Dendronized DNA Chimeras Harness Scavenger Receptors To Degrade Cell Membrane Proteins

Bispecific chimeras bridging cell membrane proteins with lysosome-trafficking receptors (LTRs) provide an effective therapeutic approach through lysosomal degradation of disease-relevant targets. Here, we report a novel dendronized DNA chimera (DENTAC) strategy that uses a dendritic DNA to engage cell surface scavenger receptors (SRs) as LTR. Using bioorthogonal strain-promoted alkyne-azide cycloaddition to conjugate the dendritic DNA with protein binder, the resulting DENTAC is able to traffic the protein target into the lysosome for elimination. We demonstrated the utility of DENTAC by degrading oncogenic membrane nucleolin (NCL) and epidermal growth factor receptor (EGFR). The anti-cancer application of NCL-targeting DENTAC was validated in a mouse xenograft model of lung cancer. This work thus presents a new avenue for rapid development of potent degraders against membrane proteins, with also broad research and therapeutic prospects.

DNA-Based Nanoprobes for Simultaneous Detection of Telomerase and Correlated Biomolecules

Telomerase (TE), a ribonucleoprotein reverse transcriptase, is enzymatically activated in most tumor cells and is responsible for promoting tumor progression and malignancy by enabling replicative immortality of cancer cells. TE has become an important hallmark for cancer diagnosis and a potential therapy target. Therefore, accurate and in site detection of TE activity, especially the simultaneous imaging of TE activity and its correlated biomolecules, is highly essential to medical diagnostics and therapeutics. DNA-based nanoprobes, with their effective cell penetration capability and programmability, are the most advantageous for detection of intracellular TE activity. This concept article introduces the recent strategies for in situ sensing and imaging of TE activity, with a focus on simultaneous detection of TE and related biomolecules, and provides challenges and perspectives for the development of new strategies for such correlated imaging.

Intranuclear Delivery of DNA Nanostructures via Cellular Mechanotransduction

DNA nanostructures are attractive gene carriers for nanomedicine applications, yet their delivery to the nucleus remains inefficient. We present the application of extracellular mechanical stimuli to activate cellular mechanotransduction for boosting the intranuclear delivery of DNA nanostructures. Treating mammalian cells with polythymidine-rich spherical nucleic acids (poly(T) SNAs) under gentle compression by a single coverslip leads to up to ∼50% nuclear accumulation without severe endosomal entrapment, cytotoxicity, or long-term membrane damage; no chemical modification or transfection reagent is needed. Gentle compression activates Rho-ROCK mechanotransduction and causes nuclear translocation of YAP. Joint compression and treatment with poly(T) oligonucleotides upregulate genes linked to myosin, actin filament, and nuclear import. In turn, Rho-ROCK, myosin, and importin mediate the nuclear entry of poly(T) SNAs. Treatment of endothelioma cells with poly(T) SNAs bearing antisense oligonucleotides under compression inhibits an intranuclear oncogene. Our data should inspire the marriage of DNA nanotechnology and cellular biomechanics for intranuclear applications.

Framework Nucleic Acids in Nuclear Medicine Imaging: shedding light on nano-bio interactions

Framework nucleic acids (FNAs) represent nanoscale oligonucleotide assemblies with unique physical, chemical, and biological properties different from their building blocks. Following simple Watson-Crick base-pairing rules, arbitrary DNA frameworks with diverse shapes, sizes, and dimensions can be prepared with high reproducibility and stability. The programmable assembly of nucleic acids into FNAs presents a highly controllable model for nano-bio interaction studies and allows for scrutiny of "nanostructure-activity relationships." Herein, we present an overview of the recent progress of FNAs in the hope of deepening our understanding of nano-bio interfacing. By investigating various FNAs, we summarize their biological profiles and immune responses as functions of their shape, sizes, and surface charges. We then highlight recent efforts of applying FNAs for biomedical applications and discuss the challenges of FNAs for potential clinical translation. We believe that this mini-review can bring up-to-date information on FNA and shed light on how their design may be harnessed for selective biomedical applications.

Bioinspired DNA Nanointerface with Anisotropic Aptamers for Accurate Capture of Circulating Tumor Cells

The capture and analysis of circulating tumor cells (CTCs) have provided a non-invasive entry for cancer diagnosis and disease monitoring. Despite recent development in affinity-based CTCs isolation, it remains challenging to achieve efficient capture toward CTCs with dynamic surface expression. Enlightened by the synergistic effect insideimmune synapses, the development of a nanointerface engineered with topology-defined anisotropic aptamers programmed by DNA scaffold (DNA nanosynapse), for accurate CTCs isolation, is herein reported. As compared to isotropic aptamers, the DNA nanosynapse exhibits enhanced anchoring on the cell membrane with both high and low epithelial cell adhesion molecule (EpCAM) expression. This nanointerface enables accurate capture toward CTCs of heterogeneous EpCAM, without dramatically proportional change inside the mixture of diverse phenotypes. By applying this nanoplatform, CTCs detection as well as downstream analysis for measuring disease status can be achieved in clinical samples from breast cancer patients.

Environment-Recognizing DNA-Computation Circuits for the Intracellular Transport of Molecular Payloads for mRNA Imaging

Programming intelligent DNA nanocarriers for the targeted transport of molecular payloads in living cells has attracted extensive attention. In vivo activation of these nanocarriers usually relies on external light irradiation. An interest is emerging in the automatic recognition of intracellular surroundings by nanocarriers and their in situ activation under the control of programmed DNA-computation circuits. Herein, we report the integration of DNA circuits with framework nucleic acid (FNA) nanocarriers that consist of a truncated square pyramid (TSP) cage and a built-in duplex cargo containing an antisense strand of the target mRNA. An i-motif and ATP aptamer embedded in the TSP are employed as logic-controlling units to respond to H⁺ and ATP inside cellular compartments, triggering the release of the sensing element for fluorescent mRNA imaging. Logic-controlled FNA devices could be used to target drug delivery, enabling precise disease treatment.

Reconfigurable Bioinspired Framework Nucleic Acid Nanoplatform Dynamically Manipulated in Living Cells for Subcellular Imaging

In nature, the formation of spider silk fibers begins with dimerizing the pH-sensitive N-terminal domains of silk proteins (spidroins) upon lowering pH, and provides a natural masterpiece for programmable assembly. Inspired by the similarity of pH-dependent dimerization behaviors, introduced here is an i-motif-guided model to mimic the initial step of spidroin assembly at the subcellular level. A framework nucleic acid (FNA) nanoplatform is designed using two tetrahedral DNA nanostructures (TDNs) with different branched vertexes carrying a bimolecular i-motif and a split ATP aptamer. Once TDNs enter acidic lysosomes within living cells, they assemble into a heterodimeric architecture, thereby enabling the formation of a larger-size framework and meanwhile subcellular imaging in response to endogenous ATP, which can be dynamically manipulated by adjusting intracellular pH and ATP levels with external drug stimuli.

Efficient Cytosolic Delivery Using Crystalline Nanoflowers Assembled from Fluorinated Peptoids

The design and synthesis of biocompatible nanomaterials as cargoes for the intracellular delivery of therapeutic proteins or genes have attracted intense attention because of their potential for use in therapeutics. Despite the advances in this area, very few nanomaterials can be efficiently delivered to the cytosol. To address these challenges, crystalline nanoflower-like particles are designed and synthesized from fluorinated sequence-defined peptoids; the crystallinity and fluorination of these particles enable highly efficient cytosolic delivery with minimal cytotoxicity. A cytosol delivery rate of 80% has been achieved for the fluorinated peptoid nanoflowers. Furthermore, these nanocrystals can carry therapeutic genes, such as mRNA and effectively deliver the payload into the cytosol, demonstrating the universal delivery capability of the nanocrystals. The results indicate that self-assembly of crystalline nanomaterials from fluorinated peptoids paves a new way toward development of nanocargoes with efficient cytosolic gene delivery capability.

DNA Nanostructure-Based Systems for Intelligent Delivery of Therapeutic Oligonucleotides

In the beginning of the 21st century, therapeutic oligonucleotides have shown great potential for the treatment of many life-threatening diseases. However, effective delivery of therapeutic oligonucleotides to the targeted location in vivo remains a major issue. As an emerging field, DNA nanotechnology is applied in many aspects including bioimaging, biosensing, and drug delivery. With sequence programming and optimization, a series of DNA nanostructures can be precisely engineered with defined size, shape, surface chemistry, and function. Simply with hybridization, therapeutic oligonucleotides including unmethylated cytosine-phosphate-guanine dinucleotide oligos, small interfering RNA (siRNA) or antisense RNA, single guide RNA of the regularly interspaced short palindromic repeat-Cas9 system, and aptamers, are successfully loaded on DNA nanostructures for delivery. In this progress report, the development history of DNA nanotechnology is first introduced, and then the mechanisms and means for cellular uptake of DNA nanostructures are discussed. Next, current approaches to deliver therapeutic oligonucleotides with DNA nanovehicles are summarized. In the end, the challenges and opportunities for DNA nanostructure-based systems for the delivery of therapeutic oligonucleotides are discussed.

Spatiotemporally and Sequentially-Controlled Drug Release from Polymer Gatekeeper-Hollow Silica Nanoparticles

Combination chemotherapy has become the primary strategy against cancer multidrug resistance; however, accomplishing optimal pharmacokinetic delivery of multiple drugs is still challenging. Herein, we report a sequential combination drug delivery strategy exploiting a pH-triggerable and redox switch to release cargos from hollow silica nanoparticles in a spatiotemporal manner. This versatile system further enables a large loading efficiency for both hydrophobic and hydrophilic drugs inside the nanoparticles, followed by self-crosslinking with disulfide and diisopropylamine-functionalized polymers. In acidic tumour environments, the positive charge generated by the protonation of the diisopropylamine moiety facilitated the cellular uptake of the particles. Upon internalization, the acidic endosomal pH condition and intracellular glutathione regulated the sequential release of the drugs in a time-dependent manner, providing a promising therapeutic approach to overcoming drug resistance during cancer treatment.

A DNA dual lock-and-key strategy for cell-subtype-specific siRNA delivery

The efficient and precise delivery of siRNA to target cells is critical to successful gene therapy. While novel nanomaterials enhance delivery efficiency, it still remains challenging for precise gene delivery to overcome nonspecific adsorption and off-target effect. Here we design a dual lock-and-key system to perform cell-subtype-specific recognition and siRNA delivery. The siRNA is self-assembled in an oligonucleotide nano vehicle that is modified with a hairpin structure to act as both the ‘smart key’ and the delivery carrier. The auto-cleavable hairpin structure can be activated on site at target cell membrane by reacting with two aptamers as ‘dual locks’ sequentially, which leads to cell-subtype discrimination and precise siRNA delivery for high efficient gene silencing. The success of this strategy demonstrates the precise delivery of siRNA to specific target cells by controlling multiple parameters, thus paving the way for application of RNAi in accurate diagnosis and intervention.

Delivery of siRNA to target cells is essential for in vivo gene therapy. Here the authors demonstrate an oligonucleotide aptamer that targets therapeutic siRNA to a specific cell type.

Imaging of transfection and intracellular release of intact, non-labeled DNA using fluorescent nanodiamonds

Efficient delivery of stabilized nucleic acids (NAs) into cells and release of the NA payload are crucial points in the transfection process. Here we report on the fabrication of a nanoscopic cellular delivery carrier that is additionally combined with a label-free intracellular sensor device, based on biocompatible fluorescent nanodiamond particles. The sensing function is engineered into nanodiamonds by using nitrogen-vacancy color centers, providing stable non-blinking luminescence. The device is used for monitoring NA transfection and the payload release in cells. The unpacking of NAs from a poly(ethyleneimine)-terminated nanodiamond surface is monitored using the color shift of nitrogen-vacancy centers in the diamond, which serve as a nanoscopic electric charge sensor. The proposed device innovates the strategies for NA imaging and delivery, by providing detection of the intracellular release of non-labeled NAs without affecting cellular processing of the NAs. Our system highlights the potential of nanodiamonds to act not merely as labels but also as non-toxic and non-photobleachable fluorescent biosensors reporting complex molecular events.

Programmable DNA Hydrogels Assembled from Multidomain DNA Strands

Hydrogels are important in biological and medical applications, such as drug delivery and tissue engineering. DNA hydrogels have attracted significant attention due to the programmability and biocompatibility of the material. We developed a series of low-cost one-strand DNA hydrogels self-assembled from single-stranded DNA monomers containing multiple palindromic domains. This new hydrogel design is simple and programmable. Thermal stability, mechanical properties, and loading capacity of these one-strand DNA hydrogels can be readily regulated by simply adjusting the DNA domains.