Biomedical subjects

Norberto Micali

Publications and source records attributed to Norberto Micali.

6 recordsLinked to original sources

PubMed2003

Fast drug stability determination by LC variable-parameter kinetic experiments.

Variable-parameter kinetic experiments were carried out using HPLC as analytical instrument. The hydrolysis of aspirin was followed both at variable-temperature and at variable-pH conditions. The peak areas relative to salicylic acid were processed by direct fit to a mathematical model and/or by differential method obtaining, by single experiments, the values of the apparent rate constant in the whole range of temperature and pH studied. The results, although the discontinuity of this kind of analysis, are in agreement with those obtained by constant-parameter kinetics but saving experimental time.

Aspirin↗

PubMed2003

Graft polymer solutions as sticky hard-sphere colloids.

We show that a solution of a graft (comb) polymer can exhibit an adhesive hard-sphere pair potential. In the present paper, static and dynamic light scattering measurements on a comb polymer at low molecular weight are performed and the results discussed in the framework of the colloidal theory for adhesive spheres. Renormalization group calculations are directly compared with experimental data on the cooperative diffusion coefficient using the scaled concentration parameter.

Biocompatible Materials↗

PubMed2003

Porphyrin deposition induced by UV irradiation.

Simple irradiation by UV light of porphyrin TpyP and its zinc(II) and manganese(III) metal derivatives in chlorinated solvents leads to the deposition on silica of mesoscale aggregates. The process is due to the photochemical decomposition of the solvent with generation of HCl, which causes the precipitation of a protonated form. The morphology of the resulting objects is driven by the nature of the inserted metal ion.

Journal Article↗

PubMed2003

Variable-ionic strength kinetic experiments in drug stability studies.

The dependence of the pseudo-first-order rate constant on the ionic strength for the alkaline hydrolysis of indomethacin has been obtained, for the first time, in a single kinetic experiment carried out by varying with time the salt concentration inside the reaction vessel. The kinetic profile obtained was processed using as a mathematical model the variable-parameter kinetic equation containing the Bronsted-Bjerrum equation as the dependence function. The results are in good agreement with those obtained by the traditional method but the experimental time is reduced to about one-tenth.

Drug Stability↗

PubMed2002

Temperature-rate profiles by polarimetric variable-temperature kinetic experiments to study racemization reactions.

The racemization of (-)-adrenaline was followed by polarimetric variable-temperature kinetic experiments obtaining activation parameters and k(obs)(T) profile in one tenth of the time usually spent for traditional kinetic runs. A polarimeter connected to a computer for the acquisition and processing of the analytical data was used. The kinetic profiles were processed by both an integral method and a differential method. The results are in good agreement with each other and with those obtained by constant-temperature kinetics.

Drug Stability↗

PubMed2002

From achiral porphyrins to template-imprinted chiral aggregates and further. Self-replication of chiral memory from scratch.

The presence of 10-13 M of chiral clusters of aromatic amino acids addresses aggregation of opposite-charged achiral porphyrin towards the formation of smart chiral assemblies. The latter supramolecular complexes are able to self-propagate and transfer their chiral information with a 100% yield. The chiral bias occurs through a correlated sequence of induction, memory, and amplification of chirality that strongly recalls possible prebiotic scenarios.

Circular Dichroism↗