Simple Fabrication of Flexible Biosensor Arrays Using Direct Writing for Multianalyte Measurement from Human Astrocytes

Abstract

Simultaneous measurements of glucose, lactate, and neurotransmitters (e.g., glutamate) in cell culture over hours and days can provide a more dynamic and longitudinal perspective on ways neural cells respond to various drugs and environmental cues. Compared with conventional microfabrication techniques, direct writing of conductive ink is cheaper, faster, and customizable, which allows rapid iteration for different applications. Using a simple direct writing technique, we printed biosensor arrays onto cell culture dishes, flexible laminate, and glass to enable multianalyte monitoring. The ink was a composite of PEDOT:PSS conductive polymer, silicone, activated carbon, and Pt microparticles. We applied 0.5% Nafion to the biosensors for selectivity and functionalized them with oxidase enzymes. We characterized biosensors in phosphate-buffered saline and in cell culture medium supplemented with fetal bovine serum. The biosensor arrays measured glucose, lactate, and glutamate simultaneously and continued to function after incubation in cell culture at 37 °C for up to 2 days. We cultured primary human astrocytes on top of the biosensor arrays and placed arrays into astrocyte cultures. The biosensors simultaneously measured glucose, glutamate, and lactate from astrocyte cultures. Direct writing can be integrated with microfluidic organ-on-a-chip platforms or as part of a smart culture dish system. Because we print extrudable and flexible components, sensing elements can be printed on any 3D or flexible substrate.

Additive Manufacturable Materials for Electrochemical Biosensor Electrodes

“…Compared to traditional fabrication techniques, DIW, also referred to as robocasting, is faster, cheaper and more customizable. [ 261 ] DIW, in contrast to FDM, is capable of printing inherently conductive polymers without needing a secondary polymer. In addition, it has a higher resolution than FDM, and can print electrodes with traces with a width of ≈30 µm, making DIW suitable for printing fine features.…”

“…Reproduced with permission. [ 261 ] Copyright 2019, Sage Publishing C) highlights the need to determine the optimal rheological window to achieve electrodes with suitable traces. Reproduced with permission.…”

“…More research is needed to see if greater increases in sensitivity can be achieved, which could consequently lead to a new strategy of increasing sensitivity without, for example, needing to increase filler content. [ 261 ] Regarding, postprocessing of DIW‐printed electrodes generally entails solvent evaporation, but for improved electrochemical performance, electrochemical activation can also be used. [ 265 ]…”

Printable Nonenzymatic Glucose Biosensors Using Carbon Nanotube-PtNP Nanocomposites Modified with AuRu for Improved Selectivity

“…Moreover, the supporting materials also play a major role in the performance of electrocatalysts due to their interactions, which facilitates the catalytic activities between metallic catalysts and support materials . To achieve a fine dispersion and high utilization, nanocatalysts are usually supported on high-surface-area materials such as carbon nanotubes (CNT), carbon nanofibers, graphene, or activated carbon. − This is due to the distinctive characteristics of such new carbon nanomaterials, such as more crystalline structures, high electrical conductivities, excellent corrosion resistances, and high purities. − Hence, in this study, we employed our previously developed high-surface-area Pt-nanoparticles (PtNPs) CNT-based nanocomposite electrodes, as an effective supporting material for one-step electrodeposition of AuNPs and RuNPs for direct oxidation of glucose …”

Flexible Analytical Devices for Point-of-Care Testing

“…While this article highlights the importance of measuring multiple biomarkers for benchmarking a primary disease marker, sensing multiple biomarkers/analytes also has an apparent advantage of providing a set of data on multiple targets that can collectively determine the state of a disease, health condition, cell culture quality, or phenotype of a biological or chemical system more accurately. Toward this end, the research article by Nolan et al 3 reports a novel direct writing method to fabricate biosensor arrays on a variety of substrates, including flexible laminate, for multianalyte measurements. Compared with conventional microfabrication techniques for creating flexible biosensors, the direct writing method presented in this article is cheaper, faster, and customizable.…”