One-step synthesis of surface passivated carbon microspheres for enhanced photoluminescence and their application in multifunctional magnetic-fluorescent imaging

Multimodality molecular imaging has recently attracted much attention, because it can take advantage of individual imaging modalities by fusing together information from several molecular imaging techniques. Herein, we report a bifunctional contrast agent connecting MR and luminescent imaging. The bifunctional contrast agent, carbon@Gd-DTPA microspheres, arise from carbon microspheres, which are synthesized on a large scale through a Na(3)cit-assisted solution route. The T-1-agent, Gd-DTPA, is then conjugated to the carbon microspheres through N-ethyl-N9-[3-(dimethylamino)propyl] carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) coupling chemistry using surface absorbed Na(3)cit molecules as an intermedium. Meanwhile, a formation mechanism of the carbon microspheres has been suggested. Furthermore, we also prove that the application of the carbon@Gd-DTPA bifunctional contrast agents for MR imaging and luminescent imaging can be established successfully. These results show that the primary Na(3)cit molecules have been confirmed to serve triplicate roles as an oriented agent to produce carbon microspheres, an intermedium to conjugate Gd-DTPA and surface passivation agents to improve photoluminescence.