Computed Tomography- and Photoacoustic Imaging-Active Bioresorbable Electrospun Bismuth Nanoparticle-Infused...

Bioresorbable small-diameter vascular grafts lack inherent radiopacity, hindering noninvasive longitudinal monitoring of device integrity and complications. Hence, this study introduces a bismuth nanoparticle (BiNP)-infused electrospun polycaprolactone (PCL) small-diameter graft (i.e., PCL-Bi) for multimodal imaging. Control (aortic autologous), PCL, and PCL-Bi were implanted as abdominal aortic grafts in Sprague-Dawley rats (n = 3 per group) and monitored over 12 weeks using computed tomography (CT), a standard technique for vascular monitoring, and ultrasound/photoacoustic (US/PA) imaging, an emerging nonionizing alternative. BiNP infusion reduced fiber diameter and pore area without changing PCL's bulk porosity, thermal, and mechanical properties. In vivo, PCL-Bi maintained high radiopacity on CT (>1000 HU) and strong signal on PA imaging (>4 AU) throughout the study. Radiopacity positively correlated with the PA signal of BiNP (R² = 0.9601, p<0.001). All grafts maintained in vivo patency, and at week 12, PCL and PCL-Bi showed comparable endothelialization, cell infiltration, and collagen deposition to control. Both PCL and PCL-Bi showed features consistent with early active remodeling. Overall, our findings suggest that BiNP infusion enables multimodal monitoring via CT and PA imaging without obvious adverse effects on early patency and biological performance. Lastly, PA imaging represents a viable, nonionizing alternative to CT for monitoring radiopaque bioresorbable devices.