Carbon Dot-Based Mechanofluorescent Hydrogel with Tunable Fluorescence for Bioengineering Applications.

Area of Science:

• Materials Science
• Biomedical Engineering
• Nanotechnology

Background:

• Fluorescent hydrogels are key for tissue engineering and soft robotics, converting mechanical stress to optical signals.
• Existing hydrogels struggle with sensitivity to low forces, fluorescence quenching, and lack of bioactivity.

Purpose of the Study:

• To develop a stimuli-responsive hydrogel with enhanced mechano-responsive fluorescence for sensitive, quantitative detection of low mechanical stress.
• To overcome limitations of existing systems, including fluorescence quenching and mechanical robustness.

Main Methods:

• Synthesized hydrogels from gelatin methacryloyl (GelMA), acrylamide (AM), and polyethylene glycol diacrylate (PEGDA).
• Incorporated carbon-based quantum dots (CQDs) derived from citric acid (GAPC) and cysteine-modified citric acid (GAPCys).
• Investigated hydrogel response to low compressive forces (250-1250 Pa) and correlated photoluminescence changes with applied stress.

Main Results:

• Demonstrated a concentration-dependent, linear decrease in photoluminescence with increasing compressive stress.
• Established a quantitative correlation between fluorescence intensity and applied mechanical stress within the operating range of soft grippers.
• Achieved robust mechanics, pH sensitivity, biocompatibility, and mitigated fluorescence quenching through CQD integration.

Conclusions:

• Developed advanced mechanofluorescent hydrogels capable of sensitive and quantitative readout of low mechanical stress.
• The integrated CQDs and tunable hydrogel matrices overcome fluorescence quenching while maintaining mechanical integrity and bioactivity.
• These hydrogels provide a versatile platform for soft robotics, tissue engineering scaffolds, and implantable sensors for precise mechanical monitoring.