A biomineralisation bimetallic oxide nanoprobe with high stability and bio-safety for long-lasting magnetic resonance angiography of head-neck vessel and accurate diagnosis of tumor

In this study, a highly efficient bimetallic oxide nanoprobe was developed through bovine serum albumin (BSA)-mediated biomineralisation of Gd and Mn species (BSA@Gd/Mn). The incorporation of both Gd and Mn species notably enhanced the spin–lattice relaxation process, resulting in ultrahigh longitudinal relaxivity (r1). The r1 values of BSA@Gd/Mn reached 9.28 mM−1 s−1 at 3 T and 3.708 mM−1 s−1 at 7 T, respectively. Additionally, BSA@Gd/Mn exhibited prolonged blood circulation, with a half-life (t1/2) of 122 min five times longer than Gd-DTPA, facilitating magnetic resonance angiography (MRA) and tumor contrast imaging. Notably, the r1 value of BSA@Gd/Mn showed a pH-dependent increase, enabling tumor-specific signal amplification and precise MRI tumor diagnosis. In vivo high-resolution MRA demonstrated that BSA@Gd/Mn achieved clear visualisation of microvessels as small as 0.15 mm, with an imaging time window extending up to 2 h. Furthermore, in vivo MRI experiments revealed that BSA@Gd/Mn significantly enhanced T1-weighted imaging (T1WI) contrast, aiding in accurate tumor diagnosis. Therefore, the BSA@Gd/Mn nanoprobe presents a promising, efficient, and safe MRI contrast agent for the precise diagnosis of cardiovascular and cerebrovascular diseases, as well as tumors.