Melt-Extrudable Biodegradable Inks for Soft Tissue Grafts
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Solution Overview
Problem
Current biodegradable polymers for 3D printing of soft tissue grafts are often too stiff, have poor adhesion to surrounding tissue, and exhibit slow degradation rates, leading to foreign body responses and inadequate integration with native tissue.
Innovation Solution
Development of melt-extrudable biodegradable inks composed of soft and hard segment blocks with a fugitive porogen, allowing for rapid customization, cellular alignment, and controlled degradation, which are extruded through heated nozzles to create grafts with anisotropic structures that mimic native tissue architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If current biodegradable polymers are used for 3D printing of soft tissue grafts, then the grafts can be manufactured, but the polymers are too stiff and have poor adhesion to surrounding tissue
Solution Approach 1:
The patent uses composite materials by combining biodegradable polymers with fugitive porogenic materials to create a composite ink formulation. This composite approach allows the polymer matrix to provide structural integrity while the porogen creates interconnected pores that enhance tissue adhesion and cellular integration, resolving the contradiction between stiffness and adhesion.
Solution Approach 2:
The patent incorporates fugitive porogenic materials that create porous structures within the printed grafts. These pores improve tissue adhesion by allowing cellular infiltration and vascular ingrowth, while the remaining polymer matrix maintains necessary mechanical strength. The porous architecture directly addresses the adhesion problem without sacrificing overall structural integrity.
2Duration of action of stationary object
If current biodegradable polymers are used for 3D printing, then the grafts can be manufactured, but they exhibit slow degradation rates leading to foreign body responses
Solution Approach 1:
The porous structure created by fugitive porogens accelerates degradation by increasing surface area exposed to hydrolytic and enzymatic attack. The interconnected pores allow faster penetration of water and enzymes throughout the material, reducing the overall degradation time and minimizing the period during which foreign body responses occur.
Solution Approach 2:
The patent changes the physical and chemical parameters of the ink formulation by incorporating porogenic materials at specific weight percentages (10-50 wt%). This parameter change creates a controlled degradation profile where the material degrades at an optimal rate that prevents chronic foreign body responses while maintaining structural integrity during the healing process.
3Reliability
If melt-extrudable inks with fugitive porogen are used, then controlled degradation and cellular alignment are achieved, but the ink formulation becomes more complex
Solution Approach 1:
The patent establishes specific parameter ranges for the ink formulation, including soft-to-hard segment ratios (1:1.2 to 1:2.0) and porogen content (10-50 wt%). These defined parameters simplify the formulation process by providing clear guidelines for achieving desired degradation rates and mechanical properties, reducing the complexity of developing consistent ink formulations.
Solution Approach 2:
While the composite nature of the ink (polymer + porogen) increases formulation complexity, it enables controlled degradation through the systematic removal of the porogen phase. The composite approach provides a predictable degradation mechanism where the porogen dissolves or is removed, leaving behind a porous polymer structure with controlled degradation characteristics.
4Reliability
If biodegradable polymers are used for soft tissue grafts, then tissue integration is possible, but the mechanical properties do not match native tissues
Solution Approach 1:
The porous architecture created by fugitive porogens mimics the natural extracellular matrix structure of native tissues. This porous structure allows cellular infiltration and tissue ingrowth while the polymer matrix provides mechanical support. The combination achieves mechanical properties closer to native soft tissues by reducing the density and increasing the compliance of the printed graft.
Solution Approach 2:
The composite ink formulation allows tuning of mechanical properties by adjusting the ratio of polymer to porogen and selecting appropriate polymer compositions. This enables the printed grafts to achieve mechanical properties that better match native tissues while maintaining the benefits of biodegradability and tissue integration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the creation of grafts with mechanical properties matching those of native tissues, promoting cellular integration, controlled degradation, and improved surgical handling, while reducing foreign body responses and enhancing tissue adhesion and sound conduction.
Implementation Method 1
The inks can be degraded via hydrolysis and/or enzymatic breakdown into byproducts that are non-ototoxic
Implementation Method 2
The inks can be degraded via hydrolysis and/or enzymatic breakdown into byproducts that are non-ototoxic
Implementation Method 3
The ink is extruded from a nozzle head via pressure
Data Source
AI summary
Described herein are melt-extrudable biodegradable inks for 3D-printing, methods of using the inks, and kits including the inks, to prepare implantable grafts, such as artificial tympanic membrane devices or artificial cartilage, nerve conduit, tendon, muscle tissue, or bone devices.