Conversion of extracted titanium tailing and waste glass to value-added porous glass ceramic with improved performances.

One of the major advances of this research is to produce porous glass ceramics (PGCs) via a feasible and cost-effective powder forming chemistry to convert solid wastes, extracted titanium tailing (ETT) and waste glass (WG) into the value-added PGCs. The maximum handling amount of ETT (30%) is determined from systematic experiments, based on the end use of these PGCs, which are manifested as controlled-crystalline porous structures of hybrid matrices. These multiscale porous networks are composed of a tunable pore size, high surface area and accessibility. The synthetic PGCs are found to display enhanced physical properties, as a result, the stewardship of their intrinsic chemical behaviors can be secured. To elucidate, the PGC shows an apparent density of 0.60 ± 0.01 g cm-3, a porosity of 76.0 ± 0.4%, a high compressive strength of 3.8 ± 0.2 MPa, an available water adsorption ratio of 4.4 ± 0.1%, a heat conductivity of 0.103 ± 0.003 W m-1 °C-1 and an applicable coefficient of thermal expansion ((5.43 ± 0.05) × 10-6 m m-1 °C -1). This study indicates that indeed the powder forming chemistry provide a simple method to advance the conversion of industry and municipal solid waste (ETT & WG) into value-added PGCs with improved physical and chemical properties.

SN-38-cyclodextrin complexation and its influence on the solubility, stability, and in vitro anticancer activity against ovarian cancer.

SN-38, an active metabolite of irinotecan, is up to 1,000-fold more potent than irinotecan. But the clinical use of SN-38 is limited by its extreme hydrophobicity and instability at physiological pH. To enhance solubility and stability, SN-38 was complexed with different cyclodextrins (CDs), namely, sodium sulfobutylether ß-cyclodextrin (SBEßCD), hydroxypropyl ß-cyclodextrin, randomly methylated ß-cyclodextrin, and methyl ß-cyclodextrin, and their influence on SN-38 solubility, stability, and in vitro cytotoxicity was studied against ovarian cancer cell lines (A2780 and 2008). Phase solubility studies were conducted to understand the pattern of SN-38 solubilization. SN-38-ßCD complexes were characterized by differential scanning calorimetry (DSC), X-ray powder diffraction analysis (XRPD), and Fourier transform infrared (FTIR). Stability of SN-38-SBEßCD complex in pH 7.4 phosphate-buffered saline was evaluated and compared against free SN-38. Phase solubility studies revealed that SN-38 solubility increased linearly as a function of CD concentration and the linearity was characteristic of an AP-type system. Aqueous solubility of SN-38 was enhanced by about 30-1,400 times by CD complexation. DSC, XRPD, and FTIR studies confirmed the formation of inclusion complexes, and stability studies revealed that cyclodextrin complexation significantly increased the hydrolytic stability of SN-38 at physiological pH 7.4. Cytotoxicity of SN-38-SBEßCD complex was significantly higher than SN-38 and irinotecan in both A2780 and 2008 cell lines. Results suggest that SBEßCD encapsulated SN-38 deep into the cavity forming stable inclusion complex and as a result increased the solubility, stability, and cytotoxicity of SN-38. It may be concluded that preparation of inclusion complexes with SBEßCD is a suitable approach to overcome the solubility and stability problems of SN-38 for future clinical applications.

Hyaluronic acid-decorated PLGA-PEG nanoparticles for targeted delivery of SN-38 to ovarian cancer.

BACKGROUND: Extreme hydrophobicity and poor stability of SN-38, a highly potent topoisomerase I inhibitor, has prevented its clinical use. Its encapsulation into nanoparticles may be a way to overcome these problems. Here we report the use of SN-38-loaded hyaluronic acid (HA)-decorated poly(lactic-co-glycolic acid)-polyethylene glycol (PLGA-PEG) nanoparticles (NPs) for targeted ovarian cancer therapy. MATERIALS AND METHODS: PLGA-PEG nanoparticles loaded with SN-38 were prepared by single- emulsion (O/W) solvent evaporation method. HA was decorated onto the nanoparticles by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) coupling and the extent of HA conjugation was quantified by hexadecyltrimmethylammonium bromide (CTAB) assay. Cancer cell specificity of the NPs was determined by flow cytometry and cytotoxicity of the NPs was tested by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium (MTT) bromide assay. RESULTS: Mean size, zeta potential and encapsulation efficiency of PLGA-PEG-HA NPs were 265.6 ± 3.8 nm, -30.4 ± 0.1 mV and 75.8 ± 4.1%, respectively. Cellular uptake of PLGA-PEG-HA NPs was 8- and 16-fold higher in CD44-positive cell lines, SKOV-3 and OVCAR-8, as compared to CD44-negative cells (CHO). Cytotoxicity of the targeted NPs was significantly higher as compared to non-targeted NPs for the above cell lines. These results suggest that PLGA-PEG-HA NPs could be an efficient delivery system for SN-38 for targeted therapy of ovarian cancer.

Use of natural products as green reducing agents to fabricate highly effective nanodisinfectants.

Disinfection of water using nanoparticles (NPs) can be achieved through selection of either metals (M) or transition metal oxides (TMO). In this research, 64 formulations of silver-titania nanocomposites (Ag/TiO2) were prepared via a feasible wet-chemistry technique using different natural products as reducing agents. Four selected products successfully reduced Ag(+) ions to Ag, allowing Ag/TiO2 composite to efficiently inactivate microbes found in the activated sludge. The degree of antibacterial activity was measured using zone of inhibition, which indicated all formulations inactivated the bacteria with high potency (0.01 I/6 h). The results from this study and comparison of literature values collectively suggest that light roasted coffee acted as one of the best natural reducing agents due to its low antioxidant index (LAI). Our selection framework also suggested any M/TMO with an oxygen reduction potentials (ORP) range of -0.41 to +1.23 V and any natural product with a LAI (<0.5) would be suitable as a reducing agent. Collectively, the high ORP and low AI provide effective disinfection of water-borne microbes.

A progressive approach on inactivation of bacteria using silver-titania nanoparticles.

A silver inserted metal oxide (Ag-TiO2) has been demonstrated to be an effective biocidal agent against prokaryotic microbes found in water. Transmission electron microscopy and electron energy loss spectroscopy indicated cellular damage after co-incubation with the nanocomposite, showing concomitant leakage of ions, which are critical for cell survival.

Facile design and nanostructural evaluation of silver-modified titania used as disinfectant.

Fundamental research has been carried out to define optimal "green" synthesis conditions for the production of titania (TiO(2)) and silver (Ag) nanocomposites (TANCs) ranging from 12.7-22.8 nm in diameter. A bottom-up colloidal approach was employed to accurately control TANC monodispersity and composition. TANCs were found to be effective at inactivating Escherichia coli (E. coli) in water. The presence of Ag in the nanocomposites induced a decrease in TiO(2) band gap energy, which favoured valence to conduction band electron transfer and allowed for electron excitation using visible light. Aggregation of ultra-fine particles was prevented through the use of a long-chain polymer as evidenced by electrophoretic mobility studies. The TANCs catalyzed oxidation of bacterial membranes and cell death or disinfection. Theoretically, the TANC mode of E. coli disinfection is via water photolysis, which results in production of hydroxyl radicals and hydrogen peroxide. These interact with the outer membrane polysaccharides and lipids, leading to lipid peroxidation, membrane weakening and resulted in cell death. Our overarching goals were to optimize the variables involved in TANC "green" synthesis and to characterize its nanostructure. High resolution (HR) transmission and scanning electron microscopic (TEM and SEM) studies demonstrated that TANCs were highly crystalline and mono-dispersive. Elemental composition of Ag and Ti, as measured by X-ray energy dispersive (EDS) and X-ray photoelectron spectroscopy (XPS) confirmed sample purity. Ultraviolet-visible (UV-VIS) spectroscopy showed that the energy band-gap of Ag modified TiO(2) was in the visible range.

Nanostructure characterization and performance evaluation of perovskite sensor composed of multi-elements.

A multi-element perovskite nanoscale film composed of Li(+) cation incorporated into Ca(2+)-doped PbTiO(3) (LCPT) was derived via colloidal chemistry, sol-gel (SG) method followed by heat-treatment. The morphology, chemical composition and structure of the LCPT nanofilms were investigated by advanced instrumentation (microscopy and spectroscopy) techniques. The characterization indicates formation of a tetragonal crystalline ceramic after sintering. The humidity sensing performances of LCPT nanofilms with various formulations were evaluated as a function of lattice distortion. The LCPT sensor doped with Li (0.5-0.1mol%) possessed the distortion of 1.041-1.046 and displayed rapid sensitivity (current changes from 1.5x10(-3) to 5.2A), high linearity (R(2)=0.997) in the whole relative humidity range (phi: 8-93% RH) under low frequency of 100Hz, and excellent long-term stability.

Green synthesis and characterization of polymer-stabilized silver nanoparticles.

Silver nanoparticles (Ag-NPs) were synthesized using a facile green chemistry synthetic route. The reaction occurred at ambient temperature with four reducing agents introduced to obtain nanoscale Ag-NPs. The variables of the green synthetic route, such as acidity, concentration of starting materials, and molar ratio of reactants were optimized. Dispersing agents were employed to prevent Ag-NPs from aggregating. Advanced instrumentation techniques, such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV-vis), and phase analysis light scattering technique (ZetaPALS) were applied to characterize the morphology, particle size distribution, elemental composition, and electrokinetic behavior of the Ag-NPs. UV-vis spectra detected the characteristic plasmon at approximately 395-410 nm; and XRD results were indicative of face-centered cubic phase structure of Ag. These particles were found to be monodispersed and highly crystalline, displaying near-spherical appearance, with average particle size of 10.2 nm using citrate or 13.7 nm using ascorbic acid as reductants from particle size analysis by ZetaPALS, respectively. The rapid electrokinetic behavior of the Ag was evaluated using zetapotential (from -40 to -42 mV), which was highly dependant on nanoparticle acidity and particle size. The current research opens a new avenue for the green fabrication of nanomaterials (including variables optimization and aggregation prevention), and functionalization in the field of nanocatalysis, disinfection, and electronics.