One-step detection of oral ulcers and oral cancer derived exosomes on wedge-shaped and high magnetic field gradient mediated chip

Oral ulcers and oral cancer are difficult to be detected not only they are similar symptoms but also lack of diagnosis biomarker. Exosomes are one kind of new liquid biopsy biomarker that can play an important role in disease early-stage diagnosis. Here, oral ulcers and oral cancer, assisted by exosomes, were one-step simultaneous detected on the wedge-shaped and high magnetic field gradient mediated microfluidic chip. For oral ulcers and oral cancer derived exosomes, the detection marker proteins were confirmed by western blot assay, and their antibodies were modified on the surface of magnetic micrometer beads (MBs) and magnetic nanopheres (MNs). Different-sized magnetic material was simultaneously mixed and immunologically captured corresponding exosomes to form an immune complex. With wedge-shaped mediated size separation and high magnetic field gradient controlling capture, the different-size immune complex could be one-step separated and trapped, of which MBs were monolayer arranged in wedge-shaped zone and MNs were trapped in high magnetic field gradient zone. Using high-luminance quantum dots as reporter, the signals of two kinds of exosomes were directly acquired online in the corresponding zones, and could achieve high sensitivity with a detection limit of 8.5 × 104 particles/mL and 4.45 × 105 particles/mL for oral ulcers and oral cancer derived exosomes respectively, and showed excellent anti-interference ability for complex clinical samples. These results indicate that this method may propose new avenues for one-step detection of multiple biomarkers for disease early diagnosis using different-sized magnetic material.