Independent control over size, valence, and elemental composition in the synthesis of DNA-nanoparticle conjugates.

DNA-nanoparticle conjugates have found widespread use in sensing, imaging, and as components of devices. However, their synthesis remains relatively complicated and empirically based, often requiring specialized protocols for conjugates of different size, valence, and elemental composition. Here we report a novel, bottom-up approach for the synthesis of DNA-nanoparticle conjugates, based on ring-opening metathesis polymerization (ROMP), intramolecular crosslinking, and template synthesis.

Discovery of and Insights into DNA "Codes" for Tunable Morphologies of Metal Nanoparticles.

The discovery and elucidation of genetic codes has profoundly changed not only biology but also many fields of science and engineering. The fundamental building blocks of life comprises of four simple deoxyribonucleotides and yet their combinations serve as the carrier of genetic information that encodes for proteins that can carry out many biological functions due to their unique functionalities. Inspired by nature, the functionalities of DNA molecules have been used as a capping ligand for controlling morphology of nanomaterials, and such a control is sequence dependent, which translates into distinct physical and chemical properties of resulting nanoparticles.

DNA-Encoded Morphological Evolution of Bimetallic Pd@Au Core-shell Nanoparticles from a High-indexed Core.

DNA-mediated synthesis of nanoparticles with different morphologies has proven to be a powerful method to synthesize and access many exclusive shapes and surface properties. While previous studies employ seeds that contain relatively low-energy facets, such as a simple cubic palladium seed in the synthesis of Pd-Au bimetallic nanoparticles, few studies have investigated whether DNA molecules can still exert their influence when the synthesis uses a seed that contains high-energy facets. Seeds that are enclosed by such high-energy facets or sites are known to act as easy nucleation sites in nanoparticles growth and could potentially suppress the effect of DNA.

Bottom-Up Strategy To Prepare Nanoparticles with a Single DNA Strand.

We describe the preparation of cross-linked, polymeric organic nanoparticles (ONPs) with a single, covalently linked DNA strand. The structure and functionalities of the ONPs are controlled by the synthesis of their parent linear block copolymers that provide monovalency, fluorescence and narrow size distribution. The ONP can also guide the deposition of chloroaurate ions allowing gold nanoparticles (AuNPs) to be prepared using the ONPs as templates.

DNA-Mediated Morphological Control of Pd-Au Bimetallic Nanoparticles.

Recent reports have shown that different DNA sequences can mediate the control of shapes and surface properties of nanoparticles. However, all previous studies have involved only monometallic particles, most of which were gold nanoparticles. Controlling the shape of bimetallic nanoparticles is more challenging, and there is little research into the use of DNA-based ligands for their morphological control.

Mechanistic Insight into DNA-Guided Control of Nanoparticle Morphologies.

Although shapes and surface characteristics of nanoparticles are known to play important roles in defining their properties, it remains challenging to fine-tune the morphologies systematically and predictably. Recently, we have shown that DNA molecules can serve as programmable ligands to fine-tune the morphologies of nanomaterials. Despite this discovery, the mechanism of how the morphology can be controlled and the roles of the DNA molecules in contributing to such control are not understood.

DNA-Encoded Tuning of Geometric and Plasmonic Properties of Nanoparticles Growing from Gold Nanorod Seeds.

Systematically controlling the morphology of nanoparticles, especially those growing from gold nanorod (AuNR) seeds, are underexplored; however, the AuNR and its related morphologies have shown promises in many applications. Herein we report the use of programmable DNA sequences to control AuNR overgrowth, resulting in gold nanoparticles varying from nanodumbbell to nanooctahedron, as well as shapes in between, with high yield and reproducibility. Kinetic studies revealed two representative pathways for the shape control evolving into distinct nanostructures.

DNA sequence-dependent morphological evolution of silver nanoparticles and their optical and hybridization properties.

A systematic investigation of the effects of different DNA sequences on the morphologies of silver nanoparticles (AgNPs) grown from Ag nanocube seeds is reported. The presence of 10-mer oligo-A, -T, and -C directed AgNPs growth from cubic seeds into edge-truncated octahedra of different truncation extents and truncated tetrahedral AgNPs, while AgNPs in the presence of oligo-G remained cubic. The shape and morphological evolution of the nanoparticle growth for each system is investigated using SEM and TEM and correlated with UV-vis absorption kinetic studies.

Applications of synchrotron-based spectroscopic techniques in studying nucleic acids and nucleic acid-functionalized nanomaterials.

In this review, we summarize recent progress in the application of synchrotron-based spectroscopic techniques for nucleic acid research that takes advantage of high-flux and high-brilliance electromagnetic radiation from synchrotron sources. The first section of the review focuses on the characterization of the structure and folding processes of nucleic acids using different types of synchrotron-based spectroscopies, such as X-ray absorption spectroscopy, X-ray emission spectroscopy, X-ray photoelectron spectroscopy, synchrotron radiation circular dichroism, X-ray footprinting and small-angle X-ray scattering. In the second section, the characterization of nucleic acid-based nanostructures, nucleic acid-functionalized nanomaterials and nucleic acid-lipid interactions using these spectroscopic techniques is summarized.

DNA as a powerful tool for morphology control, spatial positioning, and dynamic assembly of nanoparticles.

CONSPECTUS: Several properties of nanomaterials, such as morphologies (e.g., shapes and surface structures) and distance dependent properties (e.

Facile and efficient preparation of anisotropic DNA-functionalized gold nanoparticles and their regioselective assembly.

Anisotropic nanoparticles can provide considerable opportunities for assembly of nanomaterials with unique structures and properties. However, most reported anisotropic nanoparticles are either difficult to prepare or to functionalize. Here we report a facile one-step solution-based method to prepare anisotropic DNA-functionalized gold nanoparticles (a-DNA-AuNP) with 96% yield and with high DNA density (120 ± 20 strands on the gold hemisphere).

DNAzyme-functionalized gold nanoparticles for biosensing.

Recent progress in using DNAzyme-functionalized gold nanoparticles (AuNPs) for biosensing is summarized in this chapter. A variety of methods, including those for attaching DNA on AuNPs, detecting metal ions and small molecules by DNAzyme-functionalized AuNPs, and intracellular applications of DNAzyme-functionalized AuNPs are discussed. DNAzyme-functionalized AuNPs will increasingly play more important roles in biosensing and many other multidisciplinary applications.

Nano-encrypted Morse code: a versatile approach to programmable and reversible nanoscale assembly and disassembly.

While much work has been devoted to nanoscale assembly of functional materials, selective reversible assembly of components in the nanoscale pattern at selective sites has received much less attention. Exerting such a reversible control of the assembly process will make it possible to fine-tune the functional properties of the assembly and to realize more complex designs. Herein, by taking advantage of different binding affinities of biotin and desthiobiotin toward streptavidin, we demonstrate selective and reversible decoration of DNA origami tiles with streptavidin, including revealing an encrypted Morse code "NANO" and reversible exchange of uppercase letter "I" with lowercase "i".

Discovery of the DNA "genetic code" for abiological gold nanoparticle morphologies.

DNA is in control: Different combinations of DNA nucleotides can control the shape and surface roughness of gold nanoparticles during their synthesis. These nanoparticles were synthesized in the presence of either homogenous oligonucleotides or mixed-base oligonucleotides using gold nanoprisms as seeds. The effect of the individual DNA bases and their combinations on shape control are shown in the figure.

Reversible cerebral vasoconstriction syndrome: an important cause of acute severe headache.

Reversible cerebral vasoconstriction syndrome (RCVS) is an increasingly recognized and important cause of acute headache. The majority of these patients develop potentially serious neurological complications. Rigorous investigation is required to exclude other significant differential diagnoses.

Site-selective localization of analytes on gold nanorod surface for investigating field enhancement distribution in surface-enhanced Raman scattering.

Understanding detailed electric near-field distributions around noble metal nanostructures is crucial to the rational design of metallic substrates for maximizing surface-enhanced Raman scattering (SERS) efficiency. We obtain SERS signals from specific regions such as the ends, the sides and the entire surfaces of gold nanorod by chemisorbing analytes on the respective areas. Different SERS intensities from designated surfaces reflect their electric near-field intensities and thus the distributions.

Time-dependent, protein-directed growth of gold nanoparticles within a single crystal of lysozyme.

Gold nanoparticles are useful in biomedical applications due to their distinct optical properties and high chemical stability. Reports of the biogenic formation of gold colloids from gold complexes has also led to an increased level of interest in the biomineralization of gold. However, the mechanism responsible for biomolecule-directed gold nanoparticle formation remains unclear due to the lack of structural information about biological systems and the fast kinetics of biomimetic chemical systems in solution.

A systems approach towards the stoichiometry-controlled hetero-assembly of nanoparticles.

A central theme in nanotechnology is to advance the fundamental understanding of nanoscale component assembly, thereby allowing rational structural design that may lead to materials with novel properties and functions. Nanoparticles (NPs) are often regarded as 'artificial atoms', but their 'reactions' are not readily controllable. Here, we demonstrate a complete nanoreaction system whereby colloidal NPs are rationally assembled and purified.

Controlled alignment of multiple proteins and nanoparticles with nanometer resolution via backbone-modified phosphorothioate DNA and bifunctional linkers.

Controlled alignment of streptavidin (STV), myoglobin, and nanoparticles with nanometer resolution has been achieved via backbone-modified phosphorothioate DNA and biotin- and maleimide-containing bifunctional linkers. Introducing triplet biotin modifications in three adjacent PSs significantly increased the STV conjugation yield. By placing phosphorothioate modifications at multiple positions of a double stranded DNA template, monomer, dimer, and trimer STV-DNA assemblies were formed with the STVs placed at controlled positions.

Fabrication of polymer nanocavities with tailored openings.

A templated fabrication of open nanocavities is reported, where rational control of partial polymer attachment on sacrificial metal cores introduces openings in the polymer shells. This approach provides a facile means to modify the structural features of polymer nanocavities by manipulating the surface chemistry of colloidal nanoparticles. In particular, the anisotropic geometry of gold nanorods is exploited to promote the anisotropic polymer attachment, such that two diametric openings occurred in the polymer shell.

Facile fabrication of triple-layer (Au@Ag)@polypyrrole core-shell and (Au@H2O)@polypyrrole yolk-shell nanostructures.

Triple-layer (Au@Ag)@polypyrrole core-shell nanoparticles are fabricated by a one-step synthesis involving simultaneous reduction of AgNO3 and polymerization of pyrrole in the presence of Au nanoparticles; the Ag layer in the resulting nanoparticles is etched to give a (Au@H2O)@polypyrrole yolk-shell structure.

High-purity separation of gold nanoparticle dimers and trimers.

An effective method was developed for separating gold-nanoparticle clusters in high resolution; dimer and trimer samples were obtained with 95% and 81% purity, respectively.

Controlled assembly of eccentrically encapsulated gold nanoparticles.

Controlled partial attachment of polymer on gold nanoparticles breaks the symmetry of their surface functionalities, allowing tailored assembly of the nanoparticles.