Tuning H₂S Release by Controlling Mobility in a Micelle Core

Area of Science:

• Polymer Chemistry
• Materials Science
• Drug Delivery

Background:

• Drug release from polymer micelles is crucial for therapeutic efficacy.
• Precise control over drug release kinetics from micelles remains a challenge.
• Hydrogen sulfide (H2S) is a signaling gas with therapeutic potential, but its controlled delivery is complex.

Purpose of the Study:

• To develop a method for precisely tuning drug release rates from polymer micelles.
• To investigate the relationship between hydrophobic core mobility and drug release kinetics.
• To apply this method for controlled, cysteine-triggered release of hydrogen sulfide (H2S).

Main Methods:

• Synthesized polymer amphiphiles with covalently linked H2S donor molecules.
• Varied hydrophobic core mobility by incorporating a plasticizing co-monomer.
• Tuned the glass transition temperature (Tg) of the micelle core.
• Performed H2S release experiments in varying ethanol/water mixtures and aqueous solutions.

Main Results:

• H2S release rates were successfully modulated by altering micelle core mobility.
• Higher ethanol concentrations increased H2S release by swelling micelle cores.
• Varying the amount of plasticizing co-monomer resulted in a 20-fold variation in H2S release rates (t½ = 0.18 - 4.2 h).
• Lower Tg hydrophobic blocks led to faster H2S release.

Conclusions:

• Micelle core mobility is a key factor in controlling drug release kinetics.
• Tuning core mobility via plasticizing co-monomers offers a precise method for modulating release rates.
• This approach is potentially applicable to various drug delivery systems for both encapsulated and covalently linked molecules.