Ultra-sensitive real-time detection of cancer-derived exosomes directly from cell supernatants by a large Goos–Hänchen signal generation on plasmonic sensing interface

Exosomes have shown great potential in serving as a cancer biomarker over these years since they carry crucial information of their parent cells. Therefore, detection of exosomes is of vital importance to the early-stage diagnostics of multiple major diseases. In this paper, we have proposed a real-time and label-free sensing technique based on 2D Ge2Sb2Te5 (GST) nanomaterial enhanced plasmonic substrate. We have achieved a detection limit down to 104 exosomes/mL based on Goos–Hänchen (GH) shift measurement, which is more than two orders of magnitude superior to conventional SPR sensing techniques. Moreover, the detection of unpurified exosomes directly in cell culture supernatant (CCS) has been successfully demonstrated with a significant experimental GH shift signal of more than 120 μm been detected. Multiple control experiments using exosome-free solutions and control antibody coated substrates have also been performed, which validates the specificity of our device. The proposed plasmonic sensing scheme with enhanced sensing performance has the capability of detecting exosomes at low concentration levels. It also possesses the ability of direct detection of exosomes in CCS, which offers a convenient and efficient platform for exosome detection and analysis. We envision that this technique can serve as a promising tool in early-stage clinical diagnostics and treatment.