Graphene-Based Opto-Electronic Platform for Ultra-Sensitive Biomarker Detection at Zeptomolar Concentrations

Matteo Piscitelli, Cinzia Di Franco*, Giuseppe Valerio Bianco, Giovanni Bruno, Eleonora Macchia, Luisa Torsi, Gaetano Scamarcio*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

A ground-breaking graphene-based biosensor designed for label-free detection of immunoglobulin M (IgM) achieving a remarkable concentration of 100 zeptomolar (10−19 m), is reported. The sensor is a two-terminal device and incorporates a millimeter-wide gold interface, bio-functionalized with ≈1012 anti-IgM antibodies and capacitively coupled to a bare graphene electrode through a water-soaked paper strip. In this configuration, few affinity binding events trigger a collective electrostatic reorganization of the protein layer, leading to an extended surface potential (SP) shift of the biofunctionalized Au surface. The SP shift, mediated by electrolyte capacitive coupling, induces a corresponding shift in the Fermi level of graphene. This shifts the graphene phonon frequencies, which are measured by Raman spectroscopy. Decoupling the sensing interface from the transducing graphene layer provides flexibility in surface chemistry modifications, while preserving the graphene integrity. A key aspect of this biosensor is its ability to precisely determine the graphene charge neutrality point from the voltage dependence of phonon frequency shifts, enabling detections of biomarker at unprecedented low concentrations. The integration of graphene with optical probing demonstrates a proof-of-concept and establishes a ground-breaking approach to in situ biomarker detection, setting the stage for a future generation of portable opto-electronic high-performance diagnostic tools for single-marker detection.
Original languageEnglish
Article number2402026
Number of pages10
JournalSmall Methods
DOIs
Publication statusPublished - 21 Jan 2025
Externally publishedYes
MoE publication typeA1 Journal article-refereed

Keywords

  • Raman spectroscopy
  • Biosensors
  • Graphene
  • Single-molecule

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