Subcellular Western Blotting Single Cells Microwell Array

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Solution Overview

Problem

Proteomic analysis of rare cell populations, such as circulating tumor cells, is challenging due to low cell concentrations and the obscuring effect of large cell populations, which makes conventional assays like Western blots and flow cytometry unsuitable, and existing methods lack the capability for subcellular fraction analysis of individual cells.

Innovation Solution

A method involving a polymeric separation medium with microwells that covalently bonds cellular components using benzophenone functional groups upon UV exposure, allowing for subcellular fractionation and separation of proteins through differential lysis and electrophoresis, enabling the detection of separated components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional Western blot and flow cytometry assays are used, then protein detection can be performed, but the assays require large cell populations (~10^6 cells) and cannot analyze rare cell populations effectively

Engineering Contradiction:
Improvecell concentration requiredVSAvoiddetection capability for rare cells
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

The invention divides the cell analysis process into subcellular compartments by using differential lysis buffers that selectively lyse specific organelles (e.g., plasma membrane first, then nuclear membrane), allowing separate analysis of cytosolic and nuclear proteins from the same single cell. This segmentation enables detection of rare cells by analyzing their unique subcellular protein profiles.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The microwell array provides localized analysis compartments, with each microwell containing a single cell or subcellular fraction. This local quality approach allows individual rare cells to be analyzed in isolation without being obscured by large cell populations, while the array format maintains high throughput capability.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If single cell analysis is performed, then rare cell population analysis becomes possible, but subcellular fraction analysis capability is lost in conventional methods

Engineering Contradiction:
Improvesingle cell detection capabilityVSAvoidsubcellular fraction analysis capability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The invention employs a dynamic, multi-step lysis process where different buffers are applied sequentially to differentially lyse subcellular compartments. First, a plasma membrane-permeable buffer lyses the cytoplasmic membrane, then a nuclear membrane-permeable buffer lyses the nuclear membrane, dynamically releasing proteins from different compartments in sequence for separate electrophoretic analysis.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The microwell array system serves multiple functions: it captures single cells, performs differential lysis of subcellular compartments, conducts electrophoresis of released proteins, and enables detection of separated components. This multi-functionality allows single cell analysis to maintain subcellular fraction analysis capability that was previously lost.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Manufacturing precision

If protein separation by electrophoresis is performed, then protein characterization is enabled, but the requirement for large cell populations limits analysis of rare cells

Engineering Contradiction:
Improveprotein separation resolutionVSAvoidcell input requirement
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The invention creates multiple copies of the electrophoresis separation process by using an array of microwells, where each microwell performs independent electrophoresis on proteins from a single cell. This array approach amplifies the signal from rare cells while maintaining the resolution of protein separation, overcoming the limitation of requiring large cell populations.

Inventive Principle:
Principle #26Copying

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables the precise measurement of protein localization and expression in single cells by fractionating subcellular compartments, improving the analysis of rare cell populations and providing detailed insights into cellular behavior.

Implementation Method 1

the polymeric separation medium includes bezophenone functional groups that covalently bond one or more cellular components to the polymeric separation medium upon application of ultraviolet light

Methodology Applied
Scientific EffectPhotochemical bonding: Photopolymerisation

Implementation Method 2

applying an electric field to the polymeric separation medium in a manner sufficient to move at least some of the set of cellular components into the polymeric separation medium to produce a set of separated cellular components

Methodology Applied
Scientific EffectElectrophoresis: Electrophoresis

Data Source

PatentEP3149476B1Subcellular western blotting of single cells
Publication Date: 2022.02.16 RGT UNIV OF CALIFORNIA
  • EP3149476B1 patent drawingFigure 1~2
  • EP3149476B1 patent drawingFigure 3A~3B
  • EP3149476B1 patent drawingFigure 4A~4C

AI summary

Electrophoretic separation methods and systems for performing the same are provided. The methods and systems find use in a variety of different electrophoretic separation applications, such as sub-cellular Western blotting of single cells.