Micro-arranged ZnO particles and conductive fillers in PCL composites for enhanced piezoelectric and dielectric properties in bone tissue engineering applications

Abstract

• Three-dimensional printing aligns zinc oxide micro-rods, improving mechanical, dielectric, and piezoelectric properties. • Thermally reduced graphene oxide enhances electrical pathways and polarization, boosting piezoelectric performance. • Ultrasound stimulation on scaffolds with piezoelectric particles improves cell adhesion, migration, and matrix secretion. Piezoelectric polymers are promising for replicating bone tissue’s piezoelectric properties. Typically, non-piezoelectric biopolymers are combined with piezoelectric particles, but this yields low piezoelectric output. We addressed this by aligning piezoelectric zinc oxide (ZnO) micro-rods in 3D-printed polycaprolactone (PCL) scaffolds and adding conductive particles like thermally reduced graphene oxide (TrGO). Our findings revealed that controlled particle alignment in PCL/ZnO composites significantly enhanced dielectric properties. TrGO further improved these properties by creating conductive pathways and micro-capacitor networks by apparent polarization due to electron displacement, promoting Maxwell-Wagner-Sillars effect. This design strategy significantly increased dielectric and piezoelectric performance, achieving values akin to bone tissue. TrGO also boosted the piezoelectric response, with maximum voltage generation of 696 ± 52 and 142 ± 9 mV during direct contact mechanical pressure by a linear actuator and remote mechanical pressure induced by ultrasound waves, respectively. The 3D-printed composites demonstrated bioactivity for MC3T3-E1, enhanced ALP activity, improved cell adhesion, migration, and extracellular matrix formation under remote ultrasound stimulation, underscoring the potential of these novel ternary composites for bone tissue engineering.

Topics & Concepts