Dual-property blue and red emission carbon dots for Fe(III) ions detection and cellular imaging

The excitation wavelength-dependent and -independent emissions are two crucial fluorescent properties of carbon dots (CDs). However, CDs reported till date exhibit only one of these properties, which limits their practical applications. Herein, dual-property carbon dots (DCDs) with both the excitation wavelength-dependent and -independent emissions were synthesized via a facile one-step solvothermal method using 4-(2-pyridylazo)-resorcinol as the carbon precursor. The multi-functional applications of the resulting DCDs were also evaluated. The as-prepared DCDs exhibited not only excellent monodispersity, high photostability, and storage stability, but also low toxicity, good biocompatibility, and cellular bioimaging capability. In addition, the DCDs exhibited excitation-dependent emission photoluminescence under low excitation wavelengths. The DCDs exhibited good Fe3+ detection by quenching the blue emission fluorescence and showed a relatively low Fe3+ detection limit of 0.067 μmol·L−1 based on three times signal-to-noise criteria (R2 = 0.99). Furthermore, the DCDs showed excitation-independent emission at low excitation wavelengths and exhibited red emission at about 598 nm to avoid damage to the body. These results demonstrate the excellent bioimaging properties of the DCDs. Owing to their dual PL properties, the as-prepared DCDs exhibited multi-functional applications: Fe3+ detection and A549 cell bioimaging. These results will be helpful in developing novel CDs for applications in various fields.