Tamarind xyloglucan from seeds (Tamarindus indica L.) purchased
from Megazyme (Bray, Ireland) was composed of xylose,
glucose, galactose and arabinose in the proportion of
38:42:16:4. The 1 % (w/v) aqueous solution of the xyloglucan
was diluted 20 times. Then it was stirred for 12 h in room
temperature. Since XG has a tendency for self-association in
aqueous solutions, the diluted sample (1.5 ml) was treated
with low power ultrasounds (vibration amplitude 32 μm
and power 130 W) for 30 s to reduce aggregates and
macroparticles. The ultrasonic processor Vibra-Cell
VCX130FSJ (Sonics & Materials, Inc., Newtown, USA)
with microtip probe of 3 mm diameter was used. The
treatment was optimized to possibly obtain a high yield
of molecule deployment during AFM scanning.
For structure characterization, 5 μl of the xyloglucan solution
was dropped onto the freshly cleaved mica and dried for
1 h in ambient air. This causes adhesion of molecules to substrate
which facilitates scanning by AFM tip of biopolymers