Photochemical degradation of digoxin tested by Na,K-ATPase activity

The photochemical degradation of digoxin aqueous solution was obtained by Xelamp irradiation. The concentrations of digoxin in irradiated solutions were detected by measurements of Na,K-ATPase activity and by HPLC analysis. The excellent agreement using two independent methods for determination of digoxin concentration in the irradiated samples was achieved.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Low-temperature synthesis and characterization of TiO2 and TiO2–ZrO2 photocatalytically active thin films

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Comparison of different characteristics of TiO[sub]2 films and their photocatalytic properties

Comparison of different characteristics of TiOsub2 films and their photocatalytic propertie

Synergism in TiO2_2 photocatalytic ozonation for the removal of dichloroacetic acid and thiacloprid

The synergistic effect of the photocatalytic ozonation process (PH-OZ) using the photocatalyst TiO$_2$ is usually attributed to influences of the physicochemical properties of the catalyst, pollutant type, pH, temperature, O$_3$ concentration, and other factors. It is also often claimed that good adsorption on the TiO$_2$ surface is beneficial for the occurrence of synergism. Herein, we tested these assumptions by using five different commercial TiO$_2$ photocatalysts (P25, PC500, PC100, PC10 and JRC-TiO-6) in three advanced oxidation systems - photocatalysis (O$_2$/TiO$_2$/UV), catalytic ozonation (O$_3$/TiO$_2$) and PH-OZ (O$_3$/TiO$_2$/UV) - for the degradation of two pollutants (dichloroacetic acid - DCAA and thiacloprid) simultaneously present in water. The synergistic effect in PH-OZ was much more pronounced in the case of thiacloprid, a molecule with low adsorption on the surface of the catalyst - in contrast to DCAA with stronger adsorption. The faster kinetics of catalytic ozonation (O$_3$/TiO$_2$) correlated with the higher exposed surface area of TiO$_2$ agglomerates, independent of the (lower) BET surfaces of the primary particles. Nevertheless, DCAA mineralization on the TiO$_2$ surface was much faster than thiacloprid degradation in solution. Therefore, we propose that a high BET surface area of the photocatalyst is crucial for fast surface reactions (DCAA mineralization), while good dispersion - the high exposed surface area of the (small) agglomerates - and charge separation play an important role in photocatalytic degradation or PH-OZ of less adsorbed organic pollutants (thiacloprid)

Chromatographic HPV-16 E6/E7 plasmid vaccine purification employing L-histidine and 1-benzyl-L-histidine affinity ligands

Affinity chromatography based on amino acids as interacting ligands was already indicated as an alternative compared to ion exchange or hydrophobic interaction for plasmid DNA purification. Understanding the recognition mechanisms occurring between histidine-based ligands and nucleic acids enables more efficient purification of a DNA vaccine, as the binding and elution conditions can be adjusted in order to enhance the purification performance. Decreasing pH to slightly acidic conditions increases the positive charge of histidine ligand, what influences the type of interaction between chromatographic support and analytes. This was proven in this work, where hydrophobic effects established in the presence of ammonium sulfate were affected at pH 5.0 in comparison to pH 8.0, while electrostatic and cation-π interactions were intensified. Histidine ligand at pH 5.0 interacts with phosphate groups or aromatic rings of plasmid DNA. Due to different responses of RNA and pDNA on mobile phase changes, the elution order between RNA and pDNA was changed with mobile phase pH decrease from 8.0 to 5.0. The phenomenon was more evident with L-histidine ligand due to more hydrophilic character, leading to an improved selectivity of L-histidine-modified chromatographic monolith, allowing the product recovery with 99% of purity (RNA removal). With the 1-benzyl- L-histidine ligand, stronger and less selective interactions with the nucleic acids were observed due to the additional hydrophobicity associated with the phenyl aromatic ring. Optimization of sample displacement chromatography parameters (especially (NH4 )2 SO4 concentration) at slightly acidic pH enabled excellent isolation of pDNA, by the removal of RNA in a negative mode, with binding capacities above 1.5 mg pDNA per mL of chromatographic support.info:eu-repo/semantics/publishedVersio

High Recovery Chromatographic Purification of mRNA at Room Temperature and Neutral pH

Messenger RNA (mRNA) is becoming an increasingly important therapeutic modality due to its potential for fast development and platform production. New emerging RNA modalities, such as circular RNA, drive the need for the development of non-affinity purification approaches. Recently, the highly efficient chromatographic purification of mRNA was demonstrated with multimodal monolithic chromatography media (CIM® PrimaS), where efficient mRNA elution was achieved with an ascending pH gradient approach at pH 10.5. Here, we report that a newly developed chromatographic material enables the elution of mRNA at neutral pH and room temperature. This material demonstrates weak anion-exchanging properties and an isoelectric point of 5.3. It enables the baseline separation of mRNA (at least up to 10,000 nucleotides (nt) in size) from parental plasmid DNA (regardless of isoform composition) with both a NaCl gradient and ascending pH gradient approach, while mRNA elution is achieved in a pH range of 5–7. In addition, the basic structure of the novel material is a chromatographic monolith, enabling convection-assisted mass transfer of large RNA molecules to and from the active surface. This facilitates the elution of mRNA in 3–7 column volumes with more than 80% elution recovery and uncompromised integrity. This is demonstrated by the purification of a model mRNA (size 995 nt) from an in vitro transcription reaction mixture. The purified mRNA is stable for at least 34 days, stored in purified H2O at room temperature