Optimisation of dynamic nuclear polarisation of [1-13C] pyruvate by addition of gadolinium-based contrast agents

► All gadolinium based contrast agents (GBCAs) gave enhanced solid state polarisation. ► Open structured GBCA gave large decreases in liquid state polarisation and T1. ► Macrocyclic structured GBCA retained enhanced liquid state polarisations with minimal decreases in T1. ► Near maximum solid state enhancement was obtained with GBCA concentrations of 2 mM.