Extraction of exosome by gel electrophoresis microfluidic chip and determination of miRNA-21 in exosome of human plasma / 生物工程学报

We developed a high-efficiency microfluidic chip for extracting exosomes from human plasma. We collected peripheral blood from normal human, designed and fabricated a microfluidic chip based on nanoporous membrane and agarose gel electrophoresis to isolate exosomes. The extracted exosomes were characterized by transmission electron microscopy, nanosight and Western blotting, the morphology, concentration and particle size of exosomes were identified and analyzed. Meanwhile, we used ultracentrifugation and microfluidic chip to isolate exosomes separately. The particle size and concentration of the exosomes extracted by two methods were compared and analyzed, and their respective extraction efficiency was discussed. Finally, the expression level of miRNA-21 in exosomes was analyzed by RT-PCR. The microfluidic chip isolated (in 1 hour) high-purity exosomes with size ranging from 30-200 nm directly from human plasma, allowing downstream exosomal miRNA analysis. By comparing with ultracentrifugation, the isolation yield of microfluidic chip was 3.80 times higher than ultracentrifugation when the volume of plasma sample less than 100 μL. The optimized parameters for exosome isolation by gel electrophoresis microfluidic chip were: voltage: 100 V; concentration of agarose gel: 1.0%; flow rate of injection pump: 0.1 mL/h. The gel electrophoresis microfluidic chips could rapidly and efficiently isolate the exosomes, showing great potential in the research of exosomes and cancer biomarkers.

Construction of Tumor Tissue Array on An Open-Access Microfluidic Chip / 分析化学

An open-access microfluidic chip which enabled automatic cell distribution and complex multi-step operations was developed.The microfluidic chip featured a key structure in which a nanoporous membrane was sandwiched by a cell culture chamber array layer and a corresponding media reservoir array layer.The microfluidic approach took advantage of the characteristics of the nanoporous membrane.On one side, this membrane permitted the flow of air but not liquid, thus acting as a flow-stop valve to enable automatic cell distribution.On the other side, it allowed diffusion-based media exchange and thus, mimicked the endothelial layer.In synergy with a liquid transferring platform, the open-access microfluidic system enabled complex multi-step operations involving medium exchange, drug treatment, and cell viability testing.By using this microfluidic protocol, a 10 × 10 tissue arrays was constructed in 90 s, followed by schedule-dependent drug testing.Morphological and immunohistochemical assays results indicated that the resultant tumor tissue was faithful to that in vivo.Drug testing assays showed that the microfluidic tissue array promised multi-step cell assays under biomimetic microenvironment, thus providing an advantageous tool for cell research.