Lei Xing,Hongyang Song,Jinjian Wei,Xue Wang,Yaozhen Yang,Pengbo Zhe,Mingming Luan,Jing Xu
Thin oxide layers form easily on the surfaces of titanium (Ti) components, with thicknesses of <100 nm. These layers have excellent corrosion resistance and good biocompatibility. Ti is susceptible to bacterial development on its surface when used as an implant material, which reduces the biocompatibility between the implant and the bone tissue, resulting in reduced osseointegration. In the present study, Ti specimens were surface-negatively ionized using a hot alkali activation method, after which polylysine and polydopamine layers were deposited on them using a layer-by-layer self-assembly method, then a quaternary ammonium salt (QAS) (EPTAC, DEQAS, MPA-N+) was grafted onto the surface of the coating. In all, 17 such composite coatings were prepared. AgainstEscherichia coliandStaphylococcus aureus, the bacteriostatic rates of the coated specimens were 97.6 ± 2.0% and 98.4 ± 1.0%, respectively. Thus, this composite coating has the potential to increase the osseointegration and antibacterial performance of implantable Ti devices.Keywords:Ti;polylysine;self-assembly technology;EPTAC;DEQAS;MPA-N+;cell viability;antibacterial properties
The separation efficiency of mono−/divalent cations by a commercial nanofiltration membrane can be enhanced by increasing the surface positive charge. In this study, a novel surface grafting method was suggested, including activation with 2-chloro-1-methyliodopyridine (CMPI), and sequent graft polyethylene-imine (PEI) and 2,3-epoxypropyltrimethylammonium chloride (EPTAC). Less flux reduction (<30%) and higher separation factor of Mg 2+ /Na + (8.03–9.77) was achieved with the modified membrane under the grafting condition of 0.05 wt% CMPI, 2 wt% PEI, and 1 wt% EPTAC. The modified membranes had higher surface positive charge, hydrophilicity and cross-linking degree. During the 32-h filtration of a mixed salt solution, the modified membranes showed larger permeance (>11 L m −2 h −1 bar −1 ) and higher ion selectivity than the pristine membrane, with separation factors of Mg 2+ /Na + and Mg 2+ /Li + ranging 36.3–46.2 for the modified membranes. The modified membranes also have higher antifouling properties and are more stable at higher pH condition. The results demonstrate a facile and scalable surface modification method to improve the cation selectivity of commercial NF membranes, which shows great potential in the application of mono−/divalent ion separation.
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