One-pot synthesis of Gd3+-functionalized gold nanoclusters for dual model (fluorescence/magnetic resonance) imaging

Abstract

Multimodal imaging that aims to advance imaging by strategically combining existing technologies with uniquely designed probes has attracted great interest in recent years. Here, Gd³⁺-functionalized gold nanoclusters (Gd-AuNCs) were synthesized for dual model (fluorescence/magnetic resonance) imaging. We designed a cyclodecapeptide that contained one tyrosine and two cysteines for the synthesis, and it biomineralized gold nanoclusters and chelated Gd³⁺ ions at the same time. The Gd-AuNC probes emit an intense red fluorescence under UV light, while exhibiting a high longitudinal relaxivity of 41.5 ± 2.5 mM⁻¹ s⁻¹ and a low r₂/r₁ ratio of 1.2 at 0.55 T. The versatility of the probes for dual model imaging has been demonstrated by means of cellular imaging and in vivo T₁-weighted MRI. Thanks to the optimal size of the nanocluster, it can freely circulate in the blood pool without significant accumulation in the liver and spleen, but with a long circulation half-life (t_1/2) of ∼128 min. Moreover, the nanoclusters can be noticeably excreted from the body within a period of 24 h through renal clearance, making it attractive for in vivo multimodal imaging.