2.3. Synthesis, photopolymerization and purification of PCDA-coated
silver nanoparticles
As prepared, H-Chit/AgNPs were coated with PCDA molecules
by adding a proper amount of monomer dissolved in ethanol to the
corresponding colloidal solutions, strictly following the protocol
described in Ref. [27]. The resulting suspension was maintained
under vigorous stirring for different incubation times (1, 2, 7 days)
and then stored at room temperature.
Photopolymerization of the diacetylene outer shell was carried
out directly in the aqueous suspension in a Rayonet photochemical
chamber reactor, operating at 254 nm and 35 W power. The 1 cm
quartz cuvettes with the PCDA-containing colloidal solutions were
kept for one minute at 10 cm distance from the UV lamps.
The crude polymerized nanohybrids were purified from free
chitosan chains, polyPCDA micelles and aggregates by centrifugation
at 8000 rpm for 15 min followed by filtration under vacuum
with a 1.2 μm glass-fiber filter. In this way, clean, stable,
blue polyPCDA/AgNPs (bpPCDA/AgNPs) were obtained (zeta
potential = 48±8mVin presence of chitosan as protecting agent),
which can be stored in aqueous suspension for months at room
temperature.