ABSTRACT
Multiomics studies at single-cell level require small volume manipulation, high throughput analysis, and multiplexed detection, characteristics that droplet microfluidics can tackle. However, the initial step of molecule bioseparation remains challenging. Here, we describe a unique magnetic device to trap and extract magnetic particles in sub-nanoliter droplets, for compartmentalisation of detection steps. Relying on electrodeposition of NiFe structures and microfluidic manipulation, the extraction of 1 µm diameter magnetic particles was achieved at high throughput (20 droplets per second) with an efficiency close to 100% in 450 pL droplets. The first demonstration of its adaptability to single-cell analysis is demonstrated with the extraction of mRNA. Using a purified nucleic acid solution, this unique magnetic configuration was able to reach a RNA extraction rate of 72%. This is the first demonstration of a physical separation in droplets at high throughput at single-cell scale.
Subject(s)
Single-Cell Analysis , Single-Cell Analysis/methods , Microfluidic Analytical Techniques/instrumentation , Microfluidic Analytical Techniques/methods , High-Throughput Screening Assays/methods , Magnetics/methods , RNA, Messenger/genetics , RNA, Messenger/isolation & purification , Humans , Microfluidics/methods , Microfluidics/instrumentationABSTRACT
The extraction and separation of cellular compounds are crucial steps in numerous biological protocols, particularly in multiomics studies, where several cellular modalities are examined simultaneously. While magnetic particle extraction is commonly used, it may not be applicable for ultralow input samples. Microfluidics has made possible the analysis of rare or low-materiality samples such as circulating tumor cells or single cells through miniaturization of numerous protocols. In this study, a microfluidics workflow for separating different cellular modalities from ultralow input samples is presented. This approach is based on magnetic tweezers technology, allowing the extraction and resuspension of magnetic particles between consecutive nanoliter droplets to perform multistep assays on small volumes. The ability to separate and recover mRNA and gDNA in samples containing less than 10 cells is demonstrated, achieving separation efficiency comparable to the one obtained with conventional pipetting but with a significantly lower amount of starting material, typically 1-2 orders of magnitude less.
