The currently applied disinfection methods during water treatment provide effective solutions to kill pathogens, but also generate harmful byproducts, which are required to be treated with additional efforts. In this work, an alternative and safer water disinfection system consisting of silver nanoparticle/multiwalled carbon nanotubes (Ag/MWNTs) coated on a polyacrylonitrile (PAN) hollow fiber membrane, Ag/MWNTs/PAN, has been developed. Silver nanoparticles of controlled sizes were coated on polyethylene glycol-grafted MWNTs. Ag/MWNTs were then covalently coated on the external surface of a chemically modified PAN hollow fiber membrane to act as a disinfection barrier. A continuous filtration test using E. coli containing feedwater was conducted for the pristine PAN and Ag/MWNTs/PAN composite membranes. The Ag/MWNT coating significantly enhanced the antimicrobial activities and antifouling properties of the membrane against E. coli. Under the continuous filtration mode using E. coli feedwater, the relative flux drop over Ag/MWNTs/PAN was 6%, which was significantly lower than that over the pristine PAN (55%) at 20 h of filtration. The presence of the Ag/MWNT disinfection layer effectively inhibited the growth of bacteria in the filtration module and prevented the formation of biofilm on the surface of the membrane. Such distinctive antimicrobial properties of the composite membrane is attributed to the proper dispersion of silver nanoparticles on the external surface of the membrane, leading to direct contact with bacterium cells.
The use of artificial cornea implants has received increasing attention for treating cornea-related diseases and vision errors due to the low side effects. To achieve long-term successful vision correction, stable and biocompatible materials of high refractive index (RI) need to be developed. Herein, we developed an interpenetrating polymer network (IPN) hydrogel containing well-dispersed ZnS nanoparticles (∼3 nm) covalently linked to the first polymer network, poly(2-hydroethyl methacrylate) (PHEMA). The second polymer network used was poly(acrylic acid) (PAA). The resultant ZnS/PHEMA/PAA IPN nanocomposite is clear and transparent at both dry and hydrated states with their RIs measured to be as high as 1.65 and 1.49, respectively. The equilibrium water content of the hydrogel nanocomposite reached 60.2% which is reasonably near to that of cornea. The material exerted minimal cytotoxicity toward primary epidermal keratinocyte cells. The high RI IPN hydrogel nanocomposite developed here might be an excellent candidate for artificial cornea implants.
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