Abstract:

Objective Cardiac patches can provide mechanical support to infarcted myocardium, thereby promoting myocardial repair. However, most existing myocardial patches are isotropic, which makes it difficult to match the anisotropy of native myocardium and hinders cardiac contraction. Additionally, cardiac patches are usually fixed to the heart via sutures, which may cause bleeding, secondary injury, and other complications. Therefore, developing sutureless anisotropic myocardial patches is crucial for enhancing the efficacy of myocardial repair.

Method A textile-based composite myocardial patch with both adhesive properties and anisotropy was fabricated by combining knitting, plasma treatment, and in-situ gelation techniques. Specifically, a hydroxyl-mediated polyvinyl alcohol (PVA) hydrogel layer was immobilized onto an oxygen plasma-modified polypropylene (PP) warp-knitted fabric, followed by in-situ crosslinking of PVA with tannic acid (TA). Regulating cross-linking time and TA concentration enabled modulation of the adhesive properties of the patch. The patch was characterized in terms of its microstructure, chemical composition, contact angle, hydrogel-monofilament interface bonding, adhesive properties, and mechanical performance.

Results After plasma treatment, the surface of PP fabric was successfully etched, exhibiting a rough morphology with significantly improved hydrophilicity. Plasma treatment had no significant impact on the fabric’s overall mechanical properties while ensuring reliable bonding between the fabric and hydrogel layer, and the fabric remained undetached from the hydrogel even after repeated tensile strain application. Owing to hydrogen bonding interactions, the hydrogel layer had a dense cross-sectional structure with small pores. As TA concentration increased, the hydrogel’s swelling ratio gradually decreased, which facilitated the patch in maintaining structural and mechanical stability in the physiological microenvironment. Fourier transform infrared analysis showed that PVA/TA hydrogel exhibited characteristic peaks of C=O stretching vibration at 1 709 cm^-1 and phenolic —OH stretching vibration at 1 313 cm^-1, confirming the successful incorporation of TA into the PVA hydrogel. In-situ cross-linking with TA significantly enhanced the tensile strength, elongation at break, and elastic modulus of the PVA/TA hydrogel. Compared with pure PVA hydrogel, the tensile strength of the cross-linked hydrogel increased from 0.15 MPa to 2.39 MPa, nearly a 16-fold improvement. The composite patch showed adhesive properties to myocardial tissue, with adhesion strength synergistically regulated by cross-linking time and TA concentration. A peak adhesion strength of 15.73 kPa was achieved at a cross-linking time of 6 h and TA concentration of 0.20 g/mL. Specifically, shorter cross-linking time and lower TA concentration led to insufficient catechol groups in the composite system, resulting in weak intermolecular interactions with tissue surface groups, whereas in contrast, longer cross-linking time and higher TA concentration caused excessive. Cross-linking, where strong hydrogen bonds formed between catechol groups and hydroxyl groups in PVA, reduced the exposure of free catechol groups and thus decreased the adhesion strength. Additionally, the patch maintained adhesive stability under various deformation conditions (e.g., stretching, bending, water flushing). The tensile elastic moduli of the patch in the transverse and longitudinal directions were 1.03 MPa and 0.49 MPa, respectively, with an anisotropy ratio of 2.1, within the range matching native myocardium (1.9-3.9). This not only provides sufficient mechanical support for infarcted myocardium but also enables the patch to conform to myocardial deformation without restricting cardiac contraction, thanks to its anisotropy matching that of native myocardium.

Conclusion A myocardial patch with anisotropy and adhesive properties was successfully fabricated via warp-knitting, plasma treatment, and in-situ gel formation. Surface morphology, chemical composition, and hydrophilicity of the patch were characterized, and the effects of process parameters on the adhesive and mechanical properties of the composite patch were investigated. The hexagonal mesh structure of the PP fabric endowed it with anisotropy matching native myocardium and sufficient strength to support cardiac contraction. Oxygen plasma treatment significantly improved the hydrophilicity of the inert PP fabric, facilitating its further functional modification. The PVA/TA gel layer provides the patch with adhesiveness, eliminating the need for suturing during epicardial implantation. The fabric and gel layer exhibit strong and secure bonding without detachment risk. Overall, this study presents a warp-knitting-based composite gel patch, offering new insights for the design and construction of anisotropic sutureless myocardial patches and the diversified applications of textile technologies.

Key words: medical textiles, warp knitted, hydrogel, myocardial patch, plasma treatment, adhesive performance, sutureless transplantation, myocardial infarction