Interaction of phenols with thermo-responsive hydrogels

Swelling and differential scanning calorimetry measurements are reported on the effect of three hydrotropic molecules, phenol, resorcinol and phloroglucinol, on poly(N-isopropyl acrylamide) (PNIPA) hydrogels. As the hydroxyl number in this molecular sequence increases the temperature range of the volume phase transition (VPT) decreases and broadens, reflecting nonuniformity in the distribution of the guest molecules inside the gel and the effects of steric hindrance. A mean-field model, based on the Curie–Weiss theory of magnetism, is used to illustrate the effect of the phenols on the gel swelling. Observations with other phenols (pyrocatechol, hydroquinone and pyrogallol) show that the depression of the VPT temperature is also governed by the relative position of the hydroxyl groups.     

Application of the Partial Least Square Technique to Identify Critical Variables in the Immunosorbent Manufacturing

The partial least square technique (PLS) was applied to the monoclonal antibody (Mab) CB.Hep-1 immunosorbent manufacturing to determine the influence of cyanate ester concentration, ligand concentration and target ligand density on Mab coupling efficiency, elution capacity, Hepatitis B surface antigen purity and ligand leakage (output variables). Results demonstrated that cyanate ester concentration, ligand concentration and density do not have an influence on output variables in assessed ranges. Conversely, the eluted antigen purity was significantly influenced by cyanate ester concentration and ligand concentration. In conclusion, the PLS application allows for the identification of critical variables and improvement of established chromatographic processes.     

Thermal analysis of the improved Hummers’ synthesis of graphene oxide

Journal of Thermal Analysis and Calorimetry - The improved Hummers’ synthesis of graphene oxide (GO) from graphite is investigated to monitor how the functional groups form during the...     

Interactions in dopamine and indole loaded thermosensitive hydrogels seen by high sensitivity microDSC. Implications for drug delivery

Journal of Thermal Analysis and Calorimetry - Controlled and targeted drug delivery systems consist of a carrier matrix and one or more active ingredients. One of the roles of the matrix is to...     

Efficient synthesis of optically active 1-(2-carboxymethyl-6-ethylphenyl)-1H-pyrrole-2-carboxylic acid: a novel atropisomeric 1-arylpyrrole derivative

An efficient synthesis and resolution of (±)-1-(2-carboxymethyl-6-ethylphenyl)-1H-pyrrole-2-carboxylic acid has been developed for the preparation of novel optically active atropisomers. The ee values were measured by a ¹H NMR spectroscopic method using quinidine as the chiral complexing agent. Absolute configurations of the separated enantiomers were determined using single crystal X-ray diffraction measurements of both the disodium salt and the (R)-1-phenylethylamine salt of the enantiomerically pure dicarboxylic acid, separately. The analysis of the CD spectra with the aid of TD-DFT quantum chemical calculations confirmed the assignment of configurations.     

Rapid Identification of Potential Drug Candidates from Multi-Million Compounds’ Repositories. Combination of 2D Similarity Search with 3D Ligand/Structure Based Methods and In Vitro Screening

Rapid in silico selection of target focused libraries from commercial repositories is an attractive and cost-effective approach in early drug discovery. If structures of active compounds are available, rapid 2D similarity search can be performed on multimillion compounds’ databases. This approach can be combined with physico-chemical parameter and diversity filtering, bioisosteric replacements, and fragment-based approaches for performing a first round biological screening. Our objectives were to investigate the combination of 2D similarity search with various 3D ligand and structure-based methods for hit expansion and validation, in order to increase the hit rate and novelty. In the present account, six case studies are described and the efficiency of mixing is evaluated. While sequentially combined 2D/3D similarity approach increases the hit rate significantly, sequential combination of 2D similarity with pharmacophore model or 3D docking enriched the resulting focused library with novel chemotypes. Parallel integrated approaches allowed the comparison of the various 2D and 3D methods and revealed that 2D similarity-based and 3D ligand and structure-based techniques are often complementary, and their combinations represent a powerful synergy. Finally, the lessons we learnt including the advantages and pitfalls of the described approaches are discussed.     

Kinetic and Spectroscopic Study of C2H5C(O)O2 Radicals Using Laser Flash Photolysis and UV Absorption Spectrometry

Rate constant for the self-combination reaction of the propionylperoxy radical was measured at room temperature using laser photolysis - transient absorption technique. The observed rate coefficient is (1.44 ± 0.14)x10⁻¹¹ cm³ molecule⁻¹ s⁻¹ at 298 K. This revised version was published online in June 2006 with corrections to the Cover Date.     

Palladium as Catalyst in a Polycondensed Matrix, Part ii

In Part I of this series results on the formation of Pd-organic amine adducts, their polymerization, and the catalytic behavior of the catalyst formed were reported [1]. In the present paper results of IR and N₂ adsorption measurements are discussed. This includes the interactions of organic amines and Pd. Conclusions were drawn on the physical structure of the catalyst. Under the applied reaction conditions the Pd-containing polymers were formed to a certain extent, but in all cases a non-negligible part of the Pd-amine adduct remains unchanged.