Frontier Technologies in Single-Cell Analysis: Synergistic Fusion of Droplet Printing and High-Performance Detection System

Abstract

Single-cell analysis provides critical insights into cellular heterogeneity, dynamic behaviours and microenvironmental interactions, driving advancements in precision medicine and disease mechanism research. However, traditional technologies face limitations due to low throughput, insufficient sensitivity and bottlenecks in multi-omics integration. Microdroplet printing technology, with its advantages in high-throughput single-cell encapsulation, picolitre-level reaction precision and oil-free phase contamination avoidance, has propelled single-cell analysis into a new era of high-throughput and high-dimensional resolution through deep integration with multimodal detection platforms. This review systematically elaborates on the theoretical framework, diverse technical systems and multi-dimensional application scenarios of microdroplet printing technology. It further dissects the deep coupling mechanisms between this technology and multimodal detection platforms such as including mass spectrometry, Raman spectroscopy, fluorescence and ultraviolet detectors, as well as its unique advantages in single-cell analysis. Such cross-technology integration has significantly accelerated innovation in fields such as single-cell drug screening and multi-omics analysis, marking a significant leap in the evolution of single-cell analytical methodologies.

Keywords: droplet; high‐performance detection; printing; single cell.

FIGURE 1

Piezoelectric, thermographic and pressure‐based printing methods. (A) Droplet formation diagram principle in piezoelectric and thermal inkjet systems. (B) Schematic diagram of an inkjet printing single‐cell MS device [18]. (C) Fluorescence map of the dynamic response of carboxyesterase of MCF‐7 cells to 10 mM calcein‐AM in a single cell [19]. (D) Process diagram of printing double emulsion on demand in air [22]. (E) Schematic diagram of a microfluidic device [22]. (F) Printed image of the agent droplet array [22].

FIGURE 2

Electric and Acoustic Wave‐Driven Printing Techniques. (A) Experimental setup for electrodynamic printing [24]. (B) Electrodynamic printer diagram. (C) Cell viability test after cell capture [26]. (D) Schematic mechanism of deterministic single‐cell printing by PULSE [29]. (E) Sonic droplet printing Schematic diagram of the device. (F) Double‐exposure image of droplet printing [30].

FIGURE 3

Mass Spectrometry‐Based Single‐Cell Monitoring. (A) Single‐cell assay diagram based on inkjet printing combined with a nano‐ESI device [34]. (B) PCA of different cell types based on PESI analysis [33]. (C) Typing of cells before and after administration [34]. (D) Schematic diagram of inkjet injection and MALDI‐QTOF‐MS [35]. (E) Schematic diagram of SCIDA using LA‐ICP‐MS [37]. (F) P, Ag and Ag transient signals in cells [37].

FIGURE 4

SERS‐Based Single‐Cell Monitoring. (A) Schematic diagram of the acoustic printing platform and confocal Raman [40]. (B) Droplet pseudocolour scanning electron microscope (SEM) image [40]. (C) 2‐component t‐SNE projection of 600 Raman spectra obtained from 100 droplet measurements [40]. (D) Normalized confusion matrix generated from 600 spectra collected from single‐cell line droplets of Staphylococcus epidermidis, Escherichia coli and mouse erythrocytes mixed with GNR and three cell mixtures using a random forest classifier [40].

FIGURE 5

Ultraviolet and Fluorescence‐Based Single‐Cell Monitoring. (A) Diagram of a cell analysis system with capillary electrophoresis [41]. (B) Schematic diagram of cell separation in capillary electrophoresis [41]. (C) Capillary electrophoresis pattern diagram of HepG2 cells with droplets of various numbers 25–400 [41]. (D) Schematic diagram of a microfluidic droplet dispenser system [43]. (E) Scatter plot showing signals from 1 mM sodium fluorescein droplets generated at different voltages in a dispenser [43].