Transfection and intracellular trafficking properties of carbon dot-gold nanoparticle molecular assembly conjugated with PEI-pDNA

Abstract

The work employs carbon dot (CD) which has been emerging as a "uorescent nanomaterial with excellent biocompatibility and perceived as a promising alternative to quantum dot (QD), to monitor the association/dissociation of polymeric carrier/plasmid DNA (pDNA) complex during transfection. To shed light on the underlying post-endosomal events and provide the insight to design rational and ef!cient gene delivery vector, the adopted strategy exploited the quenching of the "uorescence of CD by Au nanoparticles. The surface of CD and Au was modi!ed with highly cationic polymer, polyethylenimine (PEI) and subsequent treatment with non-labeled pDNA gave rise to quenched delivery complex. High salt concentration triggered the dissociation of the complex with accompanied "uorescence recovery arising due to the increase in distance between CD and Au. The studies revealed the potential of the developed CD-PEI/Au-PEI/pDNA ternary nano-assembly as a highly ef!cient hybrid transfecting agent with high cell viability under the optimum condition. The changes occurred at the intracellular level during transfection especially post-endosomal step were monitored by "uorescence measurement using "uorescence microscope. This nano-assembly system was found to be very effective at monitoring the carrier/pDNA dissociation in a non-labeled manner, thus