Exploring Biomechanical Properties of Microporous Annealed Particle Hydrogel (MAP Gel) in Comparison with MAP-treated Natural Tissues

M. Motezaker, J.J. Daniero, P.E. Hopkins
University of Virginia,
United States

Keywords: biomechanical properties, microporous annealed particle hydrogel (MAP Gel), atomic force microscopy (AFM), rabbit vocal tissue, tissue repair


The emergence of Microporous Annealed Particle hydrogel (MAP gel) in 2015 marked a significant advancement in tissue integration. Unlike conventional degradation-based approaches, MAP gel employed an innovative open pore architecture formed between spherical building blocks. The transition from a flowable slurry of polyethylene glycol (PEG) microspheres to a solid scaffold through an on-demand white light-catalyzed reaction resulted in a MAP iteration with exceptional in situ permanence, adaptability to light-based curing, and accelerated host tissue integration. In contrast to traditional injectable sol-gel hydrogels like hyaluronic acid, MAP gel actively promotes wound healing, facilitates cellular infiltration, and seamlessly integrates with surrounding tissues along its periphery, avoiding impediments commonly associated with other materials. In our research, utilizing Atomic Force Microscopy (AFM), we tried to explore the biomechanical properties of MAP gels and compare them with various soft biological tissues, including rabbit vocal folds. The comparison of MAP gel to tissues revealed a similarity in their Young’s modulus, signifying a close match in stiffness and pointing to a significant connection. This observed likeness underscores MAP gel's engineered properties, mimicking the mechanics of natural tissues. Young's modulus was meticulously measured using the force-distance curves technique, employing linear fitting on unloading curves. This mechanical similarity further emphasizes MAP gel's potential in tissue repair and integration. We conducted force-distance measurements on multiple particles of both cured and uncured MAP gel particles, as well as different spots of the vocal folds of MAP-treated rabbits. These comprehensive measurements provided valuable insights into the material's mechanical behavior across various conditions and locations. In addition, the adhesion forces of samples were measured using the force-distance technique, and topography images were employed to measure particle size and thickness, contributing to a comprehensive understanding of the material's characteristics. In summary, our investigation into MAP gel's biomechanical properties showcases its remarkable similarity to natural tissues, presenting a compelling case for its potential applications in tissue repair and integration. The meticulous measurements conducted through AFM not only confirm the material's close match in stiffness but also provide crucial data for further research and customization. MAP gel's unique characteristics, including its porosity and seamless tissue integration, position it as a promising biomaterial with diverse applications in the evolving landscape of tissue engineering and regenerative medicine.