Research article

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A key challenge in soft tissue engineering is developing biocompatible scaffolds with tunable stiffness and controlled degradation. Composite cryogels combining a porous polymer network, reinforcing microparticles, and encapsulation capacity address this challenge. In this study, we prepared poly(vinyl alcohol) (PVA)-based cryogels containing 5 and 10 wt% PVA and 1, 5, 10, and 20 wt% poly(3-hydroxybutyrate) (P(3HB)) microparticles (5.8–42.6 μm in diameter) by cyclic freeze–thaw. The P(3HB) microparticles reduced porosity (from 31 to 16%) and the swelling ratio (from 226 to 143%) without altering mean pore diameter (50–300 μm), with greater effects at 10 wt% PVA. Mechanical testing showed that increasing microparticle content enhanced the elastic modulus (from 8.7 to 18.3 kPa) and compressive strength (from 39 to 47 kPa) for 10 wt% PVA cryogels, whereas 5 wt% PVA cryogels showed minimal modulus improvement and reduced strength. Biocompatibility (ISO 10993-5) was confirmed for all 5 wt% PVA composites and for the 10 wt% PVA composite with 20 wt% P(3HB) (viability 72.8%). P(3HB) microparticles loaded with brilliant green significantly slowed its release from both cryogel matrices. These results establish PVA/P(3HB) composite cryogels as promising scaffolds with tunable stiffness and controlled release for soft tissue engineering.