Taking a cue from electronics: A 'mattertronic' approach for controlling label-free cells

(Nanowerk News) Researchers from Daegu Gyeongbuk Institute of Science and Technology have developed a digital circuitry for programmable manipulation and local storage of label-free matters. This approach supersedes existing cell manipulation methods and enables multiplex cell control, paving the way for a broad range of applications such as gene sequencing, disease diagnosis, and single-cell analysis.
The study of molecular and cellular processes has attracted particular attention in recent years owing to the deep insights it brings to the diagnosis and treatment of various diseases. Single-cell isolation and analysis are key processes for assessing cellular characteristics and dynamics within a cell population. Although there are several methods for single-cell analysis, magnetophoresis (the migration of particles in a magnetic field) offers significant advantages. However, existing magnetophoresis-based methods do not provide accurate and programmable manipulation of label-free single cells. They are also incapable of handling multiplex cell control for local storage.
In a study published in Nature Communications ("Mattertronics for programmable manipulation and multiplex storage of pseudo-diamagnetic holes and label-free cells"), a research team led by Prof. CheolGi Kim of Daegu Gyeongbuk Institute of Science and Technology (DGIST), Korea, developed a mattertronic circuitry control and multiplexed individual storage for single label-free cells. Describing the inspiration behind the study, Prof. Kim says, "Single-cell studies are crucial in diagnostics, drug response testing, and immunotherapy. Therefore, a manipulation technique that had less adverse effect on cells had to be developed."
A mattertronic circuit is designed using general circuit theory to transport, switch, and store label-free cells, mimicking the functionality of electrical conductors, diodes, and capacitors. The researchers used a biocompatible ferrofluid medium with a substantially greater magnetization. As a result, the suspended non-magnetic particles and label-free cells exhibit strong diamagnetism. Non-magnetic particles and label-free cells are therefore referred to as "pseudo-diamagnetic (PsD) holes," akin to electronic holes.
To begin, the researchers adjusted the magnetization of ferrofluids to achieve desirable PsD hole transportation on the conductor. Consequently, the holes moved along linear negative micro-magnetic patterns. Next, they developed eclipse diode patterns for efficient switching of various PsD holes. Depending on the diode configuration, the eclipse diode patterns controlled and selectively switched these holes. Eclipse heights and junction gaps have an impact on the switching efficiency of PsD holes. The junction gaps and eclipse heights of 7 and 4 µm, respectively, offered the best combination for 100% switching efficiency.
Furthermore, the researchers designed capacitor patterns to store multiple PsD holes in one compartment as well as single PsD holes in individual compartments. The capacitor patterns prevent multiple PsD hole occupancies in a single compartment due to magnetic Coulomb-like interactions. Consequently, the individual PsD hole occupancy was found to be 96% accurate.
When the device was configured for parallel processing, the throughput improved significantly. Although the researchers concentrated on a specific region of the chip, dozens of similar microstructures may be installed in a single chip, further increasing the throughput. Prof. Kim excitedly concludes, "Using these automated magnetic patterns, it is possible to manipulate cells independently for each location, even within a single lab-on-a-chip! This novel platform for controlling label-free single cells sets the stage for more focused therapy, potentially reducing disease recurrence."
Source: Daegu Gyeongbuk Institute of Science and Technology
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