Contrast Agent Design to Deliver Improved Ultrasound Echogenicity from Medical Devices: A Route to In-Ward Device Placement Tracking.

This work reports a scalable strategy for producing polymeric medical devices with enhanced ultrasound (US) echogenicity via tailored dispersant design to support safer image-guided medical device placement. Real-time US imaging offers an alternative to X-ray imaging, reducing radiation exposure while enabling accurate device positioning/monitoring. Previous studies showed that including bioabsorbable phosphate-based glass (PBG) microspheres into thermoplastic polyurethane (TPU) could improve echogenicity. However, aggregation and processing defects limited the performance. To address this, two classes of acid-functionalized dispersants were synthesized to improve the microsphere dispersion and compatibility with TPU. These, i.e., dodecenylsuccinic diacid (DDSD) and oligomeric methacrylate/acrylates prepared using acid-functionalized chain-transfer agents, were grafted onto PBG microspheres via dip-coating and thermal treatment. Successful surface modification was confirmed by separation testing, SEM, and XPS. TPU composites containing the coated microspheres were then extruded into catheter-like structures and shown to demonstrate enhanced, more uniform echogenicity under clinical US imaging conditions without compromising the mechanical properties.