Transdermal Hydrogen Sulfide Delivery Enabled by Open-Metal-Site Metal-Organic Frameworks

Area of Science:

• Materials Science
• Chemical Engineering
• Dermatology

Background:

• Hydrogen sulfide (H₂S) is a vital endogenous gasotransmitter with significant anti-inflammatory and antioxidant properties.
• H₂S plays a crucial role in skin health, including wound healing and mitigating inflammatory skin conditions.
• Current transdermal H₂S delivery methods using small molecules have limitations, including suboptimal delivery and potential toxicity from byproducts.

Purpose of the Study:

• To investigate metal-organic frameworks (MOFs) as a superior alternative for controlled transdermal hydrogen sulfide (H₂S) delivery.
• To evaluate the suitability of the Mg-based MOF, Mg₂(dobdc), for safe and effective transdermal H₂S administration.

Main Methods:

• Screened 11 MOFs for H₂S delivery capabilities using gas sorption and powder X-ray diffraction (PXRD).
• Characterized Mg₂(dobdc) for H₂S binding affinity, capacity, and toxicity.
• Utilized synchrotron PXRD and Rietveld refinement to analyze H₂S binding sites within the Mg₂(dobdc) structure.
• Assessed sustained transdermal H₂S delivery through porcine skin over 24 hours.

Main Results:

• Mg₂(dobdc) demonstrated strong, reversible H₂S binding with a high capacity (14.7 mmol/g) and no observed toxicity.
• PXRD and synchrotron data revealed three distinct binding sites within Mg₂(dobdc) contributing to its high H₂S uptake.
• Sustained transdermal H₂S delivery from Mg₂(dobdc) was achieved over 24 hours, outperforming traditional sodium sulfide.

Conclusions:

• Mg₂(dobdc) represents a promising, solid-state H₂S source for controlled and safe transdermal delivery.
• This study marks the first successful demonstration of controlled transdermal delivery of pure H₂S gas using a MOF.
• H₂S-loaded Mg₂(dobdc) offers a therapeutically viable platform for managing skin disorders and promoting wound healing.