Cytotoxicity of CdSe and CdSe/ZnS nanoparticles has been investigated for different surface modifications such as coating with mercaptopropionic acid, silanization, polymer coating. For all cases, quantitative values the onset cytotoxic effects in serum-free culture media are given. These correlated microscope images which uptake particles by cells investigated. Our data suggest that addition to release toxic Cd2+ ions from also their chemistry, particular stability toward aggregation, plays...

A general strategy is described which allows for transferring hydrophobically capped nanocrystals from organic to aqueous solution by wrapping an amphiphilic polymer around the particles. In particular, high quality CoPt3, Au, CdSe/ZnS, and Fe2O3 have been water-solubilized in this way. Analysis with transmission electron microscopy, gel electrophoresis, fluorescence correlation spectroscopy demonstrates that monodispersity of particles conserved upon phase transfer solution.

To investigate the potential of DNA origami constructs as programmable and noncytotoxic immunostimulants, we tested immune responses induced by hollow 30-helix tubes covered with up to 62 cytosine-phosphate-guanine (CpG) sequences in freshly isolated spleen cells. Unmethylated CpG that are highly specific for bacterial recognized a specialized receptor innate system localized endosome, Toll-like 9 (TLR9). When incubated oligonucleotides containing CpGs, cells stimulated through TLR9 produce...

Circular dichroism spectra of naturally occurring molecules and also synthetic chiral arrangements plasmonic particles often exhibit characteristic bisignate shapes. Such consist peaks next to dips (or vice versa) result from the superposition signals originating many individual objects oriented randomly in solution. Here we show that by first aligning then toggling orientation DNA-origami-scaffolded nanoparticle helices attached a substrate, are able reversibly switch optical response...

We study the distance-dependent quenching of fluorescence due to a metallic nanoparticle in proximity fluorophore. In our single-molecule measurements, we achieve excellent control over structure and stoichiometry by using self-assembled DNA structures (DNA origami) as breadboard where both fluorophore 10 nm are positioned with nanometer precision. The spectroscopy method employed here reports on co-localization particle dye, while lifetime imaging is used directly obtain correlation...

We demonstrate the assembly of functional hybrid nanopores for single molecule sensing by inserting DNA origami structures into solid-state nanopores. In our experiments, artificial based on are repeatedly inserted in and ejected from with diameters around 15 nm. show that these can be employed detection λ-DNA molecules. Our approach paves way future development adaptable single-molecule nanopore sensors combination self-assembly.

Many tiny force sensors Several techniques can measure forces on biomolecules, but the need to connect molecule macroscopic world often limits rate at which data be taken. Nickels et al. created large arrays of nanoscale by using DNA origami structures. Single-stranded molecules different lengths attached interest acted as entropic springs, with shorter strands exerting more force. The authors used their setup study bending induced TATA-binding protein. Science , this issue p. 305

We report that plasmonic nanoantennas made by DNA origami can be used as reliable and efficient probes for surface-enhanced Raman spectroscopy (SERS). The nanoantenna is built up two gold nanoparticles are linked together a three-layered block at separation distance of 6 nm in order to achieve coupling the formation "hot spot". properties hybrid structure optically characterized dark-field imaging polarization-dependent spectroscopy. SERS measurements on molecules embedded bridges gap were...

Abstract 3D crystals assembled entirely from DNA provide a route to design materials on molecular level and arrange guest particles in predefined lattices. This requires schemes that high rigidity sufficiently large open space. A DNA‐origami‐based “tensegrity triangle” structure assembles into rhombohedral crystalline lattice with an which 90% of the volume is empty space presented here. Site‐specific placement gold nanoparticles within demonstrates these are spacious enough efficiently host...

Abstract Doxorubicin (DOX) is a common drug in cancer chemotherapy, and its high DNA-binding affinity can be harnessed preparing DOX-loaded DNA nanostructures for targeted delivery therapeutics. Although DOX has been widely studied, the existing literature of DNA-carriers remains limited incoherent. Here, based on an in-depth spectroscopic analysis, we characterize optimize loading into different 2D 3D scaffolded origami (DONs). In our experimental conditions, all DONs show similar binding...

The label-free identification of individual proteins from liquid samples by surface-enhanced Raman scattering (SERS) spectroscopy is a highly desirable goal in biomedical diagnostics. However, the small cross-section most (bio-)molecules requires means to strongly amplify their signal for successful measurement, especially single molecules. This amplification can be achieved plasmonic hotspot that forms between two adjacent gold nanospheres. (≈1-2 nm) gaps typically required single-molecule...

Colloidal self-assembly allows rational design of structures on the micrometer and submicrometer scale. One architecture that can generate complete three-dimensional photonic bandgaps is diamond cubic lattice, which has remained difficult to realize at length scales comparable with wavelength visible or ultraviolet light. In this work, we demonstrate crystals self-assembled from DNA origami act as precisely programmable patchy colloids. Our DNA-based nanoscale tetrapods crystallize into a...

We present the concept of multifunctional nanoengineered polymer capsules and outline their applications as new drug delivery systems or supramolecular toolboxes containing, for example, enzymes capable converting nontoxic prodrugs into toxic drugs at a designated location. Such functionalized nanocontainers offer wide range including enzymatic catalysis, controlled release, directed in medicine due to multifunctionality. The unique advantage comparison other is that they can be loaded...

We introduce a method for the bottom-up assembly of biomolecular structures that combines precision atomic force microscope (AFM) with selectivity DNA hybridization. Functional units coupled to oligomers were picked up from depot area by means complementary strand bound an AFM tip. These transferred and deposited on target create basic geometrical structures, assembled different functions. Each these cut-and-paste events was characterized single-molecule spectroscopy fluorescence microscopy....

pH oscillations generated by a nonequilibrium chemical reaction are used to switch pH-sensitive DNA structure between two distinct conformations. The utilization of oscillator represents novel method for achieving autonomous motion in molecular devices. oscillatory is variant the Landolt and produces variations range 5 7. In this range, cytosine-rich strand can be switched random coil conformation folded i-motif structure. conformational changes monitored simultaneously with value...

We propose a method to detect and track multiple moving biological spot-like particles showing different kinds of dynamics in image sequences acquired through multidimensional fluorescence microscopy. It enables the extraction analysis information such as number, position, speed, movement, diffusion phases of, e.g., endosomal particles. The consists several stages. After detection stage performed by three-dimensional (3-D) undecimated wavelet transform, we compute, for each detected spot,...

The application of three-dimensional DNA origami objects as rigid mechanical mediators or force sensing elements requires detailed knowledge about their complex properties. Using magnetic tweezers, we directly measure the bending and torsional rigidities four- six-helix bundles assembled by this technique. Compared to duplex DNA, find be greatly increased while are only moderately augmented. We present a model explicitly including crossovers between individual helices in structure that...