Here, we report the preparation of carbon dots (CDs) and doping with different elements namely boron, nitrogen and phosphorous using facile single step hydrothermal method. We used biopolymers as the source material for CDs synthesis. The prepared carbon dots and elements (B, N and P) doped carbon dots’ physicochemical properties are investigated using different analytical techniques. Several analytical characteristics such as Uv-visible spectroscopy, fluorescent spectroscopy and transmission electron microscopy confirm the doping of element into carbon dots. From DLS analysis it was found that the prepared carbon dots are range from 3-9 nm. Excitation dependent fluorescence with high quantum yields for B and N doped CDs showed 47% and 44%, respectively. The doped CDs impact on cell viability was investigated against neuronal PC12 cells. Interestingly, the prepared carbon dots did not affect the differentiation process of neuronal cells. Hence, the highly fluorescent CDs can be served as excellent materials for neural tissue engineering as well as biomedical engineering applications.
In this work, we exploited time-resolved fluorescence polarization anisotropy (TRFA) to characterize un-doped and doped carbon dots (CDs). The rotational correlation time related to the size of the particle through classical Stokes-Einstein -Debye equation. The TRFA technique applied in this study achieves picoseconds time resolution, which approximately corresponds to the particle size determination at sub-nanometer precision. The calculated diameter of the CDs from the measured depolarization time constants in aqueous solution is well matches with the actual size of the CDs within the precision. This study proves that the TRFA method is highly complementary with other size determination techniques.