Novel Synergistic Strategy for Enhanced Performance in NIR-II FI-PAI-MRI Trimodal Imaging

The integration of emerging imaging modalities, such as fluorescence imaging (FI) and photoacoustic imaging (PAI), with conventional techniques like magnetic resonance imaging (MRI), not only mitigates the former's limitations in tissue penetration depth but also compensates for the latter's shortcomings in temporal resolution and molecular sensitivity. This study proposed an emerging strategy for multifunctional synergistic enhancement of imaging performance. Specifically, a triple-modality imaging probe capable of near-infrared-II (NIR-II) FI-PAI-MRI has been constructed, which coencapsulated the NIR-I fluorophore ICG, NIR-II fluorophore IR-1061, and ultrasmall copper sulfide quantum dots (u-Cu_2-x S QDs). The results demonstrated that co-loading ICG and IR-1061 enables a Förster resonance energy transfer (FRET) effect, effectively enhancing its NIR-II fluorescence performance by 2-fold. In vivo imaging revealed a clearer visualization of murine vascular structures. Furthermore, IR-1061 exhibited photothermal properties within the probe, which synergized with u-Cu_2-x S QDs to augment the PAI performance. The magnetic resonance properties of u-Cu_2-x S QDs were integrated with the second NIR-II FI and PAI capabilities, thereby compensating for the limitations of optical imaging in tissue penetration depth. This work proposes a multimodal synergistic enhancement strategy, offering a novel design paradigm for advancing NIR-II multimodal imaging.