ИСТИНА

Background: Implantable systems have a wide range of applications in biomedicine. They are used in reconstructive surgery, telemedicine and telemetric research, and as drug delivery systems. The status of the implants requires close monitoring, creating the need for materials effectively visualized by imaging diagnostics. Some implantable materials (i.e. silicone or metal alloys) meet this requirement, but others (i.e. gel fillers) cannot be visualized without specific modifications. This study assessed the possibility to enhance visualization of silicone/hydrogel implants in photon-counting computed tomography (PCCT) studies by Ln-based composite contrasting of their components. Methods: Two contrasting approaches were evaluated. First, Ln2O3 (Ln = La, Gd, Yb) was added into silicone, gelatine and polyacrylamide (PAM) during molding. Second, Ln2O3@C core-shell nanoparticles were cross-linked with PAM by co-polymerization using a novel synthetic route. The composition, structure, physico-chemical properties and biocompatibility of materials were assessed by variety of methods. Prototype implants with contrasted components were evaluated by PCCT. Results and Conclusions: Direct addition of Ln2O3 into implant components gave sub-optimal results. The contrasted silicone and gelatine could be visualized by energy-integrative CT (with CT numbers > 1000 HU) and determined by PCCT. However, PCCT revealed the presence of Ln2O3 particles not bound with the materials, indicating a risk to stability and toxicity. The PAM fillers with cross-linked Ln2O3@C core-shell nanoparticles had lower CT numbers but could be also distinguished by PCCT. No abnormalities in their composition were detected, suggesting high potential of these materials.