Construction and Application of DNAzyme-based Nanodevices

Nanosized DNA Hydrogel Functionalized with a DNAzyme Tetrahedron for Highly Efficient Gene Silencing

DNAzymes are DNA oligonucleotides that have catalytic activity without the assistance of protein enzymes. In particular, RNA-cleaving DNAzymes were considered as ideal candidates for gene therapy due to their unique characteristics. Nevertheless, efforts to use DNAzyme as a gene therapeutic agent are limited by issues such as their low physiological stability in serum and intracellular delivery efficiency. In this study, we developed a nanosized synthetic DNA hydrogel functionalized with a DNAzyme tetrahedron (TDz Dgel) to overcome these limitations. We observed remarkable improvement in the gene-silencing effect as well as intracellular uptake without the support of gene transfection reagents using TDz Dgel. The improved catalytic activity of the DNAzyme resulted from the combination of the cell-penetrating DNA tetrahedron structure and high stability of DNA hydrogel. We envision that this approach will become a convenient and efficient strategy for gene-silencing therapy using DNAzyme in the future.

The design strategies for CRISPR-based biosensing: Target recognition, signal conversion, and signal amplification

Rapid, sensitive and selective biosensing is highly important for analyzing biological targets and dynamic physiological processes in cells and living organisms. As an emerging tool, clustered regularly interspaced short palindromic repeats (CRISPR) system is featured with excellent complementary-dependent cleavage and efficient trans-cleavage ability. These merits enable CRISPR system to improve the specificity, sensitivity, and speed for molecular detection. Herein, the structures and functions of several CRISPR proteins for biosensing are summarized in depth. Moreover, the strategies of target recognition, signal conversion, and signal amplification for CRISPR-based biosensing were highlighted from the perspective of biosensor design principles. The state-of-art applications and recent advances of CRISPR system are then outlined, with emphasis on their fluorescent, electrochemical, colorimetric, and applications in POCT technology. Finally, the current challenges and future prospects of this frontier research area are discussed.

Photodynamic O2 Economizer Encapsulated with DNAzyme for Enhancing Mitochondrial Gene-Photodynamic Therapy

Emerging research suggests that mitochondrial DNA is a potential target for cancer treatment. However, achieving precise delivery of deoxyribozymes (DNAzymes) and combining photodynamic therapy (PDT) and DNAzyme-based gene silencing together for enhancing mitochondrial gene-photodynamic synergistic therapy remains challenging. Accordingly, herein, intelligent supramolecular nanomicelles are constructed by encapsulating a DNAzyme into a photodynamic O2 economizer for mitochondrial NO gas-enhanced synergistic gene-photodynamic therapy. The designed nanomicelles demonstrate sensitive acid- and red-light sequence-activated behaviors. After entering the cancer cells and targeting the mitochondria, these micelles will disintegrate and release the DNAzyme and Mn (II) porphyrin in the tumor microenvironment. Mn (II) porphyrin acts as a DNAzyme cofactor to activate the DNAzyme for the cleavage reaction. Subsequently, the NO-carrying donor is decomposed under red light irradiation to generate NO that inhibits cellular respiration, facilitating the conversion of more O2 into singlet oxygen (1 O2 ) in the tumor cells, thereby significantly enhancing the efficacy of PDT. In vitro and in vivo experiments reveal that the proposed system can efficiently target mitochondria and exhibits considerable antitumor effects with negligible systemic toxicity. Thus, this study provides a useful conditional platform for the precise delivery of DNAzymes and a novel strategy for activatable NO gas-enhanced mitochondrial gene-photodynamic therapy.

Multicomponent DNAzyme Nanomachines: Structure, Applications, and Prospects

Nucleic acids (NAs) are important components of living organisms responsible for the storage and transmission of hereditary information. They form complex structures that can self-assemble and bind to various biological molecules. DNAzymes are NAs capable of performing simple chemical reactions, which makes them potentially useful elements for creating DNA nanomachines with required functions. This review focuses on multicomponent DNA-based nanomachines, in particular on DNAzymes as their main functional elements, as well as on the structure of DNAzyme nanomachines and their application in the diagnostics and treatment of diseases. The article also discusses the advantages and disadvantages of DNAzyme-based nanomachines and prospects for their future applications. The review provides information about new technologies and the possibilities of using NAs in medicine.

A versatile MOF-derived theranostic for dual-miRNA controlled accurate cancer cell recognition and photodynamic therapy

Precise detection and monitoring of microRNAs (miRNAs) in living tumor cells is significant for the prompt diagnosis of cancer and provides important information for treatment of cancer. A significant challenge is developing methods for imaging different miRNAs simultaneously to further enhance diagnostic and treatment accuracy. In this work, a versatile MOF-derived theranostic system (DAPM) was constructed using photosensitive metal-organic frameworks (PMOF, PM) and a DNA AND logic gate (DA). The DAPM exhibited excellent biostability and enabled sensitive detection of miR-21 and miR-155, achieving a low limit of detection (LOD) for miR-21 (89.10 pM) and miR-155 (54.02 pM). The DAPM probe generated a fluorescence signal in tumor cells where miR-21 and miR-155 co-existed, demonstrating the enhanced ability of tumor cell recognition. Additionally, the DAPM achieved efficient ROS generation and concentration-dependent cytotoxicity under light irradiation, providing effective photodynamic therapy for anti-tumors. The proposed DAPM theranostic system enables accurate cancer diagnosis, and provides spatial and temporal information for PDT.