Hyaluronic Acid Substrate for In Vitro SPF Determination
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Solution Overview
Problem
Current methods for determining the Sun Protection Factor (SPF) of sunscreens rely on in vivo clinical studies, which raise ethical concerns and are not suitable for widespread product development, while existing in vitro methods using substrates like PMMA do not accurately reflect skin protection against UV radiation.
Innovation Solution
An in vitro method using hyaluronic acid (HA) as a substrate in both solid and liquid states to evaluate the protection offered by sunscreens against UV radiation, correlating HA degradation with SPF values, allowing for controlled exposure and transmittance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If in vivo clinical studies are used to determine SPF, then measurement precision is improved, but ethical concerns and volunteer exposure risks worsen
Solution Approach 1:
The patent creates an in vitro model that copies the essential characteristics of human skin (using hyaluronic acid as a key skin component) to simulate UV radiation effects. This allows SPF determination without exposing actual human volunteers, replacing the in vivo clinical study model with a laboratory-based simulation that maintains measurement relevance while eliminating ethical concerns and volunteer risks
2Object-affected harmful factors
If existing in vitro methods using PMMA substrates are used, then volunteer exposure risks are reduced, but measurement precision worsens due to inaccurate reflection of skin protection
Solution Approach 1:
The patent changes the fundamental parameter of the substrate material from PMMA (polymethyl methacrylate) to hyaluronic acid. This parameter change transforms the in vitro model from an artificial plastic-based system to a biologically-relevant system that actually reflects skin composition and UV interaction, thereby improving measurement precision while maintaining the in vitro advantage of eliminating volunteer exposure
Solution Approach 2:
Hyaluronic acid serves as an intermediary substance that bridges the gap between artificial in vitro testing and actual skin protection. It mediates the UV radiation interaction in a way that accurately represents real skin behavior, allowing the in vitro method to achieve precision comparable to in vivo studies without the ethical drawbacks
3Measurement precision
If hyaluronic acid is used as substrate, then measurement precision is improved by reflecting actual skin protection, but device complexity increases
Solution Approach 1:
The patent extracts and isolates the critical functional component (hyaluronic acid) from the complex biological system of human skin. By focusing on this single key component rather than attempting to recreate entire skin tissue structures, the method achieves accurate SPF measurement while keeping the device and procedure relatively simple and manageable
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 method provides a reliable and ethical alternative for determining SPF, reducing volunteer exposure risks and offering a technological advancement in sun protection product development by accurately estimating protection levels against UV radiation.
Implementation Method 1
hyaluronic acid (HA) stands out, showing a high sensitivity to UVA-UVB radiation dependent on exposure time, and its degradation has been associated with premature aging of the skin
Implementation Method 2
it was established by quantification by hydroxyproline that it is highly sensitive to UV radiation, producing degradation and, in turn, fiber rupture evidenced histologically in tissue ex vivo
Data Source
AI summary
The invention provides an in vitro method for the determination of sun protection factor (SPF), in order to gain reproducibility and accuracy and replace the use of tests on living beings. Natural substrates of the human skin, like hyaluronic acid are tested in the form of solutions or in the form of a solid film in a modified spectrophotometer, at concentrations below 1% w/v. Once calibrated, the method is used to corroborate the protection factor offered by commercial sunscreens.