Charge-sensitive optical detection of binding kinetics between phage displayed peptide ligands and protein targets
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Solution Overview
Problem
Current methods for measuring the binding kinetics of phage-displayed peptides are challenging due to the large mass of phage shifting detection ranges, limited surface density, and multivalent nature, making it difficult to obtain accurate one-to-one binding kinetics data.
Innovation Solution
The integration of charge-sensitive optical detection (CSOD) with phage display technology allows for direct measurement of peptide binding kinetics by detecting charge changes using an optical fiber probe exposed to an alternating electric field, enabling precise quantification without the need for peptide synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional mass-sensitive detection methods (SPR, BLI) are used to measure phage-displayed peptide binding kinetics, then the method is label-free and relatively simple, but the huge mass of phage shifts the baseline out of detection range and limits measurement precision
Solution Approach 1:
The patent replaces mass-sensitive mechanical detection (SPR, BLI) with charge-sensitive optical detection. The CSOD system uses optical fiber sensors that detect charge changes through optical signals rather than mechanical mass changes, thereby eliminating the baseline shifting problem caused by phage mass while maintaining label-free detection capability.
2Quantity of substance
If phage are loaded onto sensor surface for binding kinetics measurement, then direct measurement is enabled, but the surface density of displayed peptides is limited by expression level and the huge mass ratio between phage and peptide
Solution Approach 1:
The CSOD system replaces mass-based detection with charge-based optical detection, allowing accurate measurement of peptide surface density on phage without being confounded by the phage-to-peptide mass ratio. The optical fiber sensor detects charge changes at the sensor surface, enabling precise quantification of peptide binding events independent of phage mass.
3Measurement precision
If target protein is loaded onto sensor surface for binding kinetics measurement, then direct measurement is enabled, but the multivalent nature of phage-expressed peptides makes sensor response curves reflect collective multivalency binding kinetics instead of one-to-one first-order binding kinetics
Solution Approach 1:
The charge-sensitive optical detection system measures charge changes that directly reflect individual peptide-protein binding events, providing cleaner kinetic data that more accurately represents one-to-one binding kinetics. The optical detection method reduces the collective signal averaging effect that occurs with mass-sensitive methods, enabling more accurate determination of first-order binding kinetics despite phage multivalency.
4Measurement precision
If custom synthesis of candidate peptides is performed for binding kinetics measurement, then accurate binding kinetics data can be obtained, but the process is costly and time-consuming
Solution Approach 1:
The CSOD system enables direct measurement of binding kinetics on phage-displayed peptides without requiring peptide extraction, purification, or custom synthesis. The method uses the phage-peptide complex itself as the measurement substrate, eliminating the time-consuming peptide preparation steps while maintaining measurement accuracy through charge-sensitive optical detection.
Solution Approach 2:
The invention extracts and measures the charge signal directly from the phage-displayed peptide complex in its native state, eliminating the need to separate or purify the peptide component. This direct measurement approach removes the peptide synthesis and purification steps entirely, significantly reducing time and cost while preserving binding kinetics accuracy.
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
CSOD provides high sensitivity and accuracy in measuring binding kinetics, overcoming mass sensitivity limits and enabling rapid triaging of peptide leads, reducing time and cost compared to conventional methods.
Implementation Method 1
charge-sensitive optical detection (CSOD) with phage display technology to enable rapid quantification of peptide binding kinetics
Implementation Method 2
a position sensitive photodetector configured to detect a position of light exiting the sensor probe
Implementation Method 3
an electrode positioned in each electrode region and configured to expose the sensor probe to an alternating electric field
Implementation Method 4
assess an amplitude of oscillation of the sensor at a frequency of the alternating electric field
Data Source
AI summary
Provided herein are systems for the label-free detection of target molecules in samples. The systems include a sensor probe positioned in a sensing region and configured to bind to receptors for the target molecules. The systems also include electrodes configured to expose the sensor probe to an alternating electric field. and a light source optically coupled to the sensor probe and configured to provide light along a length of the sensor probe. In addition, the systems also include a position sensitive photodetector configured to detect a position of light exiting the sensor probe, and a processor configured to assess. based at least in part on the position of the light exiting the sensor probe. an amplitude of oscillation of the sensor at a frequency of the alternating electric field and a direction of a displacement of the sensor. Additional systems and related methods are also provided.