A recent study in Advanced Materials introduces a biofabrication technique called fiber-assisted structured light (FaSt-Light), designed to improve precision and flexibility in in situ tissue engineering.
The method uses image guide fibers to deliver structured light, enabling high-resolution photoresin crosslinking for the rapid formation of complex tissue constructs and grafts. It offers a more adaptable alternative to traditional benchtop systems and aims to support personalized, minimally invasive treatments in regenerative medicine.
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Advancements in Light-Based Biofabrication
Over the last 20 years, light-based biofabrication methods like two-photon polymerization (2PP) and digital light processing (DLP). These methods enable high-resolution fabrication (down to 150 nm) and support the rapid creation of complex structures at micro and macro scales.
Despite these capabilities, most systems are limited to benchtop use. They often require specific substrates and post-processing, which complicates clinical application. To address these challenges, recent work has focused on in situ photo-crosslinking of hydrogels, allowing direct fabrication inside the body.
The FaSt-Light System: Mechanism and Functionality
The authors developed the FaSt-Light system to project structured light into hard-to-access areas using image guide fibers. It integrates a multi-wavelength laser setup (405, 450, and 520 nm) with a digital micromirror device (DMD) for macroscale patterning. It also uses optical modulation instability to create microscale features like internal microfilaments. This dual-scale approach allows for precise control over material structuring.
The system uses coherent image guide fibers—commonly used in endoscopy—to deliver light flexibly. It applies wavelength-specific photoinitiators: LAP (Type I) for 405 nm, a redox system (Ru-SPS) for 450 nm, and EY-TEOA-NVP (Type II) for 520 nm. Gelatin methacryloyl (GelMA) in phosphate-buffered saline (PBS) was selected for its known biocompatibility.
To evaluate the system, researchers projected light through the fibers onto photoresin samples in cuvettes and well plates, adjusting factors like fiber diameter, projection distance, and lens setup. This allowed precise polymerization and resulted in constructs that supported both cell alignment and infiltration, key requirements for successful tissue regeneration.
Key Findings: Enhancing Precision and Flexibility
The results showed that FaSt-Light reliably produced tissue constructs that supported strong cell alignment and infiltration. Microfilaments formed within the structures were key in guiding cell growth, improving overall tissue organization.
Resolution varied depending on the photoinitiation system: the 405 nm wavelength delivered the highest precision, producing microfilaments between 2 and 6 µm in diameter. Constructs made with 450 nm light were larger and less defined due to oxidative side effects from the Ru-SPS system, leading to nonspecific crosslinking.
Cell viability remained above 80 % after 14 days, confirming the cytocompatibility of the system. Constructs, typically sized between 150 and 200 µm, showed improved mechanical and biological performance thanks to the internal microfilament structures formed via optical modulation instability.
The study also found that light dose and photoinitiator type affected both resolution and structural consistency, emphasizing the need to carefully tune exposure parameters for optimal outcomes.
Potential Applications in Regenerative Medicine
The FaSt-Light system enables in situ fabrication of complex tissue constructs, offering innovative solutions for treating muscle injuries, tendon damage, chronic wounds, and peripheral nerve injuries. Its adaptable design allows tailored applications across different anatomical sites, supporting personalized treatment strategies.
The ability to project images remotely through fiber bundles facilitates precise resin crosslinking in hard-to-reach areas, making the system suitable for minimally invasive procedures like cardiac and nerve repair.
Additionally, FaSt-Light's multi-wavelength projection capability enables the fabrication of multimaterial constructs by combining different biomaterials, facilitating the development of scaffolds that closely replicate native tissue architecture and functionality. The system also has the potential for integration with robotic platforms, allowing for automated, real-time biofabrication during surgery.
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Conclusion: Future Directions in Optics-Driven Biofabrication
FaSt-Light presents a practical solution for in situ tissue fabrication, expanding the capabilities of light-based biofabrication for clinical use. It enables precise, adaptable tissue engineering directly in the body, with potential applications across multiple areas of regenerative medicine.
Future research should focus on reducing the size of the projection system, improving light delivery through fiber-lens interfaces, and refining crosslinking chemistries for better biocompatibility. Integrating this technology with robotic platforms and imaging tools could support real-time, minimally invasive fabrication, bringing automated tissue repair closer to clinical reality.
Journal Reference
Chansoria, P., et al. Structured Light Projection Using Image Guide Fibers for In Situ Photo-biofabrication. Advanced Materials, 2419350 (2025). DOI: 10.1002/adma.202419350, https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202419350
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