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Mechanical Engineering

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ACS Applied Materials & Interfaces





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Solution phase printing of graphene-based electrodes has recently become an attractive low-cost, scalable manufacturing technique to create in-field electrochemical biosensors. Here we report a graphene-based electrode developed via Inkjet Maskless Lithography (IML) for the direct and rapid monitoring of triple-O linked phosphonate organophosphates (OPs); these constitute the active compounds found in chemical warfare agents and pesticides that exhibit acute toxicity as well as long-term pollution to soils and waterways. The IML printed graphene electrode is nano/microstructured with a 1000 mW benchtop laser engraver and electrochemically deposited platinum nanoparticles (dia. ~25 nm) to improve its electrical conductivity (sheet resistance decreased from ~10 000 Ω/sq. to 100 Ω/sq.), surface area, and electroactive nature for subsequent enzyme functionalization and biosensing. The enzyme phosphotriesterase (PTE), also known as organophosphate hydrolase (OPH), was conjugated to the electrode surface via glutaraldehyde cross-linking. The resulting biosensor was able to rapidly measure (5 sec response time) the insecticide paraoxon (a model organophosphate) with a low detection limit (3 nM), and high sensitivity (370 nA/µM) with negligible interference from similar nerve agents. Moreover, the biosensor exhibited high reusability (average of 0.3% decrease in sensitivity per sensing event), stability (90% anodic current signal retention over 1000 seconds), longevity (70% retained sensitivity after 8 weeks), and the ability to selectively sense OP in actual soil and water samples. Hence, this work presents a scalable printed graphene manufacturing technique that can be used to create OP biosensors that are suitable for in-field applications as well as, more generally, for low-cost biosensor test strips that could be incorporated into wearable or disposable sensing paradigms.


This article is published as Hondred, John A., Joyce Breger, Nathan Alves, Scott A. Trammell, Scott A. Walper, Igor L. Medintz, and Jonathan C. Claussen. "Printed Graphene Electrochemical Biosensors Fabricated by Inkjet Maskless Lithography for Rapid and Sensitive Detection of Organophosphates." ACS Applied Materials & Interfaces 10, no. 13 (2018): 11125-11134. DOI: 10.1021/acsami.7b19763. Posted with permission.


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