A Thrombin-Responsive Nanoprobe for In Vivo Visualization of Thrombus Formation through Three-Dimensional Optical/Computed Tomography Hybrid Imaging

Abstract

Early spontaneous detection of thrombin activation benefits precise theranostics for thrombotic vascular disease. Herein, a thrombin-responsive nanoprobe conjugated by a FITC dye, PEGylated Fe 3 O 4 nanoparticles, and a thrombin-sensitive peptide (LASG) was constructed to visualize thrombin activation and subsequent thrombosis in vivo. The FITC dye was linked to the LASG coated on the Fe 3 O 4 nanoparticles for sensing the thrombin activity via the Forster resonance energy transfer effect. In vitro fluorescence imaging showed that the fluorescence signal intensity increased significantly after incubation with thrombin in contrast to that of the control group (p < 0.05), and the signal intensity was enhanced with the increase in thrombin concentration. Further in vivo fluorescence imaging also revealed that the signal elevated markedly in the left common carotid artery (LCCA) lesion of the mice thrombosis model after nanoprobe injection, in contrast to that of the control + nanoprobe group (p < 0.05). Moreover, the thrombin inhibitor bivalirudin could decrease the filling defect of the LCCA. Three-dimensional fusion images of micro-CT and fluorescence confirmed that filling defects in the LCCA were nicely colocalized with fluorescence signal caused by nanoprobes. The nanoplatform based on a thrombin-activatable visualization system could provide smart responsive and dynamic imaging of thrombosis in vivo.

LPS-Induced Coagulation and Neuronal Damage in a Mice Model Is Attenuated by Enoxaparin

“…Although this study did not include a control group treated with enoxaparin only, we assume that its effects are due to the interaction between enoxaparin and inflammation during increased BBB disruption. This is supported by a previous study indicating that enoxaparin treatment in healthy wild-type mice did not affect brain intrinsic inflammation and behavior [ 61 ]. As mentioned above, evaluation of peripheral inflammatory markers is difficult in mice, calling for future research in other models.…”

Theranostic nanoparticles for the management of thrombosis

“…Similar to the responsive systems previously described, sensitivity to thrombin may be incorporated through the use of a thrombin-sensitive peptide. Thus, by conjugating a fluorescent dye through this thrombin-sensitive peptide to fluorescence-quenching nanoparticles, nanoprobes that only display a fluorescence signal in the presence of thrombin have been created 125 , 126 . Unfortunately, such an approach is limited by the low depth of penetration of optical imaging, thus nanoprobes with thrombin-responsive US 127 and X-ray-excited luminescence (X-ray photon in, optical photon out) 128 have also been developed.…”

Molecular nanoprobe for diagnosis of cardiovascular diseases

“…In another example, Cao and co-workers prepared a PEGylated Fe 3 O 4 NPs (FITC-LASG-PEGylated Fe 3 O 4 NP) with a fluorescent dye (FITC) attached to its surface by thrombin-sensitive peptide (LASG) for FL/MR dualimaging of thrombus (Figure 6G) [102]. Based on the principle that quenching occurred when FITC was attached to the Fe 3 O 4 NPs surface, after LASG was specifically cleaved by thrombin, FITC left the Fe 3 O 4 NPs and emitted FL.…”