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Two sulfobetaine-based zwitterionic monomers, including 3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide (MPDSAH) and 2-(methacryloyloxyethyl) ethyl-dimethyl-(3-sulfopropyl) ammonium (MEDSA) were successfully grafted from poly(vinylidene fluoride) (PVDF) hollow fiber membrane outside surface via chemical activation and atom transfer radical polymerization (ATRP). The ATRP time at 2 h under the 2 mol/L of zwitterionic monomers was the minimum period for the complete coverage of grafted sulfobetaine polymers on the PVDF membrane surface. The surface hydrophilicity of the sulfobetaine-modified PVDF membranes was significantly enhanced. The poly-MPDSAH-g-PVDF (GA: 247 lg/cm 2 ) and poly-MEDSA-g-PVDF membranes (GA: 338 lg/cm 2 ) efficiently resisted to the adsorption of both negative and positive charged proteins, and showed excellent anti-protein-fouling performance with flux recovery ratio (RFR) higher than 90% and total fouling (RT) less than 25% during the cyclic filtration of bovine serum albumin solution. After cleaned in membrane cleaning solution for 12 days, the grafted MPDSAH layer on PVDF membrane could maintain without change, however, the poly-MEDSAg-PVDF membrane lost the grafted MEDSA layer. Therefore, the amide group of sulfobetaine, which made a great contribution to the higher hydrophilicity and stability, was significant in modifying the PVDF membrane for a stably anti-protein-fouling performance.

A highly hydrophilic hollow fiber poly(vinylidene fluoride) (PVDF) membrane [PVDF-cl-poly(vinyl pyrrolidone) (PVP) membrane] was prepared by a cross-linking reaction with the hydrophilic PVP, which was immobilized firmly on the outer surface and cross-section of the PVDF hollow fiber membrane via a simple immersion process. The cross-linking between PVDF and PVP was firstly verified via nuclear magnetic resonance measurement on PVP solution after cross-linking. The hydrophilic stability of the modified PVDF membrane was evaluated by measuring the pure water flux after different times of immersion and drying. The antifouling properties were estimated by cyclic filtration of protein solution. When the cross-linking time was as long as 6 hr and the PVP content reached 5 wt %, the pure water flux (J v ) was constant as $ 600 L m À2 hr À1 . The hydrophilicity of the PVDF-cl-PVP membrane was significantly enhanced and exhibited a good stability. The PVDF-cl-PVP membrane showed an excellent anti-proteinfouling performance during the cyclic filtration of bovine serum albumin solution. Therefore, a highly hydrophilic and anti-proteinfouling PVDF hollow fiber membrane with a long-term stability can be prepared by a simple and economical cross-linking process with PVP.

We report an inducible epitope imprinting strategy that as a template, a flexible peptide chain can have a disordered-to-ordered conformational change by suitable inducement through a molecular imprinting procedure, and the formed nanoparticles can, in turn, remold the original peptide into the expected conformation and specifically bind to the corresponding protein.