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Viruses are among the simplest biological systems and are highly effective vehicles for the delivery of genetic material into susceptible host cells. Artificial viruses can be used as model systems for providing insights into natural viruses and can be considered a testing ground for developing artificial life. Moreover, they are used in biomedical and biotechnological applications, such as targeted delivery of nucleic acids for gene therapy and as scaffolds in material science. In a natural setting, survival of viruses requires that a significant fraction of the replicated genomes be completely protected by coat proteins. Complete protection of the genome is ensured by a highly cooperative supramolecular process between the coat proteins and the nucleic acids, which is based on reversible, weak and allosteric interactions only. However, incorporating this type of supramolecular cooperativity into artificial viruses remains challenging. Here, we report a rational design for a self-assembling minimal viral coat protein based on simple polypeptide domains. Our coat protein features precise control over the cooperativity of its self-assembly with single DNA molecules to finally form rod-shaped virus-like particles. We confirm the validity of our design principles by showing that the kinetics of self-assembly of our virus-like particles follows a previous model developed for tobacco mosaic virus. We show that our virus-like particles protect DNA against enzymatic degradation and transfect cells with considerable efficiency, making them promising delivery vehicles.

DNA-based coatings possess beneficial properties useful for medical and dental implants. The present study evaluated the potential in vivo bioactivity of DNA-based coatings, either or not pretreated in simulated body fluid (SBF). DNA-based coatings were generated on titanium cylinders using layer-by-layer deposition, with bis-ureido-surfactant as the cationic component and DNA as the anionic component. Noncoated titanium implants and CaP-coated implants served as controls. A total of 80 implants, divided in four experimental groups (n = 10) were implanted unilaterally into the lateral femoral condyles of 80 rats. After implantation periods of 1 and 4 weeks, the bone-to-implant contact and bone volume around the implants were determined histomorphometrically. The results of this study showed that DNA-based coatings and CaP coatings increased bone-to-implant contact after 1 week compared to noncoated controls. After 4 weeks of implantation, bone-to-implant contact increased significantly for SBF pretreated DNA coatings and CaP coatings, whereas DNA-coated implants showed no additional effect. The bone-to-implant contact of noncoated controls increased to the level of the DNA-coated implants. Consequently, this study demonstrates that DNA-based coatings are histocompatible and favor early bone responses. SBF-pretreated DNA-based coatings were found to increase both early and late peri-implant bone responses., ((c) 2009 Wiley Periodicals, Inc.)

Aqueous interfaces are of paramount importance in the study of biological systems as well as in the biomedical sciences. To study these interfaces at the nanometer level it is of interest to develop methods that allow their observation with cryogenic transmission electron microscopy (cryo-TEM). Prevention of dehydration to preserve the "native" state during sample preparation prior to vitrification is often one of the most important parameters to control in cryo-TEM experiments. For the preparation of these types of samples, we felt the need for an extended workspace with temperature and humidity control; a 'glove-box' that seamlessly connects to the vitrification instrument, the Vitrobot. In this paper we describe the use of the glove-box in the 2D and 3D cryo-TEM study of DNA adsorption and calcium carbonate mineralization to Langmuir films. The data presented illustrates the necessity of a humidity-controlled environment to preserve the original "native" state of the monolayer system.

The layer-by-layer self-assembly of thin films consisting of alternating layers of DNA and bis-urea nanoribbons prevents diffusion of the components within the film and allows the anchoring of biotinylated molecules through molecular recognition in a predetermined layer of the film. Electron tomography demonstrates with nanometer precision the location of gold-labeled streptavidin bound to the incorporated biotinylated molecules.

Vascularization is important in wound healing and essential for tissue ingrowth into porous tissue-engineering matrices. Furthermore, peri-implant tissue vascularization is known to be important for the functionality of subcutaneously implanted biosensors (e.g., glucose sensors). As a first exploration of the use of deoxyribonucleic acid (DNA)-based coatings for the optimization of biosensor functionality, this study focused on the effect of DNA-based coatings functionalized with vascular endothelial growth factor (VEGF) on in vitro endothelial cell behavior and vascularization of the peri-implant tissue in vivo. To that end, DNA-based coatings consisting of poly-D-lysine and DNA were functionalized with different amounts of VEGF (25 and 250 ng) and compared to non-coated controls and non-functionalized DNA-based coatings. The results demonstrated the superiority of VEGF-functionalized DNA-based coatings in increasing endothelial cell proliferation and migration in vitro over non-coated controls and non-functionalized DNA-based coatings. In vivo, a significant increase in vascularization of the peri-implant area was observed for VEGF-functionalized DNA-based coatings. Because no dosage-dependent effects were observed, future experiments should focus on optimizing VEGF concentration for this purpose. Additionally, the administration of VEGF in combination with other (pro-angiogenic) factors should be considered.

This study describes the fabrication of two types of multilayered coatings onto titanium by electrostatic self-assembly (ESA), using deoxyribosenucleic acid (DNA) as the anionic polyelectrolyte and poly-d-lysine (PDL) or poly(allylamine hydrochloride) (PAH) as the cationic polyelectrolyte. Both coatings were characterized using UV-vis spectrophotometry, atomic force microscopy (AFM), X-ray photospectroscopy (XPS), contact angle measurements, Fourier transform infrared spectroscopy (FTIR), and for the amount of DNA immobilized. The mutagenicity of the constituents of the coatings was assessed. Titanium substrates with or without multilayered DNA-coatings were used in cell culture experiments to study cell proliferation, viability, and morphology. Results of UV-vis spectrophotometry, AFM, and contact angle measurements clearly indicated the progressive build-up of the multilayered coatings. Furthermore, AFM and XPS data showed a more uniform build-up and morphology of [PDL/DNA]-coatings compared to [PAH/DNA]-coatings. DNA-immobilization into both coatings was linear, and approximated 3microg/cm(2) into each double-layer. The surface morphology of both types of multilayered DNA-coatings showed elevations in the nanoscale range. No mutagenic effects of DNA, PDL, or PAH were detected, and cell viability and morphology were not affected by the presence of either type of multilayered DNA-coating. Still, the results of the proliferation assay revealed an increased proliferation of primary rat dermal fibroblasts on both types of multilayered DNA-coatings compared to non-coated controls. The biocompatibility and functionalization of the coatings produced here, will be assessed in subsequent cell culture and animal-implantation studies.

We report on two diaminotriazine-equipped naphthalene derivatives that bind reversibly to a single-stranded DNA template or "tape-measure molecule" via hydrogen bonding, yielding monodisperse double-stranded DNA hybrids with one strand consisting of a supramolecular naphthalene backbone. These assemblies have been investigated extensively, both experimentally and theoretically. The structure and the templated self-assembly process of the complex have been characterized with UV-vis spectroscopy, circular dichroism spectroscopy, molecular dynamics simulations, cryo-transmission electron microscopy, liquid atomic force microscopy, electrospray ionization mass spectrometry, light scattering, and 1H NMR and infrared spectroscopy. We have found that the DNA hybrid complexes have a right-handed helical arrangement stabilized by π-π interactions and hydrogen bonds. The hydrophilic hydroxyl group at the end of the ethylene glycol of the guest molecule suppressed both the nontemplated self-assembly of the naphthalene guest molecules and the further aggregation of the entire DNA hybrid complex. Through the use of a theoretical mass-action model for the templated self-assembly, the host-guest and guest-guest interaction energies were estimated by fitting to the spectroscopic data. The differently estimated values of the interaction energies and thermodynamic parameters vary within experimental error, showing the self- consistency of the model. From the obtained correlation between the positions of the guest molecules bound on the template, we have obtained a qualitative theoretical picture of the way in which the guests are physically distributed on the templates. For short templates, the templates are filled one-by-one, even at moderate fractions of bound sites. For larger templates, the templates first have alternating sequences of filled and empty sections, after which, at large fractions of bound sites, virtually all of the binding sites for all template lengths are filled. [ABSTRACT FROM AUTHOR]