ABSTRACT
MXenes are a group of inorganic two-dimensional (2D) nanomaterial, and have raised significant interests in biomedical areas. Ti3C2Tx, as an important member of MXene family, is widely studied because of its biodegradability and low-cytotoxicity. However, their single antibacterial mechanism and poor stability in aqueous solution need to be improved, especially for the antimicrobial applications. In this work, a MXene-based hybrid antibacterial system (M-HAS) was developed and its synergistic antibacterial activity was investigated. In the M-HAS, 2D few-layer Ti3C2Tx(FL-Ti3C2Tx) was modified with hydrophilic polymers and thereby used as carriers for silver nanoparticles (Ag NPs). By assembling these two substrates, photodynamic performance of the prepared system is significantly improved with a large amount of reactive oxygen species produced under 660 nm laser. Antibacterial effects of the M-HAS are enhanced by over 4 times with irradiation. In another word, the developed hybrid system displays excellent photodynamic antibacterial synergistic properties. This work takes advantage of the photodynamic properties of each component in the M-HAS to achieve efficient antibacterial activity and proposes an innovative approach to develop the 2D FL-Ti3C2Tx-based antibacterial platform.
ABSTRACT
Effective osteogenesis remains a challenge in the treatment of bone defects. The emergence of artificial bone scaffolds provides an attractive solution. In this work, a new biomineralization strategy is proposed to facilitate osteogenesis through sustaining supply of nutrients including phosphorus (P), calcium (Ca), and silicon (Si). We developed black phosphorus (BP)-based, three-dimensional nanocomposite fibrous scaffolds via microfluidic technology to provide a wealth of essential ions for bone defect treatment. The fibrous scaffolds were fabricated from 3D poly (l-lactic acid) (PLLA) nanofibers (3D NFs), BP nanosheets, and hydroxyapatite (HA)-porous SiO2 nanoparticles. The 3D BP@HA NFs possess three advantages: i) stably connected pores allow the easy entrance of bone marrow-derived mesenchymal stem cells (BMSCs) into the interior of the 3D fibrous scaffolds for bone repair and osteogenesis; ii) plentiful nutrients in the NFs strongly improve osteogenic differentiation in the bone repair area; iii) the photothermal effect of fibrous scaffolds promotes the release of elements necessary for bone formation, thus achieving accelerated osteogenesis. Both in vitro and in vivo results demonstrated that the 3D BP@HA NFs, with the assistance of NIR laser, exhibited good performance in promoting bone regeneration. Furthermore, microfluidic technology makes it possible to obtain high-quality 3D BP@HA NFs with low costs, rapid processing, high throughput and mass production, greatly improving the prospects for clinical application. This is also the first BP-based bone scaffold platform that can self-supply Ca2+, which may be the blessedness for older patients with bone defects or patients with damaged bones as a result of calcium loss.
ABSTRACT
The present paper represents a facile and rapid synthesis of silver-reduced graphene oxide Ag/rGO (Ag/reduced graphite oxides) composites with the help of microwave irradiation. This is a rapid green route requiring power microwave irradiation only 400 W(30 s) and 200 W (60 s) for the uniform Ag nanoparticles with average diameter of ~10 nm embedded on rGO sheets. In the microwave irradiation process, rGO samples absorb electromagnetic energy to be heated rapidly due to their intrinsic dielectric and conductive losses. Local hot sheets appear in aqueous solution, facilitating homogeneous nucleation, as well as the grain growth of Ag crystallites throughout the rGO sheets. The obtained Ag/rGO composites exhibited significant antibacterial property towards Gram-negative bacteria (E. coli and P. aeruginosa), Gram-positive bacteria (S. aureus and Enterococcus), and white rot fungus. The minimum bactericidal concentration of the Ag /rGO nanocomposite against E. coli was about 1 µg/mL. Strong interaction between Ag/rGO composites and bacteria contributed to the totally non-activity of bacteria. We designed Ag/rGO nanocomposite with excellent antibacterial activities by facile andrapid microwave-assisted green route. In Ag/rGO nanocomposite, the morphology and size distributions of Ag particles anchored on the rGO sheets can controlled via the microwave irradiation power and time. The results suggested that in the microwave field, GO reduced into unique rGO sheets and uniform AgNPs with average size of 12 nm can be decorated on rGO sheets at 30 s and at 200 W, respectively. we successfully demonstrated small silver particles anchored on graphene displayed great antibacterial activities against Gram-negative bacteria (E. coli and P. aeruginosa), Gram-positive bacteria (S. aureus and Enterococcus) and white rot fungus. Ag/rGO nanocomposites may have potential applications as antibacterial agent for daily life.
