Tuning Electrostatic Gating of Semiconducting Carbon Nanotubes by Controlling Protein Orientation in Biosensing Devices

Abstract

The ability to detect proteins through gating conductance by their unique surface electrostatic signature holds great potential for improving biosensing sensitivity and precision. Two challenges are: (1) defining the electrostatic surface of the incoming ligand protein presented to the conductive surface; (2) bridging the Debye gap to generate a measurable response. Herein, we report the construction of nanoscale protein‐based sensing devices designed to present proteins in defined orientations; this allowed us to control the local electrostatic surface presented within the Debye length, and thus modulate the conductance gating effect upon binding incoming protein targets. Using a β‐lactamase binding protein (BLIP2) as the capture protein attached to carbon nanotube field effect transistors in different defined orientations. Device conductance had influence on binding TEM‐1, an important β‐lactamase involved in antimicrobial resistance (AMR). Conductance increased or decreased depending on TEM‐1 presenting either negative or positive local charge patches, demonstrating that local electrostatic properties, as opposed to protein net charge, act as the key driving force for electrostatic gating. This, in turn can, improve our ability to tune the gating of electrical biosensors toward optimized detection, including for AMR as outlined herein.

Parallel Field-Effect Nanosensors Detect Trace Biomarkers Rapidly at Physiological High-Ionic-Strength Conditions

“…Previously, it was demonstrated with streptavidin probes and single-molecule DNA sensors that the λ D of the solution must be less than the height of the target–probe complex for a signal to be generated. Previous approaches to solve this include passivating the sensor surface with neutral polymers using aptamer probes, , or controlling the orientation of binding molecules but it is important to note that we do not use these strategies in this work. Instead, we hypothesize that the aligned suspended device’s ability to sense in high-ionic-strength conditions results from the high density of probe molecules on the covalently functionalized double-wall CNT surface.…”

The molecular origin of the electrostatic gating of single-molecule field-effect biosensors investigated by molecular dynamics simulations

“…Taken together, these experimental results strongly suggest that the conductance kinetics of the carbon nanotube bioFET depends directly on the electrostatic potential generated by the biomolecule as it performs its function or as it folds. Following studies based on similar constructs also support this view: on the interaction between the immunoglobulin E antibody and an aptamer-modified carbon nanotube, 26 on DNA hybridization 20,21 and folding 16 as well as on the function of the several enzymes such as the Klenow fragment of DNA polymerase I, 23,27 the β-lactamase, 28 the Histone deacetylase 8, 29 the protein kinase A, 24 and the lysozyme. 25,30,31 Similar observations were also made using a silicon nanowire-based field-effect transistor (SiNW-FET).…”

Bioengineering a glucose oxidase nanosensor for near-infrared continuous glucose monitoring

“…5 Compared to conjugative methods that rely on naturally available residues that are oen abundant on protein surfaces, 6 such controlled orientation oen requires the introduction of rare or mutated sites that are uniquely susceptible to the reaction of interest. 13,14 Addressing these challenges through improved and novel bioconjugation strategies is the focus of recent studies. 7,13,15,16 In this work, we immobilize GOx using a hydrophobic crosslinker that is covalently conjugated to engineered cysteine residues.…”

“…13,14 Addressing these challenges through improved and novel bioconjugation strategies is the focus of recent studies. 7,13,15,16 In this work, we immobilize GOx using a hydrophobic crosslinker that is covalently conjugated to engineered cysteine residues. While wild type GOx has three native cysteines, these residues are not accessible for conjugation; two cysteines form a disulde bond (Cys164-Cys206), and the third (Cys521) is buried within the protein.…”

“…13,14 Addressing these challenges through improved and novel bioconjugation strategies is the focus of recent studies. 7,13,15,16…”