Poster O17 - Porous Elastomer Integrated with 3D Printed Electronics for Biodegradable Implants

Saturday, October 26, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

He Sun, PhD (she/her/hers)

Postdoctoral Research Scholar
Joint Department of Biomedical Engineering UNC-Chapel Hill / NC State University
Raleigh, North Carolina, United States

Co-Author(s)

Kirstie Queener, MS (she/her/hers)

PhD Student
Joint Department of Biomedical Engineering UNC-Chapel Hill / NC State University, United States
HD

Halston Deal, n/a

PhD Student
Joint Department of Biomedical Engineering UNC-Chapel Hill / NC State University, United States

Primary Investigator(s)

Michael Daniele, PhD

Professor & University Faculty Scholar
Joint Department of Biomedical Engineering UNC-Chapel Hill / NC State University, United States

Introduction: The development of biomedical implants has driven the creation of advanced polymers that combine biocompatibility, mechanical compliance, and biodegradability. This is particularly crucial for implantable sensors, which must completely integrate with host tissues while performing their intended functions. Poly (octamethylene maleate (anhydride) citrate) (POMaC) stands out as a versatile elastomer for such implants owing to its adjustable degradation and mechanical properties, which is particularly advantageous for creating biodegradable implants that can match the mechanical behavior of various soft tissues. In this study, we focused on improving POMaC functionality through introducing porous structures and incorporating 3D printed biodegradable electronics. The porous structures promote tissue integration by facilitating cell penetration, which is essential for the biocompatibility and functionality of implants. Meanwhile, the incorporation of 3D printed electronics to the POMaC substrate seeks to give real-time monitoring capabilities for physiological parameters, accomplishing the growing demand for effectively diagnostic and therapeutic tools in healthcare.

Materials and

Methods: POMaC pre-polymer was synthesized from citric acid, maleic anhydride, and 1,8-octanediol. Sodium chloride (reagent grade) and powdered sugar (food grade) were used as porogens to create porous structures. POMaC pre-polymer was mixed with ground salt or sugar at varying volume ratios to explore the effects of porogen concentration on pore sizes and structures. The mixture was coated onto glass slides with a sacrificial dextran layer, cured at 80°C for 2 days, then immersed in deionized water for 3 days to leach out the porogens. After the leaching process, the resulting porous POMaC was lyophilized to eliminate any remaining water. Scanning electron microscopy (SEM) and micro computed tomography (Micro-CT) were utilized to provide detailed characterization of the pore sizes and distribution. Meanwhile, carbon-based biodegradable electronic circuits were printed onto the POMaC substrates by utilizing 3D bioprinter. Photoinitiators and printing parameters were optimized to achieve the best resolution. For the cytocompatibility tests, human dermal fibroblasts (HDFn) were co-cultured with flat and porous POMaC samples to observe the morphology of cells and detect the penetration depth, and cell viability was assessed using LIVE/DEAD fluorescence imaging after 24 and 72 hours.

Results, Conclusions, and Discussions: The fabrication process successfully manufactured POMaC porous structures with controllable pore size and layer thickness. This tunability is critical for optimizing the material for different applications, as smaller pores are beneficial to match cell sizes, while larger pores may be needed for other functional requirements. Here, we used pore sizes ranging from 10 µm to 20 µm to facilitate cell penetration, which is crucial for tissue integration. Additionally, the design with ~50% thickness of porous layer supports the integration of 3D printed electronics on the remaining flat POMaC surface. The 3D printed electronic circuits on flat POMaC substrates exhibited sufficient resolution for practical applications in physiological monitoring. The circuits were flexible and adhered well on the POMaC surface to maintain their integrity and functionality. Furthermore, human dermal fibroblasts (HDFn) cultured on both flat and porous POMaC showed high viability, with over 80% of cells remaining viable after 72 hours. While the penetration depth of cells in porous POMaC is ~2.5 times deeper than flat POMaC. In summary, the porous structures supported both cell penetration and survival, demonstrating good cytocompatibility. Future research will focus on improving the functionality of 3D printed electronics to evaluate the performance for vital signs monitoring, such as the heart rate, blood pressure and electrocardiogram (ECG). Meanwhile, long-term in vivo investigations will be necessary to assess the sensing performance and degradation behavior of porous POMaC implants in biological environments. In conclusion, our study highlights the potential of POMaC as a base material for biodegradable implants. The combination of tunable porous structures and integrated 3D printed electronics offers a promising approach to developing advanced implantable sensors that meet the stringent requirements of biocompatibility, mechanical compliance, and biodegradability.

Acknowledgements (Optional):