Printable Bioink with Sacrificial Microparticles for Tissue Models
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Solution Overview
Problem
Existing bioinks for extrusion-based printing face challenges in balancing printability and biocompatibility, as they often restrict cellular processes due to nanometer-scale pores and limited degradability, which do not faithfully recapitulate the in vivo microenvironment.
Innovation Solution
A bioink comprising an uncrosslinked extracellular matrix precursor and sacrificial microparticles with a melting temperature above the crosslinking temperature of the polymer, allowing for the creation of microporous structures that mimic the cellular environment by forming pores comparable to individual cell sizes after crosslinking and melting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sacrificial microparticles are added to the bioink to create microporous structures, then biocompatibility and cellular process capability are improved, but the complexity of the bioink formulation and processing is increased
Solution Approach 1:
Sacrificial microparticles serve as an intermediary substance that temporarily occupies space during printing and is subsequently removed to create desired porous structures. These microparticles mediate between the printing process requirements and the final biocompatible porous structure, enabling both printability and cellular functionality without requiring complex direct pore-forming mechanisms in the base bioink.
Solution Approach 2:
The bioink formulation is segmented into distinct functional components: the base ECM precursor material, the sacrificial microparticles, and any cellular components. This segmentation allows each component to be optimized independently - the ECM precursor for printability and structural integrity, the microparticles for pore formation, and cells for biological function - while maintaining overall system compatibility.
2Strength
If the ECM precursor is crosslinked to maintain structural integrity, then printability and shape retention are improved, but cellular processes like proliferation and migration are restricted
Solution Approach 1:
The ECM precursor is crosslinked after the sacrificial microparticles are removed, rather than before. This preliminary action sequence ensures that the microparticles can first perform their function of creating pores and providing a permissive environment for cellular processes, and only afterward does the crosslinking occur to provide structural integrity. This temporal separation resolves the contradiction between structural stability and cellular functionality.
Solution Approach 2:
The system exhibits dynamic properties where the ECM precursor transitions from an uncrosslinked, cell-permissive state during and after printing to a crosslinked, structurally stable state after the sacrificial material is removed. This dynamic transition allows the material to adapt its mechanical properties to different functional requirements at different stages of the process, resolving the contradiction between printability and biocompatibility.
3Stability of the object's composition
If conventional hydrogels are used to provide a supportive matrix, then structural stability is improved, but pore size remains too small and degradability is limited
Solution Approach 1:
The invention creates a porous ECM material by incorporating sacrificial microparticles with controlled sizes that can be precisely engineered to match desired pore dimensions. These microparticles serve as templates that define the pore structure, enabling precise control over pore size while maintaining structural stability through the surrounding ECM precursor matrix. The porosity is not inherent to the base material but is created through the controlled removal of sacrificial particles.
Solution Approach 2:
The system utilizes parameter changes in the sacrificial microparticle properties (size, shape, material composition, melting temperature) to control the final pore characteristics. By adjusting these parameters, the pore size, distribution, and morphology can be precisely tuned to match specific tissue requirements while maintaining overall structural integrity through appropriate selection of the ECM precursor material.
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
This approach enhances the printability of previously difficult-to-extrude biomaterials, providing a conducive microenvironment for cellular processes like proliferation, migration, and differentiation, while maintaining the structural integrity of the printed ECM material.
Implementation Method 1
the first sacrificial microparticles are melted to form pores in the first ECM material
Implementation Method 2
the first ECM precursor is crosslinked to form a first ECM material
Data Source
AI summary
A bioink for extrusion-based printing includes an extracellular matrix (ECM) precursor comprising an uncrosslinked polymer, and sacrificial microparticles dispersed in the ECM precursor. The sacrificial microparticles have a melting temperature above a crosslinking temperature of the uncrosslinked polymer. A method of fabricating a tissue/organ model or therapeutic construct comprises extruding a bioink comprising a first ECM precursor and first sacrificial microparticles through a nozzle moving relative to a deposition bath, and depositing an extruded filament comprising the bioink into the deposition bath as the nozzle moves. After deposition, the first ECM precursor is crosslinked to form a first ECM material, and after the crosslinking, the first sacrificial microparticles are melted to form pores in the first ECM material. The pores may have a width or diameter comparable to that of individual cells.