Abstract No. 616 Bismuth gadolinium oxide (BiGdO3) nanoparticles as biocompatible contrast agents for non-invasive in vivo imaging of biodegradable implants

Abstract

Temporary biodegradable implants offer a favorable alternative for patients, as they provide short-term support and degrade at a rate matching tissue formation, and thus, eliminate the need for surgical removals. However, these biomaterials are radiolucent, making direct radiographic visualization a challenge. Here, we synthesized biocompatible BiGdO3 nanoparticles (BiGdNPs) with high X-ray attenuation that can be incorporated in biodegradable medical implants to provide radiopacity for image-guided delivery and allow non-invasive monitoring. BiGdNPs were synthesized by thermal decomposition of bismuth (III) acetate and gadolinium (III) acetate and characterized in terms of size, morphology, and radiopacity. BiGdNPs were incorporated into biodegradable polycaprolactone (PCL) nanocomposite scaffold by dispersing BiGdNPs in 12% (w/v) PCL in (4:1) toluene/MeOH solution and electrospun using a spraybase system. Quantification of the infused bismuth and gadolinium was done using elemental analysis, tensile strength measurement using Instron universal testing machine, and in vitro cytotoxicity against RF24 cells using a standard alamarBlue assay. Imaging was performed using X-ray, micro-, and dual energy computed tomography (CT). Synthesized BiGdNPs had an average size of 20 nm±4 nm and were successfully loaded uniformly in PCL scaffolds at 3% by weight. In vitro cytotoxicity showed no significant difference in cell viability between the treated and untreated PCL scaffolds (one-way ANOVA, p < 0.05). Improved structural integrity and increased radial stiffness were observed in the BiGdNPs-PCL scaffolds in comparison with the control (PCL only). Imaging studies showed higher attenuation with BiGdNP-treated PCL as compared to the control providing excellent contrast in X-ray and CT imaging. Controlled synthesis of radiopaque BiGdNPs was successfully achieved. These nanoparticles were then incorporated to the biodegradable PCL scaffolds without compromising its physical and mechanical properties. The high X-ray attenuation allows real time visualization, through fluoroscopy or CT, to monitor accurate placement of the device and its degradation over time.