DNA Nanoflowers Research Articles

Ru(dcbpy)2 dppz]2+ /Fullerene Cosensitized PTB7-Th for Ultrasensitive Photoelectrochemical MicroRNA Assay.

A new cosensitization photoelectrochemical (PEC) strategy was established by using a donor-acceptor-type photoactive material, poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl} (PTB7-Th), as a signal indicator, which was cosensitized with bis(4,4'dicarboxyl-2,2'-bipyridyl)(4,5,9,14-tetraazabenzo[b]triphenylene)ruthenium(II) ([Ru(dcbpy)2 dppz]2+ ) embedded in the grooves of the DNA duplex and fullerene (nano-C60 ) immobilized on the surface of DNA nanoflowers for microRNA assay. [Ru(dcbpy)2 dppz]2+ and nano-C60 could effectively enhance the photoelectric conversion efficiency (PCE) of PTB7-Th as a result of well-matched energy levels among nano-C60 , [Ru(dcbpy)2 dppz]2+ and PTB7-Th, leading to a clearly enhanced photocurrent signal. Meanwhile, a target recycling magnification technique based on duplex-specific nuclease was applied in this work to obtain higher detection sensitivity. The proposed biosensor demonstrated excellent analytical properties within a linear detection range of 2.5 fm to 2.5 nm and a limit of detection down to 0.83 fm. Impressively, this cosensitization PEC strategy offers an effective and convenient avenue to significantly improve the PCE of a photoactive material, resulting in a remarkably improved photocurrent signal for ultrasensitive and highly accurate detection of various targets.

Engineering of Bioinspired, Size-Controllable, Self-Degradable Cancer-Targeting DNA Nanoflowers via the Incorporation of an Artificial Sandwich Base.

In this article, we used an artificial DNA base to manipulate the formation of DNA nanoflowers (NFs) to easily control their sizes and functionalities. Nanoflowers have been reported as the noncanonical self-assembly of multifunctional DNA nanostructures, assembled from long DNA building blocks generated by rolling circle replication (RCR). They could be incorporated with myriad functional moieties. However, the efficacy of these DNA NFs as potential nanocarriers delivering cargo in biomedicine is limited by the bioavailability and therapeutic efficacy of their cargo. Here we report the incorporation of metal-containing artificial analogues into DNA strands to control the size and the functions of NFs. We have engineered bioinspired, size-controllable, self-degradable cancer-targeting DNA nanoflowers (Sgc8-NFs-Fc) via the incorporation of an artificial sandwich base. More specifically, the introduction of a ferrocene base not only resulted in the size controllability of Sgc8-NFs-Fc from 1000 to 50 nm but also endowed Sgc8-NFs-Fc with self-degradability in the presence of H2O2 via Fenton's reaction. In vitro experiments confirmed that Sgc8-NFs-Fc/Dox could be selectively taken up by protein tyrosine kinase 7 (PTK7)-positive cancer cells and subsequently cleaved via Fenton's reaction, resulting in rapid release kinetics, nuclear accumulation, and enhanced cytotoxicity of their cargo. In vivo experiments further confirmed that Sgc8-NFs-Fc has good tumor-targeting ability and could significantly improve the therapeutic efficacy of doxorubicin in a xenograft tumor model. On the basis of their tunable size and on-demand drug release kinetics upon H2O2 stimulation, the Sgc8-NFs-Fc nanocarriers possess promising potential in drug delivery.

Preparation and characterization of manganese, cobalt and zinc DNA nanoflowers with tuneable morphology, DNA content and size.

Recently reported DNA nanoflowers are an interesting class of organic-inorganic hybrid materials which are prepared using DNA polymerases. DNA nanoflowers combine the high surface area and scaffolding of inorganic Mg2P2O7 nanocrystals with the targeting properties of DNA, whilst adding enzymatic stability and enhanced cellular uptake. We have investigated conditions for chemically modifying the inorganic core of these nanoflowers through substitution of Mg2+ with Mn2+, Co2+ or Zn2+ and have characterized the resulting particles. These have a range of novel nanoarchitectures, retain the enzymatic stability of their magnesium counterparts and the Co2+ and Mn2+ DNA nanoflowers have added magnetic properties. We investigate conditions to control different morphologies, DNA content, hybridization properties, and size. Additionally, we show that DNA nanoflower production is not limited to Ф29 DNA polymerase and that the choice of polymerase can influence the DNA length within the constructs. We anticipate that the added control of structure, size and chemistry will enhance future applications.

DNA nanoflower blooms in nanochannels: a new strategy for miRNA detection

By employing DNA nanoflower blooming in the nanochannels of porous anodic alumina (PAA), a nanochannel platform for microRNA (miRNA) detection has been proposed. Significant steric and electrostatic hindrance of the miRNA-initiated DNA-nanoflower growth may also amplify the signal readout for miRNA detection to give excellent sensitivity, selectivity and reproducibility.

Biodegradable, multifunctional DNAzyme nanoflowers for enhanced cancer therapy

Safety and efficiency remain the critical hurdles hindering the practical application of gene agents, even though great effort has been made to develop various gene carriers. Herein, we present a novel biodegradable cancer therapeutic system based on DNA nanoflowers (DNFs) for targeted dual gene silencing. The therapeutic system was constructed by copying a rolling circle amplification template to produce long single-stranded DNAs with cell targeting and dual gene-silencing capability. The structure of the DNFs collapsed at acidic pH due to the decomposition of the co-assembled magnesium pyrophosphate, generating Mg2+ ions that act as cofactors for the DNAzymes and increase their ability to recognize and cleave target mRNAs. In vitro and in vivo studies demonstrated that the multifunctional DNFs showed promise for targeted cancer cell recognition, gene silencing, induction of apoptosis and inhibition of tumor growth. Considering the enhanced therapeutic effect and biocompatibility of this therapeutic platform, it is anticipated to be of great interest for the clinical treatment of cancers.

In situ generation of electrochemiluminescent DNA nanoflowers as a signal tag for mucin 1 detection based on a strategy of target and mimic target synchronous cycling amplification.

A sensitive electrochemiluminescent (ECL) aptasensor consisting of a novel ECL signal tag of DNA nanoflowers (DNA NFs) and a highly efficient target conversion strategy for the MUC1 assay was developed, which not only increased the stability for luminophore loading, but also greatly improved the detection sensitivity.

Self-assembled multifunctional DNA nanoflowers for the circumvention of multidrug resistance in targeted anticancer drug delivery

Cancer chemotherapy has been impeded by side effects and multidrug resistance (MDR) partially caused by drug efflux from cancer cells, which call for targeted drug delivery systems additionally able to circumvent MDR. Here we report multifunctional DNA nanoflowers (NFs) for targeted drug delivery to both chemosensitive and MDR cancer cells and circumvent MDR in both leukemia and breast cancer cell models. NFs are self-assembled via liquid crystallization of DNA generated by Rolling Circle Replication, during which NFs are incorporated with aptamers for specific cancer cell recognition, fluorophores for bioimaging, and Doxorubicin (Dox)-binding DNA for drug delivery. NF sizes are tunable (down to ~200 nm in diameter), and the densely packed drug-binding motifs and porous intrastructures endow NFs with high drug loading capacity (71.4%, wt/wt). The Dox-loaded NFs (NF-Dox) are stable at physiological pH, yet drug release is facilitated in acidic or basic conditions. NFs deliver Dox into target chemosensitive and MDR cancer cells, preventing drug efflux and enhancing drug retention in MDR cells. Consequently, NF-Dox induces potent cytotoxicity in both target chemosensitive cells and MDR cells, but not nontarget cells, thus concurrently circumventing MDR and reducing side effects. Overall, these NFs are promising to circumvent MDR in targeted cancer therapy.

Preparation and biomedical applications of programmable and multifunctional DNA nanoflowers.

We describe a comprehensive protocol for the preparation of multifunctional DNA nanostructures termed nanoflowers (NFs), which are self-assembled from long DNA building blocks generated via rolling-circle replication (RCR) of a designed template. NF assembly is driven by liquid crystallization and dense packaging of building blocks, which eliminates the need for conventional Watson-Crick base pairing. As a result of dense DNA packaging, NFs are resistant to nuclease degradation, denaturation or dissociation at extremely low concentrations. By manually changing the template sequence, many different functional moieties including aptamers, bioimaging agents and drug-loading sites could be easily integrated into NF particles, making NFs ideal candidates for a variety of applications in biomedicine. In this protocol, the preparation of multifunctional DNA NFs with highly tunable sizes is described for applications in cell targeting, intracellular imaging and drug delivery. Preparation and characterization of functional DNA NFs takes ∼5 d; the following biomedical applications take ∼10 d.

DNA Nanoflowers for Multiplexed Cellular Imaging and Traceable Targeted Drug Delivery

AbstractWe present a facile approach to make aptamer‐conjugated FRET (fluorescent resonance energy transfer) nanoflowers (NFs) through rolling circle replication for multiplexed cellular imaging and traceable targeted drug delivery. The NFs can exhibit multi‐fluorescence emissions by a single‐wavelength excitation as a result of the DNA matrix covalently incorporated with three dye molecules able to perform FRET. Compared with the conventional DNA nanostructure assembly, NF assembly is independent of template sequences, avoiding the otherwise complicated design of DNA building blocks assembled into nanostructures by base‐pairing. The NFs were uniform and exhibited high fluorescence intensity and excellent photostability. Combined with the ability of traceable targeted drug delivery, these colorful DNA NFs provide a novel system for applications in multiplex fluorescent cellular imaging, effective screening of drugs, and therapeutic protocol development.

DNA nanoflowers for multiplexed cellular imaging and traceable targeted drug delivery.

We present a facile approach to make aptamer-conjugated FRET (fluorescent resonance energy transfer) nanoflowers (NFs) through rolling circle replication for multiplexed cellular imaging and traceable targeted drug delivery. The NFs can exhibit multi-fluorescence emissions by a single-wavelength excitation as a result of the DNA matrix covalently incorporated with three dye molecules able to perform FRET. Compared with the conventional DNA nanostructure assembly, NF assembly is independent of template sequences, avoiding the otherwise complicated design of DNA building blocks assembled into nanostructures by base-pairing. The NFs were uniform and exhibited high fluorescence intensity and excellent photostability. Combined with the ability of traceable targeted drug delivery, these colorful DNA NFs provide a novel system for applications in multiplex fluorescent cellular imaging, effective screening of drugs, and therapeutic protocol development.

Noncanonical self-assembly of multifunctional DNA nanoflowers for biomedical applications.

DNA nanotechnology has been extensively explored to assemble various functional nanostructures for versatile applications. Mediated by Watson-Crick base-pairing, these DNA nanostructures have been conventionally assembled through hybridization of many short DNA building blocks. Here we report the noncanonical self-assembly of multifunctional DNA nanostructures, termed as nanoflowers (NFs), and the versatile biomedical applications. These NFs were assembled from long DNA building blocks generated via rolling circle replication (RCR) of a designer template. NF assembly was driven by liquid crystallization and dense packaging of building blocks, without relying on Watson-Crick base-pairing between DNA strands, thereby avoiding the otherwise conventional complicated DNA sequence design. NF sizes were readily tunable in a wide range, by simply adjusting such parameters as assembly time and template sequences. NFs were exceptionally resistant to nuclease degradation, denaturation, or dissociation at extremely low concentration, presumably resulting from the dense DNA packaging in NFs. The exceptional biostability is critical for biomedical applications. By rational design, NFs can be readily incorporated with myriad functional moieties. All these properties make NFs promising for versatile applications. As a proof-of-principle demonstration, in this study, NFs were integrated with aptamers, bioimaging agents, and drug loading sites, and the resultant multifunctional NFs were demonstrated for selective cancer cell recognition, bioimaging, and targeted anticancer drug delivery.