3D-Printed Piezoionic/Bioelectronic Hydrogel for Electro-Metabolic Regulation of Osteogenic Differentiation

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Nanotechnology

Background:

• Large bone defects from trauma, tumors, or infection require advanced biomaterials.
• Piezoelectric biomaterials offer conductivity and extracellular matrix-mimicking properties for bone regeneration.

Purpose of the Study:

• To develop a 3D-printable, biodegradable, adhesive, and piezoionic-conductive nanocomposite hydrogel for bone regeneration.
• To investigate the hydrogel's potential as a piezoionic nanogenerator and for biosensing applications.

Main Methods:

• Fabrication of a polypyrrole-grafted gelatin methacrylate (GelMA-PPy) and MXene nanocomposite hydrogel (GPMx) using direct ink writing 3D printing.
• Characterization of the hydrogel's mechanical strength, conductivity, adhesiveness, and piezoelectric properties.
• Evaluation of biocompatibility with human bone mesenchymal stem cells (hBMSCs) and osteogenic differentiation.
• Development of an antibody-functionalized hydrogel for label-free electrochemical sensing of alkaline phosphatase.

Main Results:

• The GPMx hydrogel exhibited excellent printability, enhanced viscoelasticity, superior mechanical strength (~450 kPa), long-term conductivity (~30 S/cm), and strong adhesiveness (~65 kPa).
• The 3D-printed hydrogel functioned as a piezoionic nanogenerator (PING), converting mechanical stress into electrical signals (~8 mV).
• The hydrogel demonstrated high biocompatibility (>99%) with hBMSCs, promoted osteogenic differentiation, and enabled label-free electrochemical sensing of alkaline phosphatase.

Conclusions:

• The developed GPMx hydrogel is a promising multifunctional biomaterial for bone regeneration, combining structural support with bioelectric stimulation.
• Its piezoionic nanogenerator capability and biosensing potential offer innovative approaches for monitoring bone health and guiding regenerative therapies.