# Single-Cell Endoscopy for Multifunctional Live-Cell Molecular Analysis

## TL;DR

Single-cell endoscopy is a promising technique for detailed molecular analysis of individual live cells, offering insights into cellular processes and aiding drug discovery.

## Contribution

This review provides a comprehensive overview of recent advancements in single-cell endoscopy techniques over the past decade.

## Key findings

- Single-cell endoscopy enables flexible manipulation and ultrasensitive sensing within individual live cells.
- The technique allows precise intracellular delivery and analysis of nucleic acids, proteins, and ions.
- Challenges remain in the development and application of single-cell endoscopy, requiring further research.

## Abstract

Molecular analyses of individual cells with high resolution, specificity, and sensitivity can not only reveal cellular heterogeneity but also provide a better understanding of diseases and accelerate drug discoveries. Single-cell endoscopy is an advanced live-cell technique that relies on a smart endoscope that allows minimally invasive probing of the interiors of individual cells. Compared with other single-cell analysis techniques, single-cell endoscopy has shown great promise in applications such as flexible single-cell manipulation, ultrasensitive sensing, and precise intracellular delivery. In this review, we aim to map out the landscape of recent advances in single-cell endoscopy techniques by focusing on both fundamental considerations and significant progress over the past decade. Specifically, we summarize the predominant live-cell endoscopes, including their fabrication and characterization. Furthermore, a series of valuable intracellular molecular sensing events, such as nucleic acids, proteins, ions, etc., are introduced with a main emphasis on how single-cell endoscopy can solve these issues and what merits single-cell endoscopy can provide. Finally, we briefly outline the remaining challenges and directions for the future development of single-cell endoscopy techniques.