A flexible strain-responsive sensor fabricated from a biocompatible electronic ink via an additive-manufacturing process

Biosensor technologies are of great interest for applications in wearable electronics, soft robotics and implantable biomedical devices. To accelerate the adoption of electronics for chronic recording of physiological parameters in health and disease, there is a demand for biocompatible, conductive & flexible materials that can integrate with various tissues while remaining biologically inert. Conventional techniques used to fabricate biosensors, such as mask lithography and laser cutting, lack the versatility to produce easily customisable, micro-fabricated biosensors in an efficient, cost-effective manner. In this paper, we describe the development and characterisation of an electronic ink made from an environmentally sustainable copolymer - x-pentadecalactone-co-e-decalactone, (PDL) incorporating silver nanowires (AgNW), which are known for their antimicrobial and conductive properties. The composites were shown to possess a low percolation threshold (1% w/w of AgNW to PDL), achieve a low electrical resistance (320 +/- 9 O/sq) and a high electrical capacitance (2.06 +/- 0.06 mF/cm2). PDL nanocomposites were biocompatible, demonstrated in vitro through the promotion of neural adhesion and prevention of astrocyte activation. An optimised ink formulation was subsequently used to fabricate strain-responsive biosensors with high spatial resolution (sub-100 mm) using a direct write additive manufacturing process. Using a customized in vitro set-up, the sensitivity of these biosensors to biologically-relevant strains was assessed under simulated physiological conditions for 21 days. Critically, these 3D printed biosensors have applications in chronic prophylactic monitoring of pressure changes within the body and related pathologies.This publication has emanated from research conducted with the financial support of the Science Foundation Ireland (SFI) Technology Innovation Development Programme, grant no. 15/TIDA/2992 and was co-funded under the European Regional Development Fund under Grant Number 13/RC/2073 and the Hardiman PhD Research Scholarship from the National University of Ireland, Galway. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 713690. The authors acknowledge the facilities and scientific and technical assistance of the Centre for Microscopy & Imaging at the National University of Ireland Galway, a facility that is funded by NUIG and the Irish Government's Programme for Research in Third Level Institutions, Cycles 4 and 5, National Development Plan 20072013.r The Basque Government GV/EJ (Department of Education, Linguistic Politics and Culture) is also acknowledged for financial support to the consolidated research groups project IT927-16 (UPV/EHU, GIC/152)

Special focus on nanoscale regeneration

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Nanoscale neuroelectrode modification via sub-20 nm silicon nanowires through self-assembly of block copolymers

Neuroelectrodes are susceptible to deterioration via scar encapsulation following implantation. Biologically relevant nanosurfaces which mimic the biological length scale may prevent this deterioration via the modulation of protein adsorption and cell adhesion. Furthermore, nanotopography may significantly enhance electrode performance via enhanced charge transfer. Here we describe a self-assembly process for the production of aligned and dense arrays of silicon nanopillars using block copolymers[1]. We discuss the effect of the surface modifications on cell-substrate interaction in vitro and how they may enhance electrode charge transfer and improve neuron/electrode integratio

Flexible, Transparent, and Cytocompatible Nanostructured Indium Tin Oxide Thin Films for Bio-optoelectronic Applications

International audienc

Nanovibrational Stimulation of Mesenchymal Stem Cells Induces Therapeutic Reactive Oxygen Species and Inflammation for Three- Dimensional Bone Tissue Engineering

There is a pressing clinical need to develop cell-based bone therapies due to a lack of viable, autologous bone grafts and a growing demand for bone grafts in musculoskeletal surgery. Such therapies can be tissue engineered and cellular, such as osteoblasts combined with a material scaffold. Because mesenchymal stem cells (MSCs) are both available and fast growing compared to mature osteoblasts, therapies that utilise these progenitor cells are particularly promising. We have developed a nanovibrational bioreactor that can convert MSCs into bone-forming osteoblasts in 2D and 3D but the mechanisms involved in this osteoinduction process remain unclear. Here, to elucidate this mechanism, we use increasing vibrational amplitude, from 30 nm (N30) to 90 nm (N90) amplitudes at 1000 Hz, and assess MSC metabolite, gene and protein changes. These approaches reveal that dose-dependent changes occur in MSCs’ responses to increased vibrational amplitude, particularly in adhesion and mechanosensitive ion channel expression, and that energetic metabolic pathways are activated, leading to low-level reactive oxygen species (ROS) production and to low-level inflammation, as well as to ROS- and inflammation-balancing pathways. These events are analogous to those that occur in the natural bone-healing processes. We have also developed a tissue engineered MSC-laden scaffold designed using cells’ mechanical memory, driven by the stronger N90 stimulation. These new mechanistic insights and cell-scaffold design are underpinned by a process that is free of inductive chemicals

Flexible, Transparent, and Cytocompatible Nanostructured Indium Tin Oxide Thin Films for Bio-optoelectronic Applications

Electrical stimulation has been used successfully for several decades for the treatment of neurodegenerative disorders, including motor disorders, pain, and psychiatric disorders. These technologies typically rely on the modulation of neural activity through the focused delivery of electrical pulses. Recent research, however, has shown that electrically triggered neuromodulation can be further enhanced when coupled with optical stimulation, an approach that can benefit from the development of novel electrode materials that combine transparency with excellent electrochemical and biological performance. In this study, we describe an electrochemically modified, nanostructured indium tin oxide/poly(ethylene terephthalate) (ITO/PET) surface as a flexible, transparent, and cytocompatible electrode material. Electrochemical oxidation and reduction of ITO/PET electrodes in the presence of an ionic liquid based on d-glucopyranoside and bistriflamide units were performed, and the electrochemical behavior, conductivity, capacitance, charge transport processes, surface morphology, optical properties, and cytocompatibility were assessed in vitro. It has been shown that under selected conditions, electrochemically modified ITO/PET films remained transparent and highly conductive and were able to enhance neural cell survival and neurite outgrowth. Consequently, electrochemical modification of ITO/PET electrodes in the presence of an ionic liquid is introduced as an effective approach for tailoring the properties of ITO for advanced bio-optoelectronic applications