Inertial-Force-Assisted, High-Throughput, Droplet-Free, Single-Cell Sampling Coupled with ICP-MS for Real-Time Cell Analysis

Abstract

Single-cell analysis facilitates perception into the most essential processes in life’s mysteries. While it is highly challenging to quantify them at the single-cell level, where precise single-cell sampling is the prerequisite. Herein, a real-time single-cell quantitative platform was established for high-throughput droplet-free single-cell sampling into time-resolved (TRA) ICP-MS and real-time quantification of intracellular target elements. The concentrated cells (2 × 106 cells mL–1) were spontaneously and orderly aligned in a spiral microchannel with 104 periodic dimensional confined micropillars. The quantification is conducted simultaneously by internal standard inducing from another branch channel in the chip. The flow-rate-independent feature of single-cell focusing into an aligned stream within a wide range of fluidic velocities (100–800 μL min–1) facilitates high-throughput, oil-free, single-cell introduction into TRA-ICP-MS. The system was used for real-time exploration of intracellular antagonism of Cu2+ against Cd2+. an obvious antagonistic effect was observed for the MCF-7 cell by culturing for 3, 6, 9, and 12 h with 100 μg L–1 Cd2+ and 100 μg L–1 Cu2+, and a rivalry rate of 12.8% was achieved at 12 h. At identical experimental conditions, however, limited antagonistic effect was encountered for a bEnd3 cell within the same incubation time period, with a rivalry rate of 4.81%. On the contrary, an antagonistic effect was not observed for the HepG2 cell by culturing for 6 h, while an obvious antagonistic effect was found by further culturing to 12 h, with a rivalry rate of 10.43%. For all three cell lines, significant heterogeneity was observed among individual cells.

Two-Dimensional Cytometry Platform for Single-Particle/Cell Analysis with Laser-Induced Fluorescence and ICP–MS

“…ICP–MS is one of the powerful techniques for elemental analysis, , and it attracts significant attention for enabling spatiotemporal high-throughput single-cell/particle analysis. ,− In this work, the VCCS unit can be directly connected to the nebulizer, and the combination of LIF with ICP–MS can be easily realized. Single-cell analysis requires cell morphological integrity to ensure that each ICP–MS spike corresponds to a single-cell event.…”

“…The iterative algorithm data processing strategy is widely used for MS data processing in single-cell analysis. ,− The iterative calculation for the whole data set through the 3 times standard deviation (3σ) finds the signal threshold, and all bursts with an intensity higher than this threshold are collected and considered as the nanoparticle or cellular events. This approach is convenient for data processing in the situation that one data point represents a single-cell signal (single-cell event).…”

Recent Advances in Microfluidic Technology for Bioanalysis and Diagnostics

“…For example, a spiral microfluidic chip for single-cell sampling assisted by inertial forces was interfaced with inductively coupled plasma MS (Figure B). By introducing an internal standard, real-time quantification of intracellular target elements was achieved . A microfluidic surface extractor coupled to electrospray-ionization quadrupole time-of-flight MS was designed for the direct study of cell membranes (Figure A).…”

Enhanced Separation Efficiency and Purity of Circulating Tumor Cells Based on the Combined Effects of Double Sheath Fluids and Inertial Focusing

“…But the low purity results increased the difficulty of CTC identification and enumeration process. To fully exploit the potential of hydrodynamics separation of inertial microfluidics, it has been proven that designing some special structures in the spiral microchannel, such as micro-obstacles ( Shen et al, 2017 ), micropillars ( Zhang et al, 2020 ), and contraction/expansion microchannel ( Gou et al, 2020 ), can provide stronger Dean effect for efficient and stable particle separation than conventional spiral microchannel. Although each of the above-mentioned sorting methods has its own advantages, when the three important indexes (throughput, purity, and recovery) are increased in parallel, there is a game relationship among them, such as increasing the purity while making a big loss in recovery and increasing the throughput will not meet the high purity.…”