SUPRAMOLECULAR ORGANIZATION AND PROCESS OF MARINE GEL
NETWORK FORMATION VISUALIZED BY ATOMIC FORCE MICROSCOPY
Tea Mišić, Vesna Svetličić, Vera Žutić
Ruđer Boškovic Institute, Bijenička 54, Zagreb, 10000, Croatia
The macroscopic marine gel phase appears episodically in the northern
Adriatic Sea. The phenomenon manifests itself in rapid production of enormous
amounts of gelatinous matter in the water column and on the sea surface. The
mechanism of marine gel formation, its stability and the role of gel state in marine
ecosystem is becoming a most challenging exercise in converging disciplines of
marine chemistry, microbiology and biophysics.
Organic fraction of marine gel is mainly composed of polysaccharides,
while proteins and lipids are present in small amounts. Although chemical
composition of marine gel has been largely studied, determination of the
structural parameters remains much more difficult, mainly due to the complexity
and heterogeneity.
Atomic force microscopy (AFM) has become an important technique for
studying biopolymers since it offers high spatial resolution in three dimensions,
down to subnanometer level with minimally perturbing sample preparation. We
used AFM to study supramolecular organization of marine gel and its
polysaccharide fraction at the molecular scale to reveal molecular mechanism of
gel formation. Thermal denaturation of marine gel network to single short
polymer fibrils upon heating and renaturation of the network after cooling was
directly visualized by AFM. These results directly demonstrate the capacity of
marine polysaccharides to selfassamble into complex gel network, but also
reveal the molecular mechanism of gel formation in the ocean.