Narrow Results

We describe the solubilization/dispersion of as-produced and purified single-walled carbon nanotubes (raw-SWNTs and p-SWNTs) with protoporphyrin IX derivatives and tetraphenylporphyrin iron(III) chloride, the spectral behavior of the octaalkylporphyrins-solubilized shortened-SWNTs (s-SWNTs), and the electrochemistry of a p-SWNTs/FePP cast film on a glassy carbon electrode. Transmission electron and atomic force microscopies, as well as UV-visible-near IR spectroscopy, revealed that the protoporphyrin IX derivatives individually dissolved the p-SWNTs in polar solvents under mild conditions of sonication using a bath-type sonicator, followed by centrifugation at 1000 g. The raw-SWNTs were more easily dissolved than the p-SWNTs with protoporphyrin IX zinc(II) (ZnPP), whereas the amount of the solubilized/dispersed p-SWNTs did not depend on the concentration of the solubilizer and sonication time. The absorption and fluorescence spectral measurements of the octaalkylporphyrins in dimethylformamide containing 1 vol% tetrahydrofuran with various amounts of the s-SWNTs showed that the absorption maxima of the octaalkylporphyrins decreased with an increase in the concentration of the s-SWNTs without wavelength shift and the fluorescence of the porphyrins was quenched by the addition of the s-SWNTs. These spectral behaviors are direct evidence for the interaction between the nanotube sidewall and the porphyrins in the solutions. The cyclic voltammograms of the p-SWNTs/hemin (FePP) and free hemin (FePP) suggest that the nanotubes act as a conduction passage for electrons between hemin (FePP) and the glassy carbon electrode.

Surfactant-assisted self-assembly of porphyrin molecules in aqueous solutions sometimes leads to the formation of hybrid supramolecular structures with unusual photophysical properties resulting from the dipole–dipole interactions between the neighboring aromatic systems. The macrocycle orientation and interchromophore distance in such assemblies are determined by the dye–surfactant interactions, and hence, strongly depend on the molecular structure of both surfactant and porphyrin molecules. In this paper we studied the influence of the number and position of the peripheral alkyl chains of amphiphilic meso-aryl-substituted porphyrins on their aggregation behavior and intermolecular interactions with different surfactants in aqueous solutions. The studies revealed a crucial role of the local acidity on the micellar surface in the protolytic equilibrium of the porphyrin derivatives, as well as the influence of the macrocycle hydrophilic–lipophilic balance on its solubilization site within a micellar system. These findings enable prediction of the photophysical properties of amphiphilic porphyrin derivatives in the presence of different solubilizing agents and membrane-mimetic systems, and hence, selection the most suitable drug delivery systems for the novel amphiphilic porphyrin-based photosensitizers.

A comparative study of the aggregation behavior of tetra-tert-butylphthalocyanine aluminum(III) in micellar aqueous solutions of different surfactants was carried out. The maximum degree of tetra-tert-butylphthalocyanine aluminum(III) monomerization was found for the Cremophor EL micellar solution. In the range of the surfactant concentrations of 0.05–1%, the binding constant of the photosensitizer to the micelles (K_b) was determined and the solubilization coefficient f_mic was calculated. The hydrodynamic diameters of Cremophor EL micelles with and without solubilized phthalocyanine were determined using the dynamic light scattering method. The change in the Gibbs free energy of binding between phthalocyanine and Crermophor EL micelles was determined.

Paclitaxel (PTX) is usual for the treatment of a variety of malignancies, however, its applications are greatly limited due to its poor water solubility. Over the past years, there has been a considerable research interest in the area of nanoscale drug delivery systems (DDSs) as carrier for PTX due to their solubilization, safety, targeting and controlled release. There are many different types and shapes of nanoscale DDSs that have been prepared to deliver PTX, including nanoliposome, lipid nanoemulsion, nanosuspension, nanocapsule, nanofiber, nanotube, nanopolymersome, micelle and nanoparticle (NP). Nanoscale DDSs can be based on lipids, proteins, polysaccharides, polymers or other materials. The recent strategic developments of PTX formulation have been discussed with emphasis on lipid-, polymer- and protein-based nanoscale DDSs. Here we focus on the comparative analysis of the preparation, morphology, solubilization, targeting, penetrability, controllability and efficacy profile of various PTX-loaded nanoscale DDSs, which were reported in the different researches. Meanwhile the advantages and disadvantages are also discussed for each type of DDS. Furthermore, the current review embodies an in-depth discussion of human serum albumin (HSA) NP formulation, which showed significantly great efficacy and low toxicity. All the information obtained in this review might shed light on designing new and better nanoscale PTX formulations for potential anticancer applications in the clinic.

In modern days, biodegradable polymeric matrix used as the kingpin of local drug delivery system is in the center of attention. This work is concentrated on the formulation of mathematical model elucidating degradation of drug-loaded polymeric matrix followed by drug release to the adjacent biological tissues. Polymeric degradation is penciled with mass conservation equations. Drug release phenomenon is modeled by considering solubilization dynamics of drug particles, diffusion of the solubilized drug through polymeric matrix along with reversible dissociation/recrystallization process. In the tissue phase, reversible dissociation/association along with internalization processes of drug are taken into account. For this, a two-phase spatio-temporal model is postulated, which has ensued to a system of partial differential equations. They are solved analytically with appropriate choice of initial, interface and boundary conditions. In order to reflect the potency of the advocated model, the simulated results are analogized with corresponding experimental data and found laudable agreement so as to validate the applicability of the model considered. This model seems to foster the delicacy of the mantle enacted by important drug kinetic parameters such as diffusion coefficients, mass transfer coefficients, particle binding and internalization parameters, which is illustrated through local sensitivity analysis.

In this study, an applicability of thermal pre-treatment for waste activated sludge in various total solid concentration, which are generated in a sewage treatment plant, was evaluated. The efficiency and characteristic was investigated with each sludge in various concentration after pre-treatment under the condition of 80~200℃ for 30 minutes. As the result, it was found that SCOD, NH₄⁺, VFA concentrations increased as the pre-treatment temperature increased. For COD solubilization, it was also higher dependent on increase of temperature resulting in acceleration on hydrolysis and acid fermentation. In the BMP (Biochemical Methane Potential) experiment, it showed the highest biogas production in the range of 160~180℃. In addition, the methane yield was increased around 62~85% in all concentration of sludge, and this means that thermal solubilization process applicability was appeared to be outstanding regardless of sludge concentration.