Incorporating Tantalum Oxide Nanoparticles into Implantable Polymeric Biomedical Devices for Radiological Monitoring

Abstract

Longitudinal radiological monitoring of biomedical devices is increasingly important, driven by the risk of device failure following implantation. Polymeric devices are poorly visualized with clinical imaging, hampering efforts to use diagnostic imaging to predict failure and enable intervention. Introducing nanoparticle contrast agents into polymers is a potential method for creating radiopaque materials that can be monitored via computed tomography. However, the properties of composites may be altered with nanoparticle addition, jeopardizing device functionality. Thus, the material and biomechanical responses of model nanoparticle‐doped biomedical devices (phantoms), created from 0–40 wt% tantalum oxide (TaOx) nanoparticles in polycaprolactone and poly(lactide‐co‐glycolide) 85:15 and 50:50, representing non, slow, and fast degrading systems, respectively, are investigated. Phantoms degrade over 20 weeks in vitro in simulated physiological environments: healthy tissue (pH 7.4), inflammation (pH 6.5), and lysosomal conditions (pH 5.5), while radiopacity, structural stability, mechanical strength, and mass loss are monitored. The polymer matrix determines overall degradation kinetics, which increases with lower pH and higher TaOx content. Importantly, all radiopaque phantoms could be monitored for a full 20 weeks. Phantoms implanted in vivo and serially imaged demonstrate similar results. An optimal range of 5–20 wt% TaOx nanoparticles balances radiopacity requirements with implant properties, facilitating next‐generation biomedical devices.

In vivo Biomedical Imaging of Immune Tolerant, Radiopaque Nanoparticle-Embedded Polymeric Device Degradation

“…Hydrophobicity is imparted by coating nanoparticles with hexadecyltriethoxysilane (HDTES, Gelest Inc., cat no SIH5922.0), an aliphatic organosilane. The coating has been shown to produce polymer composites with homogeneous nanoparticle distributions [11].…”

“…Phantoms were created with micro-scale porosity (< 100μm) and with macro-scale porosity (200 - 500 μm) to mimic tissue engineering constructs which must accommodate both nutrient diffusion and cell and tissue infiltration [11]. For in vitro experiments, films mimicking the surface of the phantom struts was created.…”

“…Specifically, we have introduced radiopacity to several FDA-approved polymers by incorporating biocompatible tantalum oxide (TaO x ) nanoparticle contrast agents into the polymer matrix [8-10]. This technique has been used to serially image porous tissue engineered devices via computed tomography (CT), a clinical imaging technique that can quickly and clearly distinguish implanted material from surrounding tissues [11].…”

Computed Tomography of Polymeric Biomedical Implants from Bench to Bedside

“…Polyester phantoms were created with micro-scale porosity (< 90μm) and macro-scale porosity (> 90 μm) to mimic tissue engineering constructs which must accommodate both nutrient diffusion and cell and tissue infiltration [13]. The synthetic polymer matrix chosen was polycaprolactone (PCL, Sigma Aldrich), a commonly used biocompatible polyester [14].…”

“…However, this is not necessarily viable when attempting to image polymer devices over a longer period of time or post-implantation. Radiopaque nanoparticles offer a facile way to introduce a radiopaque element into the matrix, without significantly altering materials properties or its biocompatibility [13,26]. They have been shown to work at the scale of clinical tomography and aide in the radiological evaluation of biomedical implants [9].…”