Carbon Dots Based Theranostic Platform for Dual-Modal Imaging and Free Radical Scavenging
Magnetofluorescent carbon dots (Cdots) doped with both P3+ and Mn2+ (abbreviated as PMn@Cdots) have been synthesized in an aqueous solution via a microwave-assisted pyrolysis method. In this system, the P3+ dopant was introduced to enhance the emission efficiency of the Cdots, while the presence of the Mn2+ dopant granted magnetic resonance imaging (MRI) capability. To the best of our knowledge, the present work is the first attempt to regulate red-emission and free radical scavenging of PMn@Cdots to be served as a dual-modal imaging nanoprobe and antioxidant agent. Unlike most red-emitting Cdots, the as-prepared PMn@Cdots can be readily purified from unreacted precursors through antisolvent precipitation instead of by time-consuming purification methods. The whole synthetic procedure is rapid, facile, efficiently reproducible, and scalable. More importantly, further conjugation of the PMn@Cdots with hyaluronic acid (termed PMn@Cdots/HA) gives them good in vivo and in vitro biocompatibility as well as the capability to selectively target CD44-overexpressing cancer cells, as investigated by flow cytometry, fluorescence, and MRI. Meanwhile, PMn@Cdots exhibit antioxidant activity against multiple DPPH, hydroxyl, and superoxide radicals, which is comparable to ascorbic acid. Favorably, PMn@Cdots/HA showed a dose-dependent cytoprotective capability against H2O2-induced oxidative stress in B16F1, HeLa, and HEL cells. Therefore, Cdots based theranostic platform can simultaneously function as potential therapeutic candidates and as dual-modal probes for enabling accurate diagnosis in future clinical applications.