Controlled Release of a Dual Zinc-Sensing and Gene Regulating Small Molecule from DNA Micelles.

Intracellular zinc ions are essential for various biological cell processes and are often dysregulated in many diseases de-pending on their location, protein binding affinity, and concentration in the cell. Due to their prevalence in diseases, it is important to not only effectively sense but chelate the often excess amount of zinc in a cell to alleviate further disease progression. N, N, N', N'-tetrakis (2-pyridinylmethyl)-1,2-ethanediamine (TPEN) is a selective zinc chelator but its water-insoluble nature and general cytotoxicity limit its therapeutic potential. To address these challenges, TPEN loaded nucleic acid nanocapsules (TL-NANs) were synthesized, and its dual ability to sense and suppress zinc levels intracellularly were evaluated. Additionally, TL-NANs were incubated in lung cells and shown to down regulate Eotaxin, a protein up-regulated during asthma, at significantly reduced concentrations of TPEN showcasing the therapeutic potential of this drug for asthma.

Chimeric siRNA-DNA Surfactants for the Enhanced Delivery and Sustained Cytotoxicity of a Gold(III) Metallodrug.

Using a recently developed nucleic acid delivery platform, we demonstrate the effective delivery of metallodrug [AuIIIBr2(SSC-Inp-OEt)] (AP228; Inp = isonipecotic moiety), a hydrophobic, low solubility gold complex cytotoxic to cancer cells. It is shown that AP228 is delivered more effectively into HeLa cells using micellular surfactant assemblies compared to that of a more polar derivative [AuIIIBr2(SSC-Inp-GlcN1)] (AP209; GlcN1 = (α,ß)-d-glucosamino moiety). When AP228 is codelivered with siRNA targeting Bcl-2, a key regulator of apoptosis, the overall cytotoxic therapeutic effects of the drug are maximized. The optimized delivery and distribution of the compound is monitored by both fluorescence microscopy and inductively coupled plasma mass spectrometry. We show that codelivery of the AP228 and Bcl-2 targeting siRNA results in a substantial increase in drug efficacy, wherein the cytotoxic therapeutic effects of the drug are maximized, reducing the IC50 from 760 nM to 11 nM. This hybrid small molecule drug and therapeutic nucleic acid delivery vehicle is shown to enable both the improved solubility and uptake of the gold(III) metallodrugs and the delivery of chemically unmodified siRNA, resulting in enhanced cytotoxic effects.

Nucleic Acid Nanocapsules for Enzyme-Triggered Drug Release.

Herein we describe a nucleic acid functionalized nanocapsule in which nucleic acid ligands are assembled and disassembled in the presence of enzymes. The particles are fully degradable in response to esterases due to an embedded ester cross-linker in the particle's core. During synthesis the nanocapsules can be loaded with hydrophobic small molecules and post self-assembly undergo covalent cross-linking using copper catalyzed click chemistry. They can then be functionalized with thiolated DNA through stepwise thiolyne chemistry using UV light irradiation. Additionally, the capsule is compatible with enzyme mediated functionalization of a therapeutic mRNA-cleaving DNAzyme at the particle's surface. The resulting particle is highly stable, monodisperse in size, and maximizes the therapeutic potential of both the particles interior and exterior.

Real-time dynamic single-molecule protein sequencing on an integrated semiconductor device.

Studies of the proteome would benefit greatly from methods to directly sequence and digitally quantify proteins and detect posttranslational modifications with single-molecule sensitivity. Here, we demonstrate single-molecule protein sequencing using a dynamic approach in which single peptides are probed in real time by a mixture of dye-labeled N-terminal amino acid recognizers and simultaneously cleaved by aminopeptidases. We annotate amino acids and identify the peptide sequence by measuring fluorescence intensity, lifetime, and binding kinetics on an integrated semiconductor chip. Our results demonstrate the kinetic principles that allow recognizers to identify multiple amino acids in an information-rich manner that enables discrimination of single amino acid substitutions and posttranslational modifications. With further development, we anticipate that this approach will offer a sensitive, scalable, and accessible platform for single-molecule proteomic studies and applications.

Towards Self-Transfecting Nucleic Acid Nanostructures for Gene Regulation.

Nanoscale structures of therapeutic nucleic acids have shown enormous potential to help clinicians realize the promise of personaliz ed medicine using gene-specific treatments. With the advent of better sequencing through bioinformatic approaches and advancements in nucleic acid stabilization chemistries, the field of synthetic nucleic acid nanomaterials has advanced tremendously. This review focuses on an emerging strategy geared at gene silencing without the use of traditional polycation-based transfection agents and discusses how such nanostructures are being chemically tailored to navigate biological systems to improve their circulation time and biodistribution. We also address important challenges moving forward, including quantification of delivery and the multiplexing of sequences for regulating gene networks - a goal well suited for this unique class of materials.