SPECTRAL ANALYSIS OF IN MONOLITHIC Katarzyna Polska Faculty

SPECTRAL ANALYSIS OF IN MONOLITHIC Katarzyna Polska Faculty of Chemistry, Maria Pl. M. C. Skłodowskiej 2,

CON A – H 2 P INTERACTIONS SILICA GELS and Stanisław Radzki Curie-Skłodowska University 20 -031 Lublin, Poland 3 rd International Conference on Sol-Gel Materials, Research, Technology, Applications June 6 -11 2004, Wrocław, Poland

PURPOSE Two water-soluble cationic porphyrins: tetrakis[4 -(trimethylammonio) phenyl] porphyrin (H 2 TTMe. PP), tetrakis(1 -methyl-4 -pyridyl) porphyrin (H 2 TMe. Py. P) and their complexes with lectin – concanavalin A (Con A) have been encapsulated in monolithic silica gels (obtained by polycondensation of tetraethoxysilane) and studied using absorption and fluorescence spectroscopic techniques. The sugar-binding and haemagglutinating properties of lectins are used for preparative and analytical purposes in chemistry, cell biology and immunology. Some lectins have ability to interact preferentially with transformed cells and they have been suggested for use as carriers in targeted delivery to tumour cells. Finding lectins with high affinity for porphyrins can open up new possibilities, such complexes can be employed in photodynamic therapy (PDT) or as a built-in sensors. Studies of lectin -porphyrin interactions are also important from the point of view of the effect of lectins on porphyrin-containing biomolecules in organisms. 3 rd International Conference on Sol-Gel Materials, Research, Technology, Applications June 6 -11 2004, Wrocław, Poland

CONCANAVALIN A is the lectin of the jack bean (Canavalia Ensiformis), its conformation depends on p. H, beetwen p. H 4 and 5 it exists as a dimer and at p. H above 7 it is predominantly tetrameric a b Fig. 1. Structure of Concanavalin A protomer (a) and 1: 1 H 2 TTMe. PP-Con A complex (b). 3 rd International Conference on Sol-Gel Materials, Research, Technology, Applications June 6 -11 2004, Wrocław, Poland

CATIONIC PORPHYRINS H 2 TTMe. PP H 2 TMe. Py. P 5, 10, 15, 20 -tetrakis [4 -trimethyl ammonio)phenyl]porphyrin 5, 10, 15, 20 -tetrakis[4 -(1 -methyl 4 -pyridyl)]-21 H, 23 H-porphyrin 3 rd International Conference on Sol-Gel Materials, Research, Technology, Applications June 6 -11 2004, Wrocław, Poland

SOL-GEL PREPARATION TEOS sol Con. A H 2 P Mixing of TEOS sol & Con. A-H 2 P solution Gel formation Aging Con A–H 2 P 3 rd International Conference on Sol-Gel Materials, Research, Technology, Applications June 6 -11 2004, Wrocław, Poland

Fig. 3. Monoliths of silica gel immobilized with H 2 TTMe. PP after 7 days, 1 month and 6 months of drying. 3 rd International Conference on Sol-Gel Materials, Research, Technology, Applications June 6 -11 2004, Wrocław, Poland

Fig. 4. Silica gel monoliths immobilized with H 2 TTMe. PP (A), Con A (B) and H 2 TTMe. PP / Con A complex (AB) after 6 months of drying. 3 rd International Conference on Sol-Gel Materials, Research, Technology, Applications June 6 -11 2004, Wrocław, Poland

SOLUTION SOL-GEL Fig. 2. Absorption and emission spectra of H 2 TTMe. PP and H 2 TTMe. PP / Con A systems measured in tris solution (p. H 8. 7) and in monolithic silica gels. 3 rd International Conference on Sol-Gel Materials, Research, Technology, Applications June 6 -11 2004, Wrocław, Poland

CONCLUSIONS Biologically important compounds encapsulated in silica gels have many unique features, as good mechanical durability, high resistance to chemical and biological degradation and, what is the most important, they retain their spectroscopic properties and biological activity. The advantages of biologicals captured in sol-gels might give them applications as biosensors, diagnostic devices and catalysts. Monolithic silica gels immobilized with Con A – H 2 P systems were obtained by the solgel polymerization of TEOS. Those monoliths were characterized by UV-Vis absorption and fluorescence methods. The results suggest that there is complexation between Con A and cationic porphyrins. The binding with Con A was found to increase the porphyrin fluorescence intensity and the red-shift in the absorption and emission maxima have been observed. 3 rd International Conference on Sol-Gel Materials, Research, Technology, Applications June 6 -11 2004, Wrocław, Poland