Template-assisted electrohydrodynamic atomization (TAEA) spraying deposition, a recently developed and an electric-driven jet-based technique has been used to prepare bioactive surface topography on titanium (Ti). Nanometer-scaled SiHA (nanoSiHA), which closely resembles the bone mineral, has been synthesized and deposited on Ti surfaces with a range of patterns, such as pillars and tracks. A human osteoblast (HOB) cell model has been used to evaluate the in vitro cellular responses to nanoSiHA deposition. alamarBlue™ assay showed that nanoSiHA patterns are able to encourage the attachment and growth of HOB cells in comparison to those of nanoSiHA coating. The preferential growth of HOB cells was found along and across the track, HOB cells were also found to stretch between two tracks. Image analysis of HOB cell responses to the size of nanoSiHA pattern showed that the length of HOB cells was proportional to the gaps between the tracks until reaching the maximum length of 110 μm. The results indicate that the distance between the structures is paramount over the width. Our study will pave the way to control and guide cellular responses for new generation of bone implants.

We analyze the apo and holo calmodulin (CaM) structures by sequentially inserting a perturbation on every residue of the protein, and monitoring the linear response. Residue crosscorrelation matrices obtained from 20 ns long molecular dynamics simulation of the apo-form are used as the kernel in the linear response. We determine two residues whose perturbation equivalently yields the experimentally determined displacement profiles of CaM, relevant to the binding of the trifluoperazine (TFP) ligand. They reside on structurally equivalent positions on the N- and C-terminus lobes of CaM, and are not in direct contact with the binding region. The direction of the perturbation that must be inserted on these residues is an important factor in recovering the conformational change, implying that highly selective binding must occur near these sites to invoke the necessary conformational change.

We aim to utilize the high surface area of a porous silicon (PSi) matrix coupled with semiconductor quantum dot (QD) amplifiers for ultrasensitive optical detection of small biomolecules using a dual-mode detection scheme. In our system, QDs attached to the target biomolecule serve as signal amplifiers by providing an additional refractive index increase beyond that of the smaller target molecules. The strong photoluminescence (PL) from the QDs serves as a secondary indication of target molecule attachment in the pores. A resulting increase in optical thickness of ∼190 nm and detection sensitivity of ∼700 nm/RIU have been demonstrated for attachment of glutathione capped CdTe QDs in the porous silicon matrix. Reflectance and PL measurements, combined with simulations, have been used to characterize the surface area coverage of the QDs within the porous framework, which is estimated at 10% for glutathione capped CdTe QDs.

Operations on biological living cells and molecular devices have driven research towards implementation of high-aspect-ratio nano-needles. However, current nano-needle fabrication is complicated to control the sizes and angles. In this work, we develop a simple method to fabricate repeatable and integrated circuit (IC)-compatible sharp silicon nano-needles based on boron etch-stop in tetramethyl ammonium hydroxide (TMAH) solutions, and the needle angles can be accurately controlled. An analytical model is proposed to efficiently predict the needle sizes and explain the etching evolution of silicon nano-needles.

A key issue in using Polydimethylsiloxane (PDMS) based micropillars as cellular force transducers is obtaining an accurate characterization of mechanical properties. The Young’s modulus of PDMS has been extended from a constant in the ideal elastic case to a time-dependent function in the viscoelastic case. However, the frequency domain information is of more practical interest in interpreting the complex cell contraction behavior. In this paper, we reevaluated the Young’s relaxation modulus in the time domain by using more robust fitting algorithms than previous reports, and investigated the storage and loss moduli in the frequency domain using the Fourier transform technique. With the use of the frequency domain modulus and the deflection of micropillars in the Fourier series, the force calculation can be much simplified by converting a convolution in the time domain to a multiplication in the frequency domain.

Our work focuses on the earliest events of homo-/heterogeneous nucleation from an initial supersaturated solution to the subsequent growth of nuclei. The combined use of conductance, together with hydrogen and calcium ISEs has provided new insights into the mechanisms of crystal nucleation and phase stability. We propose that two types of ACP are formed during HAP nucleation. The initial subcritical calcium-phosphate ion clusters form an amorphous [CaHPO4·xH2O] phase (ACP-1), which transforms to amorphous [Ca3(PO4)2] (ACP-2), and subsequently to HAP. This study is a major step forward in our understanding of the earliest nucleation events in vitro and in vivo. Additives may influence HAP nucleation by interacting with ACP clusters during the early induction period.

We present a versatile and facile route for highly sensitive detection of analytes through coupling the enlargement of gold nanoparticles (Au NPs) with fluorescence decrease. The fluorescence intensity of dye molecules (e.g., fluorescein or rhodamine B) significantly decreased with the increasing concentration of reducing agents, such as hydrogen peroxide and hydroquinone. The sensitivity for the detection of reducing agents was much higher than other detection methods based on the absorbance measurement of enlarged gold nanoparticles or quantum dot-enzyme hybridization. We could successfully detect acetylthiocholine with the detection limit of several nM orders, using an enzymatic reaction by acetylcholinesterase, a key route for the detection of toxic organophosphate compounds. The fluorescence decreasing approach described in this work requires only a simple addition of fluorescence dye to the reaction solution without any chemical modification. The strategy of fluorescence decrease coupled with nanoparticle growth will be applied on the fluorescent substrate to develop detection templates for highly sensitive optical biosensor.

We describe the biosynthesis and characterization of protein materials comprised of two distinct self-assembling domains (SADs): elastin (E) found in tissue for its elastic properties and cartilage oligomeric matrix protein coiled-coil (COMPcc, C) predominantly locatedin joint and in bones. Based on earlier studies on protein block polymers comprised these two SADs, orientation and number of blocks play a crucial role in the overall stimuli-responsive supramolecular assembly behavior. Here we fabricate a range of EnC and CEn block polymers in which the E domain is systematically truncated to explore the effects of the E domain on the overall physicochemical behavior.

Freestanding, strip-shaped magnetoelastic (ME) biosensors are a class of wireless, mass-based biosensors that are being developed for the real-time detection of pathogenic bacteria for food safety and bio-security. The mass sensitivity of these biosensors operating in longitudinal-vibration modes is known to be largely dependent on the position of masses attached to the sensor surfaces. Hence, considering this dependence is crucial to the detection of low-concentration target pathogens, including single pathogenic bacteria, because their local attachment may cause varying sensor responses. In a worst case scenario, the resultant sensor responses (i.e., mass-induced resonance frequency changes of the sensor) may be too small to be detected despite the attachment of the target pathogenic masses. To address the issue, phage-coated ME biosensors (magnetostrictive strips (4 mm × 0.8 mm × 30 μm) coated with a phage probe specifically binding streptavidin protein) with localized masses (streptavidin-coated polystyrene beads) were fabricated, and mass-position-dependence of the sensor’s sensitivity under the fundamental-mode vibration was experimentally measured. In addition, three-dimensional finite element (FE) modal analysis was performed using the CalculiX software to simulate the phenomena. The experimental and theoretical results show close agreement: (1) the mass sensitivity was low when the mass was positioned in the middle of the sensor’s longest dimension and (2) a much higher mass sensitivity was, by contrast, obtained for the equivalent masses placed at both ends of the strip-shaped sensor. Furthermore, FE models were constructed for differently sized, phage-coated ME biosensors (100 – 500 μm in length with different widths and thicknesses) loaded with a single bacterial mass (2 μm × 0.4 μm × 0.4 μm, 1.05 g/cm3) at varying longitudinal positions. The mass sensitivity was found to be approximated by a mass-position-dependent Boltzmann function whose amplitude is inversely proportional to the length squared, width, and thickness of the sensor.

Cortical and cancellous bones were demineralized and deproteinized using 1 N HCl and 6% NaOCl, respectively. Experiments were performed at 37°C. The rate constants were calculated and the structural features of untreated and completely demineralized and deproteinized samples were studied by scanning electron microscopy, showing that intact, contiguous structures were obtained. For both cases, the rate constant was higher for cancellous bone than the cortical bone.

Chemotaxis is one of the essential mechanisms responsible for various complex biological processes. For a crawling cell, the interface between the cell and the substrate plays an important role in the chemotactic migration. This paper presents a three-dimensional dynamic model to investigate the effect of the interface between a crawling cell and a substrate on its chemotaxis. The coupled mechanisms of chemotaxis, the surface energy of the cell, and the interface between the cell and the substrate are incorporated into a diffuse interface model. Simulations reveal rich dynamics of a crawling cell associated with the interfacial condition, and confirm the high possibility of adequate predictions.

We have developed a reproducible protocol for studying the effect of microwave radiation on the mechanical behavior of Bombyx mori cocoon silk. In the course of this work, we identified multiple improvements that can be made to ASTM F 1317-98, the standard according to which microwave oven power output is calibrated.

Exposure to microwaves does not significantly affect mechanical properties of silkworm silk, if samples are kept in a desiccator after degumming (or after degumming and microwaving) and prior to testing in a dry environment. This finding contrasts with previous work in which samples were not kept in a desiccator, and were tested in a relatively humid environment.

Because the effect of microwave radiation on the mechanical behavior of silk is sensitive to ambient moisture, meaningful comparison or pooling of test results acquired in different laboratories is contingent on standardization of both the sample storage environment and the environment in which samples are tested. Interpretation of the extensive existing literature on silk mechanical properties must take account of the reality that the sample storage and testing environments are not standardized and are usually not reported.

The dissolution kinetics of type B carbonate apatite (CAp) disks sintered at different temperatures were investigated under acidic conditions similar to an osteoclastic desorption process in bone remodeling. The type B CAp disks, which were uniaxially pressed at 98MPa and sintered at temperatures of 600 to 700 ºC, showed single crystalline phase and a high relative density of 60-62 % compared to the stoichiometric density of 3.16g/cm3 of hydroxyapatite (HAp). The dissolution rate of type B CAp disks sintered at 650 ºC was 3.5 times faster than that of HAp disks at 650 ºC. These results indicate that the Type B CAp sintered disks show potential use as a biodegradable material for artificial bone.

We report the heterogeneous integration of a multifunctional sensor based on polymer porous photonic bandgap (P3BG) structure and xerogel based luminescence sensor technology. The P3BG structure was fabricated using holographic interferometry. Initially, holographic interferometry of a photo-activated prepolymer syrup that included a volatile solvent as well as monomer, photoinitiator, and co-initiator was used to initiate photopolymerization. Subsequent UV curing resulted in well defined lamellae of the polymer separated by porous polymer regions that created a high quality photonic bandgap structure. The resulting P3BG structure was then integrated with the xerogel based luminescence element to produce a luminescence sensor with a selective narrow band reflector. The prototype xerogel based luminescence sensor element consisted of an O2 sensing material based on spin coated tetraethylorthosilane (TEOS) composite xerogel films containing tris (4,7-diphenyl-1,10-phenanthroline) ruthenium (II) ([Ru(dpp)3]2+) luminophore. We demonstrated enhancement of the signal-to-noise ratio (SNR) of this integrated multifunctional sensor while maintaining the same sensitivity to O2 sensing of the xerogel based element. The resulting advantages and enhanced SNR of this integrated sensor will provide a template for other luminescence based assays to support highly sensitive and cost-effective sensor systems for biomedical applications.

Today the company seeks alternative natural medicine that are compatible with the body, which does not produce side effects and hang time are easily accessible and cost of those who currently have. The concern of researchers and specialists in the development of new materials is to seek, to experiment and create products that can be useful and compatible with human beings so as to obtain a curative effect without a side effect originates.

The development of pharmacologically active materials has increased in recent years. People lack access to most drugs and is therefore a need for more rapid and less expensive than current, which can be applied to cellular systems in vitro, in order to evaluate the biocompatibility of new materials. The current study seeks to experiment in a new line of research that helps health care and have a better quality of life.

The excipients in the drug are auxiliary substances that help the active ingredient is the one with the therapeutic action, can be formulated in an effective and pleasant for the patient. It is one or more substances that are incorporated into the product to facilitate its preparation, maintenance or administration. We therefore tested clay known as bentonite to serve as a vehicle for transport of an active substance (ursolic acid) [1] and some scientific studies have shown that it possesses anti-inflammatory, antibacterial, antifungal and highly cytotoxic capacity. Both materials were mixed to generate a new biomaterial that has anti-inflammatory activity. Evaluation of this model was under the inhibition of edema produced by 13-acetate-12-ortho-tetradecanoylphorbol (TPA) in mouse ear.

Partially demineralized (DM) bone is of interest due to its promising osteointegrative properties for advanced bone grafts. Structural features of partially DM (35 vol.%, 45 vol.% and 55 vol.% reduction), and untreated cortical bone samples were studied by scanning electron microscopy. Mechanical properties were investigated by compression testing in three anatomical directions at different stages of DM. The radial direction appears to be the stiffest and strongest bone direction for the all DM stages.

The atypical mechanical behavior of white matter and its influence on the mechanical properties of brain tissue necessitate adoption of a mutli-scale model of white matter for accurate computational analysis. Herein, we present a micromechanical analysis coupled with finite elements into a biomechanical interacting model of white matter. A representation of the white matter of central nervous system is identified and its microstructure is generated. The geometric descriptions of the axon and the surrounding matrix are obtained from neurofilament immunohistochemistry images. Consecutively, linear elastic material constitutive models are applied to describe the behavior of axons and their surrounding matrix subjected to small deformations. This model facilitates determination of the tissue’s stress and strain fields, and enables an understanding of the effects of axon undulation on local fields. The fundamental nature of the model enables future scale-up for structural tissue analysis and predictions of axon damage at the microscale.

This article presents the first man-made material based on the structure of nacre that successfully duplicates the mechanism of tablet sliding. This material was made of millimeter size PMMA tablets arranged in columns and held by fasteners. Strain hardening was provided by tablet waviness, delaying localization and leading to strains at failure 3-5 times greater than bulk PMMA. Analytical and finite element models successfully captured the locking mechanisms, enabling a rigorous design and optimization of similar composites based on different materials or at different length scales. This work demonstrates how key features and mechanisms in natural nacre can be successfully harnessed in engineering materials. Interestingly, the development of this model material and of its associated models also unveiled two new mechanisms, the effect of free surfaces and “unzipping”. Both mechanisms may be relevant to natural materials such as nacre or bone.

Porous silicon waveguides with integrated porous silicon grating couplers are demonstrated as small molecule biosensors. Two fabrication methods are presented for the grating couplers: standard electron beam lithography with reactive ion etching and a new technique based on direct imprinting of porous substrates. Although the gratings fabricated using standard lithographic techniques have steeper sidewalls and enable a larger available sensing surface area inside the waveguide, the imprinted gratings have the advantage of rapid and low-cost fabrication. Both the lithographically and imprinted sensors are shown to have waveguide losses on the order of 10 dB/cm, and both are demonstrated for detection of 16mer nucleic acids.