by Keyword: Nanostructure

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Barba, A., Diez-Escudero, A., Espanol, M., Bonany, M., Sadowska, J. M., Guillem-Marti, J., Öhman-Mägi, C., Persson, C., Manzanares, M. C., Franch, J., Ginebra, M. P., (2019). Impact of biomimicry in the design of osteoinductive bone substitutes: Nanoscale matters ACS Applied Materials and Interfaces 11, (9), 8818-8830

Bone apatite consists of carbonated calcium-deficient hydroxyapatite (CDHA) nanocrystals. Biomimetic routes allow fabricating synthetic bone grafts that mimic biological apatite. In this work, we explored the role of two distinctive features of biomimetic apatites, namely, nanocrystal morphology (plate vs needle-like crystals) and carbonate content, on the bone regeneration potential of CDHA scaffolds in an in vivo canine model. Both ectopic bone formation and scaffold degradation were drastically affected by the nanocrystal morphology after intramuscular implantation. Fine-CDHA foams with needle-like nanocrystals, comparable in size to bone mineral, showed a markedly higher osteoinductive potential and a superior degradation than chemically identical coarse-CDHA foams with larger plate-shaped crystals. These findings correlated well with the superior bone-healing capacity showed by the fine-CDHA scaffolds when implanted intraosseously. Moreover, carbonate doping of CDHA, which resulted in small plate-shaped nanocrystals, accelerated both the intrinsic osteoinduction and the bone healing capacity, and significantly increased the cell-mediated resorption. These results suggest that tuning the chemical composition and the nanostructural features may allow the material to enter the physiological bone remodeling cycle, promoting a tight synchronization between scaffold degradation and bone formation.

Keywords: Biomimetic, Calcium phosphate, Carbonated apatite, Foaming, Nanostructure, Osteogenesis, Osteoinduction

Roki, N., Tsinas, Z., Solomon, M., Bowers, J., Getts, R. C., Muro, S., (2019). Unprecedently high targeting specificity toward lung ICAM-1 using 3DNA nanocarriers Journal of Controlled Release 305, 41-49

DNA nanostructures hold great potential for drug delivery. However, their specific targeting is often compromised by recognition by scavenger receptors involved in clearance. In our previous study in cell culture, we showed targeting specificity of a 180 nm, 4-layer DNA-built nanocarrier called 3DNA coupled with antibodies against intercellular adhesion molecule-1 (ICAM-1), a glycoprotein overexpressed in the lungs in many diseases. Here, we examined the biodistribution of various 3DNA formulations in mice. A formulation consisted of 3DNA whose outer-layer arms were hybridized to secondary antibody-oligonucleotide conjugates. Anchoring IgG on this formulation reduced circulation and kidney accumulation vs. non-anchored IgG, while increasing liver and spleen clearance, as expected for a nanocarrier. Anchoring anti-ICAM changed the biodistribution of this antibody similarly, yet this formulation specifically accumulated in the lungs, the main ICAM-1 target. Since lung targeting was modest (2-fold specificity index over IgG formulation), we pursued a second preparation involving direct hybridization of primary antibody-oligonucleotide conjugates to 3DNA. This formulation had prolonged stability in serum and showed a dramatic increase in lung distribution: the specificity index was 424-fold above a matching IgG formulation, 144-fold more specific than observed for PLGA nanoparticles of similar size, polydispersity, ζ-potential and antibody valency, and its lung accumulation increased with the number of anti-ICAM molecules per particle. Immunohistochemistry showed that anti-ICAM and 3DNA components colocalized in the lungs, specifically associating with endothelial markers, without apparent histological changes. The degree of in vivo targeting for anti-ICAM/3DNA-nanocarriers is unprecedented, for which this platform technology holds great potential to develop future therapeutic applications.

Keywords: 3DNA, DNA nanostructure, Drug nanocarrier, Endothelial and lung targeting, ICAM-1, In vivo biodistribution

Samitier, Josep, Correia, A., (2019). Biomimetic Nanotechnology for Biomedical Applications (NanoBio&Med 2018) Biomimetics MDPI

Emerging nanobiotechnologies can offer solutions to the current and future challenges in medicine. By covering topics from regenerative medicine, tissue engineering, drug delivery, bionanofabrication, and molecular biorecognition, this Special Issue aims to provide an update on the trends in nanomedicine and drug delivery using biomimetic approaches, and the development of novel biologically inspired devices for the safe and effective diagnosis, prevention, and treatment of disease.

Keywords: Bioinspired nanotechnologies, Bionanofabrication, Bio-nano measurement and microscopy, Nanomaterials for biological and medical applications, Nanoassemblies, Nanostructured surfaces, Drug delivery, Nanobioelectronics, Integrated systems/nanobiosensors, Nanotoxicology, Graphene-based applications

Sebastian, P., Giannotti, M. I., Gómez, E., Feliu, J. M., (2018). Surface sensitive nickel electrodeposition in deep eutectic solvent ACS Applied Energy Materials , 1, (3), 1016-1028

The first steps of nickel electrodeposition in a deep eutectic solvent (DES) are analyzed in detail. Several substrates from glassy carbon to Pt(111) were investigated pointing out the surface sensitivity of the nucleation and growth mechanism. For that, cyclic voltammetry and chronoamperometry, in combination with scanning electron microscopy (SEM), were employed. X-ray diffraction (XRD) and atomic force microscopy (AFM) were used to more deeply analyze the Ni deposition on Pt substrates. In a 0.1 M NiCl2 + DES solution (at 70 °C), the nickel deposition on glassy carbon takes place within the potential limits of the electrode in the blank solution. Although, the electrochemical window of Pt|DES is considerably shorter than on glassy carbon|DES, it was still sufficient for the nickel deposition. On the Pt electrode, the negative potential limit was enlarged while the nickel deposit grew, likely because of the lower catalytic activity of the nickel toward the reduction of the DES. At lower overpotentials, different hydrogenated Ni structures were favored, most likely because of the DES co-reduction on the Pt substrate. Nanometric metallic nickel grains of rounded shape were obtained on any substrate, as evidenced by the FE-SEM. Passivation phenomena, related to the formation of Ni oxide and Ni hydroxylated species, were observed at high applied overpotentials. At low deposited charge, on Pt(111) the AFM measurements showed the formation of rounded nanometric particles of Ni, which rearranged and formed small triangular arrays at sufficiently low applied overpotential. This particle pattern was induced by the (111) orientation and related to surface sensitivity of the nickel deposition in DES. The present work provides deep insights into the Ni electrodeposition mechanism in the selected deep eutectic solvent.

Keywords: AFM, Deep eutectic solvent, Glassy carbon, Nanostructures, Nickel electrodeposition, Platinum electrode, Pt(111), SEM, Surface sensitive

Barba, A., Diez-Escudero, A., Maazouz, Y., Rappe, K., Espanol, M., Montufar, E. B., Bonany, M., Sadowska, J. M., Guillem-Marti, J., Öhman-Mägi, C., Persson, C., Manzanares, M. C., Franch, J., Ginebra, M. P., (2017). Osteoinduction by Foamed and 3D-Printed Calcium Phosphate Scaffolds: Effect of Nanostructure and Pore Architecture ACS Applied Materials & Interfaces 9, (48), 41722-41736

Some biomaterials are osteoinductive, that is, they are able to trigger the osteogenic process by inducing the differentiation of mesenchymal stem cells to the osteogenic lineage. Although the underlying mechanism is still unclear, microporosity and specific surface area (SSA) have been identified as critical factors in material-associated osteoinduction. However, only sintered ceramics, which have a limited range of porosities and SSA, have been analyzed so far. In this work, we were able to extend these ranges to the nanoscale, through the foaming and 3D-printing of biomimetic calcium phosphates, thereby obtaining scaffolds with controlled micro- and nanoporosity and with tailored macropore architectures. Calcium-deficient hydroxyapatite (CDHA) scaffolds were evaluated after 6 and 12 weeks in an ectopic-implantation canine model and compared with two sintered ceramics, biphasic calcium phosphate and β-tricalcium phosphate. Only foams with spherical, concave macropores and not 3D-printed scaffolds with convex, prismatic macropores induced significant ectopic bone formation. Among them, biomimetic nanostructured CDHA produced the highest incidence of ectopic bone and accelerated bone formation when compared with conventional microstructured sintered calcium phosphates with the same macropore architecture. Moreover, they exhibited different bone formation patterns; in CDHA foams, the new ectopic bone progressively replaced the scaffold, whereas in sintered biphasic calcium phosphate scaffolds, bone was deposited on the surface of the material, progressively filling the pore space. In conclusion, this study demonstrates that the high reactivity of nanostructured biomimetic CDHA combined with a spherical, concave macroporosity allows the pushing of the osteoinduction potential beyond the limits of microstructured calcium phosphate ceramics.

Keywords: 3D-printing, Calcium phosphate, Foaming, Nanostructure, Osteoinduction

Castaño, O., Eltohamy, M., Kim, H. W., (2012). Electrospinning technology in tissue regeneration Nanotechnology in Regenerative Medicine - Methods and Protocols (Methods in Molecular Biology) (ed. Navarro, M., Planell, J. A.), Springer (New York, USA) 811, 127-140

Electrospinning is one of the most versatile and effective tools to produce nanostructured fibers in the biomedical science fields. The nanofibrous structure with diameters from tens to hundreds of nanometers largely mimics the native extracellular matrix (ECM) of many tissues. Thus far, a range of compositions including polymers and ceramics and their composites/hybrids have been successfully applied for generating electrospun nanofibers. Different processing tools in electrospinning set-ups and assemblies are currently developed to tune the morphology and properties of nanofibers. Herein, we demonstrate the electrospinning process and the electrospun biomaterials for specific use in tissue regeneration with some examples, involving different material combinations and fiber morphologies.

Keywords: Ceramic, Composites, Electrospinning, Nanofi bers, Nanostructured fi bers, Polymer, Tissue regeneration

Fumagalli, L., Gramse, G., Esteban-Ferrer, D., Edwards, M. A., Gomila, G., (2010). Quantifying the dielectric constant of thick insulators using electrostatic force microscopy Applied Physics Letters , 96, (18), 183107

Quantitative measurement of the low-frequency dielectric constants of thick insulators at the nanoscale is demonstrated utilizing ac electrostatic force microscopy combined with finite-element calculations based on a truncated cone with hemispherical apex probe geometry. The method is validated on muscovite mica, borosilicate glass, poly(ethylene naphthalate), and poly(methyl methacrylate). The dielectric constants obtained are essentially given by a nanometric volume located at the dielectric-air interface below the tip, independently of the substrate thickness, provided this is on the hundred micrometer-length scale, or larger.

Keywords: Borosilicate glasses, Finite element analysis, Insulating thin films, Mica, Nanostructured materials, Permittivity, Polymers, Scanning probe microscopy

Fernandez, Javier G., Mills, C. A., Samitier, J., (2009). Complex microstructured 3D surfaces using chitosan biopolymer Small 5, (5), 614-620

A technique for producing micrometer-scale structures over large, nonplanar chitosan surfaces is described. The technique makes use of the rheological characteristics (deformability) of the chitosan to create freestanding, three-dimensional scaffolds with controlled shapes, incorporating defined microtopography. The results of an investigation into the technical limits of molding different combinations of shapes and microtopographies are presented, highlighting the versatility of the technique when used irrespectively with inorganic or delicate organic moulds. The final, replicated scaffolds presented here are patterned with arrays of one-micrometer-tall microstructures over large areas. Structural integrity is characterized by the measurement of structural degradation. Human umbilical vein endothelial cells cultured on a tubular scaffold show that early cell growth is conditioned by the microtopography and indicate possible uses for the structures in biomedical applications. For those applications requiring improved chemical and mechanical resistance, the structures can be replicated in poly(dimethyl siloxane).

Keywords: Biocompatible Materials/ chemistry, Cell Adhesion, Cell Culture Techniques/ methods, Cell Proliferation, Cells, Cultured, Chitosan/ chemistry, Crystallization/methods, Endothelial Cells/ cytology/ physiology, Humans, Materials Testing, Nanostructures/ chemistry/ ultrastructure, Nanotechnology/methods, Particle Size, Surface Properties, Tissue Engineering/methods

Ruiz, A., Mills, C. A., Valsesia, A., Martinez, E., Ceccone, G., Samitier, J., Colpo, P., Rossi, F., (2009). Large-area, nanoimprint-assisted microcontact stripping for the fabrication of microarrays of fouling/nonfouling nanostructures Small 5, (10), 1133-1137

Methods for the accurate positioning of nanometric beads on a substrate have been developed over a number of years, and range from serial atomic force microscopy (AFM)techniques for single-bead positioning to parallel techniques for the positioning of large populations of beads in monolayer or multilayer architectures, typically from a liquid suspension. For example, topographic cues have been used for bead-based protein array production, although in this case, there is a random distribution of beads within the topography. Bead patterning has also been achieved in capillaries using a micromolding in capillaries (MIMIC) technique. Line patterns with micrometer widths are possible with this technique, achieving good multilayer organization. For monolayer bead patterning at micrometer dimensions, electrostatic forces and similar electrostatic assemblies using nanoxerography, as well as patterning by selective chemical functionalization, by transfer of particles from a liquid–liquid interface, and by subtracting top–down processes, are possible.

Keywords: Microcontact stripping, Nanostructures, Poly(acrylic acid), Polystyrene, Surface patterning

Martinez, E., Lagunas, A., Mills, C. A., Rodriguez-Segui, S., Estevez, M., Oberhansl, S., Comelles, J., Samitier, J., (2009). Stem cell differentiation by functionalized micro- and nanostructured surfaces Nanomedicine 4, (1), 65-82

New fabrication technologies and, in particular, new nanotechnologies have provided biomaterial and biomedical scientists with enormous possibilities when designing customized supports and scaffolds with controlled nanoscale topography and chemistry. The main issue now is how to effectively design these components and choose the appropriate combination of structure and chemistry to tailor towards applications as challenging and complex as stem cell differentiation. Occasionally, an incomplete knowledge of the fundamentals of biological differentiation process has hampered this issue. However, the recent technological advances in creating controlled cellular microenvironments can be seen as a powerful tool for furthering fundamental biology studies. This article reviews the main strategies followed to achieve solutions to this challenge, particularly emphasizing the working hypothesis followed by the authors to elucidate the mechanisms behind the observed effects of structured surfaces on cell behavior.

Keywords: Cell pattering, Differentiation, Microcontact printing, Micropatterning, Microstructure, Nanoimprinting, Nanostructure, Stem cells

Mir, M., Cameron, P. J., Zhong, X., Azzaroni, O., Alvarez, M., Knoll, W., (2009). Anti-fouling characteristics of surface-confined oligonucleotide strands bioconjugated on streptavidin platforms in the presence of nanomaterials Talanta 78, (3), 1102-6

This work describes our studies on the molecular design of interfacial architectures suitable for DNA sensing which could resist non-specific binding of nanomaterials commonly used as labels for amplifying biorecognition events. We observed that the non-specific binding of bio-nanomaterials to surface-confined oligonucleotide strands is highly dependent on the characteristics of the interfacial architecture. Thiolated double stranded oligonucleotide arrays assembled on Au surfaces evidence significant fouling in the presence of nanoparticles (NPs) at the nanomolar level. The non-specific interaction between the oligonucleotide strands and the nanomaterials can be sensitively minimized by introducing streptavidin (SAv) as an underlayer conjugated to the DNA arrays. The role of the SAv layer was attributed to the significant hydrophilic repulsion between the SAv-modified surface and the nanomaterials in close proximity to the interface, thus conferring outstanding anti-fouling characteristics to the interfacial architecture. These results provide a simple and straightforward strategy to overcome the limitations introduced by the non-specific binding of labels to achieve reliable detection of DNA-based biorecognition events.

Keywords: DNA/ analysis, Gold, Nanostructures/ chemistry, Oligonucleotide Array Sequence Analysis/ instrumentation, Oligonucleotides/ chemistry, Streptavidin/ chemistry, Sulfhydryl Compounds