In Situ Single-Cell Stimulation and Real-Time Electrochemical Detection of Lactate Response Using a Microfluidic Probe

Recent advancements in single-cell metabolic analysis for pharmacological research

Cellular heterogeneity is crucial for understanding tissue biology and disease pathophysiology. Pharmacological research is being advanced by single-cell metabolic analysis, which offers a technique to identify variations in RNA, proteins, metabolites, and drug molecules in cells. In this review, the recent advancement of single-cell metabolic analysis techniques and their applications in drug metabolism and drug response are summarized. High-precision and controlled single-cell isolation and manipulation are provided by microfluidics-based methods, such as droplet microfluidics, microchamber, open microfluidic probe, and digital microfluidics. They are used in tandem with variety of detection techniques, including optical imaging, Raman spectroscopy, electrochemical detection, RNA sequencing, and mass spectrometry, to evaluate single-cell metabolic changes in response to drug administration. The advantages and disadvantages of different techniques are discussed along with the challenges and future directions for single-cell analysis. These techniques are employed in pharmaceutical analysis for studying drug response and resistance pathway, therapeutic targets discovery, and in vitro disease model evaluation.

A Self-Made Optical Tweezers Integrated Upconversion Luminescence Confocal Scanning Instrument Enables Stable and Noninvasive Long-Term In Situ Imaging a Single Suspension Cell Under Exceptionally Efficient Luminescent Resonance Energy Transfer Sensing

It is necessary to explore labeling probes with worthy optical properties and a noninvasive fluorescence imaging manner for stable long-term in situ measuring a single suspension cell. In response to these goals, we herein make a breakthrough on two fronts. On one hand, a co-sensitizer-induced efficient 808 nm near-infrared light-excited luminescence-confined upconversion nanoparticle with a low thermal effect is fabricated by employing a layer-by-layer seed growing approach to develop a sandwich structure, under which the luminescence domain is vastly restricted into an extremely thin inner shell (∼ 2.77 nm) to finally bring about a high-efficiency luminescent resonance energy transfer (LRET) sensing behavior. On the other hand, a self-made optical tweezers integrated upconversion luminescence confocal scanning instrument is applied to enhance the imaging accuracy, after which the liquid viscous force is sufficiently overcome by the resulting single beam gradient force and the analyzed suspension cell is always immobilized to the focal plane to ensure a constant luminescence excitation condition. By making use of a metal ion-dependent DNAzyme and a hairpin DNA strand to design a corresponding LRET sensing system, our nanoprobe shows satisfactory assay performance for two model biomolecules (Ca²⁺ and TK1 messenger RNA). Following the optical trapping-assisted imaging, this exceptional measurement method is capable of effectively monitoring the intracellular target changes in different physiological states, endowing a powerful toolbox for single cell analysis.