Carbon　dots　(CD)　are　luminescent　nanomaterial　with　unique　properties　that　show　great　potential　in　many　applications.　Herein,　branched　polyethyleneimine-based　carbon　dots　(PCD)　are　prepared　from　branched　polyethyleneimine　by　oxidation　and　a　modified　hydrothermal　reaction.　Structure　and　composition　analysis　indicate　that　obtained　PCD　possesses　a　3-4　am　in　diameter　and　a　graphitic　structure　with　lattice　spacing　of　0.30　nm.　The　PCD　has　a　quantum　yield　of　54.3%.　The　bright　photoluminescence　shows　that　it　can　be　used　for　cell　imaging.　The　PCD　exhibits　extremely　good　biocompatibility　and　can　be　applied　for　gene　delivery.　Because　of　its　specific　nanostructure　and　photoluminescence　property　the　multifunctional　PCD　prepared　shows　potential　for　applications　in　bioimaging　and　gene　delivery.　(C)　2013　Elsevier　Ltd.　All　rights　reserved.