Surface　functionalization　of　nanomaterials　with　highly　specific　recognition　elements,　such　as　biomolecules　and　organic　molecules,　has　made　possible　many　novel　nanosensors　for　bio/chemical　analysis　and　target　bioimaging.　In　this　report,　a　fluorescent　nanosensor　which　exhibits　highly　specific　recognition　capability　towards　Zn2+　over　competing　metal　ions　has　been　developed　through　covalently　functionalizing　carbon　dots　(C-dots)　with　the　quinoline　derivatives　which　show　response　to　Zn2+.　The　nanosensor　exhibits　excellent　water　solubility,　biocompatibility,　and　cell-membrane　permeability,　and　demonstrates　high　selectivity　towards　Zn2+　with　a　detection　limit　as　low　as　6.4　nM.　Additionally,　the　rapid　response　of　the　nanosensor　towards　Zn2+　can　be　achieved　within　1　min.　The　large　amount　of　recognition　units　on　the　outer　surface　of　an　individual　nanoparticle　enables　the　signal　amplification,　hence　making　the　immediate　and　highly　sensitive　detection　of　Zn2+　possible.　Therefore,　a　reliable　and　highly　specific　nanosensor　has　been　demonstrated　for　both　rapid　quantitative　detection　of　Zn2+　in　aqueous　solution　and　real-time　imaging　of　intracellular　Zn2+,　suggesting　its　potential　and　significance　in　bioanalysis　and　biomedical　detection　in　the　future.　©　2014　the　Partner　Organisations.