Femtomolar Level-Specific Detection of Lead Ions in Aqueous Environments, Using Aptamer-Derivatized Graphene Field-Effect Transistors

Abstract

The detection of lead ion (Pb2+) contamination in aqueous media is relevant for preventing endemic health issues as well as damage to cognitive and physical health. Existing home kit tests are unable to achieve clinically relevant sensitivity and specificity. Here, a label-free graphene field-effect transistor sensor for detecting Pb2+ at the femtomolar (fM) level, discriminating between confounding ions, is reported. The sensing principle is based on electrically monitoring Pb2+-binding-mediated conformational changes of a specific aptamer tethered to graphene, modeled through the Hills–Langmuir mechanism. A record sensitivitythrough a limit of detection of ∼61 fM, for Pb2+ was demonstrated. For model verification, specific discrimination of Pb2+ from other ions at the 1 picomolar (pM) level was shown. The reported work provides motivation for development of portable, label-free, point-of-care devices with both high specificity and sensitivity.

Graphene Multiplexed Sensor for Point-of-Need Viral Wastewater-Based Epidemiology

“…Electronic sensors are potentially the most promising as they can simultaneously offer multiplexed, low-cost, high sensitivity detection with minimal human effort. Here, there is growing interest in graphene field effect transistors (GFET), which have shown the capability to detect everything from lead ions (Velusamy et al 2022; Dong et al 2023) to bacteria and oral disease biomarkers (Ping et al 2016b; Gao et al 2016; Kumar, Gray, et al 2020), though few have shown multiplexing capabilities (Lu et al 2022; Kumar et al 2022; Kumar, Gray, et al 2020). Nonetheless, only two groups, including ours, have demonstrated GFET’s use for detection of analytes in wastewater.…”

Modulation of Electrokinetic Potentials Using Graphene-Based Surfaces and Variable Substrate Charge Density

“…In this work, we hypothesize that extending the notion of surfaces to two-dimensional (2D) materials such as graphene or transition-metal dichalcogenides (TMDs), where the charge state could be tuned while retaining the aspect of hydrophobicity, could help in modulating the V s generation and related power conversion efficiency. We focus on the use of graphene based on extensive and prior reported work related to its electrical characteristics, structural and mechanical attributes, as well as the possibility of its deployment in applications, which could benefit from self-powered devices, e.g., pressure sensors, biosensors, flexible wearable devices, etc. Additionally, previous reports using graphene-based surfaces in micro-/nanofluidics, , with a focus on pressure-driven streaming flow and ionic concentration variations were also considered.…”

Challenges for Field-Effect-Transistor-Based Graphene Biosensors

“…Graphene has the potential for such sensitive detection and has been applied to a wide variety of detection targets over the past 15 years, starting with the earliest research studies [30,31]. Such targets range from ions [32][33][34], gases [35][36][37], organic molecules [38,39], nucleic acids [40,41], and proteins [42] to viruses [43][44][45], bacteria [30,46], and cells [47,48]. The detection mechanisms of graphene biosensors are also diverse, including those based on electrical methods, such as those using field-effect transistors (FETs) [49,50] and electrochemical techniques [51][52][53], and optical methods, such as the use of molecular beacons [54,55], chemiluminescence assays [56,57], surface plasmon resonance spectroscopy [58,59], and Raman scattering spectroscopy [58,60].…”