NCAFM2023 Programme Booklet

HIGH RESOLUTION 3D MAPPING OF pH, ROS AND METAL IONS USING SICM

A. Erofeev 1 , P.Gorelkin 1 , C. Edwards 2 , Y. Korchev 1,2,3

1 National university of Science and Technology “MISiS’, Moscow, Russia 2 Imperial College London, London, United Kingdom 3 Life Science Institute (WPI-NanoLSI), Kanazawa University, Kanazawa, Japan Email: erofeev.as@misis.ru

The purpose of an abstract submitted to NCAFM2023 is to tell the Technical Chair what new results you will present. Nanopipettes have been used in different applications with integration into Scanning Ion Conductance Microscopy (SICM). Earlier, we reported on the development of a label-free pH-sensitive nanoprobe consisting of a self-assembled zwitterion-like nanomembrane at the tip of a nanopipette [1]. This platform allows for SICM feedback-controlled precise positioning of the nanoprobe to the cell surface to monitor the local pHe with high spatiotemporal resolution and high sensitivity. The probe was developed by cross-linking glucose oxidase and poly-l-lysine at the tip of a glass nanopipette, resulting in drying-mediated self-assembly of a pH-selective nanomembrane with a sensitivity higher than 0.01 units, capable of fast response times (down to ~2 ms), and a high spatial resolution (~50 nm). Additionally, nanopipette probes still hold great promises as intracellular biosensors. We described the fabrication, characterization, and tailoring of carbon nanoelectrodes based on nanopipette for intracellular electrochemical recordings. The functionalization of the nanoelectrode with platinum allowed to study the redox biochemistry and biology of cells, tissues and organisms. We applied the nanoelectrode to perform intracellular reactive oxygen species (ROS) measurement in cultured cancer cells and three-dimensional (3D) spheroids [2-3]. We have shown that our new method can measure the ROS response to chemotherapy in tumor-bearing mice in real-time. ROS levels were measured in vivo inside the tumor at different depths in response to doxorubicin [4]. A series of ligands of Cu(+2) and Cu(+1) copper complexes with different geometries, oxidation states of the metal, and redox activities were synthesized [6]. ROS formation in MCF-7 cells and three-dimensional (3D) spheroids was proven using the Pt-nanoelectrode. Drug accumulation and ROS formation at 40-60 μm spheroid depths were found to be the key factors for the drug efficacy in the 3D tumor model, governed by the Cu+2/Cu+1 redox potential. Recently, we have expanded the application of a Pt-nanoelectrode, providing direct intracellular and intratumoral quantitative electrochemical detection of Pt(II) species [6]. References [1] Y. Zhang et al., Nat. Commun, 2019, 10 , p. 1–9. [2] A. Erofeev et al., Sci. Rep., 2018, 8 , p. 1–11 [3] A. Krasnovskaya et al., J Med Chem . 2020, 63 , p. 13031-13063 [4] A. Vanev et al., Anal. Chem., 2020, 92 p. 8010–8014 [5] A. Krasnovskaya et al., J Med Chem . 63 (2020) p. 13031-13063 [6] A. Vanev et al., Anal. Chem., 2022, 94 , p. 4901-4905

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