Biomimetic HA-Reinforced PCL/PLA Fibrous Structures via Solution Blow Spinning: Cocoon-Inspired Design for Bone Regeneration

Bioinspired materials have been studied for applications in various fields, including aerospace and tissue engineering. In this study, biomimetic fibrous structures, inspired by the cocoons of the <i>Rothschildia</i> sp. moths, were produced by solution blow spinning (SBS) using biodegradable polymers such as polycaprolactone (PCL) and poly-(lactic acid) (PLA), selected for their distinct melting temperatures, enabling the fabrication of hot-pressed fiber-reinforced composites, with the addition of hydroxyapatite (HA) microparticles, due to its osteoconductive capacity. Cocoons were analyzed using scanning electron microscopy (SEM), tensile tests, Fourier-transform infrared spectroscopy (FTIR), and thermogravimetry (TG) and differential scanning calorimetry (DSC). The results showed that cocoons consist of fibroin dispersed in a sericin matrix, interspersed with HA particles, forming a fibrous multilayered structure. To replicate this structure, fibrous layers were produced using a multinozzle SBS system that spun PLA (fibrous phase) and PCL (matrix). A hot-press process at varying temperatures and spun layers was applied to melt PCL while preserving the fibrous morphology of PLA. Characterization of the bioinspired structures followed the same techniques used for the cocoons, revealing similar morphology with PLA fibers in a PCL-HA matrix. Mechanical strength varied, with the six-layer fibrous membrane, pressed at 90 °C for 30 min, exhibiting the highest strength. Overall, this research demonstrates the potential of developing bioinspired nanocomposites with customized properties based on the structure of moth cocoons.