Surface Functionalization of Halloysite Nanotubes with Poly(acrylic acid) and Evaluation of Their Hemostatic Activity

Clays are widely used functional materials in industrial production due to their low cost, diversity, and easy accessibility. Since clays generally exhibit limited compatibility with other molecules, surface functionalization is often employed to modify their properties and expand their potential applications, particularly in biomaterials research. In this study, the potential of halloysite nanotubes (HNTs) as hemostatic materials was investigated by modifying their surface properties via photoinduced polymerization of acrylic acid (AA). PAA was coated onto MAPTES-silanized HNT substrates to enrich functional groups and modify the surface properties of the clay. The polymerization process was conducted at different polymerization times and MAPTES ratios to modulate the overall organic coating content on the HNT substrate. The structure–property relationships of the synthesized composites were comprehensively characterized, and their in vitro coagulation and platelet-recovery behaviors were evaluated. The results revealed that PAA modification altered the coagulation behavior of HNTs, resulting in changes in PT and aPTT responses that depended on the modification conditions. Furthermore, PAA modification altered the extent of platelet depletion from the recoverable plasma fraction compared with unmodified HNTs. These findings suggest that PAA modification influences the interaction between HNTs and blood components and provides a tunable surface-modification strategy, suggesting that PAA modification can modulate HNT–blood component interactions. Further studies using whole-blood and in vivo models are required to establish the hemocompatibility and hemostatic performance of the modified materials.