Polyaniline Protrusions on MoS2 Nanosheets for PVDF Scaffolds with Improved Electrical Stimulation

Piezoelectric polyvinylidene fluoride (PVDF) provided an opportunity for non-invasive in situ electrical stimulation of cell behavior, yet its electroactive β phase was difficult to obtain due to its instability in the molten state. Herein, polyaniline (PANI) protrusions were in situ oxidation-polymerized on molybdenum disulfide (MoS2) nanosheets (PANI-MoS2). Then, PANI-MoS2 was introduced into laser additive-manufactured PVDF scaffolds. On the one hand, PANI protrusions produced steric hindrance between adjacent MoS2 nanosheets and inhibited the stacking and aggregating of MoS2. On the other hand, PANI-MoS2 could serve as a platform to achieve interfacial polarization locking. Specifically, Mo–S dipoles in MoS2 and π electron clouds over the N atom in PANI locked −CH2 dipoles in PVDF through electrostatic and hydrogen bond interactions, respectively, which forced −CH2 to align perpendicularly to the basal plane of MoS2 and bialy to one side of the PVDF main chain, thereby forming a full-reverse planar zigzag configuration of the polarized β phase and maintaining its stable existence. The results demonstrated that the β phase of the scaffolds was significantly increased from 43 to 90%, which resulted in an enhanced electrical output performance. The improved electrical output greatly promoted osteoblast-like cell proliferation and differentiation. Furthermore, owing to the pulling-out effect of MoS2 and improved interfacial stress transfer between MoS2 and the polymer matrix, the mechanical properties of scaffolds were also enhanced. These findings suggested that the piezoelectric scaffolds had great potential in bone tissue engineering.