Manganese-Doped Carbon Dots with Redshifted Orange Emission for Enhanced Fluorescence and Magnetic Resonance Imaging
Sijia Sun, Lining Zhao, Di Wu, Hongxin Zhang, Haichen Lian, Xiaolong Zhao, Aiguo Wu, Leyong Zeng
Abstract
Metal-doped carbon dots (CDs) exhibited promising application in fluorescence and magnetic resonance (MR) imaging, but developing manganese-doped CDs (Mn-CDs) with long wavelength emission and enhanced MR performance is a challenge. Herein, using a one-step solvothermal method, Mn-CDs with redshifted orange emission and enhanced longitudinal relaxation were synthesized for fluorescence and MR imaging. The results indicated that the prepared Mn-CDs had a uniform size distribution, and the average size was 5 nm. Moreover, Mn-CDs possessed a stronger fluorescence performance than Mn-free CDs, and simultaneously, the emission wavelength can redshift from 542 nm (green emission) to 578 nm (orange emission), owing to the increasing N-doping. Because of the movement limit of Mn2+, Mn-CDs exhibited high T1-weighted MR imaging performance with a longitudinal relaxation rate of 12.69 mM–1·s–1. The in vivo experiments demonstrated their excellent fluorescence and MR imaging with safety and reliability. Therefore, the prepared Mn-CDs with orange emission can be an excellent candidate as a dual-modal nanoprobe for fluorescence and MR imaging.