Surface　functionalization　with　advanced　nanomaterials　offers　tailored　control　and　targeted　design　of　surface　properties,　endowing　materials　with　enhanced　or　new　qualities　such　as　high　hydrophilicity,　excellent　selectivity　and　permeability,　and　enhanced　antimicrobial　activity.　In　this　study,　we　develop　two　strategies　(two-step　deposition/co-deposition)　that　use　mussel-inspired　polydopamine　(PDA)　to　strongly　immobilize　copper　nanoparticles　(CuNPs)　onto　a　porous　polymeric　membrane,　bridging　the　surface　cavities　from　ultrafiltration　(UF)　to　loose　nanofiltration　(NF).　To　confirm　the　optimization　of　membrane　properties,　a　series　of　characterizations　were　carried　out:　SEM,　EDX　analysis,　AFM,　water　contact　angle,　and　zeta　potential　measurements.　The　results　indicate　an　overall　high　performance　of　surface　properties　with　a　homogeneous　nanoparticle　distribution,　low　roughness,　favorable　hydrophilicity,　and　relatively　neutral　charge.　Co-deposition　of　PDA　and　CuNPs　exhibits　a　facile　and　time-saving　process　that　expedited　a　higher　CuNP　loading　compared　to　the　two-step　strategy,　as　confirmed　by　SEM　and　AFM　images.　The　integration　of　polyethylenimine　(PEI)-modified　CuNPs　with　high　density　of　positive　charges　plays　an　important　role　in　fine-tuning　the　hydrophilicity　and　compatibility　with　PDA　and　in　largely　neutralizing　the　negative　charge　of　PDA,　thus　promoting　an　outstanding　salt　permeation　(82%　Na2SO4,　98%　NaCl).　In　addition,　CuNP/PDA-modified　membranes　show　an　ultra-high　rejection　of　three　types　of　textile　dyes　(600-800　Da,　＞99.0%),　demonstrating　superior　NF　performance.　Furthermore,　the　functionalized　membranes　display　distinct　bactericidal　activity　with　a　great　reduction　of　93.7%　in　the　number　of　live　Escherichia　coli　(E.　coli)　bacteria.　This　study　highlights　a　fast,　facile　co-deposition　strategy　to　assemble　multifunctional　coating　onto　a　UF　support,　which　renders　a　vast　potential　for　the　fractionation　of　dye/salt　mixtures.　©　2016　The　Royal　Society　of　Chemistry.