Advancing Analytical Sciences Through Innovative Probe Designs

Abstract

Micro- and nano-sized glass pipettes have garnered significant attention from researchers due to their numerous advantages, including ease of fabrication, low cost, tunable geometry, and modifiable surface properties. These favorable characteristics have facilitated a wide range of applications in the fields of analytical chemistry, material science, and cellular biology. This dissertation presents three innovative probe designs that facilitate the analysis of challenging samples. First, we demonstrate the utilization of nanopipettes as probes in scanning ion conductance microscopy (SICM) to collect topographical images of live platelets near their resting state. This approach enables the imaging of live human platelets without subjecting them to excessive mechanical stimulation. Second, we demonstrate the reconstitution of a functional ligand-gated ion channel, the eGFP-Kir6.2 protein, into a polymer scaffolding-stabilized black lipid membrane (BLM) suspending across the opening of a surface modified glass micropipette. Our results reveal that the reconstituted ion channel retains its ability to undergo conformational changes and remains sensitive to its ligand. Furthermore, we establish the groundwork for an innovative expansion of the ion channel probe (ICP) sensing platform using double-barrel theta pipettes. We describe the fabrication process of these pipettes and propose a protocol for constructing a dual ion channel-functionalized double-barrel ICP system capable of concurrently quantifying two analytes. Additionally, we explore the potential of combining scanning ion conductance microscopy with the ICP system for simultaneous topographical and chemical mapping. Third, we present a rapid and cost-effective method to enhance the sensitivity of native mass spectrometry (MS) and charge-detection mass spectrometry (CD-MS) by surface modifying micropipettes for nanoelectrospray ionization (nESI). Additionally, we conduct a thorough investigation into the mechanisms that underlies the observed improvements. Overall, this dissertation encompasses three approaches that utilize the unique capabilities of micro and nano-sized glass pipettes in three diverse analytical techniques. These approaches enhance the analytical capability of these techniques and enable the analysis of challenging samples.