DNA Nanodevices for Base Excision Repair Regulates ATP In Situ Imaging and Tumor Therapy

Functionalizing tetrahedral framework nucleic acids-based nanostructures for tumor in situ imaging and treatment

Timely in situ imaging and effective treatment are efficient strategies in improving the therapeutic effect and survival rate of tumor patients. In recent years, there has been rapid progress in the development of DNA nanomaterials for tumor in situ imaging and treatment, due to their unsurpassed structural stability, excellent material editability, excellent biocompatibility and individual endocytic pathway. Tetrahedral framework nucleic acids (tFNAs), are a typical example of DNA nanostructures demonstrating superior stability, biocompatibility, cell-entry performance, and flexible drug-loading ability. tFNAs have been shown to be effective in achieving timely tumor in situ imaging and precise treatment. Therefore, the progress in the fabrication, characterization, modification and cellular internalization pathway of tFNAs-based functional systems and their potential in tumor in situ imaging and treatment applications were systematically reviewed in this article. In addition, challenges and future prospects of tFNAs in tumor in situ imaging and treatment as well as potential clinical applications were discussed.

Design of Uracil-Modified DNA Nanotubes for Targeted Drug Release via DNA-Modifying Enzyme Reactions

DNA nanostructure-based responsive drug delivery has become an increasingly potent method in cancer therapy. However, a variety of important cancer biomarkers have not been explored in searching of new and efficient targeted delivery systems. Uracil degradation glycosylase and human apurinic/apyrimidinic endonuclease are significantly more active in cancer cells. Here, we developed uracil-modified DNA nanotubes that can deliver drugs to tumor cells through an enzyme-induced disassembly process. Although the reaction of these enzymes on their natural DNA substrates has been established, their reactivity on self-assembled nanostructures of nucleic acids is not well understood. We leveraged molecular dynamic simulation based on coarse-grained model to forecast the enzyme reactivity on different DNA designs. The experimental data are highly consistent with the simulation results. It is the first example of molecule simulation being used to guide the design of enzyme-responsive DNA nano-delivery systems. Importantly, we found that the efficiency of drug release from the nanotubes can be regulated by tuning the positions of uracil modification. The DNA nanotubes equipped with cancer-specific aptamer AS1411 are used to deliver doxorubicin to tumor-bearing mice not only effectively inhibiting tumor growth but also protecting major organs from drug-caused damage. We believe that this work provides new knowledge on and insights into future design of enzyme-responsive DNA-based nanocarriers for drug delivery.

Ag@Pyc Nanocapsules as Electrochemiluminescence Emitters for an Ultrasensitive Assay of the APE1 Activity

Herein, Ag@pyrenecarboxaldehyde nanocapsules (Ag@Pyc nanocapsules) as emitters were prepared to construct an ultrasensitive electrochemiluminescence (ECL) biosensor for the detection of the human apurinic/apyrimidinic endonuclease1 (APE1) activity. Ag nanoparticles on the surface of Pyc nanocapsules as coreaction accelerators could significantly promote coreactant peroxydisulfate (S₂O₈^2-) to generate massive reactive intermediates of sulfate radical anion (SO₄^•-), which interacted with the Pyc nanocapsules to achieve a strong ECL response. In addition, with the aid of APE1-triggered 3D DNA machine, trace target could be converted into a large number of mimic targets (MTs), which were positively correlated with the activity of APE1. Consequently, the proposed ECL biosensor realized an ultrasensitive detection of APE1 activity with an exceptional linear working range from 5 × 10^-10 to 5 × 10^-4 U·μL^-1 and a lower limit of detection of 1.36 × 10^-11 U·μL^-1. This strategy provided a new approach to construct an efficient ternary system for the detection of biomolecules and early diagnosis of diseases.

ATP-Triggered Drug Release of Self-Assembled 3D DNA Nanostructures for Fluorescence Imaging and Tumor Therapy

Stimulus-responsive materials are ideal carriers for precisely controlled drug delivery due to their high selectivity. However, the complex physiological environment hinders its development in clinical medicine. Here, we aim to design a self-assembled three-dimensional (3D) DNA nanostructure drug delivery system with adenosine-5'-triphosphate (ATP)-triggered drug release for tumor fluorescence imaging analysis and targeted drug delivery. Dox@3D DNA nanostructures are self-assembled by a simple one-pot annealing reaction and embedded with drugs, which are structurally stable but can be induced using high concentrations of ATP in tumor cells to cleave and release drugs rapidly, facilitating the rapid accumulation of drugs in tumors and exerting therapeutic effects, thus effectively avoiding damage to normal tissues. This work demonstrates that 3D DNA nanostructures can be used as efficient drug nanocarriers with promising applications in tumor therapy.

ATP-Triggered Intracellular In Situ Aggregation of a Gold-Nanoparticle-Equipped Triple-Helix Molecular Switch for Fluorescence Imaging and Photothermal Tumor Therapy

Isotropic gold nanoparticles (AuNPs) can generate a plasma-plasma interaction when aggregating and can also produce ideal photothermal effects. Some studies have designed ATP-responsive nanodrug delivery systems by taking advantage of the differences between internal and external ATP in tumor cells, but few studies have focused on the photothermal effects of ATP-induced AuNP aggregation in tumors. Here, a triple-helix probe (THP) molecular switch and MUC1 aptamer-functionalized AuNPs were constructed for fluorescence imaging analysis and photothermal therapy (PTT). The MUC1 aptamer guides THP-AuNP targeting in tumor cells, followed by the high concentration of ATP inducing structural changes in triple-helix probes and causing the intracellular aggregation of AuNPs, which cannot escape from the tumor site, enabling tumor imaging while performing PTT. Therefore, the designed THP-AuNPs have promising applications in fluorescence imaging and PTT.

Hairpin-functionalized DNA tetrahedra for miRNA imaging in living cells via self-assembly to form dendrimers

A DNA tetrahedron-based intramolecular catalytic hairpin self-assembly platform that uses fluorescence signals to image miRNAs in live cells for accurate tumor cell identification.

Smart Catalyzed Hairpin Assembly-Induced DNAzyme Nanosystem for Intracellular UDG Imaging

Uracil DNA glycosylase (UDG) is one of the key initiators for the base excision repair pathway. Since abnormal UDG expression is associated with various diseases, sensitive detection of UDG activity is critical for early clinical diagnosis. Here, a smart catalyzed hairpin assembly (CHA)-DNAzyme nanosystem is developed for intracellular UDG imaging by incorporating CHA and DNAzyme onto MnO₂ nanosheets. In this strategy, the biodegradable MnO₂ nanosheets are employed as nanocarriers for efficiently adsorbing and delivering five DNA probes into cells by endocytosis. Then, the MnO₂ nanosheets are degraded by cellular glutathione to release the DNA modules at the same intracellular position. Liberated Mn²⁺, an indispensable DNAzyme cofactor, was used to promote catalytic cleavage for facilitating the cascade process in cells. Based on the uracil site-recognition and -excision operation of the target UDG, the activated CHA-DNAzyme nanosystem generates lots of DNAzyme-assisted CHA products, turning on the fluorescence resonance energy transfer response. This autocatalytic CHA-DNAzyme nanosystem provides a detectable minimum UDG concentration of 0.23 mU/mL, which is comparable to some reported UDG detection approaches. As a multiple signal amplification strategy, the CHA-DNAzyme nanosystem realizes the UDG imaging in living cells with enhanced sensitivity, indicating great promise in the prediction and diagnosis of early-stage cancer.

Aptamer-Programmed DNA Nanodevices for Advanced, Targeted Cancer Theranostics

DNA has been demonstrated to be a versatile material for construction at the nanoscale. DNA nanodevices are highly programmable and allow functionalization with multiple entities such as imaging modalities (fluorophores), targeting entities (aptamers), drug conjugation (chemical linkers), and triggered release (photoresponsive molecules). These features enhance the use of DNA nanodevices in biological applications, catalyzing the rapid growth of this domain of research. In this review, we focus on recent progress in the development and use of aptamer-functionalized DNA nanodevices as theranostic agents, their characterization, applications as delivery platforms, and advantages. We provide a brief background on the development of aptamers and DNA nanodevices in biomedical applications, and we present specific applications of these entities in cancer diagnosis and therapeutics. We conclude with a perspective on the challenges and possible solutions for the clinical translation of aptamer-functionalized DNA nanodevices in the domain of cancer therapeutics.