To develop metal-free magnetic resonance imaging (MRI) contrast agents, organic radical based contrast agents have been proposed as a promising alternative to obtain less toxic and safer MRI contrast agents. However, the low relaxivity and rapid in vivo reduction have limited the application of organic radicals as MRI contrast agents. As a special class of polymer, dendrimers with three-dimensional molecular structure and multiple tunable functional groups on surface, enable the facile chemical modification with organic radicals. With dendrimer as scaffold, a considerable amount of effort has been made to develop completely organic contrast agents. Herein, this mini review reports the recent advances of contrast agents with dendrimers as scaffold functionalized with radicals on the surface.

The authors would like to acknowledge the financial support from the Spanish Government (PID2019-105622RB-I00, CTQ2017-90596-REDT and Severo Ochoa FUNFUTURE-FIP-2020 projects), CSIC (Intramural CSIC projects 201760E080 and 202360E61), Generalitat de Catalunya (2021 SGR 00438) and CIBER-BBN (BBN23PIV01 project). ICMAB acknowledges Spanish MICINN through the Severo Ochoa Centres of Excellence Programme Grant CEX2019-000917-S. Songbai Zhang acknowledges the China Scholarship Council.

With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Peer reviewed