Modified Dextran Fluorophore Labeling for Glucose Assay Stability
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Solution Overview
Problem
Conventional glucose assays face stability issues due to lipophilic dye labeling of dextran, leading to conformational changes and reduced binding ability, as well as photobleaching caused by excitation of fluorophores to higher energy states, resulting in unstable calibration and assay performance.
Innovation Solution
The use of multi-labeled glucose analogs with agents promoting hydrophilicity and blue-shifted reference fluorophores in fluorescent competitive binding assays, which enhance the hydrophilic-hydrophobic balance and prevent undesirable conformal changes, thereby stabilizing the assay complex and reducing photobleaching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If dextran is labeled with a large number of lipophilic dye molecules, then fluorescence signal intensity is improved, but water solubility decreases and precipitation occurs
Solution Approach 1:
The patent modifies the chemical parameters of the dextran-dye conjugate by introducing hydrophilic groups (such as carboxyl, hydroxyl, or amino groups) that change the overall hydrophilicity parameter of the molecule. This allows the system to maintain high fluorescence signal intensity while improving water solubility and preventing precipitation.
Solution Approach 2:
The patent creates a composite structure where hydrophilic groups are incorporated into the dextran-dye conjugate system. This composite approach combines the fluorescent properties of lipophilic dyes with the water solubility of hydrophilic groups, resolving the contradiction between signal intensity and solubility.
2Measurement precision
If dextran is labeled with lipophilic dyes, then fluorescence labeling is achieved, but conformational changes occur and binding ability to glucose receptor decreases
Solution Approach 1:
The patent changes the hydrophilic-hydrophobic balance parameter of the dextran molecule by incorporating hydrophilic groups. This parameter change prevents undesirable conformational changes that would otherwise occur with pure lipophilic labeling, thereby maintaining both fluorescence labeling capability and binding ability to the glucose receptor.
3Use of energy by moving object
If fluorophores are excited using light of lower wavelength with more energy, then excitation efficiency is improved, but photobleaching increases due to transition to second excited state
Solution Approach 1:
The patent inverts the conventional approach by using a reference fluorophore that is blue-shifted (shorter wavelength) relative to the assay fluorophore. This inversion allows the reference fluorophore to be excited at a wavelength that does not cause excessive photobleaching, while still providing effective reference signal for calibration stability.
4Ease of operation
If dyes are shielded intra-molecularly on dextran, then steric hindrance is reduced, but calibration stability decreases over time
Solution Approach 1:
The patent changes the overall charge and hydrophilicity parameters of the dextran-dye conjugate by incorporating hydrophilic groups. This parameter change counteracts the stabilizing effect of intra-molecular shielding, maintaining calibration stability over time while preserving adequate steric accessibility for binding.
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 approach results in more stable glucose assays with reduced sensor dose response loss, improved solubility, and prolonged stability, allowing for accurate and reliable glucose monitoring with minimized calibration frequency.
Implementation Method 1
a first fluorophore labeled glucose receptor and a second fluorophore labeled dextran which together form a Forster Resonance Energy Transfer (FRET) pair
Implementation Method 2
a reference fluorophore which is blue-shifted relative to the assay fluorophore
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2B
AI summary
The invention is directed to a competitive glucose binding affinity assay comprising a glucose receptor (typically mannan binding lectin) labeled with an assay fluorophore and a modified glucose analog (typically dextran) labeled with a reference fluorophore. In certain embodiments, the glucose analog is dextran and is coupled to both a reference fluorophore and a quencher dye (e.g. hexamethoxy crystalviolet-1). Optionally the reference fluorophore is blue shifted relative to the assay fluorophore.