Phase Transition of High-Surface-Area Glycol-Thermal Synthesized Lanthanum Manganite.

Cubic and rhombohedral phases of lanthanum manganite were synthesized in a high-pressure reactor. A mixture of La and Mn nitrates with ethylene glycol at a synthesis temperature of 200 °C and a calcination temperature of up to 1000 °C, resulted in a single-phase perovskite, LaMnO3 validated using X-ray diffraction. Significant changes in unit cell volumes from 58 to 353 Å3 were observed associated with structural transformation from the cubic to the rhombohedral phase. This was confirmed using structure calculations and resistivity measurements. Transmission electron microscopy analyses showed small particle sizes of approximately 19, 39, 45, and 90 nm (depending on calcination temperature), no agglomeration, and good crystallinity. The particle characteristics, high purity, and high surface area (up to 33.1 m2/g) of the material owed to the inherent PAAR reactor pressure, are suitable for important technological applications, that include the synthesis of perovskite oxides. Characteristics of the synthesized LaMnO3 at different calcination temperatures are compared, and first-principles calculations suggest a geometric optimization of the cubic and rhombohedral perovskite structures.

Histidine-Tagged Folate-Targeted Gold Nanoparticles for Enhanced Transgene Expression in Breast Cancer Cells In Vitro.

Nanotechnology has emerged as a promising treatment strategy in gene therapy, especially against diseases such as cancer. Gold nanoparticles (AuNPs) are regarded as favorable gene delivery vehicles due to their low toxicity, ease of synthesis and ability to be functionalized. This study aimed to prepare functionalized AuNPs (FAuNPs) and evaluate their folate-targeted and nontargeted pCMV-Luc-DNA delivery in breast cancer cells in vitro. CS was added to induce stability and positive charges to the AuNPs (Au-CS), histidine (Au-CS-His) to enhance endosomal escape and folic acid for folate-receptor targeting (Au-CS-FA-His). The FAuNP:pDNA nanocomplexes possessed favorable sizes (<135 nm) and zeta potentials (<-20 mV), strong compaction efficiency and were capable of pDNA protection against nuclease degradation. These nanocomplexes showed minimal cytotoxicity (>73% cell viability) and enhanced transgene activity. The influence of His was notable in the HER2 overexpressing SKBR3 cells, which produced higher gene expression. Furthermore, the FA-targeted nanocomplexes enhanced receptor-mediated endocytosis, especially in MCF-7 cells, as confirmed by the receptor competition assay. While the role of His may need further optimization, the results achieved suggest that these FAuNPs may be suitable gene delivery vehicles for breast cancer therapeutics.

Amino Acid Functionalized Hydrotalcites for Gene Silencing.

Hydrotalcites and amino acid functionalized hydrotalcites (aa-HTs) were synthesized using the co-precipitation method. These compounds were characterized using X-ray diffraction (XRD), inductively coupled plasma-optical emission spectroscopy (ICP-OES), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). The optimal siRNA binding capacity was determined using gel retardation assays. Cytotoxicity studies using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that the siRNA:HT complexes were relatively non-cytotoxic to HeLa-tat-luc cells. Gene silencing studies showed that the aa-HTs elicited significantly higher levels of gene knockdown when compared to the non-functionalized HTs. Overall, these HTs have shown the potential to bind, protect and efficiently deliver siRNA, in vitro.

Removal of 2,4-Dichlorophenoxyacetic acid from water and organic by-product minimization by catalytic ozonation.

BACKGROUND: 2,4-dichlorophenoxyacetic acid (2,4-DCPA acid) is a toxic herbicide. Earlier studies to remove 2,4-DCPA acid from water used expensive and/or toxic reagents, resulting in the formation of toxic organic by-products (Org-BPs). This study evaluates the removal of 2,4-DCPA acid from aqueous media using uncatalysed and catalytic ozonation with Fe doped with Ni and Co respectively. METHODS: Mixed metal oxides of Ni and Co loaded on Fe respectively, prepared by co-precipitation and physical mixing were used as catalyst for ozone facilitated oxidation degradation of 2,4-DCPA acid. Their surface properties were determined by employing SEM, BET and NH3-TPD. HPLC, IC and TOC data were used for quantifying substrate and oxidation products. RESULTS: Conversion of 2,4-DCPA acid increased from 38% in acidic water to 73% in basic water, however, only 26% of the total carbon was removed and 9.5% in the form of Org-BPs. With 7:3 Fe:Ni (Co-ppt) catalyst (surface area 253 m2 g-1; particle size 236 nm), 97% of pollutant was converted. Most importantly, 92% of carbon was removed and Org-BP formation was minimized to 1.5%. With 7:3 Fe:Ni (Mixed) catalyst (surface area 12 m2 g-1; particle size 1274 nm), 68% of 2,4-DCPA acid was converted, while 23% of TOC was removed, however, 66% of Org-BP's still remained. CONCLUSION: In uncatalysed ozonation degradation of 2,4-DCPA acid improved with the increase in hydroxide ion concentration. Ozonation in presence of 7:3 Fe:Ni (Co-ppt) catalyst resulted in highest activity for dechlorination, TOC removal and Org-BP minimization, thus improving the quality of contaminated water.

Simultaneous removal of 2,4,6-tribromophenol from water and bromate ion minimization by ozonation.

The study investigates the degradation of 2,4,6-tribromophenol (2,4,6-TBP) and the influence of solution pH, alkalinity, H2O2 and O3 dosage. Debromination efficiency of 2,4,6-TBP was the highest in basic water (pH = 10.61). The extent of TOC removal compared favourably with the amount of substrate converted, suggesting favourable mineralization of oxygenated by-products (OBPs). Ozonation in basic water favoured the formation of toxicBrO3-, while in acidic water (pH = 2.27) BrO3- yield was lowest. In acidic water the presence of CO32- showed negligible effect on conversion, TOC and BrO3- yield compared to ozonation alone. In basic water both 2,4,6-TBP conversion and TOC removal decreased with an increase in CO32-, hence minimizing BrO3- formation. The O3/H2O2 process showed an improvement in the debromination efficiency and TOC data revealed that total mineralization of OBP's was achieved. However, only 10% H2O2 was able to effectively decrease BrO3- formation. Increasing the ozone concentration from 20 to 100 ppm enhanced the conversion of 2,4,6-TBP and TOC removal. At low ozone concentrations poor mineralization of OBP's occurred, while complete mineralization was achieved at higher ozone dose. The reaction pathways for ozone degradation of 2,4,6-TBP in acidic and basic waters is proposed.

Synthesis and characterization of layered double hydroxides and their potential as nonviral gene delivery vehicles.

Layered double hydroxides (LDHs) exhibit characteristic anion-exchange chemistry making them ideal carriers of negatively charged molecules like deoxyribonucleic acid (DNA). In this study, hydrotalcite (Mg-Al) and hydrotalcite-like compounds (Mg-Fe, Zn-Al, and Zn-Fe), also known as LDHs, were evaluated for their potential application as a carrier of DNA. LDHs were prepared by coprecipitation at low supersaturation and characterized by Powder X-ray diffraction (XRD), infrared (IR), Raman, and inductively coupled plasma-optical emission spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD patterns showed strong and sharp diffraction peaks for the (003) and (006) planes indicating well-ordered crystalline materials. TEM images yielded irregular circular to hexagonal-shaped particles of 50-250 nm in size. Varying degrees of DNA binding was observed for all the compounds, and nuclease digestion studies revealed that the LDHs afford some degree of protection to the bound DNA. Minimal toxicity was observed in human embryonic kidney (HEK293), cervical cancer (HeLa) and hepatocellular carcinoma (HepG2) cell lines with most showing a cell viability in excess of 80 %. All LDH complexes promoted significant levels of luciferase gene expression, with the DNA:Mg-Al LDHs proving to be the most efficient in all cell lines.