# A novel inherent fluorescence biodegradable polyurethane

## TL;DR

This paper introduces a new type of biodegradable polyurethane with built-in fluorescence to track and adjust its degradation for tissue regeneration.

## Contribution

The novelty lies in integrating a fluorescent molecule into the polyurethane structure for real-time degradation tracking and tunability.

## Key findings

- IFPU materials showed excellent fluorescence and adjustable degradation in vitro and in vivo.
- 3D-printed IFPU scaffolds had high porosity, mechanical strength, and supported cell growth and biocompatibility.
- Hard segments were found to regulate degradation rates through hydrophilic properties.

## Abstract

In situ tissue regeneration using biodegradable biomaterials provides a viable strategy to harness endogenous regenerative potential for tissue repair. Ideally, biomaterials should have appropriate biodegradability to accommodate new tissue formation. However, the limited adjustability and trackability of their degradation behaviors pose a considerable challenge in achieving suitable biodegradability that matches the tissue regeneration process. Herein, we developed a series of novel inherent fluorescence biodegradable polyurethane (IFPU) materials by incorporating a fluorescent small molecule (thiazolpyridinic acid) as both the hard segment composition and the fluorescent probe to adjust and track their degradation behaviors. These IFPUs, both in solid films and porous scaffolds, exhibited outstanding fluorescence performance, enabling the rapid visualization of their adjustable degradation behaviors both in vitro and in vivo. By fast-tracking the degradation behavior of IFPU scaffolds through fluorescent visualization, we comprehensively elucidated the degradation mechanism and process of biodegradable polyurethane. We clarified how hard segments regulate the degradation rate by hydrophilia. Moreover, IFPUs presented outstanding printability, and their 3D-printed scaffolds not only showed high porosity (>70%) and high mechanical properties, including compression modulus of up to 127.7 ± 17.5 MPa and strength of up to 14.0 ± 0.7 MPa, but also promoted cell recruitment, adhesion and proliferation, as well as exhibited excellent biocompatibility in vivo, positioning them as promising candidates for tissue-regenerative biomaterials.