Multivalent Tagging Agents for CTC Capture in Microfluidics
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Solution Overview
Problem
Current methods for isolating circulating tumor cells (CTCs) from blood samples are limited by the rarity of CTCs and low expression of surface antigens, leading to low yield and purity, making it challenging to detect and characterize these cells effectively.
Innovation Solution
The use of multivalent tagging agents, comprising a selective analyte binding moiety and multiple binding agents, such as biotin molecules, that bind to CTCs and then interact with surface-bound capture agents in a microfluidic channel, enhancing capture efficiency by providing a clustered configuration for binding, thereby improving the detection of rare cells with low antigen expression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If surface-bound antibodies are used to capture CTCs in microfluidic channels, then the capture method is simple, but the capture efficiency is low due to rarity of CTCs and low antigen expression
Solution Approach 1:
The capture system is segmented into two distinct components: surface-bound antibodies that provide simple anchoring to the microfluidic channel, and multivalent tagging agents (containing multiple biotin molecules) that amplify binding to CTCs. This segmentation allows the surface to remain simple while the tagging agents provide enhanced capture efficiency through clustered biotin configuration.
Solution Approach 2:
Multivalent tagging agents serve as intermediaries between the surface-bound antibodies and the CTCs. These tagging agents contain multiple biotin molecules that can simultaneously interact with multiple surface-bound antibodies, creating a bridging effect that significantly enhances capture efficiency without complicating the overall system architecture.
2Ease of manufacture
If conventional single-biotin tagging is used, then the tagging process is simple, but the binding configuration does not optimize capture of low antigen expressing cells
Solution Approach 1:
The tagging agent is designed as a composite structure containing multiple biotin molecules linked to a common core. This composite configuration maximizes the interaction with surface-bound antibodies while maintaining a relatively simple tagging process, thereby enhancing detection sensitivity for low antigen expressing cells without proportionally increasing manufacturing complexity.
3Ease of operation
If high concentrations of CTCs are present, then detection is easier, but the method must also work at low concentrations which reduces detection sensitivity
Solution Approach 1:
The system changes the binding parameter configuration by using multivalent tagging agents with clustered biotin molecules. This parameter change in binding configuration allows the system to maintain high detection sensitivity even when CTC concentrations are low, as the clustered biotin provides multiple interaction points that amplify the binding signal.
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
This approach significantly increases the capture efficiency of CTCs and other low-antigen expressing cells, allowing for higher purity and sensitivity in microfluidic devices, even at low concentrations, by optimizing the binding configuration and presentation of biotin molecules on the cell surface.
Implementation Method 1
combining the sample with a multivalent tagging agent that includes two parts. The first part is a selective analyte binding moiety, e.g., a moiety that selectively binds to an analyte
Implementation Method 2
The second part is a plurality of binding agents, e.g., 2 to 10 or more binding agents, such as biotin molecules, that are each linked or coupled to each analyte binding moiety. Once the multivalent tagging agents are bound to the analytes of interest, the sample is flowed along a surface to which is bound one or more capture agents to capture the multivalent tagging agent. The capture agent includes a ligand that binds, e.g., binds strongly, to the binding agents of the multivalent tagging agent (e.g., the ligand can be a surface-bound biotin-binding conjugate, such as surface-bound avidin or streptavidin).
Data Source
AI summary
Methods and systems for selectively capturing analytes, such as cells, e.g., circulating tumor cells (CTCs), from fluid samples are disclosed. The methods include contacting the sample with an analyte binding moiety that selectively binds to the analytes; optionally separating first components of the sample including a majority of the analytes bound to the binding moieties from second components of the sample using size-based separation, e.g., in a microfluidic channel; adding to the first components of the sample a plurality of binding agents under conditions that enable a plurality of the binding agents to be linked to the analyte binding moieties to form multivalent tagging agents bound to the analyte; passing the first components of the sample past a surface to which is attached a plurality of capture agents that selectively bind to the binding agents; and capturing the analytes by providing conditions that enable the multivalent tagging agents bound to the analytes to bind to one or more of the capture agents.