Emerging on-chip electrokinetic based technologies for purification of circulating cancer biomarkers towards liquid biopsy: A review

Rapid purification and multiparametric characterization of circulating small extracellular vesicles utilizing a label-free lab-on-a-chip device

Nano-scale extracellular vesicles are lipid-bilayer delimited particles that are naturally secreted by all cells and have emerged as valuable biomarkers for a wide range of diseases. Efficient isolation of small extracellular vesicles while maintaining yield and purity is crucial to harvest their potential in diagnostic, prognostic, and therapeutic applications. Most conventional methods of isolation suffer from significant shortcomings, including low purity or yield, long duration, need for large sample volumes, specialized equipment, trained personnel, and high costs. To address some of these challenges, our group has reported a novel insulator-based dielectrophoretic device for rapid isolation of small extracellular vesicles from biofluids and cell culture media based on their size and dielectric properties. In this study, we report a comprehensive characterization of small extracellular vesicles isolated from cancer-patients' biofluids at a twofold enrichment using the device. The three-fold characterization that was performed using conventional flow cytometry, advanced imaging flow cytometry, and microRNA sequencing indicated high yield and purity of the isolated small extracellular vesicles. The device thus offers an efficient platform for rapid isolation while maintaining biomolecular integrity.

Microfluidics: the propellant of CRISPR-based nucleic acid detection

Since the discovery of collateral cleavage activity, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas systems have become the new generation of nucleic acid detection tools. However, their widespread application remains limited. A pre-amplification step is required to improve the sensitivity of CRISPR systems, complicating the operating procedure and limiting quantitative precision. In addition, nonspecific collateral cleavage activity makes it difficult to realize multiplex detection in a one-pot CRISPR reaction with a single Cas protein. Microfluidics, which can transfer nucleic acid analysis process to a chip, has the advantages of miniaturization, integration, and automation. Microfluidics coupled with CRISPR systems improves the detection ability of CRISPR, enabling fast, high-throughput, integrated, multiplex, and digital detection, which results in the further popularization of CRISPR for a range of scenarios.