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calcium alginate beads containing AgNPs as well as the blank beads (with no AgNPs), and these
prepared beads will be used as an antibacterial beads for a further medical application.
Methods
Materials
All chemicals were purchased from Sigma–Aldrich (Singapore), unless otherwise indicated.
Methods
1. Preparation of calcium alginate beads containing AgNPs
There are two steps used to prepare calcium alginate beads containing AgNPs as follows:
1.1 Preparation of AgNP suspension
AgNPs were prepared according to Jana
FUǰBM
. [11] as follows: The mixture (600 ml) of silver
nitrate (0.25 mM) and sodium citrate (0.25 mM) was prepared in deionized water under magnetic
stirring at room temperature. Sodium borohydride (10 mM, 18 ml) was added to such mixture under
magnetic stirring at room temperature, and this mixture was vigorously stirred for a further 2 h at room
temperature. The AgNP suspension (~600 ml) was then evaporated (Heidolph, Germany) at 37ºC until a
final volume of 50 ml was obtained. This suspension was subsequently kept at 4°C and protected from
light.
1.2 Preparation of calcium alginate beads containing AgNPs
The mixture (100 ml) of alginate (2 %w/v; Carlo Erba Reagents) and AgNP suspension (section
1.1; final concentration of 60 μg/ml) was prepared in deionized water and stirred using a stirring rod.
This mixture was dropped in calcium nitrate solution (2 %w/v, 200 ml) using a syringe. Then, calcium
alginate beads containing AgNPs were formed, and they were left in the calcium nitrate solution for a
further 30 min. Blank calcium alginate beads (with no AgNPs) were prepared in the same procedure
and used as a control. Thereafter, both beads were dried at room temperature for 24 h, and the dried
beads were kept in a desiccator.
2. Size measurement
Size of the beads was measured using an optical microscope. A diameter of the beads was
measured from four different positions of the diameter of the beads, and at least 13 beads were
calculated (mean±S.D.).
3. Water loss
