Identifying macrophage enrichment in atherosclerotic plaques by targeting dual-modal US imaging/MRI based on biodegradable Fe-doped hollow silica nanospheres conjugated with anti-CD68 antibody.

Macrophage recruitment has emerged as the crucial force driving the initiation and progression of atherosclerotic lesions. Therefore, the identification of macrophages in plaques is of vital importance for identifying vulnerable plaques, and noninvasive imaging methods are particularly desirable. Some studies have reported that MRI can detect plaque macrophages through targeted nanoparticles, but it is still hard for an US to detect macrophages in atherosclerotic plaque. In this study, anti-CD68 receptor-targeted Fe-doped hollow silica nanoparticles (CD68-Fe-HSNs) were fabricated as a dual-modal US/MRI contrast agent for identifying macrophages of aorta ventralis atherosclerotic plaques in ApoE-/- mice, confirmed by immunofluorescence and bio-TEM. This system possesses biodegradable characteristics even though it is an inorganic mesoporous nanosystem, indicating its potential high biocompatibility for further in vivo research. We expect that these dual-modal US/MRI nanoparticles will play a role in assessing vulnerable plaque in future research studies.