# Cross‐Platform Biosensing of Immune Receptors Using Peptide‐Functionalized Graphene

## TL;DR

A new graphene-based biosensor detects immune receptors on living cells with high sensitivity, using two platforms for potential use in diagnostics and immune monitoring.

## Contribution

A peptide-functionalized graphene biosensor is developed for platform-independent detection of immune receptors on living cells.

## Key findings

- The biosensor successfully detects FPR2 on HEK293T cells and primary human neutrophils with high reproducibility.
- Both optical (SPR) and electrical (gFET) platforms demonstrate sensitive and reliable detection of FPR2.
- The technology shows potential for point-of-care diagnostics and immune monitoring.

## Abstract

Changes in the composition of specific cell‐surface molecules on immune cells are important early markers of directed immune responses. Current biosensors largely focus on detecting soluble disease markers. Here, a peptide‐functionalized graphene biosensor is presented capable of platform‐independent, highly sensitive detection of specific immune receptors on living cells. Formyl peptide receptor 2 (FPR2) is targeted, a key modulator of innate immune cells, and validated the technology in two complementary formats: i) graphene‐enhanced surface plasmon resonance (SPR) as a robust optical benchmark, and ii) graphene field‐effect transistors (gFETs) as a compact, cost‐effective electrical alternative. Target specificity is first confirmed using HEK293T cells selectively overexpressing FPR2. Detection of FPR2 on primary human neutrophils is achieved with high reproducibility using fewer than 10 000 cells mL−1, demonstrating both sensitivity and reliability. By demonstrating sensitive and reproducible detection across both optical and electrical platforms, this work bridges materials science and immunology, highlighting the potential of peptide‐functionalized graphene biosensors for point‐of‐care diagnostics, immune monitoring, and early sepsis triage.

A peptide‐functionalized graphene biosensor enables sensitive and selective detection of living immune cells. Targeting Formyl‐Peptide Receptor 2 (FPR2), the assay is demonstrated on model cells and primary human neutrophils. The same assay is applied to two complementary platforms: graphene‐enhanced surface plasmon resonance for optical benchmarking and graphene field‐effect transistors for compact electrical readout, highlighting potential for immune monitoring and point‐of‐care diagnostics.