A DNA Nanotube-Peptide Biocomplex for mRNA Detection and Its Application in Cancer Diagnosis and Targeted Therapy.

A biocomplex of DNA nanotube-peptide, consisting of six concatenated DNA strands, three locked DNA strands, and a cell-penetrating peptide, is reported. The barrel-structured DNA nanotube-peptide was successfully applied as a codrug-delivery system for targeting cancer therapy. The mucin 1 protein (MUC-1) aptamer is part of a DNA nanotube that can specifically recognize MUC-1 protein on the surface of MCF-7 cells. Cyclo (Arg-Gly-Asp-d-Phe-Lys; cRGD), as a cell-penetrating peptide, facilitates recruitment and uptake of targeting drugs by binding to integrin receptors (αv β3 ) of the cytomembrane surface. Anticancer drugs doxorubicin (DOX) and paclitaxel (PTX) were loaded into the capsulated DNA nanotube-peptide (CDNP), which was used as codrug cargo models. The as-prepared biocomplex can be utilized not only to deliver drugs, but also to achieve anticancer effects in vivo. Experimental results suggested that the treatment efficacy of the codrug delivery platform (CDNP/DOX/PTX) was better than that of a single-drug delivery platform (CDNP/DOX or CDNP/PTX). This system, which is composed of DNA strands and peptide, has good biocompatibility and biodegradability. Furthermore, the system can readily detect target mRNA in MCF-7 cells in vitro. The detection limits of mRNA are 9.7×10-8 and 1.8×10-8  m with CDNP/DOX and CDNP/PTX-FITC (FITC=fluorescein isothiocyanate), respectively, as probes.