| Nanomaterials that integrate multifunction of imaging and gene delivery have been of great interest owing to their potential use in simultaneous diagnosis and therapy. Herein, polycation-b-polysulfobetaine block copolymer, poly [2-(dimethylamino) ethyl methacrylate]-b-poly[N-(3-(methacryloylamino) propyl)-N,N-dimethyl-N-(3-sulfopropyl) ammonium hydroxide](PDMAEMA-b-PMPDSAH) grafted luminescent carbon dots(CDs) were prepared via surface initiated atom transfer radical polymerization(ATRP) and investigated as a multifunctional gene delivery system(denoted as CD-PDMA-PMPD) in which the CD cores acted as multicolor cell imaging probes, the cationic PDMAEMA acted as a DNA condensing agent, and the outer shell of zwitterionic PMPDSAH block protected the vector against non-specific interactions with serum components. As revealed by the fluorescent spectrum study, the photoluminescent attributes of modified CDs especially the tunable emission property, were well inherited from the parent CDs. The CD-PDMA-PMPD could condense plasmid DNA(pDNA) into nanospheres with sizes of approximate 50 nm at a proper complex ratio, posing little cytotoxicity at higher ratios. It was shown that the hybrid vector exhibited significantly suppressed protein adsorption and superior hemocompatibility compared to the widely used PEI25 k. In the in vitro transfection assay, an increased serum concentration from 10% to 50% caused a dramatic drop in PEI25 k transfection performance, whereas the transfection efficiency of CD-PDMA-PMPD was well maintained; the transfection efficiencies of CD-PDMA80-PMPD40 were 14 and 29 times those of PEI25 k at 30% and 50% serum concentration, respectively. Intriguingly, the CD-polymer/pDNA complexes in the transfected cells could be detected by observing the excitation-dependent fluorescent emissions, portending that these polycation-polyzwitterion modified CDs will be a promising theranostic vector with excellent serum-resistant performance. |
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