Cascaded microfluidic circuits for pulsatile filtration of extracellular vesicles from whole blood for early cancer diagnosis

Abstract

Tumor-derived extracellular vesicles (EVs) hold the potential to substantially improve noninvasive early diagnosis of cancer. However, analysis of nanosized EVs in blood samples has been hampered by lack of effective, rapid, and standardized methods for isolating and detecting EVs. To address this difficulty, here we use the electric-hydraulic analogy to design cascaded microfluidic circuits for pulsatile filtration of EVs via integration of a cell-removal circuit and an EV-isolation circuit. The microfluidic device is solely driven by a pneumatic clock pulse generator, allowing for preprogrammed, clog-free, gentle, high-yield, and high-purity isolation of EVs directly from blood within 30 minutes. We demonstrate its clinical utility by detecting protein markers of isolated EVs from patient blood using a polyethylene glycol–enhanced thermophoretic aptasensor, with 91% accuracy for diagnosis of early-stage breast cancer. The cascaded microfluidic circuits can have broad applications in the field of EV research.

Hydraulic–electric analogy for design and operation of microfluidic systems

“…With these improvements, the microfluidic circuits can accelerate the development of new diagnostic and therapeutic tools and find numerous applications in point-of-care diagnosis, drug delivery, and other biochemical applications. 77,126,127…”

“…Pressure-driven oscillators have been exploited for a wide assortment of applications including plasma extraction, 75–77 on-chip cell culture, 78 pulsatile mixing, 79,80 and layer-by-layer assembly. 81 For instance, a microfiltration system integrating a pressure-driven oscillator, a filtration pump, and a membrane filter has been developed for autonomous, clogging-free plasma extraction from whole blood (Fig.…”

“…4b). 75–77 The actuation of microfiltration is realized by means of a constant water head pressure which is converted to pulsatile pressure and flow by the oscillator. The filtration pump uses the pulsatile flow to extract plasma through the membrane filter.…”

Filtration-based technologies for isolation, purification and analysis of extracellular vesicles

“…A pulsatile filtration technique was introduced by Li Z. et al in the form of cascaded microfluidic circuits that can be applicable for disease diagnostics and monitoring with low biofluid volume. 91 The chip consists of three PDMS layers, where the middle layer allows flow only in one direction and contains a 50 mm thick elastomeric membrane (Table 1). The top layer contains a microchamber above the membrane, valve and microchannel connected to the filtrate outlet.…”

Microfluidic Device-Based In Vivo Detection of PD-L1-Positive Small Extracellular Vesicles and Its Application for Tumor Monitoring

“…Currently, various methods exist for the in vitro detection of sEVs. For example, dynamic light scattering (DLS), nanoparticle tracking analysis (NTA) and flow cytometry can directly analyze the particle size or concentration of sEVs. , Enzyme-linked immunosorbent assay (ELISA) is used to quantify sEVs relying on specific molecular markers present in sEVs. , Meanwhile, some novel biosensing platforms have been reported for sEVs detection, such as surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS), fluorescence methods, colorimetric methods, electrochemical methods, and microfluidics-based methods. − Specially, microfluidics-based methods have many advantages such as simple operation, low-volume consumption, and high efficiency. , These in vitro methods can efficiently achieve quantitative detection of sEVs in liquid biopsy.…”