Biodegradable nanoparticle-assisted and multiplexed imaging of asymmetric RNA expressions in live cells for precise cancer diagnosis and prognosis

Endogenous mRNA-Driven "One-To-More" Signal Amplification of DNA Probe for Intracellular miR155 Sensing

The detection of specific intracellular microRNAs could be potentially helpful in understanding the underlying mechanisms of cancer metastasis and invasion. MiRNAs are usually present in lower expression levels, especially in early stage of cancer. Here, we proposed a "one-to-more" amplification strategy for miRNA imaging, by virtue of DNA strand displacements with dual-amplification. This approach involves leveraging high-abundance endogenous mRNA as fuel strand to drive cascade reactions between DNA strands for amplification, enabling the monitoring of low-abundance intracellular microRNA155. Notably, in comparison to the traditional "one-to-one" signal triggering mode, our "one-to-more" amplification strategy led to a remarkable 11.8-fold increase in fluorescence signal. Our approach not only demonstrates a high sensitivity and specificity in detecting miR155, but also allows for discrimination of miR155 expression levels in different cell lines. With the advantages of intracellular signal amplification and reduced background signal, this approach holds substantial potential in the early diagnosis of cancer.

Orthogonally Sequential Activation of Self-Powered DNAzymes Cascade for Reliable Monitoring of mRNA in Living Cells

Ratiometric imaging of tumor-related mRNA is significant, yet spatiotemporally resolved regulation on the ratiometric signals to avoid non-specific activation in the living cells remains challenging. Herein, orthogonally sequential activation of concatenated DNAzyme circuits is, first, developed for Spatio Temporally regulated Amplified and Ratiometric (STAR) imaging of TK1 mRNA inside living cells with enhanced reliability and accuracy. By virtue of the synthesized CuO/MnO2 nanosheets, orthogonally regulated self-powered DNAzyme circuits are operated precisely in living cells, sequentially activating two-layered DNAzyme cleavage reactions to achieve the two ratiometric signal readouts successively for reliable monitoring of low-abundance mRNA in living cells. It is found that the ratiometric signals can only be derived from mRNA over-expressed tumor cells, also irrespective of probes' delivery concentration. The presented approach could provide new insight into orthogonally regulated ratiometric systems for reliable imaging of specific biomarkers in living cells, benefiting disease precision diagnostics.

A DNAzyme dual-feedback autocatalytic exponential amplification biocircuit for microRNA imaging in living cells

Autocatalytic biocircuit are powerful tools for analysing intracellular biomarkers, but these tools are constrained by limitations in amplification capacity and intracellular delivery efficiency. In this work, we developed a DNAzyme-based dual-feedback autocatalytic exponential amplification biocircuit sustained by a honeycomb MnO2 nanosponge (EDA2@hMNS) for live-cell imaging of intracellular low-abundance microRNAs (miRNA). The EDA2 biocircuit comprises a blocked DNAzyme (b-DNAzyme), a Fuel strand and a Substrate strand. In the EDA2 biocircuit, target miRNAs are recycled and feedback for rounds of DNAzymatic amplification, and the DNAzymatic reactions continuously generate target miRNA analogues for dual-feedback to achieve multiple parallel cascade DNAzymatic reactions that improve amplification capacity substantially. In addition, the hMNS ensures high loading and delivery efficiency of biocircuit probes into living cells and also provides sufficient Mn2+ DNAzyme cofactor from in situ decomposition by intracellular glutathione (GSH). The EDA2@hMNS realized a detection limit of 17 pM, which is 288-fold lower than the b-DNAzyme lacking the DNAzymatic amplification. These results demonstrate the great promise for this critical tool in analysing low-abundance biomarkers and cancer diagnostics.

On-Site-Activated Transmembrane Logic DNA Nanodevice Enables Highly Specific Imaging of Cancer Cells by Targeting Tumor-Related Nucleolin and Intracellular MicroRNA

The ability to specifically image cancer cells is essential for cancer diagnosis; however, this ability is limited by the false positive associated with single-biomarker sensors and off-site activation of "always active" nucleic acid probes. Herein, we propose an on-site, activatable, transmembrane logic DNA (TLD) nanodevice that enables dual-biomarker sensing of tumor-related nucleolin and intracellular microRNA for highly specific cancer cell imaging. The TLD nanodevice is constructed by assembling a tetrahedral DNA nanostructure containing a linker (L)-blocker (B)-DNAzyme (D)-substrate (S) unit. AS-apt, a DNA strand containing an elongated segment and the AS1411 aptamer, is pre-anchored to nucleolin protein, which is specifically expressed on the membrane of cancer cells. Initially, the TLD nanodevice is firmly sealed by the blocker containing an AS-apt recognition zone, which prevents off-site activation. When the nanodevice encounters a target cancer cell, AS-apt (input 1) binds to the blocker and unlocks the sensing ability of the nanodevice for miR-21 (input 2). The TLD nanodevice achieves dual-biomarker sensing from the cell membrane to the cytoplasm, thereby ensuring cancer cell-specific imaging. This TLD nanodevice represents a promising strategy for the highly reliable analysis of intracellular biomarkers and a promising platform for cancer diagnosis and related biomedical applications.

Gold nanostructure-mediated delivery of anticancer agents: Biomedical applications, reversing drug resistance, and stimuli-responsive nanocarriers

The application of nanoarchitectures in cancer therapy seems to be beneficial for the delivery of antitumor drugs. In recent years, attempts have been made to reverse drug resistance, one of the factors threatening the lives of cancer patients worldwide. Gold nanoparticles (GNPs) are metal nanostructures with a variety of advantageous properties, such as tunable size and shape, continuous release of chemicals, and simple surface modification. This review focuses on the application of GNPs for the delivery of chemotherapy agents in cancer therapy. Utilizing GNPs results in targeted delivery and increased intracellular accumulation. Besides, GNPs can provide a platform for the co-delivery of anticancer agents and genetic tools with chemotherapeutic compounds to exert a synergistic impact. Furthermore, GNPs can promote oxidative damage and apoptosis by triggering chemosensitivity. Due to their capacity for providing photothermal therapy, GNPs can enhance the cytotoxicity of chemotherapeutic agents against tumor cells. The pH-, redox-, and light-responsive GNPs are beneficial for drug release at the tumor site. For the selective targeting of cancer cells, surface modification of GNPs with ligands has been performed. In addition to improving cytotoxicity, GNPs can prevent the development of drug resistance in tumor cells by facilitating prolonged release and loading low concentrations of chemotherapeutics while maintaining their high antitumor activity. As described in this study, the clinical use of chemotherapeutic drug-loaded GNPs is contingent on enhancing their biocompatibility.

A novel method for miRNA detection based on target-triggered transcription of a light-up RNA aptamer

We herein describe a novel method for miRNA detection based on target-triggered transcription of a light-up RNA aptamer (TTRApt), consequently producing a highly enhanced fluorescence signal through specific binding of a light-up RNA aptamer to the corresponding dye. Using this strategy, we successfully identified target miRNA down to 59.4 aM with excellent specificity.

Light-Activated Nanodevice for On-Demand Imaging of miRNA in Living Cells via Logic Assembly

Low-abundance biomarker amplification detection systems have been widely used to detect miRNAs; however, "always active" systems are insufficient for high spatial and temporal control of miRNAs. Here, we constructed a light-activated nanodevice (LAN) based on DNA nanotechnology for high spatial and temporal precision detection of low-abundance miRNA. Light-activated hairpin probes and triple-helix molecular switches were modified on the surface of gold nanoparticles (AuNPs) to trigger miRNA on-demand imaging analysis by UV light activation. In the presence of both UV light and miRNA, the LAN releases hairpin DNA and completes the hybridization chain reaction (HCR) with the conformation-altered triple-helix molecular switch, enabling fluorescence imaging of low-abundance miRNAs in living cells. The current work provides an opportunity to develop light-activated signal amplification sensors that can accurately image miRNAs on-demand in both temporal and spatial dimensions.

3D DNA Scaffold-Assisted Dual Intramolecular Amplifications for Multiplexed and Sensitive MicroRNA Imaging in Living Cells

The simultaneous live-cell imaging of multiple intracellular and disease-related microRNAs (miRNAs) with low abundances is highly important to enhance specificity and accuracy for disease diagnosis. On the basis of the improved cell internalization and accelerated reaction kinetics, we develop a three-dimensional (3D) DNA nanoprobe that integrates intramolecular DNAzyme (intra-Dz) and catalytic hairpin assembly (intra-CHA) amplifications to simultaneously monitor multiple miRNAs in living cells. The sensing components are loaded on a DNA scaffold via the sticky-end hybridization of the DNA sequences to increase the local concentrations of the signal probes. The miRNA-21 and miRNA-155 target sequences can trigger intra-Dz and -CHA amplifications on the nanoprobes to show significantly amplified and distinct fluorescence at different wavelengths for simultaneously monitoring low levels of miRNAs. Real-time fluorescence microscopy reveals that such a 3D DNA nanoprobe design with the intra-Dz and -CHA amplifications can accelerate the reaction rate compared to that of the conventional free Dz and CHA because of the increased local concentrations of the sensing components. Importantly, the 3D DNA nanoprobe has desirable stability and biocompatibility and can be readily delivered into living cells to achieve multiplexed and highly sensitive sensing of intracellular miRNA-155 and miRNA-21 sequences. With the demonstration of its intracellular application, the developed 3D DNA nanoprobe thus holds promising potential for biological studies and accurate disease diagnosis.