H. Bouloussa
University of Missouri-Kansas City,,
United States
Keywords: biomaterials, 4D printing
Summary:
Introduction: While the beginning of the 21st century was marked by the predominance of digitization, a more subtle revolution is taking place: the exponential popularization of medical implants. They have dramatically improved our lives as these devices are now able to prevent or control target diseases. Yet, despite their rapid improvements in mechanical performance, design, and even connectivity, there has been little effort to address anatomical variations especially in diverse populations. This requires research and development of shape-change devices beyond the “four sizes fit all”. Also, there has been a push towards the development of remote-controlled medical devices to limit invasiveness and decrease the number of repeat procedures for complex conditions. More recently, 4D printing was demonstrated to be a promising method of enabling shape-change by light activation. The purpose of this study was to assess the feasibility of controlling the shape of an implanted biomaterial by near infra-red (NIR) light illumination through the skin of cadaveric mice. Materials and Methods: Four 1cm flat squares of gelatin-metacryloyl (1mm thick) were coated by 3D printing using a proprietary solution of a self-assembled polymer and graphene oxide nanoparticles (Interstellar Therapeutics, Inc). This resulted in 4D coated biomaterials. The biomaterials were bent with pliers with a 30-degree angle and inserted in cadaveric mice in several anatomical regions of interest with various depths: subcutaneous tissues on the back of mice, posterior lumbar spine (submuscular, anterior to the paraspinal muscles, 0.5cm depth), retrohepatic region (1cm depth), and in the pre-aortic space (3cm depth). A commercial NIR source (Rotsha “FineWell-2IN1”) with 5 LEDs with the following wavelengths was used (2x660nm, 830nm, 850nm, and 940nm). The NIR irradiation lasted 15 minutes and the source was placed at 1cm away from the skin. Following irradiation, samples were recovered, and photographs were taken for qualitative analysis. Results: All samples were able to be slowly straightened to their memorized shape, within 15 minutes, with minimal deformity left in all conditions except when samples were located in the pre-aortic space (3cm depth). There were no macroscopic signs peri-implant tissue damage. Discussion: These results confirm the feasibility of light-assisted remote control on implanted biomaterials. Controlling the shape of implants in deeper locations may be facilitated by increasing the energy of the light source. This transformative technology could allow remote and gradual correction of limb and spinal deformities, remote control of body fluid transport, or even deployment of complex 3D printed medical devices through minimally invasive ports.