Fabrication of hydrogel particles with tantalum oxide nanoparticle payloads as computed tomography contrast agents

This paper reports the fabrication of hydrogel microparticles using a combined imprinting and photolithography (CIP) methods, with tantalum oxide (TaOx) nanoparticle payloads as X-ray attenuating media for size and shape specific computed tomography (CT) contrast agents. TaOx nanoparticles were successfully synthesized and characterized with superior X-ray attenuating properties compared to current iodine-based CT contrast agents. The CIP fabrication method eliminates the formation of a flash layer that connects individual particles, thereby avoiding the necessity of an additional etching step that could damage the hydrogel particles and/or the biological materials they may carry. The future potential of scaling this technique down to nanoscale, for fabricating hydrogel nanorods with controllable size, aspect ratio, and elasticity is also discussed, with some preliminary efforts reported.