Nitric Oxide Skin Dressing pH Self-Regulation
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Solution Overview
Problem
Existing nitric oxide releasing systems for topical application often result in prolonged exposure to acidic conditions, which can be harmful, and may generate nitrogen dioxide instead of nitric oxide, lacking sufficient reducing power and vasodilating properties.
Innovation Solution
A skin dressing comprising a source of protons and a nitrite salt with a pKa of 1.0 to 4.0, using a non-thiol reductant to generate nitric oxide while maintaining a self-regulating pH, avoiding additional acids with pKa between 1 to 4, ensuring efficient conversion of nitrite to nitric oxide and preventing nitrogen dioxide formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acids with pKa between 1 to 4 are used to buffer the formulation to maintain continuous nitric oxide generation, then nitric oxide release efficiency is improved, but prolonged exposure of skin to acidic conditions (pH 1-4) causes harm
Solution Approach 1:
The buffering system is segmented into multiple components: a weak acid buffer (pKa 4.5-7.0) for initial pH control and nitrite for sustained buffering as pH rises. This segmentation allows the system to maintain nitric oxide generation efficiency while avoiding prolonged acidic exposure, as the weak acid buffer has higher pH than strong acids and nitrite buffering kicks in as pH increases
Solution Approach 2:
The invention changes the pH parameter profile over time by using a weak acid buffer system instead of strong acids. The pH starts in the acidic range for efficient nitric oxide generation but naturally rises to neutral range as the reaction progresses and nitrite buffering takes over, thereby maintaining productivity while reducing harmful effects
2Productivity
If strong reducing agents are used to generate nitric oxide from nitrite, then nitric oxide production is improved, but nitrogen dioxide may be generated instead which lacks vasodilating properties
Solution Approach 1:
The invention changes the chemical parameter of the reducing agent from strong reducing agents (which can produce nitrogen dioxide) to mild reducing agents present in physiological systems. This parameter change ensures selective production of nitric oxide without nitrogen dioxide by controlling the reduction potential and reaction conditions through pH management
Solution Approach 2:
The invention uses transient, naturally-occurring reducing agents (like ascorbic acid or glutathione) that are consumed in the reaction rather than stable strong reducing agents. These short-living reducing agents provide just enough reducing power to generate nitric oxide without the side reactions that produce nitrogen dioxide
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 system effectively releases nitric oxide while maintaining a mild pH environment, ensuring efficient conversion and avoiding harmful acidic conditions, with the pH self-regulating as nitric oxide is generated, providing therapeutic benefits like vasodilation and wound healing.
Implementation Method 1
Nitric oxide can be produced by chemical reduction of nitrous acid. Many different reducing agents can be used to reduce nitrous acid
Implementation Method 2
the nitrite itself... capable of maintaining pH in the range between about 3 to 4... As the nitric oxide generation proceeds and nitrite concentration decreases, the buffering capacity in the system will decrease. Simultaneously, protons are consumed during nitrite conversion to nitric oxide. Consequently, the pH of the activated system will increase closer to neutral values
Data Source
Figure 1~2
AI summary
A skin dressing is provided comprising a first component comprising a source of protons, a second component comprising a nitrite salt, the dressing comprising a non- thiol reductant, such that, when the first and second components are brought together and applied to a skin site the nitrite reacts to generate nitric oxide, increasing the pH of the dressing in contact with the skin from an acidic value to a more neutral value.