Albumin nanocomposites with MnO/GdO motifs for precise MR imaging of acute myocardial infarction in rabbit models.

The severe mortality and morbidity of myocardial infarction requests appropriate and accurate detection. Considering pathological profile of the acidic myocardial infarction microenvironments, herein, the low pH-sensitive albumin nanocomposites with MnO motifs (MnO@BSA) have been engineered for T-weighted MR imaging of myocardial infarction, while using non-pH-responsive GdO@BSA nanocomposites as control. The nanocomposites were 20-30 nm in diameter with spheroid morphology. Besides, the MnO@BSA have exhibited pH-triggered releasing of Mn, demonstrating approximately 38-fold and 55-fold increased molecular relaxivity at acute myocardial infarction-mimicking pH 6.5 (13.08 mMs) and macrophage intracellular pH 5.0 (18.76 mMs) compared to the extremely low relaxivity (0.34 mMs) at normal physiological conditions (pH 7.4). However, the GdO@BSA with molecular relaxivity approximately 10 mMs were without pH-sensitive properties. Furthermore, the MnO@BSA have demonstrated high accumulation in the acute myocardial infarction regions and fast metabolism from the body after systemic injection, accounting high contrast enhancement for accurate MR imaging of acute myocardial infarction in rabbit models, demonstrating better diagnostic performance over the controls.