PEG Spacer Cell Separation via Biotin Competition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current cell separation methods using biotin/streptavidin systems are not fast or reliable enough for labeling and unlabeling living cells, often leading to incomplete or difficult-to-control release due to unknown kinetics and potential cell damage from unselective release mechanisms.
Innovation Solution
A biotinylated antibody conjugate with a polyethylene glycol spacer between the biotin moiety and the antibody is used, allowing for selective dissociation by a release agent like biotin or streptavidin, facilitating rapid and efficient cell separation and labeling removal under physiological conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If biotin/streptavidin affinity systems are used for cell separation, then high binding affinity and specificity are achieved, but the release of target cells is slow and difficult to control
Solution Approach 1:
The system is divided into two independent components: a biotinylated antibody that binds to the target cell and a streptavidin-conjugated magnetic bead that provides separation capability. The biotin-streptavidin interface allows controlled release by adding excess biotin, which competes for streptavidin binding sites and releases the antibody-bound cells. This segmentation enables both reliable binding and controlled release.
Solution Approach 2:
The biotin-streptavidin interaction serves as an intermediary mechanism between the target cell (via biotinylated antibody) and the magnetic bead (via streptavidin). This intermediary allows the system to achieve both strong binding during separation and controlled release by introducing excess biotin as a competing ligand, thus resolving the contradiction between binding reliability and release speed.
2Ease of operation
If modified biotin or streptavidin is used to improve release properties, then dissociation is facilitated, but the modification process is laborious and complex
Solution Approach 1:
The invention uses unmodified, commercially available biotin and streptavidin reagents, avoiding the need for complex chemical modifications. The system relies on the natural high-affinity interaction between these readily available reagents, and release is achieved by adding excess unmodified biotin, thus keeping the system simple and avoiding laborious modification processes.
Solution Approach 2:
Instead of modifying the biotin or streptavidin molecules, the invention changes the parameters of the system by controlling the concentration of free biotin in the solution. By adjusting the biotin concentration, the equilibrium of the biotin-streptavidin interaction is shifted, enabling controlled release without any molecular modifications, thus maintaining system simplicity.
3Productivity
If unselective release mechanisms (enzymatic degradation, chemical reactions, mechanical forces) are used, then cell release is achieved, but cell integrity and viability are compromised
Solution Approach 1:
The invention converts the extremely high binding affinity of biotin-streptavidin, which initially causes difficulty in release, into a benefit by using competitive inhibition. Excess biotin competes for streptavidin binding sites, gently displacing the biotinylated antibody without requiring harsh conditions. This converts the strong binding (potential harm for release) into a controllable, gentle release mechanism that preserves cell integrity.
Solution Approach 2:
The invention changes the chemical environment by adding excess biotin, which shifts the binding equilibrium through mass action. This parameter change (biotin concentration) enables selective and gentle release of the target cells from magnetic beads without employing harsh enzymatic, chemical, or mechanical methods, thus maintaining cell viability while achieving efficient release.
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 method enables fast and reliable separation of target cells with preserved integrity and viability, utilizing a competition reaction that can be controlled for efficient release, improving the kinetics and reliability of cell labeling and detection processes.
Implementation Method 1
The ability of biotin to bind streptavidin, avidin, and other biotin-binding molecules has been exploited for several decades, because of the high affinity, specificity, and broad applicability of this system.
Implementation Method 2
a biotinylated ligand having a biotin moiety, a ligand moiety and a biotin-binding molecule bound to the biotin moiety of the biotinylated ligand, wherein the biotin moiety and the ligand moiety of the biotinylated ligand are separated by a spacer group consisting of polyethylene glycol
Implementation Method 3
biotin/streptavidin systems can also be cleaved by a ligand competition mechanism. For example, a biotinylated molecule can be released from a streptavidin-support by adding an excess of free biotin, thereby replacing the biotinylated molecule.
Implementation Method 4
the biotin-binding molecule (bbm) is a second antibody which comprises a magnetic particle as solid support, b) separation of the cells labeled with the a solid support obtained in step a) from the cell sample by applying an magnetic field
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention is directed to a releasable conjugate comprising a biotinylated ligand having a biotin moiety, a ligand moiety (Ligand1) and a biotin-binding molecule (bbm) bound to the biotin moiety of the biotinylated ligand characterized in that the biotin moiety and the ligand moiety of the biotinylated ligand are separated by a spacer group consisting of polyethylene glycol according to the general formula I with n = 1 - 500, and X, Y = same or different, substituted alkyl groups having 1 to 20 carbon atoms with amine, amide, and/or thioether residues, wherein the ligand is a first antibody and the biotin-binding molecule (bbm) is a second antibody which comprises a detection means selected from the group chromophor unit, fluorescence unit, radioactive unit, and solid support. Furthermore, the invention relates to a method for cleaving the releasable conjugate by providing biotin or streptavidin and an auxiliary release agent in a sufficient concentration to displace the biotin-binding molecule (bbm) from the biotin moiety of the biotinylated ligand and a method for separation of target cells from a cell sample utilizing the conjugate.