Nanodiamonds as a novel T1-contrast agent for MRI

Motivation: The structural defects in diamond particles, are known for their paramagnetic properties. Here we aim to determine if the presence of paramagnetic centers in detonation nanodiamonds particles can be exploited to enhance longitudinal relaxation time (T1). Goal(s): Introduce nanodiamonds as a novel T1-contrast agent and contrast differences with gadolinium chelates. Approach: Using high-field, 7 T MRI, longitudinal and transverse relaxation rates were measured and compared between detonation and air-oxidized detonation nanodiamonds. In-vivo demonstration was carried out using chicken embryos. Results: Air-oxidized detonation nanodiamonds have superior longitudinal and transverse relaxivity compared to detonation nanodiamonds. We demonstrate their potential as an alternative, gadolinium-free T1-contrast agent. Impact: Nanodiamonds hold great promise for biomedical applications mostly due to their biocompatibility, non-toxicity and versatile functionalization. A possibility for direct visualization by means of T1-weighted MRI is opening new venues for tracking over time without a concern for Gd3+-toxicity.