As-synthesized CQDs/TiO2 composite nanofiber was also used
to test the antibacterial activity by the zone inhibition method using
E. coli as the model organism, as shown in Fig. 6. Pristine TiO2
nanofibers (Fig. 6a) show a little zone of inhibition because TiO2
nanofiber is UV light driven photocatalyst. On the other hand,
CQDs/TiO2 composite nanofibers (Fig. 6b) show significant zones
of inhibition which confirms that anchoring of CQDs in to TiO2
nanofibers enhances antibacteria lefficiency due to their capability
to absorb visible light and hence can generate electron–hole pairs.
The mechanism of antibacterial activity of CQDs/TiO2 composite
nanofibers towards E. coli is similar to the dye degradation process.
The electron–hole pairs react with O2 or OH to give rise to active
oxygen species,which are able to react with DNA, cell membranes,and cellular proteins,leading to bacterial cell death