2.6. Preparation of OSP–agarose gel films
Agarose powder (0.2 g), OSP (0.3 g), and 5mL of deionized water
were put in a 20-mL glass vial and intensively vortexed for
3min. The glass vial was then oven-heated at 110 ◦C for 10min.
The melting solution was poured into a petri dish (9 cm-dia)
while avoiding air bubble formation. After cooling, a thick
film was formed. Finally, the gel was cut for use as packing
materials.
To obtain carbon dots-entrapped OSP–agarose gel film,
agarose powder (0.2 g), OSP (0.1 g) and carbon dots (1.2mL)
were mixed in 5mL of deionized water within 20-mL glass
vials. After following the above-outlined protocol,the thin film
was tested for water permeabilization and color detection of
Mn2+ and Fe3+ ions at 0.1, 1.0, and 10 ppm.