Abstract:

Objective Current cardiac patches often fail to simultaneously replicate the complex mechanical anisotropy and electrical conductivity of native myocardium, limiting their efficacy in tissue repair. This study aims to develop a hierarchical composite patch integrating structural biomimicry with functional electrical properties. By combining structural design with material modification, the research provides a multi-dimensional platform that supports cell retention, mimics heart tissue mechanics, and facilitates electrical signal propagation for myocardial regeneration.

Method A dual-process manufacturing strategy combining melt differential electrospinning and melt electrowriting (MEW) was employed using polycaprolactone (PCL) and carbon nanotubes (CNTs). First, a PCL microfiber base membrane was fabricated via differential electrospinning to serve as a cell barrier. Subsequently, a rhombus-patterned PCL backbone was deposited onto the membrane using MEW, with grid angles adjusted to customize mechanical anisotropy. Finally, multi-walled CNTs were coated onto the scaffold via ultrasonic dispersion to confer conductivity. The patches underwent physicochemical characterization and in vitro evaluation with H9c2 cardiomyocytes.

Results Characterization revealed that the melt-electrospun substrate membrane were 9.36 μm, effectively preventing cell leakage while maintaining permeability. The MEW process successfully modulated mechanical properties, the stent with a 70° grid angle exhibited a non-linear J-shaped stress-strain behavior and a longitudinal-to-transverse elastic modulus ratio of 3.55, falling within the physiological range of native myocardium (1.9-3.9). Decreasing the grid angle enhanced longitudinal strength, with the 50° stent achieving peak longitudinal modulus. Following ultrasonic CNT treatment, the stent achieved a longitudinal conductivity of 1.15×10^-3 S/cm. Stability tests in physiological conditions showed a slight initial conductivity decay, stabilizing at 1.09×10^-3 S/cm after 21 d. Biologically, the composite patch demonstrated excellent biocompatibility, with cell viability exceeding 90% after 3 d culture. Crucially, fluorescence staining indicated that the anisotropic rhombic topology and conductive cues synergistically induced H9c2 cardiomyocytes to adhere, spread, and align along the fiber direction, significantly improving morphological maturation compared to isotropic controls.

Conclusion This study successfully constructed a hierarchical PCL/CNTs cardiac patch that overcomes the limitations of conventional isotropic stent. By innovating the anti-leakage substrate + anisotropic skeleton + conductive coating strategy, the patch achieves precise matching of myocardial mechanics and restores electrical connectivity. The 70° diamond-shaped structure provides effective contact guidance cues, promoting cardiomyocyte alignment, while the CNT integration facilitates electrical functionality. These results suggest that the composite patch offers a promising biomimetic strategy for preventing ventricular remodeling and promoting functional recovery in myocardial infarction treatment. Future work will focus on in vivo implantation to assess tissue integration, vascularization, and long-term biodegradation kinetics.

Key words: cardiac patch, melt electrowriting, melt differential electrospinning, conductive stent, polycaprolactone, carbon nanotube, medical textile material