Photothermal driven BMSCs osteogenesis and M2 macrophage polarization on polydopamine-coated Ti3C2 nanosheets/poly(vinylidene fluoride trifluoroethylene) nanocomposite coatings.

Mild thermal stimulation plays an active role in bone tissue repair and regeneration. In this work, a bioactive polydopamine/Ti3C2/poly(vinylidene fluoride trifluoroethylene) (PDA/Ti3C2/P(VDF-TrFE)) nanocomposite coating with excellent near-infrared light (NIR)-triggered photothermal effect was designed to improve the osteogenic ability of implants. By incorporating dopamine (DA)-modified Ti3C2 nanosheets into the P(VDF-TrFE) matrix and combining them with alkali initiated in situ polymerization, the resulting PDA/Ti3C2/P(VDF-TrFE) nanocomposite coating gained high adhesion strength on Ti substrate, excellent tribological and corrosion resistance properties, which was quite important for clinical application of implant coatings. Cell biology experiments showed that NIR-triggered mild thermal stimulation on the coating surface promoted cell spreading and growth of BMSCs, and also greatly upregulated the osteogenic markers, including Runt-Related Transcription Factor 2 (RUNX2), alkaline phosphatase (ALP), osteopontin (OPN), osteocalcin (OCN). Simultaneously, the synthesis of heat shock protein 47 (HSP47) was significantly promoted by the mild thermal stimulation, which strengthened the specific interaction between HSP47 and collagen Ⅰ (COL-Ⅰ), thereby activating the integrin-mediated MEK/ERK osteogenic differentiation signaling pathway. In addition, the results also showed that the mild thermal stimulation induced the polarization of macrophages towards M2 phenotype, which can attenuate the inflammatory response of injured bone tissue. Antibacterial results indicated that the coating exhibited an outstanding antibacterial ability against S. aureus and E. coli. Conceivably, the versatile implant bioactive coatings developed in this work will show great application potential for implant osseointegration.

Fabrication and characterization of magnetic mesoporous nanoparticles for efficient determination and magnetic separation of sulfonamides in food samples.

A magnetic, mesoporous core/shell structured Fe3O4@SiO2@mSiO2 nanocomposite was synthesized and employed as a magnetic solid phase extraction (MSPE) sorbent for the determination of trace sulfonamides (SAs) in food samples. The synthesized nanocomposite was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, X-ray diffraction, N2 sorption analysis and vibrating sample magnetometry. The results showed that Fe3O4@SiO2@mSiO2 possessed a mesoporous structure with a large surface area. Batch experiments were carried out to investigate the adsorption ability for SAs. Fe3O4@SiO2@mSiO2 showed fast kinetics and high adsorption capacity, and the pseudo-second-order model and Langmuir adsorption isotherm are well fitted with the experimental data, indicating that chemical adsorption might be the rate-limiting step. Moreover, the high adsorption capacity can be maintained for at least 8 runs, indicating excellent stability and reusability. The proposed method exhibited good linearity in the range of 0.2-500 µg L-1, the R2 values of all the analytes were greater than 0.99 and the LODs were all lower than 0.2 µg L-1. Furthermore, real food samples were successfully analyzed with Fe3O4@SiO2@mSiO2 and high recoveries varying from 89.7% and 110.6% were obtained with low relative standard deviations ranging from 1.78% to 6.91%. The Fe3O4@SiO2@mSiO2 magnetic nanocomposite is a promising sorbent for the efficient extraction of SAs from complex food samples.

Formation mechanism of a novel core-shell with tetradecyl dimethyl benzyl ammonium-modified montmorillonite interlayer nanofibrous membrane and its antimicrobial properties.

A novel core-shell with a tetradecyl dimethyl benzyl ammonium chloride-modified montmorillonite (TDMBA/MMT) interlayer silk fibroin (SF)/poly(lactic acid) (PLLA) nanofibrous membrane was fabricated using a simple conventional electrospinning method. Scanning electron microscopy and pore size analyses revealed that this core-shell with TDMBA/MMT interlayer maintained its nanofibrous morphology and larger pore structure more successfully than SF/PLLA nanofibrous membranes after treatment with 75% ethanol vapor. Transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses testified that the SF/PLLA-TDMBA/MMT nanofibers exhibited a core-shell with an interlayer structure, with SF/PLLA in the core-shell layer and TDMBA/MMT in the interlayer. The formation of a core-shell with interlayer nanofibers was primarily attributed to the uniform dispersion of TDMBA/MMT nanosheets in a solution owing to its exfoliation using hexafluoroisopropanol and then preparing a stable spinning solution similar to an emulsion. Compared to SF/PLLA nanofibrous membranes, the core-shell structure with TDMBA/MMT interlayers of SF/PLLA nanofibrous membranes exhibited enhanced hydrophilicity, thermal stability, mechanical properties as well as improved and long-lasting antimicrobial performance against Escherichia coli and Staphylococcus aureus without cytotoxicity.