pH-Responsive nanoplatform synergistic gas/photothermal therapy to eliminate biofilms in poly(L-lactic acid) scaffolds.

To date, implant-associated infection is still a significant clinical challenge, which cannot be effectively eliminated by single therapies due to the formation of microbial biofilms. Herein, a pH-responsive nanoplatform was constructed via the in situ growth of zinc sulfide (ZnS) nanoparticles on the surface of Ti3C2 MXene nanosheets, which was subsequently introduced in poly(L-lactic acid) (PLLA) to prepare a composite bone scaffold via selective laser sintering technology. In the acidic biofilm microenvironment, the degradation of ZnS released hydrogen sulfide (H2S) gas to eliminate the biofilm extracellular DNA (eDNA), thus destroying the compactness of the biofilm. Then, the bacterial biofilm became sensitive to hyperthermia, which could be further destroyed under near-infrared light irradiation due to the excellent photothermal property of MXene, finally achieving gas/photothermal synergistic antibiofilm and efficient sterilization. The results showed that the synergistic gas/photothermal therapy for the composite scaffold not only evidently inhibited the formation of biofilms, but also effectively eradicated the eDNA of the already-formed biofilms and killed 90.4% of E. coli and 84.2% of S. aureus under near infrared light irradiation compared with single gas or photothermal therapy. In addition, the composite scaffold promoted the proliferation and osteogenic differentiation of mouse bone marrow mesenchymal stem cells. Thus, the designed scaffold with excellent biofilm elimination and osteogenesis ability has great potential as an alternative treatment for implant-associated bone infections.

Direct osteogenesis and immunomodulation dual function via sustained release of naringin from the polymer scaffold.

Many traditional Chinese medicine monomers, such as naringin (NG), can regulate the local immune microenvironment to benefit osteogenesis. However, the rapid release of NG from scaffolds severely influences the osteogenesis-promoting effect. Herein, NG was loaded into mesoporous bioglass (MBG) to achieve sustained release through physical adsorption and the barrier role of mesoporous channels, then MBG loaded with NG was added to poly(L-lactic acid) (PLLA) to fabricate composite scaffolds by selective laser sintering (SLS) technology. The results showed that the NG-MBG/PLLA scaffolds could continuously and slowly release NG for 14 days compared with NG/PLLA scaffolds, and the cumulative release amount for the NG-MBG/PLLA scaffolds was 44.26%. In addition, the NG-MBG/PLLA scaffolds can promote the proliferation and osteogenesis differentiation of mouse bone marrow mesenchymal stem cells (mBMSCs). Meanwhile, the composite scaffolds decreased the reactive oxygen species (ROS) level of RAW264.7 under the stimulation of lipopolysaccharide (LPS) and significantly suppressed interleukin-6 (IL-6) and enhanced arginase-1 (Arg-1) protein expressions. Moreover, calcium nodule and alkaline phosphatase production of mBMSCs in a macrophage-conditioned medium for the NG-MBG/PLLA group also evidently increased compared with the PLLA and MBG/PLLA groups. These NG sustained-release composite scaffolds with osteo-immunomodulation function have great application prospects in the clinic.

Silver-decorated black phosphorus: a synergistic antibacterial strategy.

Black phosphorus (BP) exhibits great potential as antibacterial materials due to its unique photocatalytic activity. However, the unsatisfactory optical absorption and quick recombination of photoinduced electron-hole pairs restrain its photocatalytic antibacterial performance. In this work, silver nanoparticles (AgNPs) were decorated on BP to construct BP@AgNPs nanohybrids and then introduced into poly-l-lactic acid scaffold. Combining the tunable bandgap of BP and the LSPR effect of AgNPs, BP@AgNPs nanohybrids displayed the broaden visible light absorption. Furthermore, AgNPs acted as electron acceptors could accelerate charge transfer and suppress electron-hole recombination. Therefore, BP@AgNPs nanohybrids achieved synergistically enhanced photocatalytic antibacterial activity under visible light irradiation. Fluorescence probe experiment verified that BP@AgNPs promoted the generation of reactive oxygen species, which could disrupt bacteria membrane, damage DNA and oxide proteins, and finally lead to bacteria apoptosis. As a result, the scaffold possessed strong antibacterial efficiency with a bactericidal rate of 97% under light irradiation. Moreover, the scaffold also exhibited good cytocompatibility. This work highlighted a new strategy to develop photocatalytic antibacterial scaffold for bone implant application.

An immuno-potentiating vehicle made of mesoporous silica-zinc oxide micro-rosettes with enhanced doxorubicin loading for combined chemoimmunotherapy.

Herein, mesoporous silica-zinc oxide (MS-Zn) micro-rosettes with controllable petal thickness were synthesized by a facile one-pot hydrothermal method. MS-Zn loaded with doxorubicin and polyinosinic-polycytidylic acid sodium salt not only significantly inhibits tumor growth but also effectively rejects tumor metastasis in vivo.