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 elec... More
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 to 100 Ω/sq)， surface area， and electroactive nature for subsequent enzyme functionalization and biosensing. The enzyme phosphotriesterase (PTE) was conjugated to the electrode surface via glutaraldehyde cross-linking. The resulting biosensor was able to rapidly measure (5 s response time) the insecticide paraoxon (a model OP) 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 s)， 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.
