Lateral Filter Array Microfluidic Device for CTC Isolation
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Solution Overview
Problem
Current methods for isolating circulating tumor cells (CTCs) face challenges due to the rarity of CTCs in blood, low sensitivity, high cost, and the heterogeneity of CTCs in physical and biological properties, which limits their universal applicability in clinical settings.
Innovation Solution
A lateral filter array microfluidic device that integrates size-based separation with immunoaffinity-enabled isolation, featuring a serpentine main channel with embedded lateral filters of varying sizes and functionalized with binding molecules such as antibodies or aptamers to capture CTCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If size-based CTC isolation is used, then CTCs can be differentiated from normal blood cells based on size, but CTCs with similar size to white blood cells cannot be effectively isolated
Solution Approach 1:
The patent combines size-based filtration with immunoaffinity-based capture in a single integrated microfluidic device. The filtration step pre-enriches CTCs by size, while the immunoaffinity step provides specific biological targeting, thereby resolving the limitation of size-based methods alone and enabling effective isolation of heterogeneous CTCs including those similar in size to white blood cells.
Solution Approach 2:
The device performs multiple functions within a single system: size-based filtration, immunoaffinity capture, and direct visualization. This multi-functional integration allows the device to handle diverse CTC populations with varying physical and biological properties, making it universally applicable across different CTC heterogeneity scenarios.
2Measurement precision
If immunoaffinity-based CTC isolation is used, then specific conjugation between biomarkers and antibodies enables CTC capture, but heterogeneity in biomarker expression limits universal applicability
Solution Approach 1:
The patent integrates size-based filtration with immunoaffinity-based capture. The size filtration provides a physical enrichment step that works independently of biomarker expression, while the immunoaffinity step provides specific biological targeting for EpCAM-positive CTCs. This combination allows the device to capture both EpCAM-positive and EpCAM-negative CTCs, resolving the limitation of immunoaffinity methods alone.
Solution Approach 2:
The isolation process is segmented into distinct stages: size-based pre-filtration followed by immunoaffinity capture. This segmentation allows each mechanism to address different aspects of CTC heterogeneity, with size filtration handling physical property differences and immunoaffinity handling biological marker differences, thereby expanding applicability to diverse CTC populations.
3Productivity
If antibody-conjugated beads are used to enlarge tumor cells, then filtration capture efficiency improves, but cell fragmentation or loss occurs
Solution Approach 1:
The patent extracts the antibody conjugation step from the bead enlargement approach and applies it directly to the filtration surface. This eliminates the need for bead attachment to cells, thereby maintaining cell integrity while still achieving efficient capture through direct antibody-antigen conjugation on the filtration membrane.
Solution Approach 2:
The filtration membrane serves as an intermediary surface that combines the size-based filtration function with the immunoaffinity capture function. Instead of using beads as an intermediary to enlarge cells, the membrane itself is functionalized with antibodies, providing a direct capture interface that maintains cell integrity while achieving high capture efficiency.
4Measurement precision
If membrane filters with small pore sizes are used, then cell purity increases, but cell clogging reduces throughput
Solution Approach 1:
The patent merges size-based filtration with immunoaffinity capture in sequence. The size filtration provides initial enrichment and removes most non-CTC cells, while the immunoaffinity step provides final specific capture. This sequential combination allows the use of appropriate pore sizes for high purity without the same throughput limitations, as the immunoaffinity step continues to capture CTCs even when filtration is optimized for purity.
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
The device achieves high capture efficiency and cell purity by ensuring direct contact between CTCs and antibody-functionalized filters, overcoming the limitations of existing technologies and providing a more user-friendly, high-throughput method for CTC isolation.
Implementation Method 1
The at least one series of boundaries may include filters that allow lateral flow of the liquid sample relative to flow in the at least one serpentine main channel
Implementation Method 2
The at least one series of boundaries may include filters that allow lateral flow of the liquid sample relative to flow in the at least one serpentine main channel. At least one boundary of the at least one series of boundaries may be functionalized to include a binding molecule having an affinity to the target isolate
Data Source
AI summary
A lateral filter array microfluidic (LFAM) device for highly efficient immunoaffinity isolation of target cells from a population of cells. The LFAM device may include of one or more serpentine main channels incorporated with lateral filter arrays. Antibodies are immobilized on the channel surface including the lateral filters and are capable of specific binding to one or more biomolecules on the surface of the target cell. The device may include one or more arrays of lateral filters with different sizes. The overall filters sizes are close to the diameter of the target cell, therefore the interaction between biomarkers on the target cells and corresponding antibodies immobilized on the filter surface is largely strengthened due to the direct contact between target cells and lateral filters. Methods include flowing a population of cells through an antibody-coated LFAM device for target cells capture, followed by washing the device to remove non-specific captured cells.