From science fiction to reality: the dawn of the biofabricator

[extract] Science is catching up to science fiction. Last year a paralysed man walked again after cell treatment bridged a gap in his spinal cord. Dozens of people have had bionic eyes implanted, and it may also be possible to augment them to see into the infra-red or ultra-violet. Amputees can control bionic limb implant with thoughts alone

Additive BIO Fabrication: Impact, Opportunities and Challenges

In recent years we have outrun our ability to fabricate structures from the amazing materials that we can now create. While this can be said of many areas of materials research it is particularly so in the area of biomaterials. Here, we are often confronted with delicate compositions with nano- to microscopic features that will not survive the traditional (hammer and chisel) approach to fabrication. There is good reason why nature “grows” complex, highly functional structures. Such structures with functionality determined by the spatial distribution of composition with nanodimensional resolution can not be chiselled from a slab of material. Additive fabrication (AdFab), often referred to as 3D Printing, involves layer-by-layer deposition and fusion of materials to create customised structures. The structure to be produced can be conceptualised, manipulated and defined within a growing array of modelling environments; from conventional parametric Computer-Aided Design (CAD) solutions such as Solidworks™ or ProE™, through to free-form animation toolsets such as Autodesk 3ds Max™, and even free web-based applications like Tinkercad™ (www.tinkercad.com). Once a design is completed, a file that describes the structures’ surface geometry is generated and a set of digitised instructions then drives the printer to create the required structure layer by layer. The fabrication process can involve several deposition modes. In fused deposition modelling / extrusion printing, a molten build material is deposited and solidified on cooling. For higher resolution structures (layer thicknesses as low as 16 µm), a fluid material precursor is ink-jetted onto a substrate and simultaneously transformed into a solid structure via a chemical reaction (UV induced polymerisation). Metal structures can be fabricated through a physical micron-scale welding process known as selective laser melting

Next generation bioelectronics: advances in fabrication coupled with clever chemistries enable the effective integration of biomaterials and organic conductors

Organic bioelectronics is making an enormous impact in the field of tissue engineering, providing not just biocompatible, but biofunctional conducting material platforms. For their true potential to be reached, it is critical to integrate organic conductors with other biopolymers in a targeted manner, allowing the development of devices and scaffold architectures capable of delivering a number of physical, chemical, and electrical stimuli. Herein, we provide an overview of the methods currently being employed to tailor organic conductors for bioapplications, with a focus on the development of fabrication techniques vital to the development of the next generation of intelligent bionic devices

Nanostructured electrically conducting biofibres produced using a reactive wet-spinning process

Electrically conducting, robust fibres comprised of both an alginate (Alg) biopolymer and a polypyrrole (PPy) component have been produced using reactive wet-spinning. Using this approach polypyrrole-biopolymer fibres were also produced with single-walled carbon nanotubes (CNTs), added to provide additional strength and conductivity. The fibres produced containing CNTs show a 78% increase in ultimate stress and 25% increase in elongation to break compared to PPy-alginate fibre. These properties are essential for studies involving the use of electrical stimulation to promote nerve regrowth and/or muscle regeneration. The resultant a novel fibres had been evaluated to develop a viable system in incorporating biological entities in the composite biomaterial. These results indicated fibres are biocompatible to living cells

Wet-spinning of PEDOT:PSS/functionalized-SWNTs composite: A facile route toward production of strong and highly conducting multifunctional fibers

With the aim of fabricating multifunctional fibers with enhanced mechanical properties, electrical conductivity and electrochemical performance, we develop wet-spinning of composite formulation based on functionalized PEG-SWNT and PEDOT:PSS. The method of addition and loading are directly correlated to the quality and the ease of spinnability of the formulation and to the mechanical and electrical properties of the resultant fibers. Both the fiber modulus (Y) and strength (σ) scaled linearly with PEG-SWNT volume fraction (Vf). A remarkable reinforcement rate of dY/dVf = 417 GPa and dσ/dVf = 4 GPa were obtained when PEG-SWNTs at Vf ≤ 0.02. Further increase of PEG-SWNTs loading (i.e. up to Vf 0.12) resulted in further enhancements up to 22.8 GPa and 254 MPa in Modulus and ultimate stress, respectively. We also show the enhancement of electrochemical supercapacitor performance of composite fibers. These outstanding mechanical, electrical and electrochemical performances place these fibers among the best performing multifunctional composite fibers

Effect of monophasic pulsed stimulation on live single cell de-adhesion on conducting polymers with adsorbed fibronectin as revealed by single cell force spectroscopy

The force required to detach a single fibroblast cell in contact with the conducting polymer, polypyrrole doped with dodecylbenzene, was quantified using the Atomic Force Microscope-based technique, Single Cell Force Spectroscopy. The de-adhesion force for a single cell was 0.64 ± 0.03 nN and predominately due to unbinding of α5β1 integrin complexes with surface adsorbed fibronectin, as confirmed by blocking experiments using antibodies. Monophasic pulsed stimulation (50 μs pulse duration) superimposed on either an applied oxidation (+500) or reduction (−500 mV) constant voltage caused a significant decrease in the de-adhesion force by 30%-45% to values ranging from 0.34 to 0.43 nN (±0.02 nN). The electrical stimulation caused a reduction in the molecular-level jump and plateau interactions, while an opposing increase in nonspecific interactions was observed during the cell de-adhesion process. Due to the monophasic pulsed stimulation, there is an apparent change or weakening of the cell membrane properties, which is suggested to play a role in reducing the cell de-adhesion. Based on this study, pulsed stimulation with optimized threshold parameters represents a possible approach to tune cell interactions and adhesion on conducting polymers

Relationship initiation between universities and industry: best practice model

Poster only

Facile electrochemical synthesis of ultrathin iron oxyhydroxide nanosheets for the oxygen evolution reaction

We propose a facile approach to synthesise ultrathin iron oxyhydroxide nanosheets for use in catalysing the electrochemical oxygen evolution reaction. This two dimensional material lowers the overpotential and provides a platform for further performance enhancement via integration of species such as nickel into an ultrathin nanosheet structure

Colour tunable electrochromic devices based on PProDOT-(Hx)2 and PProDOT-(EtHx)2 polymers

The most commonly used method to tune the colour transition states of an ECD is to modify the chemical structure of the electrochromic polymers to achieve the desired transparent to dark state switching colours. However, this approach can present significant synthetic challenges that typically result in a compromise in device performance parameters such as contrast range or stability as well as solvent processability. In this study we have investigated tuning the dark-state colour of an ECD (at +0.8 V) by solution mixing poly(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine) (PProDOT-(Hx)2), which has an excellent contrast performance but with an esthetically undesirable purple colour transition, with poly(3,3-bis(2-ethylhexyl)-3,4-dihydro-2H-thieno [3,4-b][1,4]dioxepine) (PProDOT-(EtHx)2), a material with a poorer contrast range but with more esthetic blue colour transition. The influence of mixtures of two cathodically colouring materials, PProDOT-(Hx)2 and PProDOT-(EtHx)2, on the spectroelectrochemistry and assembled ECDs was explored. Photopic contrast, electrochemical properties and the influence of the type of ionic liquid electrolyte employed in the device assembly were also investigated to determine how the dark-state colour of ECDs can be tuned while maintaining device contrast over 55%

Toward biodegradable Mg-air bioelectric batteries composed of silk fibroin-polypyrrole film

Biodegradable active implantable devices can be used to diagnose and/or treat disease and eventually disappear without surgical removal. If an external energy source is required for effective operation then a biocompatible and biodegradable battery would be ideal. In this study, a partially biodegradable Mg-air bioelectric battery (biobattery) is demonstrated using a silk fibroin-polypyrrole (SF-PPy) film cathode coupled with bioresorbable Mg alloy anode in phosphate buffered saline (PBS) electrolyte. PPy is chemically coated onto one side of the silk substrate. SF-PPy film shows a conductivity of ≈1.1 S cm−1 and a mild catalytic activity toward oxygen reduction. It degrades in a concentrated buffered protease XIV solution, with a weight loss of 82% after 15 d. The assembled Mg-air biobattery exhibits a discharge capacity up to 3.79 mA h cm−2 at a current of 10 μA cm−2 at room temperature, offering a specific energy density of ≈4.70 mW h cm−2. This novel partially biodegradable battery provides another step along the route to biodegradable batteries