different additives on the rate of release of the bioactive agent (trifluralin) is reported. The results showed that the produced films have controlled release properties and the presence of cross-linked agent decreased the release rate of trifluralin.

Study of the thermal stabilities of some polymeric schiff-bases containing sulphur

Abstract The relationship of the thermal stabilities of some polymeric Schiff-bases to their chemical structures was studied by using thermogravimetric analysis and differential thermal analysis. Polymeric Schiff-bases were prepared by the condensation of 5,5′-methylene-bis-salicylaldehyde, terephthalaldehyde, di( p -formylphenyl) terephthalate or di( p -acetylphenyl) terephthalate with various diamines containing sulphur, such as thiocarbohydrazide, bis (4-aminophenyl) sulphone, 4,4′-diaminostilbene-2,2′-disulphonic acid and 3,5-diaminobenzene sulphonic acid. Two monomeric prototypes of these polymeric Schiff-bases were prepared in order to compare their thermal stabilities with the corresponding polymers.