Hyaluronic Acid Quantification in Crosslinked Hydrogels

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Solution Overview

Problem

Current methods for quantifying hyaluronic acid (HA) in hydrogels, particularly cross-linked forms used in dermal fillers, are not specific and suffer from interference issues, leading to unreliable results and variability, necessitating a more reliable and efficient analysis method.

Innovation Solution

A method involving a sonication step to dissolve crosslinked hydrogels, followed by a carbazole-based assay with specific reagents and conditions, improves the reproducibility and accuracy of HA content determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional quantification methods are used for hyaluronic acid in hydrogels, then the analysis can be performed with standard procedures, but the results are not specific and suffer from interference issues leading to unreliable results

Engineering Contradiction:
ImproveHA content determination accuracyVSAvoidresult reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The method segments the analysis into distinct stages: hydrogel dissolution, sonication treatment, and carbazole-based colorimetric detection. This segmentation allows each step to be optimized independently, with sonication specifically addressing the dissolution of crosslinked structures to eliminate interference and improve measurement reliability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the physical-chemical parameters of the hydrogel sample through controlled sonication (acoustic energy input, temperature control, and time parameters). These parameter changes transform the crosslinked hydrogel into a homogeneous solution suitable for accurate colorimetric analysis, resolving the contradiction between using standard procedures and achieving reliable results

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If crosslinked hydrogels are analyzed without sonication, then the analysis procedure is simpler, but the homogeneity of the sample is insufficient leading to high variability

Engineering Contradiction:
ImproveHA content determination accuracyVSAvoidanalysis procedure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention applies mechanical vibration through sonication to break down the crosslinked hydrogel network and achieve homogeneous dissolution. This mechanical energy input transforms the complex crosslinked structure into a uniform solution, enabling accurate measurement without requiring complex chemical dissolution procedures

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

The sonication process induces phase transitions in the hydrogel matrix, transforming it from a gel phase to a homogeneous solution phase. This phase transition eliminates the need for complex chemical treatments while ensuring complete dissolution and homogeneity for accurate analysis

Inventive Principle:
Principle #36Phase transitions

3Reliability

If crosslinked hydrogels are dissolved without sonication, then the process is faster, but the homogeneity of the solution is insufficient leading to high standard deviation

Engineering Contradiction:
ImprovereproducibilityVSAvoiddissolution time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The invention employs periodic sonication action to achieve complete and homogeneous dissolution of the crosslinked hydrogel. The periodic acoustic energy input efficiently breaks down the crosslinked network structure, achieving reproducible results in a controlled time frame that balances speed and reliability

Inventive Principle:
Principle #19Periodic action

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 provides a reproducible and reliable quantification of HA content in hydrogels with low standard deviation, addressing the limitations of existing methods by enhancing the homogeneity of the sample and reducing interference from crosslinkers and additives.

Implementation Method 1

A method involving a sonication step to dissolve crosslinked hydrogels

Methodology Applied
Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

followed by a carbazole-based assay with specific reagents and conditions

Methodology Applied
Scientific EffectColorimetric reaction: Absorption Spectroscopy

Data Source

PatentEP4070090B1Method for the determination of sodium hyaluronate content in a hydrogel
Publication Date: 2023.06.07 UB CARE SRL
  • EP4070090B1 patent drawingFigure 1
  • EP4070090B1 patent drawing

AI summary

The present invention is directed to a method for the determination of the hyaluronic acid content of a hydrogel, the method comprising the following steps: a) preparing, as reagent A, a solution of sodium tetraborate in sulfuric acid; b) preparing reagent B by dissolving carbazole in ethanol; c) preparing test solutions by dissolving the hydrogel in an aqueous solution; d) treating the test solution with ultrasounds for a period of time sufficient to obtain a macroscopically homogeneous solution; e) preparing a reference stock solution by dissolving glucuronic acid, or a glucuronic acid-containing substance in an aqueous solution; f) preparing at least 3 reference solutions by dilution of the reference stock solution in aqueous solution, preferably at concentration comprised between 0.0005% w/v and 0.0100% w/v, preferably between 0.0010 % w/v and 0.0050 % w/v; g) preparing the test tubes by admixing reagent A, reagent B and one of the following: reference solution, test solution, aqueous solution (blank), and optionally solution for interference (crosslinker sample or additive sample); placing each test tube on a water bath for at least 5 min, then cool them to room temperature; h) reading the absorbance at a wavelength comprised between 500 and 580 nm, preferably at about 530 nm, against the blank and optionally the sample for interference.