Carbonaceous nanostructures featuring unique structural characteristics and high cytocompatibility offer a wealth of possibilities to impart enhancements of mechanical properties and biological activities for osteogenic tissue scaffolds. Here, we unveil the fabrication of osteoconductive and antibacterial porous poly­(lactic acid) (PLA) membranes by direct electrospinning of microfibers impregnated with coffee-ground-derived quantum dots (QDs). It enabled a straightforward pathway to regulate the diameter and its distribution for the electrospun PLA microfibers, as well as the improved hydrophilicity. The QDs exhibited high affinity to the PLA matrix, permitting remarkable promotion of tensile strength and elastic modulus for the QD-modified PLA membranes while maintaining comparable extensibility. More importantly, osteoblast adhesion and stretching on the electrospun membranes were significantly enhanced with the existence of QDs, as exemplified by the nearly 1.8-fold increase in cell viability cultured onto the composite membrane loaded with 1.5% QDs compared to that of pure PLA. This was accompanied by rapid biomimetic mineralization and uniform apatite formation in an osteo-friendly manner. Unexpectedly, immediate and broad-spectrum antibacterial performance was achieved for the composite membranes, likely arising from the synergistic effects of QD-imparted membrane stress and oxidative stress. The unusual combination of mechanical, biomineralization, biological, and antibacterial performances makes the biodegradable membrane scaffolds promising for guided bone/tissue regeneration therapy.

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Graphene oxide (GO) featuring a two-dimensional (2D) sheetlike structure and extensive oxygen functionalities occupies indispensable research branches in polymer composites. Key to the property translation from GO nanosheets to host polymers is the proper exfoliation and controlled dispersion that are profoundly governed by the competitive evolution between GO−GO intersheet attractions and GO−polymer interfacial interactions. Here, a microwave-assisted synthetic approach was proposed to enable direct in situ growth of carbon nanotubes (CNTs) at GO templates, engendering a minute-level and one-pot route to create three-dimensional (3D) hierarchical nanohybrids (GO@CNT). Featuring a unique 3D structure, the nanohybrids were homogeneously dispersed and properly exfoliated in racemic polylactide (PLA) blends, in clear contrast to microscale local aggregation of GO due to extensive intersheet attractions. Albeit present at an extremely low amount (0.05 wt %), GO@CNT significantly outperformed GO in terms of boosting PLA stereocomplexation, achieving distinct overall improvements in gas barrier performance (oxygen permeability coefficient as low as 0.25 × 10 −15 cm 3 cm cm −2 s −1 Pa −1 ) and mechanical properties (tensile strength of ∼70 MPa and Young's modulus of ∼2 GPa) for stereocomplexed PLAs. This work affords elucidation of direct covalent functionalization of 2D nanosheets and property-by-morphology understanding in polymer composites, which may motivate further extension to other 2D/one-dimensional (1D) hierarchical hybrids in need for the fabrication of multifunctional polymer composites.

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