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Trends in Interdisciplinary Studies Revealing Porphyrinic Compounds Multivalency Towards Biomedical Application

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Autori: Socoteanu R. P., Boscencu R., Hirtopeanu A., Manda G., Oliveira A.S., Ilie M., Vieira Ferreira L.F.

Editorial: Reza Fazel , InTech, Trends in Interdisciplinary Studies Revealing Porphyrinic Compounds Multivalency Towards Biomedical Application, în Biomedical Engineering - From Theory to Applications, ISBN 978-953-307-637-9, 2011.


Over the past few decades, many research groups have set as main target to investigate biological uses of porphyrins. To understand the trend of these applications, and most important to be able to predict some of the future steps it is useful first to review the general physical properties of this essential class of molecules, in parallel with the presentation of main aspects of the involved biomedical fields. Therefore, the first section of this survey provides a description of the general properties porphyrins as biomedical structures. Specific biomedical applications of these compounds are then discussed in the following order: uses as medical devices, nanobiomaterials and in vitro studies. The multivalency character is underlined by three features: the capacity of free bases to coordinate a central metal, the wide range of partnerships with several structures from amino acids to fullerenes and the ability to play an important role, even fundamental, in PDT of cancer, antimicrobial and antiviral activities, act as biomarkers and even as anti-HIV agent. As relevant example of the multivalency a good reference is the metalloporphyrin geometry. In this respect function of the metal ion volume and his adjacent oxidation state, the complexation of the metalloporphyrin could ensue through the reaction from one or two monodentated ligands, the molecular geometry following the order: planar- pyramidal- octaedrical. The porphyrins that contain Mg(II), Cd(II), Zn(II) as central metal ion easily react with a monodentated ligands forming penta-coordinated complexes with square- pyramidal geometry whereas Fe(II), Co(II), Mn(II) metalloporphyrins could coordinate two extraligands with octaedrical geometries; all those configurations having direct influence in further biomedical use.
Also, the place of metalloporphyrins among the successive three photosensitizer generations will be correlated with last decade applications. Because the porphyrinic core act as tetradentated ligand within the available space for metal ion coordination (around the value of 3.7 Å), is suitable for a wide range of metal insertions (it is used to refer as „periodic table of porphyrins” due this remarkable capacity). The last decades trends include Fe(II), Co(II), Zn(II) and also Pd(II) metalloporphyrins as statistically mainly involved in recent studies with biomedical involvement. Those compounds with improved properties include in all studies: high purity, large absorption peaks in the red and near-infrared regions of the electromagnetic spectrum, good even excellent singlet oxygen quantum yields and high uptake in cancer cells or other kind of pathogenic media.
One of the general trends is to combine porphyrins with other compounds equal powerful in disease treatment, emphasizing the asymmetry features.
In metalloporphyrins the influence of incorporated metal in biomedical studies is essential, one hand because the metal itself bring his one therapeutic qualities, on the other hand the due to the effect of coordinated metal ion on the redox potential (at his turn essential in bio-processes) who increase the photobleaching in the case of Mg(II) and Zn(II) with lower oxidation potential vs. first row of the transition metal ions metalloporphyrins.
The approach to evaluate the themes regarding the entire chain of these studies of the porphyrin in one exhaustive monographic study is justified by the actual importance in medical research, especially in photosensibilization in cancer diagnosis and therapy field.
The domain is interdisciplinary one, and, from this point of view, the studied theme try to demonstrate the importance of the notion interference between complex combination chemistry, chemical-physics, biochemistry and medicine in one profound approach of this subject.

Cuvinte cheie: porphyrins, biomedical engineering, applications