Evaluation of dynamic scaling of growing interfaces in EEG fluctuations of seizures in animal model of temporal lobe epilepsy.

Epileptic seizures, as a dynamic phenomenon in brain behavior, obey a scale-free behavior, frequently analyzed by electrical activity recording. This recording can be seen as a surface that roughens with time. Dynamic scaling studies roughening processes or growing interfaces. In this theory, a set of exponents -obtained from scale invariance properties- characterize rough interfaces growth. The aim of the present study was to investigate scaling behavior in EEG time series fluctuations of a chemical animal model of temporal lobe epilepsy, with dynamic scaling to detect changes on seizure onset. We analyzed local variables in different sampling intervals and estimated rough, scaling and dynamic exponents. Results exhibited long-range correlations in interictal activity. Results of renormalization and data collapsing confirmed that each epoch of EEG fluctuations for interictal, preictal and postictal collapse in a curve in different scales, each segment independently; remarkably, we found non-scaling behavior in seizures epochs. Data for the different sampling intervals for ictal period do not collapse in one curve, which implies that ictal activity does not exhibit the same scaling behavior than the other epochs. Statistical significant differences of growth exponent were found between interictal and ictal segment, while for scaling exponent, significant differences were found between interictal and postictal segment. These results confirm the potential of scaling exponents as characteristic parameters to detect changes on seizure onset, which suggests their use as inputs for analysis methods for seizure detection in long-term recordings, while changes in growth exponent are potentially useful for prediction purposes.

Catalytic nanomedicine technology: copper complexes loaded on titania nanomaterials as cytotoxic agents of cancer cell.

The anticancer properties of pure copper (II) acetate and copper (II) acetylacetonate, alone and loaded on functionalized sol-gel titania (TiO(2)), were determined in four different cancer cell lines (C6, RG2, B16, and U373), using increasing concentrations of these compounds. The copper complexes were loaded onto the TiO(2) network during its preparation by the solgel process. Once copper-TiO(2) materials were obtained, these were characterized by several physical-chemical techniques. An in vitro copper complex-release test was developed in an aqueous medium at room temperature and monitored by ultraviolet spectroscopy. The toxic effect of the copper complexes, alone and loaded on TiO(2), was determined using a cell viability 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, when cancer cells were treated with increasing concentrations (15.75-1000 mg/mL) of these. Characterization studies revealed that the addition of copper complexes to the TiO(2) sol-gel network during its preparation, did not generate changes in the molecular structure of the complexes. The surface area, pore volume, and pore diameter were affected by the copper complex additions and by the crystalline phases obtained. The kinetic profiles of both copper complexes released indicated two different stages of release: The first one was governed by first-order kinetics and the second was governed by zero-order kinetics. The cell viability assay revealed a cytotoxic effect of copper complexes, copper-TiO(2), and cisplatin in a dose-dependent response for all the cell lines; however, the copper complexes exhibited a better cytotoxic effect than the cisplatin compound. TiO(2) alone presented a minor cytotoxicity for C6 and B16 cells; however, it did not cause any toxic effect on the RG2 and U373 cells, which indicates its high biocompatibility with these cells.

Nanostructured Pt(NH(3))(4)Cl(2)/SiO(2) for nanomedicine: catalytic degradation of DNA in cancer cells.

In vivo suppression of glioblastoma multiforme (GBM) in Wistar rats using silica-shelled biocatalytic Pt(NH(3))(4)Cl(2) nanoparticles is reported. These nanoparticles were synthesized by a sol-gel technique and characterized by SEM and HRTEM imaging. We confirmed morphological uniformity (30 nm) and surface acidity of the nanoparticles, respectively, by TEM imaging and FTIR spectral analysis. Interestingly, treatment of Wistar rats intraperitoneally inoculated with C(6) cells using the biocatalysts resulted in considerable tumor shrinkage. Efficiency of the biocatalyst to shrink a tumor is superior to that by the commercial cytotoxic agent cisplatin. The tumor suppression property of Pt(NH(3))(4)Cl(2) nanoparticles is attributed to catalytic damage of DNA in C(6) cells.

Study of the stabilization of zinc phthalocyanine in sol-gel TiO2 for photodynamic therapy applications.

Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for cancer. It is a two-step procedure that uses a combination of molecular oxygen, visible light, and photosensitizer (PS) agents; phthalocyanine (Pc) was supported over titanium oxide but has not yet been used for cell inactivation. Zinc phthalocyanine (ZnPc) molecules were incorporated into the porous network of titanium dioxide (TiO(2)) using the sol-gel method. It was prepared from stock solutions of ZnPc and TiO(2). ZnPc-TiO(2) was tested with four cancer cell lines. The characterization of supported ZnPc showed that phthalocyanine is linked by the N-pyrrole to the support and is stable up to 250°C, leading to testing for PDT. The preferential localization in target organelles such as mitochondria or lysosomes could determine the cell death mechanism after PDT. The results suggest that nanoparticulated TiO(2) sensitized with ZnPc is an excellent candidate as sensitizer in PDT against cancer and infectious diseases.

The effect of water on particle size, porosity and the rate of drug release from implanted titania reservoirs.

The implantation of controlled drug release devices represents a new strategy in the treatment of neurodegenerative disorders. Sol-gel titania implants filled with valproic acid, have been used for this purpose to treat induced epilepsy in rats. The kinetics of the drug release depend on: (a) porosity, (b) chemical interactions between valproic acid and surface hydroxyl groups of titania, (c) particle size, and (d) particle size agglomerates. The concentration of water used in the hydrolysis reaction is an important variable in the degree of porosity, hydroxylation, and structural defects of the nanostructured titanium oxide reservoir. The titanium n-butoxide/water ratio was systematically varied during the sol-gel synthesis, while maintaining the amount of valproic acid constant. Characterization studies were performed using DTA-TGA, FTIR, Raman, TEM, SEM, BET, and in vitro release kinetic measurements. The particle agglomerate size and porosity were found to depend on the amount of water used in the sol-gel reaction.

Treatment of Parkinson's disease: nanostructured sol-gel silica-dopamine reservoirs for controlled drug release in the central nervous system.

INTRODUCTION: We have evaluated the use of silica-dopamine reservoirs synthesized by the sol-gel approach with the aim of using them in the treatment of Parkinson's disease, specifically as a device for the controlled release of dopamine in the striatum. Theoretical calculations illustrate that dopamine is expected to assume a planar structure and exhibit weak interactions with the silica surface. METHODS: Several samples were prepared by varying the wt% of dopamine added during the hydrolysis of tetraethyl orthosilicate. The silica-dopamine reservoirs were characterized by N(2) adsorption, scanning and transmission electron microscopy, and Fourier transform infrared spectroscopy. The in vitro release profiles were determined using ultraviolet visible absorbance spectroscopy. The textural analyses showed a maximum value for the surface area of 620 m(2)/g nanostructured silica materials. The stability of dopamine in the silica network was confirmed by infrared and (13)C-nuclear magnetic resonance spectroscopy. The reservoirs were evaluated by means of apomorphine-induced rotation behavior in hemiparkisonian rats. RESULTS: The in vitro dopamine delivery profiles indicate two regimes of release, a fast and sustained dopamine delivery was observed up to 24 hours, and after this time the rate of delivery became constant. Histologic analysis of formalin-fixed brains performed 24-32 weeks after reservoir implantation revealed that silica-dopamine implants had a reddish-brown color, suggesting the presence of oxidized dopamine, likely caused by the fixation procedure, while implants without dopamine were always translucent. CONCLUSION: The major finding of the study was that intrastriatal silica-dopamine implants reversed the rotational asymmetry induced by apomorphine, a dopamine agonist, in hemiparkinsonian rats. No dyskinesias or other motor abnormalities were observed in animals implanted with silica or silica-dopamine.

Cortisol controlled release by mesoporous silica.

In this study four types of SBAs were synthesized and then impregnated with hydrocortisone. One is a straight SBA-15, obtained using Pluronics P123 as structuring agent; two others were modified using 1,3,5-trimethylbenzene as additive, and the fourth one was prepared using sodium iodide as additive. Three of these have in common a p6 mm symmetry with nanotubes packed hexagonally, yet they differ in their functional groups. The fourth sample is basically disordered. The drug release kinetics showed two stages: a fast-rate early stage dominated by the controlled release of the hydrocortisone adsorbed in the macropores of the reservoir, followed by a slow-rate delivery that we assume is controlled by the hydrocortisone diffusion through the nanopores. It is shown that the release kinetics can be strongly influenced by using different co-additives.