Multifunctional tri-modal heterogeneous smart scaffold: Piezocatalytic antibacterial, electroregenerative, and mechanically reinforced characteristics

• The coordination bond between Cu-BTC and PLLA enhances the interfacial coupling between the MoS 2 @Cu-BTC heterojunction and PLLA, thereby significantly improving the mechanical properties of the scaffold. • Due to the piezoelectric properties of MoS 2 and the Type-II heterojunction MoS 2 @Cu-BTC with staggered energy bands, which is constructed based on the matched work functions of MoS 2 and Cu-BTC, the MoS 2 @Cu-BTC/PLLA scaffold enables rapid separation of electron-hole pairs and formation of a built-in electric field under ultrasound. • The Type-II heterojunction scaffold MoS 2 @Cu-BTC/PLLA fabricated by SLS can achieve ultrasound-activated sonocurrent stimulated of osteoblast differentiation and upregulation of related osteogenic proteins. Molybdenum disulfide (MoS 2 ), a sonosensitizer material, shows promising application potential in the fields of piezoelectric catalytic antibacterial activity and electrical stimulation-induced regeneration. However, MoS 2 has two major limitations: the difficulty in separating electron-hole pairs, which results in low antibacterial catalytic activity; and the inability to form chemical bonds with biopolymers, leading to the failure of its composite scaffolds to effectively transmit mechanical stimuli. To address these issues, we propose a three-in-one strategy: in-situ growth of Cu-BTC (the abbreviation for HKUST-1, a MOF structure) on the surface of MoS 2 to construct a Type-II heterojunction, which can form a built-in electric field to accelerate electron-hole separation; the excited electrons form a current loop in the MoS 2 matrix to stimulate bone regeneration; Cu-S bonds are formed between MoS 2 and Cu, while Cu ions form coordination bonds with carboxyl groups in the polylactic acid polymer chains, thereby constructing a “plane-point-line” ternary structure. This structure hinders the movement of polylactic acid polymer chains through “mechanical interlocking” of the layered structure and chemical bonding, thus improving the mechanical properties of the composite scaffold. Experimental results showed that the compressive strength of the scaffold was increased by 140%; the inhibition rates against Staphylococcus aureus ( S.aureus ) and Escherichia coli ( E.coli ) reached 99.3% and 99%, respectively. Notably, the ultrasound-induced sonocurrent could stimulate the expression of osteogenic factors such as BMP-2, RUNX-2, and Wnt-10b, increased the differentiation efficiency of osteoblasts by 37.5% in the late stage of osteogenesis. Scheme 1. Schematic of MoS 2 @Cu-BTC/PLLA heterojunction scaffold fabrication, antibacterial-osteogenic mechanisms, and interface coupling enhancement.