A simple and direct SPR platform combining three-in-one multifunctional peptides for ultra-sensitive detection of PD-L1 exosomes.

• Here we describe a strategy to detect PD-L1 exosomes through graphene modified gold chip using a multifunctional peptide as a recognition supermolecules. • Graphene assembly domains in the M-Pep enhanced the inclusion affinities between the graphene and supermolecules. • Antifouling chain makes the sensors surface prevent unnecessary non-specific adsorption, thus increasing the detection accuracy. • The detection limit of 20 particles·mL−1 was reached without signal amplification. Exosomes are lipid-bilayer-enclosed extracellular vehicles (EVs) derived from all cells and circulating in the blood. Identification of cancer specific exosomes in body fluids has shown great potential for cancer diagnostics. The low concentration in blood and likely to deplete their native character on the solid surface makes it difficult to measure it in real time sensitively. Here we describe a strategy to detect PD-L1 exosomes through graphene modified gold chip using a multifunctional peptide (M-Pep, SS-IMVTESSDYSSY-KK-FHYQRDTPKSYN) as a recognition supermolecule. Graphene assembly, antifouling and PD-L1 specific binding domains in the M-Pep enhanced the inclusion affinities between the graphene and supermolecules and ensure keeping its recognition properties efficiently. The fabricated direct-real-time SPR sensor based on M-Pep shows a good sensitivity for the detection of PD-L1 exosomes. Own to its simple, convenient and effective, this M-Pep based SPR sensor provides a useful platform to facilitate clinical investigations of exosomes for noninvasive disease diagnoses. This approach may serve as a potential non-invasive diagnostic and screening tool to detect cancer biomarker and facilitate possible curative therapy. [ABSTRACT FROM AUTHOR]