Y-Shaped Backbone-Rigidified DNA Tiles for the Construction of Supersized Nondeformable Tetrahedrons for Precise Cancer Therapies.

While engineered DNA nanoframeworks have been extensively exploited for delivery of diagnostic and therapeutic regents, DNA tiling-based DNA frameworks amenable to applications in living systems lag much behind. In this contribution, by developing a Y-shaped backbone-based DNA tiling technique, we assemble Y-shaped backbone-rigidified supersized DNA tetrahedrons (RDT) with 100% efficiency for precisely targeted tumor therapy. RDT displays unparalleled rigidness and unmatched resistance to nuclease degradation so that it almost does not deform under the force exerted by the atomic force microscopy tip, and the residual amount is not less than 90% upon incubating in biological media for 24 h, displaying at least 11.6 times enhanced degradation resistance. Without any targeting ligand, RDT enters the cancer cell in a targeted manner, and internalization specificity is up to 15.8. Moreover, 77% of RDT objects remain intact within living cells for 14 h. The drug loading content of RDT is improved by 4-8 times, and RDT almost 100% eliminates the unintended drug leakage in a stimulated physiological medium. Once systemically administrated into HeLa tumor-bearing mouse models, doxorubicin-loaded RDTs preferentially accumulate in tumor sites and efficiently suppress tumor growth without detectable off-target toxicity. The Y-DNA tiling technique offers invaluable insights into the development of structural DNA nanotechnology for precise medicine.

Structure-switchable aptamer-arranged reconfigurable DNA nanonetworks for targeted cancer therapy.

The structural DNA nanotechnology holds great potential application in bioimaging, drug delivery and cancer therapy. Herein, an intelligent aptamer-incorporated DNA nanonetwork (Apt-Nnes) is demonstrated for cancer cell imaging and targeted drug delivery, which essentially is a micron-scale pattern with the thickness of double-stranded monolayer. Cancer cell-surface receptors can make it perform magical transformation into small size of nanosheet intermediates and specifically enter target cells. The binding affinity of Apt-Nnes is increased by 3-fold due to multivalent binding effect of aptamers and it can maintain the structural integrity in fetal bovine serum (FBS) for 8 h. More interestingly, target cancer cells can cause the structural disassembly, and each resulting unit transports 4963 doxorubicin (Dox) into target cells, causing the specific cellular cytotoxicity. The cell surface receptor-mediated disassembly of large size of DNA nanostructures into small size of fractions provides a valuable insight into developing intelligent DNA nanostructure suitable for biomedical applications.

Hybridization chain reaction and its applications in biosensing.

To pursue the sensitive and efficient detection of informative biomolecules for bioanalysis and disease diagnosis, a series of signal amplification techniques have been put forward. Among them, hybridization chain reaction (HCR) is an isothermal and enzyme-free process where the cascade reaction of hybridization events is initiated by a target analyte, yielding a long nicked dsDNA molecule analogous to alternating copolymers. Compared with conventional polymerase chain reaction (PCR) that can proceed only with the aid of polymerases and complicated thermal cycling, HCR has attracted increasing attention because it can occur under mild conditions without using enzymes. As a powerful signal amplification tool, HCR has been employed to construct various simple, sensitive and economic biosensors for detecting nucleic acids, small molecules, cells, and proteins. Moreover, HCR has also been applied to assemble complex nanostructures, some of which even act as the carriers to execute the targeted delivery of anticancer drugs. Recently, HCR has engendered tremendous progress in RNA imaging applications, which can not only achieve endogenous RNA imaging in living cells or even living animals but also implement imaging-guided photodynamic therapy, paving a promising path to promote the development of theranostics. In this review, we begin with the fundamentals of HCR and then focus on summarizing the recent advances in HCR-based biosensors for biosensing and RNA imaging strategies. Further, the challenges and future perspective of HCR-based signal amplification in biosensing and theranostic application are discussed.