Graphene-based　nanocomposites　have　a　vast　potential　for　wide-ranging　antibacterial　applications　due　to　the　inherently　strong　biocidal　activity　and　versatile　compatibility　of　such　nanocomposites.　Therefore,　graphene-based　functional　nanomaterials　can　introduce　enhanced　antibiofouling　and　antimicrobial　properties　to　polymeric　membrane　surfaces.　In　this　study,　reduced　graphene　oxide-copper　(rGOC)　nanocomposites　were　synthesized　as　newly　robust　biocides　via　in　situ　reduction.　Inspired　by　the　emerging　method　of　bridging　ultrafiltration　membrane　surface　cavities,　loose　nanofiltration　(NF)　membranes　were　designed　using　a　rapid　(2　h)　bioinspired　strategy　in　which　rGOC　nanocomposites　were　firmly　codeposited　with　polydopamine　(PDA)　onto　an　ultrafiltration　support.　A　series　of　analyses　(SEM,　EDS,　XRD,　XPS,　TEM,　and　AFM)　confirmed　the　successful　synthesis　of　the　rGO-Cu　nanocomposites.　The　secure　loading　of　rGOC　composites　onto　the　membrane　surfaces　was　also　confirmed　by　SEM　and　AFM　images.　Water　contact　angle　results　display　a　high　surface　hydrophilicity　of　the　modified　membranes.　The　PDA-rGOC　functionalization　layer　facilitated　a　high　water　permeability　(22.8　L　m-2　h-1　bar-1).　The　PDA-rGOC　modification　additionally　furnished　the　membrane　with　superior　separation　properties　advantageous　for　various　NF　applications　such　as　dye　purification　or　desalination,　as　ultrahigh　(99.4%　for　0.5　g　L-1　reactive　blue　2)　dye　retention　and　high　salt　permeation　(7.4%　for　1.0　g　L-1　Na2SO4,　2.5%　for　1.0　g　L-1　NaCl)　was　achieved　by　the　PDA-rGOC-modified　membranes.　Furthermore,　after　3　h　of　contact　with　Escherichia　coli　(E.　coli)　bacteria,　the　rGOC-functionalized　membranes　exhibited　a　strong　antibacterial　performance　with　a　97.9%　reduction　in　the　number　of　live　E.　coli.　This　study　highlights　the　use　of　rGOC　composites　for　devising　loose　NF　membranes　with　strong　antibacterial　and　separation　performance.　©　2017　American　Chemical　Society.