Segmentation-based analysis of single-cell immunoblots

Single-cell differential detergent fractionation for detection of cytokeratin 8 proteoforms

Simultaneous profiling of proteoforms and nucleic acids at the single-cell level, i.e., multi omics, directly links the central dogma. However, current single-cell approaches are limited in their ability to identify proteoforms while preserving the nucleus for further analysis. This limitation is especially pronounced in proteins where their proteoforms present diverse biological functions such as cytokeratin 8 (CK8), which, while commonly known for its structural role, is also involved in several diseases. Here, we present a single-cell western blot (scWB) integrated with differential detergent fractionation (DDF) to selectively solubilize and separate CK8 proteoforms while preserving nuclear integrity for subsequent nucleus-based assays. We report on assay development, including screening a panel of lysis buffers based on nonionic detergents and electrophoresis conditions to achieve a separation resolution between two proteoforms of up to 0.94 with an electric field of 30 V/cm, while preserving an intact nucleus. The cytoplasm-specific lysis approach (DDF buffer) demonstrated comparable solubilization efficiency to whole-cell solubilization (RIPA buffer), achieving proteoform solubilization in 14.3% and 10.3% of solubilized cells using DDF and RIPA buffers, respectively, while keeping the nucleus intact. To understand the broad applicability of the assay conditions, we scrutinized electrophoresis performance for resolving CK8 proteoforms across a panel of widely used breast cancer cell lines (MCF7, SKBR3, and MDA-MB-231), showing presence of proteoforms only in MCF7. Our approach allows for tailored solubilization, achieving reliable proteoform detection and nuclear retention across different cell types. Proteoform profiling at the single-cell level forms a basis for the exploration of the role of specific CK8 molecular forms in cellular processes.

The development of microfluidic-based western blotting: Technical advances and future perspectives

Over the past two decades significant technical advancement in the field of western blotting has been made possible through the utilization of microfluidic technologies. In this review we provide a critical overview of these advancements, highlighting the advantages and disadvantages of each approach. Particular attention is paid to the development of now commercially available systems, including those for single cell analysis. This review also discusses more recent developments, including algorithms for automation and/or improved quantitation, the utilization of different materials/chemistries, use of projection electrophoresis, and the development of triBlots. Finally, the review includes commentary on future advances in the field based on current developments, and the potential of these systems for use as point-of-care devices in healthcare.

Trapping and releasing of single microparticles and cells in a microfluidic chip

A microfluidic device was designed and fabricated to capture single microparticles and cells by using hydrodynamic force and selectively release the microparticles and cells of interest via negative dielectrophoresis by activating selected individual microelectrodes. The trap microstructure was optimized based on numerical simulation of the electric field as well as the flow field. The capture and selective release functions of the device were verified by multi-types microparticles with different diameters and K562 cells. The capture efficiencies/release efficiencies were 95.55% ± 0.43%/96.41% ± 1.08% and 91.34% ± 0.01%/93.67% ± 0.36% for microparticles and cells, respectively. By including more traps and microelectrodes, the device can achieve high throughput and realize the visual separation of microparticles/cells of interest in a large number of particle/cell groups.