Ethosomes which are phospholipid vesicular systems embodying ethanol in relatively high concentrations have ever been discovered for enhanced skin delivery of drugs. The development of competent ethosome-like catanionic vesicles for dermal drug delivery is demonstrated in this work. Double-chained ion-pair-amphiphiles (IPAs or catanionic surfactants) were prepared from single-chained cationic and anionic surfactants by the precipitation method. These lipid-like surfactants were thereafter used as the material to prepare the catanionic vesicles with the aid of ethanol as the cosolvent in aqueous buffer solution by a simple semispontaneous process. Formability and physical stability of the as-prepared ethosome-like catanionic vesicles were discussed based on the viewpoint of mixed solvent dielectric constant. The potential application of the ethosome-like catanionic vesicles as nano-carriers in dermal drug delivery was illustrated by the encapsulation of hydrophobic and hydrophilic drugs. Furthermore, effects of ethanol and cholesterol addition on physical stability, bilayer membrane rigidity, encapsulation efficiency, and release rate of the ethosome-like catanionic vesicles were systematically studied. The performance of ethosome-like catanionic vesicles as drug delivery nano-carriers, eventually, can be tailored by the concentrations of ethanol and. cholesterol. The results of gelation of drugs loaded ethosome-like catanionic vesicles by water soluble polymers with and without hydrophobical modifications, as revealed by the phase maps and the rheological properties, then provide useful information for practical use of the ethosome-like catanionic vesicles in dermal delivery of drugs.

Here we introduce a highly stretchable Printed Circuit Board (PCB) inter-connection technology achieved through the combination of flexibility allowed by the silver nanowire (AgNW)-based electrode and stretchability provided by the meander-shaped substrate. Horseshoe-shaped elastic material, polydimethylsiloxane, is used as a substrate of the AgNW conductors for relaxed stress concentration. Continuously maintained 2-D percolation of stretchable AgNW networks overcomes the usage restrictions with ordinary rigid Printed Circuit Board (PCB). The horseshoe-shaped inter-connection is physically reliable with repeated stretching/releasing processes and maintains its conductivity under tensile strains up to 20 %, allowing the durable and stretchable PCB inter-connecting applications.

Because of the aesthetics, handy and low cost features, acrylic resin is the main material in denture fabrication last 40 years. The purpose of this study is to improve mechanical properties of acrylic based dental composites used in dentistry by applying nanofiber approaches. Polymethylmethacrylate (PMMA) is commonly used as a base acrylic denture material with benefits of rapid and easy handling but sometime this material can be fractured or cracked in clinical use because of the strength issues that is frequently used in restorative dentistry in recent years. A wide variety of fillers that are used to produce PMMA composites draw the attention in literature. Using PMMA composite resins with electrospun polyvinylalcohol (PVA) nanofiber fillers is our first novelty. Also the producing and using aligned electrospun fibers as a filler is our second novelty of this practice. PVA was selected as composite filler because of biocompatibility and preparing easily also has non-toxic solvent. Electrospinning system is manufactured that allows manipulation of electric field used in the application of alignment in lab scale. Various auxillary electrode systems are used for different patterns of alignment with the manufactured device and electrode systems produce fibers in different range of diameter. Scanning electron microscopy (SEM) is used for physical characterization and determined the range of fiber diameters. After the optimization of concentration step non-woven and aligned fibers are also analyzed. Non-woven fiber has no unique pattern because of the nature of electrospinning but aligned fibers has crossed lines. These produced fibers structured as layer-by-layer form with different features are used in producing PMMA dental composites with different volume ratios. In the last part of the research, PMMA dental composites are produced with aligned and formless fibers that are characterized with three-point bending test. The maximum flexural strength figure shows that fiber load by weight %0.25 and above improves the maximum. The change of flexural strength, elastic modulus values and toughness are obtained and compared with formless and aligned PVA nanofiber included composite specimens. As a result, mechanical properties of PMMA dental composites are improved with using PVA nanofibers as a filler also with the usage of aligned fibers instead of the formless ones the effects of improvement gets better with maximum values as 5.1 MPa (flexural strength), 0.8 GPa (elastic modulus), 170kJ/m3 (toughness).

To modify the rigid structure of alginate, polyvinyl alcohol was mixed. Rheological properties and viscoelastic properties of the polymer blend solution were investigated. Complex and shear viscosity and tangent delta of the solution were obtained to find optimum condition of spinning dope. Effect of blend ratio on morphology and property change was investigated.

The present work focuses on the fabrication of environmental friendly ZnO nanocrystals and chitosan/cellulose films hosting ZnO nanoparticles (NPs) as an attempt to produce nanocomposites with enhanced bactericidal capacity. The solution casting method was used to fabricate the chitosan/cellulose blend films. Highly monodisperse ZnO nanoparticles were synthesized using Zinc acetate and Triethylene glycol (TEG) via a modified Polyol route. ZnO crystal size was controlled by the heterogeneous nucleation approach. Optical properties of ZnO nanoparticles were studied by UV–vis spectroscopy and Photoluminescence Spectroscopy (PL) techniques. The nanoparticles’ size and morphology were determined by Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD), respectively. Obtained results confirmed the effectiveness of the size-controlled synthesis employed. The chitosan/cellulose/ZnO nanocomposites were characterized by Fourier Transform – Infrared spectroscopy (FTIR) and X-ray diffraction (XRD) methods. The mechanical properties of produced bare and ZnO-bearing composites were determined from stress-strain tests. The Standard Plate Count and the Halo Zone methods were used to evaluate the bactericidal properties of the ZnO nanoparticles, chitosan/cellulose blend films and chitosan/cellulose/ZnO nanocomposites against Escherichia coli (ATCC 35218).

With increasing attention towards long-term health monitoring, there is a pressing need to create noninvasive sensors that monitor vital bioelectronic signals. Particular importance is placed on measuring electrocardiogram (ECG) signals as heart issues are widespread and can be prevented with the proper warning and care of potential problems. Currently, ECGs are taken in a hospital setting using disposable silver-silver chloride (Ag/AgCl) pre-gelled electrodes. Unfortunately, this cannot translate to a long-term monitoring setting due to the electrolytic gel of the electrodes drying and causing skin irritation. This paper presents a soft, skin-mountable dry electrode based on silver nanowires (AgNWs) for measuring ECG signals that can be used in long-term, wearable health monitoring due to the elimination of the electrolytic gel. The AgNWs are embedded in polydimethylsiloxane (PDMS), which creates a robust design that will not suffer from delamination or cracking problems that can eventually lead to loss of conductivity. The electrode is characterized by electrode-skin impedance as a function of frequency and by the surface resistance as the electrode is stretched. The performance of the dry electrode is evaluated and comparable to that of conventional Ag/AgCl electrodes. The ability of the dry electrode to conform to skin is believed to compensate for the lack of an electrolytic gel.

Through a unique combination of magnetophoretic and photopolymerization processes, approximately 150 μm thick functionally graded films based on a UV-curable matrix and containing Fe3O4@SiO2 core-shell nanoparticles are synthesized. Owing to their continuous composition gradients and to the considerable variations in elastic modulus (up to ≈70 %) when going from particle-depleted to particle-enriched regions, such materials are highly efficient in reducing the mechanical stress arising from thermal variations, therefore improving the material efficiency towards durability and delamination problems.

The agricultural industry worldwide is facing several challenges including environmental pollution problems (soils and water) caused by the unsuitable control on the use of agrochemicals. Recently, nanotechnology has become an option to improve the existing crop management techniques. Polymer nanoparticles can be used for storage and controlledrelease of agrochemicals, such as pesticides and fertilizers. In this regard, chitosan nanoparticles have been considered for agricultural applications due to the capability of size control at the nanoscale and porosity control capability, in addition to biodegradable and biocompatible characteristics. On this basis, this work focuses on the development of a sizecontrolled synthesis method for chitosan nanoparticles for further use as a platform for the controlled-release system of agrochemicals. The chitosan nanoparticles were synthesized by polymerization using methacrylic acid in water. Several chitosan precursor concentrations (0.2- 0.8 wt.%) were evaluated in order to manipulate the size of produced nanoparticles. The hydrodynamic diameter of those nanoparticles was determined by using a Malvern Zetasizer and the suspension stability trough zeta potential measurements. The morphology and geometrical size were investigated by Transmission Electron Microscopy (TEM). Chitosan nanoparticles size was around 17 nm when a precursor 0.2 wt.% chitosan solution was used. X-ray diffraction and Fourier Transform Infrared Spectroscopy techniques confirmed the chitosan nanoparticles formation and its interaction with functional groups of methacrylic acid.

Here we introduce a facile method to fabricate a flexible piezoelectric sensor using one-dimensional (1-D) piezoelectric poly(vinylidene fluoride) (PVDF) nanofibers directly produced onto flexible printed electrodes by electro-spinning without an additional poling process. The flexible silver electrodes are fabricated on polyethylene terephthalate (PET) using silver nanowires by easy and cost-effective spraying deposition. The electrospun PVDF nanofibers have uniaxially aligned arrays on the electrodes by using a rotating collector. The fabricated PVDF piezoelectric sensors demonstrate the piezoelectric responses with repeated mechanical stimuli with good flexibility and high sensitivity. We expect that the facile fabrication of PVDF piezoelectric sensors on flexible printed electrodes can be usefully exploited to integrate the piezoelectric sensors into flexible and stretchable functional electronic devices.

Active contraction of smooth muscle results in the myogenic response and vasomotion of arteries, which adjusts the blood flow and nutrient supply of the organism. It involves coupled electrobiochemical and chemomechanical processes. This paper presents a new constitutive model to describe the myogenic response of the artery wall under different transmural pressures. The model includes two major components: a cell-level model for the electrobiochemical process, and a tissue-level model for the chemomechanical coupling. The electrochemical model is a lumped Hodgkin-Huxley-type cell membrane model for the nanoscopic ionic currents: calcium, sodium, and potassium. The calculated calcium concentration serves as input for the chemomechanical portion of the model; its molecular binding and the reactions with other enzymes cause the relative sliding of thin and thick filaments of the contractile unit. In the chemomechanical model, a new nonlinear viscoelastic model is introduced to describe the time varying behavior of the smooth muscle. Specifically, this model captures the filament overlap effect, active stress evolution, initial velocity, and elastic recoil in the media layer. Using the proposed constitutive model and a thin-walled equilibrium equation, the myogenic response is calculated for different transmural pressures. The integrated model is able to capture the pressure-diameter relationship incorporating fewer parameters than previous work and with clear physical meanings.

In this paper, we report on a new micropillar sensor array that is stretchable, flexible, and has high sensitivity in the tactile sensing regime (<10 kPa). The sensor array is capable of detecting deformation modes other than pressure such as shear and planar extension. The capacitance-type sensor is fabricated using soft nanolithography whereby the micropillars are individually electroded using a sputtering technique. Buckled gold electrodes are used in this study to enable large sensor stretches up to 55%. Three micropillar aspect ratios were considered in this work (1:1, 1:2, 1:3). Here we present the highest reported sensitivity [0.8 kPa-1] of a capacitance type flexible/stretchable sensor. Our results show that this sensor is also able to detect very low pressures down to 5.4 Pa, which is in the range of ultra-low detection pressures recently reported. Finally, the microstructured sensor array naturally lends itself to the development of pixel-type pressure sensors. We present preliminary results for a 25 pixel array.

Emerging applications for hydrogels such as soft robotics and tissue engineering require hydrogels with enhanced mechanical performance. We report the mechanical characteristics of two types of hydrogels: i) ionic-covalent entanglement (ICE) network hydrogels based on calcium cross-linked gellan gum and genipin cross-linked gelatin and ii) ICE microsphere reinforced gelatin hydrogels. This investigation showed that ICE gels can recover up 80% of their mechanical behavior during 5 repeated compressions. In addition, the optimum mechanical performance of gelatin reinforced gels was achieved with inclusion of 40% of ICE microspheres.