We have developed a novel class of colloidal particles capable of shape and size recognition as well as specific binding to the target cells. These colloid particles were fabricated using a nanoimprinting technology which yields inorganic imprints of the chosen target microorganisms. The products of the templating process are partially fragmented inorganic shells which can selectively bind to their biological counterparts, therefore impairing microbial cell growth, replication and infection. We have named this class of particles, which are capable of selectively recognizing bacterial shape and size, “nanoantibiotics”, which can be further functionalized to kill the target cells. The selective binding is driven by the increased area of contact upon recognition of the cell shape and size between the cells and their matching inorganic shell fragments. Here, we demonstrate the cell recognition and binding action of such particles using two different microbial test organisms.

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-acquired infections (HAI). HAI affect approximately 1.7 million patients each year in the U.S., resulting in up to 100,000 excess deaths, which leads to an estimated cost of more than $35 billion per year. Hence, there is an urgent clinical need to develop new therapies to reduce infections, without resorting to the use of antibiotics for which bacteria are developing a resistance towards. In this study, we designed superparamagnetic iron-oxide nanoparticles (SPION) to treat antibiotic-resistant biofilms and showed that SPION efficacy increases when they are used in combination with fructose.

The purpose of this study was to achieve a descellularized scaffold from cartilage tissue, which can be used as xenograft for cartilage tissue regeneration.

This work presents the results obtained using one method to wash porcine trachea in order to remove cellular material from the extracellular matrix and to avoid the immune reaction using enzymatic detergent and partial enzymatic degradation with Deoxyribonuclease I (DNase-I), Ethylenediaminetetraacetic Acid (EDTA) and Trypsin. This treatment was qualitatively evaluated by Scanning Electron Microscopy (SEM), and H&E Stain (Histology), and quantitatively evaluated by DNA quantification. The thermal characterization of the descellularized scaffold was carried out using Termogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The type of collagen obtained from the scaffold was determined through SDS-PAGE electrophoresis. When using Enzymatic Treatment (ET) to wash trachea tissue, it is possible to obtain an acellular xenograft; this procedure has the potential to avoid rejection reactions of the xenograft.

In order to establish defined biomimetic systems, type I collagen was functionalised with 1,3-Phenylenediacetic acid (Ph) as aromatic, bifunctional segment. Following investigation on molecular organization and macroscopic properties, material functionalities, i.e. degradability and bioactivity, were addressed, aiming at elucidating the potential of this collagen system as mineralization template. Functionalised collagen hydrogels demonstrated a preserved triple helix conformation. Decreased swelling ratio and increased thermo-mechanical properties were observed in comparison to state-of-the-art carbodiimide (EDC)-crosslinked collagen controls. Ph-crosslinked samples displayed no optical damage and only a slight mass decrease (∼ 4 wt.-%) following 1-week incubation in simulated body fluid (SBF), while nearly 50 wt.-% degradation was observed in EDC-crosslinked collagen. SEM/EDS revealed amorphous mineral deposition, whereby increased calcium phosphate ratio was suggested in hydrogels with increased Ph content. This investigation provides valuable insights for the synthesis of triple helical collagen materials with enhanced macroscopic properties and controlled degradation. In light of these features, this system will be applied for the design of tissue-like scaffolds for mineralized tissue formation.

Molecular sensing using stimuli-responsive viscoelastic property of amphiphilic polymer hydrogel was demonstrated. Thermo-responsive poly(N-isopropylacrylamide); NIPA, hydrogel immobilizing bovine serum albumin (BSA) in its polymer chain was synthesized on the AT-cut QCM (Quartz crystal microbalance). The device was provided to the sensing of anti-BSA antibody. The resonance behavior of QCM in response to the adsorption of anti-BSA antibody on the hydrogel was observed based on both the resonance frequency and resistance of QCM with impedance analysis. The QCM device coated with the LCST polymer hydrogel revealed a characteristic resonance behavior in response to the adsorption of anti-BSA antibody in the collapse phase of gel at which the gel lost most of its hydrated water. The resonance frequency and resistance in the collapsed gel were highly sensitive and their changes in response to the target adsorption were much larger than in the swelling state of gel. The use of the device at the LCST of NIPA gel is ideal because the largest amplification of the adsorption signal is available along with the largest phase change of NIPA gel.

Remoras (echeneid fish) reversibly attach and detach to marine hosts, almost instantaneously, to “hitchhike” and feed. The adhesion mechanisms that they use are remarkably insensitive to substrate topology and quite different from the latching and suction cup-based systems associated with other species at similar length scales. Remora adhesion is also anisotropic; drag forces induced by the swimming host increase adhesive strength, while rapid detachment occurs when the remora reverses this shear load. In this work, an investigation of the adhesive system’s functional morphology and tissue properties was carried out initially through dissection and x-ray microtomographic analyses. Resulting finite element models of these components have provided new insights into the adaptive, hierarchical nature of the mechanisms and a path toward a wide range of engineering applications.

In this study, we demonstrate the fabrication of hybrid membranes that exhibit discrete and reversible changes in permeability in response to changes in calcium ion (Ca2+) concentration and temperature. Fusion proteins comprising calmodulin (CAM) and elastin-like polypeptides (ELPs) were used as stimuli-responsive elements due to their ability to undergo a reversible lower critical solution temperature (LCST) phase transition, which is sensitive to Ca2+ binding. The calmodulin elastin-like polypeptides fusions (CAM-ELPs) were incorporated into polymerizing silica networks using a simple sol-gel process and spin coating. Permeation experiments with solutions of crystal violet showed that the membranes are both Ca2+-responsive and thermally responsive. Under suitable pressure drop across the membranes, in the absence of Ca2+ or below the LCST of the ELPs, the hybrid membranes are impermeable to water. After addition of Ca2+ or above the LCSTs, they become permeable to water. The permeability can be toggled back and forth by sequential addition of calcium and ethylenediamine tetraacetic acid (EDTA). These results demonstrate that CAMELP/silica hybrid membranes can serve as tunable molecular filters whose permeability can be switched on and off in response to Ca2+ and temperature.

We have fabricated novel shellac-cells composite microcapsules capable of pH-stimulus induced release of cells in a narrow pH range. The microcapsules were produced with yeast cells as a model for probiotics which were co-precipitated from an aqueous solution of ammonium shellac doped with pH-sensitive polyelectrolytes. The yeast cells in the composite shellac-cell microcapsules retained their viability even when treated with aqueous solutions of very low pH and subjected to shear stress. We studied the pH triggered release of cells from these microcapsules and measured their disintegration times. These microcapsules showed versatile responses ranging from slow release to explosive swelling at higher pH depending on the type and concentration of the polyelectrolyte integrated in the shellac microcapsules. We also observed growth-triggered release of cells from these microcapsules upon exposure to culture media. In both cases the cells retained their viability following their release from the microcapsules into the aqueous solution.

Various metallic structures of complex shape, resembling natural objects such as plants, mushrooms, and seashells, were produced when growing nanowires by means of pulsed current electroplating in porous membranes. These structures occur as the result of nanowires self-assembling (biomimetics) if the electroplating is continued after the nanowires reach the membrane surface. By varying the membrane geometry and the pulsed current parameters, and alternating electroplating from two baths with different electrolytes, various models were fabricated, including a hollow container with wall thickness of 10-30 nm. The possibility of shape regulation for models was demonstrated: in certain conditions, mushroom- and shell-like convex-concave models of the same kind were obtained. The hierarchical structure of models at the nano-, micro- and mesoscopic levels is shown through fragmentation and chemical etching. This biomimetic method suggests an analogy between the shape-forming processes of natural plants and their metallic models. Nanostructured mesoscopic objects of metals (Ag, Pd, Rh, Ni, Bi), alloys (PdNi, PdCo, PbIn) as well as their combinations (PdNi/ Pb, PdNi/ PbIn) were obtained. The technological simplicity of the present method makes it suitable for fabricating nanostructured materials that may be efficient in catalysis, superhydrophobic applications, medical filters, and nanoplasmonics.

Strategies for controlled imbibition utilizing both topographical cues as well as patterned surface chemistries are presented. Triangle-like microstructures were used for directional wetting of liquids into a limited sector of the surface. Chemical patterns on top of a nanopillar geometry allowed the patterning of both water and oil droplets. Applications of controlled imbibition in dried droplet mass spectrometry as well as liquid-liquid extraction are also presented.

This study reveals that an “old” mechanism for shape memory in oriented polymers is in fact just one separate contribution for “supercontraction” in Nephila spider major ampulate silks. When Nephila spider silks are in contact with liquid water, they “super”-contract up to 28% of the original stretched length. However, we discovered that under glass transition conditions these silks only relax with a maximum shrinkage of 13%, and this phenomenon is defined as Tg-contraction. Structural components permanent order (PO), permanent disorder (PD), meta order (MO) and meta disorder (MD) were proposed from the primary amino-acid sequence of the silk protein to explain morphological changes in the two contraction phenomena: MD contributes 13% of the full supercontraction and contributes to Tg-contraction; whereas MO (the proline-containing motifs) contributes the rest for the full super-contraction and does not contribute to Tg-contraction. The morphology in Nephila spider silk structure suggests two separate mechanisms to generate the shape memory effect in synthetic polymers.

The amyloidosis of amyloid β (1-42) was investigated by the well-defined glyco-cluster interface. We prepared monovalent, divalent, and trivalent 6-sulfo-N-acetyl-D-glucosamine immobilized substrates. The interaction between amyloid β and 6-sulfo-N-acetyl-D-glucosamine was amplified by multivalency of divalent and trivalent 6-sulfo-N-acetyl-D-glucosamine. The morphology of amyloid β were investigated by AFM, and we found the morphology of amyloid β aggregates were determined by the kinds of displayed saccharide-valency. Amyloid β had tendency to form spherical objects on the multivalent 6-sulfo-N-acetyl-D-glucosamine, but form fibrils on the monovalent 6-sulfo-N-acetyl-D-glucosamine. Spherical amyloid β was more toxic than fibrillar amyloid β to HeLa cells. These results suggested that the multivalency of was significant in its morphology and aggregation effects at the surface of the cell membrane mimic.

Materials that offer the ability to influence tissue regeneration are of vital importance to the field of Tissue Engineering. Because valid 3-dimensional scaffolds for nerve tissue are still in development, advances with 2-dimensional surfaces in vitro are necessary to provide a complete understanding of controlling regeneration. Here we present a method for controlling nerve cell growth on Au electrodes using Atomic Force Microscopy -aided protein assembly. After coating a gold surface in a self-assembling monolayer of alkanethiols, the Atomic Force Microscope tip can be used to remove regions of the self-assembling monolayer in order to produce well-defined patterns. If this process is then followed by submersion of the sample into a solution containing neuro-compatible proteins, they will self assemble on these exposed regions of gold, creating well-specified regions for promoted neuron growth.

We have developed a method of a stepwise construction of a gel consisting of (i) astral-shaped actin filaments with their plus end connected on photo-responsive polymer beads and (ii) bipolar myosin filaments as linkers in order to mimic sarcomeric structure, the basic unit of a muscle. In the method, firstly, 4 μm diam. beads were prepared from an acrylate polymer containing azobenzene moiety by a good-solvent evaporation technique. Next, gelsolin, which servers and remains bound to the plus end of an actin filament, was adsorbed and then immobilized on the bead surface by exposure to light from blue light-emitting diodes, and then fluorescent actin filaments were mixed with the beads. Formation of star-like, astral actin filaments on the beads were observed in fluorescent microscopy. Finally, the beads with actin filaments were mixed with myosin mini filaments with ca. 1 μm in length. Dozens of the beads were observed to be assembled into a gel form in optical microscopy. After adding adenosine triphosphate to the gel solution, the gel was slowly contract up to 60% comparing with its original volume, suggesting that linker myosin filaments moved on the actin filaments toward the plus end on the beads.

Acid hydrolysis of cellulose leads to the formation of nanowhiskers, which can self-assemble to form a liquid crystal phase at a concentration determined by their aspect ratio. This work investigates the properties of the un-hydrolysed materials on which the length of the nanowhiskers depend. It was found that the length is determined by the branching pattern of the cellulose microfibrils and the crystallinity of the material.

Liposome was synthesized by using mixture of dipalmitoylphosphatidylcholine and cholesterol in the ultrapure water or physiological saline. Phase transformation temperature and vibrational mode of dipalmitoylphosphatidylcholine molecule were detected by using transmission Fourier-transform infrared spectroscopy for aqueous solution, which we developed. The liposomes were fixed on an amorphous carbon mesh for ultra-high resolution transmission electron microscopy observation and stained with platinum thymidine blue. As-prepared liposomes reinforced with cholesterol were spherical in shape with size larger than 100 nm in diameter and still stable in the vacuum. Under the strong electron irradiation condition, the solution enclosed in the liposomes became unstable and then collapsed. On the other hand, the liposome synthesized in the physiological saline sometimes contains crystallized salt. As a result, the liposome shows proper strength to hold wet material in itself in a vacuum and can be used for the transmission electron microscopy observation.

We are interested in designing nanostructured biomaterials using nanoscopic building blocks such as functionalized nanotubes and lipid molecules. In our earlier work, we summarized the multiple control parameters which direct the equilibrium morphology of a specific class of nanostructured biomaterials. Individual lipid molecules were composed of a hydrophilic head group and two hydrophobic tails. A bare nanotube encompassed an ABA architecture, with a hydrophobic shaft (B) and two hydrophilic ends (A). We introduced hydrophilic hairs at one end of the tube to enable selective transport through the channel. The dimensions of the nanotube were set to minimize its hydrophobic mismatch with the lipid bilayer. We used a Molecular Dynamics-based mesoscopic simulation technique called Dissipative Particle Dynamics which simultaneously resolves the structure and dynamics of the nanoscopic building blocks and the hybrid aggregate. The amphiphilic lipids and functionalized nanotubes self-assembled into a stable hybrid vesicle or a bicelle in the presence of a hydrophilic solvent. We showed that the morphology of the hybrid structures was directed by factors such as the temperature, the rigidity of the lipid molecules, and the concentration of the nanotubes. Another type of hybrid nanostructured biomaterial could be multi-component lipid bilayers. In this paper, we present approaches to design hybrid nanostructured materials using multiple lipid species with different chemistries and molecular chain stiffness.

Magnetite (Fe3O4) formation within Magnetospirillum magneticum strain AMB-1 occurs under the influence of the Mms6 protein. It is hypothesised that if key iron binding sites within the C-terminus of the Mms6 protein are substituted for alanine, the protein’s overall iron binding ability is diminished. In this study, an atomistic model of Mms6-driven magnetite formation was developed and the attachment of series amino acid repeats (alanine-alanine, alanine-glutamic acid & glutamic acid-glutamic acid) to the {100} & {111} magnetite surfaces were investigated. Our results suggest the substitution of glutamic acid for alanine residues significantly reduces iron binding affinity of the system, thus confirming the hypothesis. In addition, it is shown that the surface of preferable attachment is the {111} magnetite surface.

Atomistic lattice-gas models for thermodynamically and kinetically directed assembly are applied to Ru nanocluster formation on a monolayer of graphene supported on Ru(0001) at 309 K. Nanocluster density, mean size, height distribution, and spatial ordering are analyzed by kinetic Monte Carlo simulations. Both models can reproduce the experimental data, but additional density functional theory analysis favors the former.

Fabrication methodologies with high precision and tenability for nanostructures of metal and metal oxides are widely explored for engineering devices such as solar cells, sensors, non-volatile memories (NVM) etc. In this direction, metal and metal oxide nanopatterned arrays are the state-of-the-art platforms upon which the device structures are built where the tunable orderly arrangement of the nanostructures enhances the device performance. We describe here a coalition of fabrication protocols that employ block copolymer self-assembly and nanoimprint lithography (NIL) to obtain metal oxide nanopatterns with sub-100 nm spatial resolution. The protocols are easily scalable down to sub-50 nm and below.

Nanopatterned arrays of ZnO created by using NIL assisted templates through area selective atomic layer deposition (ALD) and radio frequency (RF) sputtering find application in NVM and photovoltaics. We have employed NIL that produced nanoporous polymer templates using Si molds derived from block copolymer lithography (BCL) for pattern transfer into ZnO. The resulting ZnO nanoarrays were highly dense (8.6 x 109 nanofeatures per cm2) exhibiting periodic feature to feature spacing and width that replicated the geometric attributes of the template. Such nanopatterns find application in NVM, where a change in the density and periodicity of the arrays influences the charge storage characteristics. The above assembly and patterning protocols were employed to fabricate metal-oxide-semiconductor (MOS) capacitor devices for investigating application in NVM. Patterned ZnO nanoarrays were used as charge storage centres for the MOS capacitor devices. Preliminary results upon investigating the flash memory performance showed good flat-band voltage hysteresis window at a relatively low operating voltage due to high charge trap density.