The latest article from Southern University of Science and Technology: Intracellular electrochemical sensing of robots adherent to cells

A research team at SUSTech has developed an automated intracellular sensing system that provides an efficient way to better study disease progression or early disease diagnosis to reveal the intrinsic characteristics and heterogeneity
of cells.
The new research paper was published Sept.
2 in
the journal Biochemical Man and Biomimetic Systems.

The measurement of intracellular biochemical processes is of great significance
for the quantitative understanding of the function of biological systems.
Nanoparticle-based intracellular sensing is an in situ, label-free, and non-destructive measurement method
.
However, the size of the cells and the tip of the nanospheres make it difficult for manual manipulation to perform intracellular measurements efficiently, which poses an obstacle
to obtaining statistically significant data.
Therefore, the researchers designed an efficient and consistent intracellular sensing system
by integrating automation technology.

First, a nanosphere sensor with a tip diameter of about 100 nm was designed, in which the platinum ring at the tip of the nanosphere was used as a working electrode for electrochemical induction of reactive oxygen species (ROS).

At the same time, the sensor is mounted on a high-precision micromanipulator with a motion resolution of 5 nm, and visual feedback
is performed using an inverted fluorescence microscope.

In addition, the team also proposed a label-free cell detection algorithm that can avoid the effect of fluorescent staining on cells, accurately locate penetration sites, and achieve efficient intracellular measurements
.
The algorithm automatically moves cells to the out-of-focus plane to maximize the gray difference between adherent cells and the background, thereby simplifying cell detection and improving cell recognition rate
.

In order to avoid tip damage caused by the collision of the tip of the nanosphere with the cell disc during autofocusing, the researchers designed a non-overshoot tip localization method
.
This method uses the normalized correlation coefficient of different z-axis positions as the focusing metric to realize the automatic focusing of the nanosphere tip and avoid superfocusing and tip damage
.

In addition, since the thickness of adherent cells varies greatly, the relative height
of the nanosphere tip to the cell surface can be accurately determined using a close detection based on ion current feedback.
As the tip of the nanosphere approaches the cell, the tip is gradually clogged by the cell, and the ion current through the tip opening
decreases.
Thus, the relative height
between the tip and the cell can be accurately measured.

Finally, cell penetration and electrochemical detection of ROS by human breast cancer cells and zebrafish embryonic cells were evaluated, and changes in ROS signal indicated that the system was able to respond highly selectively to ROS and quantitatively measure intracellular ROS
.

This work provides a systematic approach to automated intracellular sensing of adherent cells, laying a solid foundation
for high-throughput detection, diagnosis, and classification of different forms of biochemical reactions within a single cell.
In addition, the system will have important applications in lineage tracing in developmental biology and high-resolution manipulation of living single-celled organelles to study the specific causes of disease and develop new treatments
.

National Natural Science Foundation of China (61903177), Shenzhen Science and Technology Plan (Grant No.
: JCYJ20190809144013494) and Guangdong Science and Technology Plan Project (Grant No.
: 2021A1515011813).

This research was partially supported by Shenzhen Science and Technology and Innovation Commission, grant number: ZDSYS20200811143601004 and partly by the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou).

The authors thank the SUSTech Core Research Facility for their help
.
Thanks to Professor Liu Dong of the Department of Biology of Southern University of Science and Technology for providing zebrafish embryos
.

Original:

 " Robotic Intracellular Electrochemical Sensing for Adherent Cells," was published in the journal Cyborg and Bionic Systems on September 2nd, 2022, at DOI: https://doi.
org/10.
34133/2022/9763420

: About Dr.
Hu Chengzhi

In 2014, he received his Ph.
D.
from the Department of Micro-Nano Systems and Engineering, Nagoya University.

From 2014 to 2018, he was a postdoctoral
fellow at the Multiscale Robotics Laboratory of ETH Zurich.
Since 2018, he has been an associate professor
in the Department of Mechanical and Energy Engineering, Southern University of Science and Technology.
He has been engaged in the development of
micro/nano robots, microfluidic chips, micro/nano tools and other biomedical system devices for bioanalytical and biomedical applications.

Personal homepage: https://faculty.
sustech.
edu.
cn/hucz/en/