Framework Nucleic Acid-Based Multifunctional Tumor Theranostic Nanosystem for miRNA Fluorescence Imaging and Chemo/Gene Therapy

Abstract

Intelligent stimulus-responsive theranostic systems capable of specifically sensing low-abundance tumor-related biomarkers and efficiently killing tumors remain a pressing endeavor. Here, we report a multifunctional framework nucleic acid (FNA) nanosystem for simultaneous imaging of microRNA-21 (miR-21) and combined chemo/gene therapy. To achieve this, two FNA nanoarchitectures labeled with Cy5/BHQ2 signal tags were designed, each of which contained an AS1411 aptamer, two pairs of DNA/RNA hybrids, a pH-sensitive DNA catcher, and doxorubicin (DOX) intercalating between cytosine and guanine in the tetrahedral DNA nanostructure (TDN). In the acidic tumor microenvironment, the DNA catchers spontaneously triggered to form an i-motif and create an FNA dimer (dFNA) while releasing DOX molecules to exert a cytotoxic effect. In addition, the overexpressed miR-21 in tumor cells dismantled the DNA/RNA hybrids to produce vascular endothelial growth factor-associated siRNA via a toehold-mediated strand displacement reaction, thus enabling a potent RNA interfering. Also importantly, the liberated miR-21 could initiate cascade-reaction amplification to efficiently activate the Cy5 signal reporters, thereby realizing on-site fluorescence imaging of miR-21 in living cells. The exquisitely designed FNA-based nanosystem showed favorable biocompatibility and stability as well as acid-driven DOX release characteristics. Owing to the aptamer-guided targeting delivery, specific uptake of the FNA-based theranostic nanosystem by HepG2 cells was verified with confocal laser scanning microscopy and flow cytometry analyses, which therefore resulted in apoptosis of HepG2 cells while doing minimal damage to normal H9c2 and HL-7702 cells. Strikingly, both in vitro and in vivo experiments demonstrated the achievements of the FNA-enabled miR-21 imaging and synergistically enhanced chemo/gene therapy. This work thus represents a noteworthy advance on the FNA-based theranostic strategy that can effectively avoid the undesirable premature leakage of anticarcinogen and off-target of siRNA, and achieve on-demand reagents release for tumor diagnostics and treatment.

Low-Background CRISPR/Cas12a Sensors for Versatile Live-Cell Biosensing

“…The formation of the Cas12a/crRNA/AS ternary complex can activate the trans -cleavage activity, and both dsDNA and ssDNA can work as activators. To the best of our knowledge, “on–off–on” is a commonly used biosensor design strategy. − Such a strategy is also promising in designing CRISPR/Cas12a-based biosensors . That is, the formation of the Cas12a/crRNA/AS ternary complex is prevented by a block strand (BS), thus switching off the trans -cleavage activity.…”

Synergistic Viro-chemoimmunotherapy in Breast Cancer Enabled by Bioengineered Immunostimulatory Exosomes and Dual-Targeted Coxsackievirus B3

“…The AS1411 aptamer is a nonimmunogenic and thermally stable DNA aptamer, comprising 26 guanine-rich nucleotides with a quadruplex structure . The AS1411 aptamer can serve not only as a detection tool to identify nucleolin, a cell surface protein that is overexpressed in many cancer cells, but also as a targeting agent on the surface of various drug delivery systems. , …”

“… 26 The AS1411 aptamer can serve not only as a detection tool to identify nucleolin, a cell surface protein that is overexpressed in many cancer cells, 27 but also as a targeting agent on the surface of various drug delivery systems. 28 , 29 …”

Responsive DNA Nanostructures for Bioanalysis and Therapy

“…Stimuli that trigger the transformation of DNA nanostructures includes external factors (such as light [21][22][23], temperature [24][25][26], or magnetic field [27][28][29]) and internal factors (such as acidity [30,31], small molecules [32][33][34], nucleic acids [35][36][37], or proteins [35,38,39]). In response to stimuli activation, the programmed DNA nanostructures would generate optical or electrical signals or release cargoes through specific conformational changes or bond breaks.…”