A Novel Cryogenic Approach to 3D Printing Cytocompatible, Conductive, Hydrogel-Based Inks.

In the field of tissue engineering and regenerative medicine, developing cytocompatible 3D conductive scaffolds that mimic the native extracellular matrix is crucial for the engineering of excitable cells and tissues. In this study, a custom cryogenic extrusion 3D printer was developed, which afforded control over both the ink and printing surface temperatures. Using this approach, aqueous inks were printed into well-defined layers with high precision.

3D printed linear soft multi-mode actuators expanding robotic applications.

Soft pneumatic actuators can produce a range of motions and deliver a high force-to-mass ratio whilst offering intrinsic compliance. Presently, the majority of soft pneumatic actuators are used to create bending motions, with very few able to produce significant linear movements. Fewer can actively produce strains in multiple directions.

Study of Proton Transport in Diethylmethylammonium Poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide]-Based Composite Membranes with Triflic Acid and Diethylmethylamine-Rich Compositions.

The study highlights the effect of acid- and base-rich conditions on the proton dynamics of diethylmethylammonium poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide, [DEMA][PSTFSI], a polymerized protic ionic liquid designed as a polymer electrolyte for nonhumidified polymer electrolyte membrane fuel cells. Different proportions of triflic acid (HTf) and diethylmethylamine (DEMA) were added to the pristine polymer. The thermal analysis of the mixtures revealed that the addition of the base increases the glassy/amorphous nature of the polymer; however, HTf plasticizes the polymer and lowers the value, so that it falls outside of the differential scanning calorimetry-studied temperature range.

Low-Hysteresis and Ultrasensitive Microcellular Structures for Wearable Electronic Applications.

Wearable technologies offer the opportunity to record human physiological signals in real time, in a noninvasive way, and the data can be used to aid in the early detection of abnormal health conditions. Here, we demonstrate how the interconnected porosity can be used to increase the sensitivity and linearity of capacitive pressure sensors. The finite element analysis supports the experimental observation that the movement of air during the dynamic mechanical loading is responsible for the high sensitivity observed (0.

Environmentally Friendly and Biodegradable Ultrasensitive Piezoresistive Sensors for Wearable Electronics Applications.

Highly sensitive, flexible sensors that can be manufactured with minimum environmental footprint and be seamlessly integrated into wearable devices are required for real-time tracking of complex human movement, gestures, and health conditions. This study reports on how biodegradation can be used to enhance the sensitivity and electromechanical performance of piezoresistive sensors. Poly(glycerol sebacate) (PGS) elastomeric porous sensor was synthesized and blended with multiwall carbon nanotubes (MWCNTs) and sodium chloride (NaCl).

Computational Investigation of Mixed Anion Effect on Lithium Coordination and Transport in Salt Concentrated Ionic Liquid Electrolytes.

The use of high concentrations of alkali metal ion salts in ionic liquids (ILs) has been demonstrated to significantly improve electrolyte performance, increase alkali metal ion transference numbers, and promote the formation of favorable SEI structures enabling long-term stable cycling. One challenge in using this material is the overall low ionic conductivity, which is a common effect of increased salt concentration. This simulation work first investigated the strategy of using mixed anions to tune the ionic conductivity in a concentrated IL (or "ionic liquid-in-salt") system having 50 mol % lithium salt.

Bioinspired Three-Dimensional-Printed Helical Soft Pneumatic Actuators and Their Characterization.

Soft pneumatic actuators (SPAs) are widely studied and applied in the field of soft robotics. To expand their applications, the SPAs should be purpose-built to generate application-specific complex motions with multiple degrees of freedom. This article describes a new SPA consisting of a series of internal chambers with the same helix angle arranged in a row, which could generate bending and twisting motions simultaneously.

Synthesis of methotrexate-loaded tantalum pentoxide-poly(acrylic acid) nanoparticles for controlled drug release applications.

Over the past decade, there has been increasing interest in the use of multifunctional nanoparticles (NPs) for cancer treatment. Of importance are systems that can deliver drugs at a sustained rate to target cancer cells, which can result in higher efficiency and reduced systemic toxicity. In this study, we present the route for the synthesis of tantalum pentoxide (TaO) NPs with a particle size of 27 nm that were individually coated with poly(acrylic acid) (PAA) with a different layer thickness of 2-8 nm by in-situ polymerization of the acrylic acid monomer.

Development of ciprofloxacin-loaded poly(vinyl alcohol) dry powder formulations for lung delivery.

Polymeric microparticles are micro carriers for the sustained drug delivery of drugs in the lungs, used as alternatives to the use of established excipients. This study aims to develop and characterize inhalable ciprofloxacin (CPx)-loaded poly(vinyl alcohol) (PVA) microparticles by a single-step spray-drying procedure. The optimization of the processing parameters was achieved by an orthogonal design of the most relevant processing parameters (polymer concentration, feed rate and inlet temperature).

Effect of multi-walled carbon nanotubes on the cross-linking density of the poly(glycerol sebacate) elastomeric nanocomposites.

Processing conditions deeply affect the mechanical, chemical and biological properties of elastomeric based nanocomposites. In this work, multi-walled carbon nanotubes (MWCNTs) were dispersed in poly(glycerol sebacate) (PGS) prepolymer, followed by curing under vacuum at 120 °C. It was observed an increase of the water contact angle with the amount of MWCNTs added, as well as the tensile strength and Young modulus, without compromising the elastomeric behaviour of the pristine PGS matrix.

Modeling and Experimental Evaluation of Bending Behavior of Soft Pneumatic Actuators Made of Discrete Actuation Chambers.

In this article, we have established an analytical model to estimate the quasi-static bending displacement (i.e., angle) of the pneumatic actuators made of two different elastomeric silicones (Elastosil M4601 with a bulk modulus of elasticity of 262 kPa and Translucent Soft silicone with a bulk modulus of elasticity of 48 kPa-both experimentally determined) and of discrete chambers, partially separated from each other with a gap in between the chambers to increase the magnitude of their bending angle.

Antibacterial and Antifungal Activity of Poly(Lactic Acid)-Bovine Lactoferrin Nanofiber Membranes.

Antimicrobial materials have become relevant for local therapies preventing microbial resistance induced by systemic antibiotic treatments. This work reports the development of electrospun poly(lactic acid) (PLLA) nanofiber membranes loaded with bovine lactoferrin (bLF) up to 20 wt%. The membranes present smooth and nondefective fibers with mean diameters between 717 ± 197 and 495 ± 127 nm, and an overall porosity of ≈80%.

An All-Integrated Anode via Interlinked Chemical Bonding between Double-Shelled-Yolk-Structured Silicon and Binder for Lithium-Ion Batteries.

The concept of an all-integrated design with multifunctionalization is widely employed in optoelectronic devices, sensors, resonator systems, and microfluidic devices, resulting in benefits for many ongoing research projects. Here, maintaining structural/electrode stability against large volume change by means of an all-integrated design is realized for silicon anodes. An all-integrated silicon anode is achieved via multicomponent interlinking among carbon@void@silica@silicon (CVSS) nanospheres and cross-linked carboxymethyl cellulose and citric acid polymer binder (c-CMC-CA).

Tailoring the wettability and mechanical properties of electrospun poly(l-lactic acid)-poly(glycerol sebacate) core-shell membranes for biomedical applications.

Tissue and biomedical engineering fields are in constant mutation and in searching for innovative processing techniques capable to tailor the material properties. In this work, poly(l-lactic acid) (PLLA) and elastomeric poly(glycerol sebacate) (PGS) were dissolved in the same solvents and electrospun together, in a single needle system. A core-shell structure where the hydrophilic PGS was placed onto the surface of the hydrophobic PLLA fibre was obtained for elastomeric concentrations up to 25wt%.

Multifunctional PLLA-ceramic fiber membranes for bone regeneration applications.

A novel method to process electrospun poly(l-lactic acid) (PLLA) membranes incorporating glass reinforced hydroxyapatite granules (gHA) interspacially between the polymeric fibers is reported, thus increasing the surface area for cellular interactions. gHA granules (≤150μm) electrospun together with the polymer solution, lead to an average fiber diameter of 550±150nm for pristine PLLA and 440±170nm for the composite samples. An increase of the overall porosity was observed, from 79±3% for the PLLA up to 88±5% for the hybrid samples, keeping material's wettability and mechanical properties.

Towards soft robotic devices for site-specific drug delivery.

Considerable research efforts have recently been dedicated to the establishment of various drug delivery systems (DDS) that are mechanical/physical, chemical and biological/molecular DDS. In this paper, we report on the recent advances in site-specific drug delivery (site-specific, controlled, targeted or smart drug delivery are terms used interchangeably in the literature, to mean to transport a drug or a therapeutic agent to a desired location within the body and release it as desired with negligibly small toxicity and side effect compared to classical drug administration means such as peroral, parenteral, transmucosal, topical and inhalation) based on mechanical/physical systems consisting of implantable and robotic drug delivery systems. While we specifically focus on the robotic or autonomous DDS, which can be reprogrammable and provide multiple doses of a drug at a required time and rate, we briefly cover the implanted DDS, which are well-developed relative to the robotic DDS, to highlight the design and performance requirements, and investigate issues associated with the robotic DDS.

Advances in hydrogels applied to degenerative diseases.

Hydrogels are currently applied in the treatment of numerous degenerative diseases because of their three dimensional (3D) nature, high water content and wide range of polymers that can be used for their fabrication. Hydrogels have been investigated and commercialized, for example, as soft contact lens-based ophthalmic drug delivery systems. These novel devices improved the bioavailability of ophthalmic drugs and their residence time.

Mechanical reinforcement of continuous flow spun polyelectrolyte complex fibers.

A simple continuous flow wet-spinning method to achieve mechanical reinforcement of the two oppositely charged biopolymers chitosan and gellan gum is described. The mechanical properties of these biopolymers are influenced by the order of addition. Using a facile method for mechanical reinforcement of gellan gum/chitosan fibers resulted in increases in Young's modulus, tensile strength, and toughness.