spectral analysis of in monolithic katarzyna polska faculty of chemistry, maria pl. m.c....
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SPECTRAL ANALYSIS OF
IN MONOLITHIC Katarzyna Polska
Faculty of Chemistry, Maria
Pl. M.C. Skłodowskiej 2,
CON A – H2P INTERACTIONS
SILICA GELS
and Stanisław Radzki
Curie-Skłodowska University
20-031 Lublin, Poland
3rd International Conference on Sol-Gel Materials, Research, Technology, ApplicationsJune 6-11 2004, Wrocław, Poland
PURPOSE
Two water-soluble cationic porphyrins: tetrakis[4-(trimethylammonio) phenyl] porphyrin
(H2TTMePP), tetrakis(1-methyl-4-pyridyl) porphyrin (H2TMePyP) 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, ApplicationsJune 6-11 2004, 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 H2TTMePP-Con A complex (b).
3rd International Conference on Sol-Gel Materials, Research, Technology, ApplicationsJune 6-11 2004, Wrocław, Poland
a b
H2TTMePP H2TMePyP
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, ApplicationsJune 6-11 2004, Wrocław, Poland
3rd International Conference on Sol-Gel Materials, Research, Technology, ApplicationsJune 6-11 2004, Wrocław, Poland
Mixing of TEOS sol& ConA-H2P solution
Gel formation Aging
TEOSsol
ConAH2P
SOL-GEL PREPARATION
Con A–H2P
3rd International Conference on Sol-Gel Materials, Research, Technology, ApplicationsJune 6-11 2004, Wrocław, Poland
Fig. 3. Monoliths of silica gel immobilized with H2TTMePP after 7 days, 1 month
and 6 months of drying.
3rd International Conference on Sol-Gel Materials, Research, Technology, ApplicationsJune 6-11 2004, Wrocław, Poland
Fig. 4. Silica gel monoliths immobilized with H2TTMePP (A), Con A (B)
and H2TTMePP / Con A complex (AB) after 6 months of drying.
3rd International Conference on Sol-Gel Materials, Research, Technology, ApplicationsJune 6-11 2004, Wrocław, Poland
H2TTMePP + Con A
exc = 430 nm
[nm]400 450 500 550 600 650 700 750 800 850 900
Inte
nsi
ty0
1e+6
2e+6
3e+6
4e+6
5e+6
6e+6
7e+6
8e+6
9e+6H
2TTMePP + Con A
H2TTMePP
688 nm
667 nmH2TTMePP + Con A
(exc430 nm)
[nm]400 450 500 550 600 650 700 750 800 850 900
Inte
nsi
ty
0
5e+5
1e+6
2e+6
2e+6
3e+6
3e+6
4e+6
4e+6
603 -> 609
648 -> 651
699 -> 710
[nm]200 250 300 350 400 450 500 550 600 650 700
Ab
sorb
ance
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
CM Con A x 106 0 20 40 60 80 100 120
Ab
sorb
ance
in 4
13 n
m
0.2
0.4
0.6
0.8
1.0
H2TTMePP + Con A [TRIS]
pH 8.7, log K = 5.64 Soret Band
413 nm280 nm
430 nm
H2TTMePP + Con A
H2TTMePP
[nm]350 400 450 500 550 600 650 700
Ab
sorb
ance
0.0
0.5
1.0
1.5
2.0
2.5
solutiongel before dryinggel after drying
518 nm
513 nm
553 nm
552 nm 592 nm
589 nm
649 nm
646 nm
SOLUTION SOL-GEL
Fig. 2. Absorption and emission spectra of H2TTMePP and H2TTMePP / 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 – H2P 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, ApplicationsJune 6-11 2004, Wrocław, Poland