Versatile ion current rectifying nanopipette sensors for biological (pathogenic DNA) and non-biological (pesticide) molecule detection Pallavi Dutta, Shekemi Denuga, Robert P. Johnson University College Dublin, Ireland Synthetic, conical nanopore systems like nanopipettes exhibit Ion Current Rectification (ICR), a phenomenon which is highly dependent on interfacial charge. Nanopipettes are thus highly appealing for use as sensors. ICR is characterized by an asymmetric diode-like current-voltage response, where the current recorded at one voltage polarity is higher than the current recorded at the same voltage of opposite polarity 1 . The measured current is affected by both the asymmetric geometry and interfacial charges of the nanopore. Subjecting these systems to a solution of electrolyte results in the formation of an electric double layer (EDL) whose thickness is defined by Debye length and is inversely proportional to concentration. Understanding the effect of electrolyte concentration on ICR is vital for the development and optimization of nanopore sensors 2 . Functionalizing nanopipettes with biorecognition agents on the pore surfaces such as antibodies and nucleic acids can be used to detect various analytes with high sensitivity 3 . The work presented herein successfully demonstrates the viability of an ICR based nanopore sensor that can detect both biological ( MRSA DNA ) and non-biological molecules ( Imidacloprid- Pesticide ). A probe DNA-functionalized nanopipette detected the complementary target DNA exposed to it. This provides proof of concept that ICR can be utilised for the development of sensitive and specific biosensors for pathogenic DNA. Building from this knowledge pipettes functionalised with aptamers were used to create sensors for imidacloprid detection. References 1. White, H. S.; Bund, A., Ion Current Rectification at Nanopores in Glass Membranes. Langmuir 2008, 24 (5), 2212-2218. 2. Duleba, D.; Dutta, P.; Denuga, S.; Johnson, R. P., Effect of Electrolyte Concentration and Pore Size on Ion Current Rectification Inversion. ACS Measurement Science Au 2022 . 3. Zhang, S.;, Chen, W.;, Song, L.; Wang, X.; Sun, W.; Song, P.; Ashraf, G.; Liu, B.; Zhao, Y.; Recent advances in ionic current rectification based nanopore sensing: a mini-review, Sensors and Actuators Reports, Volume 3, 2021.
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