Chitosan based fibers embedding carbon dots with anti-bacterial and fluorescent properties

Due to the intriguing properties of Chitosan (CS), many efforts have been paid for CS-based fiber preparation. As it is impossible to prepare CS fiber directly, facilitating polymers such as polyvinyl alcohol (PVA) possessing necessary properties that enable CS-based fiber fabrication is used. For this purpose, 3 wt% of CS in 90% acetic acid solution and 6 wt% PVA solution in DI water used in CS/PVA fiber preparation at different proportions for example, 2:1, 9:1 and 10:1 by weight to fabricate fibers by electrospinning method. Furthermore, to render fluorescent property to CS/PVA (9:1) fibers, N-doped carbon dots (C-dots) added into fiber precursor during fiber preparation. The emission peak of C-dots based fibers that with fluorescent features was observed at around 436 nm. The morphological, structural and, thermal characterizations of CS-based fibers were done with scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analyzer, respectively. Anti-bacterial activity of bare CS/PVA was increased with the increase in amounts of C-dots embedding. The inhibition of zone of CS/PVA (9:1) fibers was increased from 1.8 +/- 0.2 cm to 2.1 +/- 0.3 cm and 2.9 +/- 0.4 cm against E. coli by increasing the amounts of C-dots from 2.9 mg and 5 mg. Also, the same behavior was observed against S. aureus where the inhibition zone is increased from 2.5 +/- 0.1 cm to 3.2 and 3.5 cm by doubling the C-dots amounts in CS/PVA fiber. Moreover, bare and C-dots containing CS/PVA fibers were found blood compatible (nonhemolytic) up to 1 mg/mL concentration according to hemolysis and blood clotting tests.