Design and additive manufacturing of flexible polycaprolactone scaffolds with highly-tunable mechanical properties for soft tissue engineering

Additive manufacturing (AM) techniques are widely used to fabricate tissue-engineered scaffolds due to their unique capability in constructing controllable macro/microarchitectures. However, it is still a huge challenge to produce flexible structures with mechanical properties comparable to those of native soft tissues by utilizing AM techniques and clinically-available biodegradable polymers. Here, a novel strategy was developed to design and fabricate flexible polycaprolactone scaffolds with highly-tunable mechanical properties by using sinusoidal filament networks rather than conventional linear filament networks. Selective laser sintering was employed to fabricate morphologically-controlled non-orthogonal scaffolds without the need for additional support structures. Uniaxial compression testing revealed that the elastic modulus of the resultant PCL scaffolds with sinusoidal filament networks can be widely tuned in the range of 1944.0 ± 228.7 kPa to 27.3 ± 12.0 kPa by adjusting the filament period and amplitude-to-period ratio. During periodical compression, the scaffolds experienced a rapid strain-induced softening process within the first 10 cycles of compression. A balanced stage with similar compression responses reached and stably maintained even when the scaffolds were further compressed to 200 times. The presented method might provide a promising approach to design and fabricate various flexible scaffolds with tissue-specific geometry and mechanical properties for soft tissue engineering.