Polyaptamer DNA nanothread-anchored, reduced graphene oxide nanosheets for targeted delivery.

Here, we report reduced graphene oxide (rGO) nanosheets anchoring receptor-specific polyaptamer nanothreads for targeted drug delivery. DNA polyaptamer nanothreads of protein tyrosine kinase 7 receptor (PTK7) were synthesized by rolling cycle amplification. To strengthen the anchoring of polyaptamer nanothreads onto rGO, oligoT bridge domain was introduced between each repeating PTK7 aptamer sequence. As compared to PTK7 polyaptamer nanothreads alone, PTK7 polyaptamer nanothreads with 22-mer oligoT bridges (PNT) showed higher anchoring capacity onto rGO nanosheets. Nanothread-coated surface morphology of PNTrGO was observed. Coating of PNT did not affect the sizes of rGO, but reduced the zeta potential. In PTK7-negative Ramos cells, the uptake of PNT-anchored rGO (PNTrGO) did not differ from that of oligoT-bridged scrambled polyaptamer-anchored rGO (SNTrGO). However, in CCRF-CEM leukemia cells overexpressing PTK7, the uptake of PNTrGO was 2.1-fold higher than that of SNTrGO after 15 min pulse. In vivo distribution to CCRF-CEM tumor tissues was 2.8-fold higher in PNTrGO than in SNTrGO at 48 h post-injection. In CCRF-CEM xenografted mice, intravenously administered doxorubicin (Dox)-loaded PNTrGO showed the higher antitumor activity than other groups, reducing the tumor weight down to 12% of tumor weights of untreated mice. These results suggest the potential of PNTrGO for target-specific drug delivery nanoplatform.