Layer-by-layer immobilizing of polydopamine-assisted ε-polylysine and gum Arabic on titanium: Tailoring of antibacterial and osteogenic properties.

Bacterial infection has become a crucial reason that give rise to failure of medical implants in clinical applications. In this regard, various antibacterial surface modifications of implants have been developed in recent years. However, it remains a challenge to enable the implant surfaces with both suitable antibacterial and osteogenic properties. In this work, ε-polylysine and gum Arabic multilayer composite films were immobilized layer by layer (LBL) on anodized titanium with the assistance of polydopamine for the first time. In vitro antibacterial results showed that the bacteria numbers decreased with an increase in the loading amount of ε-polylysine. Furthermore, long-term antibacterial property up to 3 weeks against both gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli) was obtained combined with the merits of covalent binding and LBL methods. Meanwhile, the cell proliferation and osteogenic differentiation of BMSCs on titanium dioxide nanotubes (TNTs) modified with composite films was significantly improved. Remarkably, a facile method to optimize anti-infective and osteogenic properties of medical titanium has been developed, and it was demonstrated that the ε-polylysine and gum Arabic multilayer composite films with assistance of polydopamine were able to endow the orthopedic implant materials both improved antibacterial property and excellent biocompatibility, which is of profound significance for practical application of titanium-based implants.

Enhanced humification of maize straw and canola residue during composting by inoculating Phanerochaete chrysosporium in the cooling period.

To enhance the humification process, Phanerochaete chrysosporium (P. chrysosporium) was inoculated during different fermentation phases of the co-composting of maize straw and canola residue. The humification process was determined by evaluating cellulose and lignin contents and key enzyme activities during composting. Results showed that the cellulose and lignin degradation efficiency and humification degree of compost were significantly enhanced in the treatment that inoculated P. chrysosporium in the cooling period (T2). At the end of composting, compared with that in T1 (no inoculation), the content of cellulose and lignin in T2 decreased significantly by 40.00% and 64.30%, respectively, and compared with that in T1 and T3 (inoculation in the initial stage of composting) the content of humus in T2 increased significantly by 55.40% and 75.20%, respectively. This study confirms that inoculating P. chrysosporium during the cooling period promoted the degradation of cellulose and lignin, and therefore enhanced the compost humification.