In recent years, biomedical research has encountered several difficult problems related to an increasing number of diseases, as consequence of life expectancy growth in the developed countries.
Two main recovering actions have been adopted:
1) precocious diagnosis of biochemical anomalies;
2) development of new pharmacological techniques aiming to minimize undesirable effects of the therapy.
Many efforts have been directed to the development of "intelligent" molecules, capable of selective recognition of target cells. Since their peculiar properties, porphyrines seems to be ideal candidates.
In particular, hydro-soluble porphyrines and their metal complexes have been recently employed in several applications, such as in the treatment of transmissible spongiform encephalopathy (called, in bovine variant, "mad cow disease"), or in chemotherapy of tumours, since their strong affinity for cancerous cells. The limit of the insolubility of porphyrines in aqueous media has been overcome by introducing ionic groups into these molecules; their charges do not significantly influence porphyrines affinity for DNA molecules. Nevertheless, interaction with cell membranes and the capability of penetration inside the cells are different respect to those of neutral molecules. However, only a few works on hydro-soluble neutral porphyrines are available in the literature.
Our research has been directed to the planning, the synthesis and the chemical characterization of hydro-soluble uncharged porphyrines; in particular, the synthesis of porphyrines bearing hydro-soluble and biocompatible polymeric chains in peripheral positions has been carried out. Structural and functional aspects of these hydro-soluble products have been appropriately investigated. Metal complexes of these porphyrin derivatives can interact with several molecules (protids, nucleic bases etc.) modifying their UV-Vis absorption spectra.
These metal-porphyrines are utilizable as "molecular-sensors" or, suitably modified, as "molecular-finders". Since their affinity for cancerous cells and their strong absorption in the visible region, metal-porphyrines are usable in the treatment of neoplasms by photodynamic therapy: when given to patient, these molecules are fixed on cancerous cells that can be photo oxidized by a laser, meanwhile closed tissues are preserved.
Studies about the behaviour of these substances in aqueous solutions have been carried out in collaboration with "Istituto per i Processi Chimico-Fisici" of CNR, with "Dipartimento di Fisica" of the University of Messina and with "Istituto Nazionale per la Fisica della Materia".
Furthermore, their "in-vitro" activities for biochemical applications have been included in a multidisciplinary European Network of Excellent.
In a closed future, our research will be developed by introducing particular peripheral groups that can recognize molecules or complex bio structures on the base of their sterical and/or chemo selective factors, to obtain an "intelligent " molecule useful for new and specifica applications.
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