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Mechanochromic Polyurethane Shape Memory Polymer for Biomedical Applications
Thalma Orado1, Bethany Yashkus2, Richard Chandardat3
1Biomedical and Chemical Engineering Department, Syracuse University, Syracuse, New York, USA.
Journal of Biomedical Materials Research. Part A
|September 22, 2025
Summary
Researchers developed smart polyurethane materials by incorporating spiropyran (SP) molecular switches. These materials change color and shape in response to mechanical stress, enabling new sensor applications.
Area of Science:
- Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Smart materials with dynamic properties are crucial for developing advanced sensor devices.
- Molecular switches, like spiropyran, can alter material characteristics in response to external stimuli.
- Polyurethane (PUR) shape memory polymers (SMPs) offer tunable mechanical and thermal properties.
Purpose of the Study:
- To incorporate spiropyran (SP) mechanophores into polyurethane (PUR) shape memory polymers (SMPs).
- To investigate the mechanochromic behavior and simultaneous shape/color changes in PUR-SP materials.
- To evaluate the potential of these materials for sensing applications, including bacteria detection.
Main Methods:
- SP mechanophores were dissolved in PUR solutions with varying hard-to-soft segment ratios.
- PUR-SP films were fabricated using solvent-casting.
- Mechanical testing, shape memory analysis, thermal analysis, and cytocompatibility assays were performed.
- Mechanochromic responses were analyzed via straining, imaging, and fluorescence microscopy.
- Bacterial protease-responsive PUR SMPs were used to confirm simultaneous shape and color changes in the presence of bacteria.
Main Results:
- Incorporation of SP into PUR resulted in mechanochromic behavior, with increased fluorescence (up to 56%) upon straining, which reversed upon shape recovery.
- The mechanochromic response was influenced by PUR's hard-to-soft segment ratio, SP concentration, and strain percentage.
- Bacteria-responsive PUR-SP materials demonstrated reduced fluorescence and biofilm removal when incubated with Staphylococcus aureus, indicating potential for color-based bacteria detection.
Conclusions:
- SP-functionalized PUR SMPs exhibit simultaneous shape and color changes in response to mechanical stimuli.
- These materials show promise as molecular force probes and for color-based detection of bacteria.
- The developed technology can be expanded to incorporate other stimuli-responsive functionalities for advanced environmental sensing.
