Automated System for Small-Population Single-Particle Processing Enabled by Exclusive Liquid Repellency

Abstract

Exclusive liquid repellency (ELR) describes an extreme wettability phenomenon in which a liquid phase droplet is completely repelled from a solid phase when exposed to a secondary immiscible liquid phase. Earlier, we developed a multi-liquid-phase open microfluidic (or underoil) system based on ELR to facilitate rare-cell culture and single-cell processing. The ELR system can allow for the handling of small volumes of liquid droplets with ultra-low sample loss and biofouling, which makes it an attractive platform for biological applications that require lossless manipulation of rare cellular samples (especially for a limited sample size in the range of a few hundred to a few thousand cells). Here, we report an automated platform using ELR microdrops for single-particle (or single-cell) isolation, identification, and retrieval. This was accomplished via the combined use of a robotic liquid handler, an automated microscopic imaging system, and real-time image-processing software for single-particle identification. The automated ELR technique enables rapid, hands-free, and robust isolation of microdrop-encapsulated rare cellular samples.

Oil Immersed Lossless Total Analysis System (OIL-TAS): Integrated RNA Extraction and Detection for SARS-CoV-2 Testing

“…The OIL-TAS assay integrates three technologies: 1) an underoil droplet microfluidic technology called Exclusive Liquid Repellency (ELR) that allows for lossless sample processing 5,6 ; 2) a rapid solid-phase analyte extraction method called Exclusion-based Sample Preparation (ESP) [7][8][9][10][11][12] ; and 3) isothermal amplification with colorimetric readout (Loop-Mediated Isothermal Amplification, LAMP 13,14 ) resulting in a simple, high throughput, low cost test that could be quickly and broadly implemented using simple tools and consumables that are widely available. The OIL-TAS device builds upon our previously reported ELR technology, which describes physical conditions where an aqueous droplet can be fully repelled from a solid surface (contact angle = 180°) in the presence of an oil phase when a specific set of oil and solid interfacial energy properties are met.…”

Prostate cancer research: The next generation; report from the 2019 Coffey‐Holden Prostate Cancer Academy Meeting

“…Additional stacking with patient-matched M2 macrophages inhibited the migration of T cells, indicating the potential for functional assessment of a patient's tumor-microenvironment interaction (Lang et al, unpublished). [140][141][142] Pushing 3D culture systems to the next level, Lang et al have now begun to utilize exclusive and/or finite liquid repellency (ELR and FLR, respectively) [143][144][145] platforms to investigate tumor cell interactions with immune cells at the single-cell level. ELR/FLR enables the culture of single cells in microbubbles submerged in oil.…”

Under‐Oil Autonomously Regulated Oxygen Microenvironments: A Goldilocks Principle‐Based Approach for Microscale Cell Culture

“…Recently, there has been renewed interest in the area of multi‐liquid‐phase microfluidics, known as under‐oil open microfluidic systems (UOMS). [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ] In UOMS cell culture, culture media and cells are contained under an oil overlay, separating the cell culture microenvironment from the ambient with an immiscible liquid (i.e., oil) rather than solid materials used in traditional microscale devices (Figure 1f ; Figure S1 , Supporting Information). Thus, compared to PDMS elastomer or other solid materials used in closed‐channel or closed‐chamber microscale devices, the oil overlay allows: i) integration of a readily tailorable diffusion barrier for a supply–demand‐balanced oxygen microenvironment by selecting/adjusting different oil properties (e.g., oil type, depth, and viscosity), and ii) facile and seamless intervention and spatially flexible deployment of external sensors (e.g., oxygen, pH, temperature, and etc.)…”