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 Lublin, Poland 3rd International Conference on Sol-Gel Materials, Research, Technology, Applications June , Wrocław, Poland

PURPOSE Two water-soluble cationic porphyrins: tetrakis[4-(trimethylammonio) phenyl] porphyrin (H 2 TTMePP), tetrakis(1-methyl-4-pyridyl) porphyrin (H 2 TMePyP) 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 photodyna- mic 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. 3rd International Conference on Sol-Gel Materials, Research, Technology, Applications June , Wrocław, Poland

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

H 2 TTMePP H 2 TMePyP CATIONIC PORPHYRINS 5,10,15,20-tetrakis [4-trimethyl ammonio)phenyl]porphyrin 5,10,15,20-tetrakis[4-(1-methyl- 4-pyridyl)]-21H,23H-porphyrin 3rd International Conference on Sol-Gel Materials, Research, Technology, Applications June , Wrocław, Poland

3rd International Conference on Sol-Gel Materials, Research, Technology, Applications June , Wrocław, Poland Mixing of TEOS sol & ConA-H 2 P solution Gel formationAging TEOS sol ConA H 2 P SOL-GEL PREPARATION Con A–H 2 P

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

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

3rd International Conference on Sol-Gel Materials, Research, Technology, Applications June , Wrocław, Poland SOLUTIONSOL-GEL Fig. 2. Absorption and emission spectra of H 2 TTMePP and H 2 TTMePP / Con A systems measured in tris solution (pH 8.7) and in monolithic silica gels.

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 sol-gel 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. 3rd International Conference on Sol-Gel Materials, Research, Technology, Applications June , Wrocław, Poland