Polythiolactone-based redox-responsive layers for the reversible release of functional molecules.

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomedical Engineering

Background:

• Developing redox-responsive macromolecular layers for drug delivery is crucial for controlled biological signaling.
• Challenges exist in preparing polythiol layers due to rapid thiol oxidation under ambient conditions.

Purpose of the Study:

• To create stable precursors for polythiol layers using thiolactone-containing copolymers.
• To enable on-demand formation of polythiol layers on gold substrates.
• To demonstrate reversible drug grafting and release using these layers.

Main Methods:

• Synthesis of water-soluble thiolactone-containing copolymers.
• Formation of polythiol layers on gold substrates.
• Characterization using electrochemistry, water contact angle, X-ray photoelectron spectroscopy (XPS), and X-ray reflectometry.
• Drug grafting and release studies using a thiolated dye and quartz crystal microbalance (QCM).

Main Results:

• Uniform copolymer layers with both anchored and free thiol groups were successfully formed.
• The density of free thiols correlated with the thiolactone content in the copolymers.
• A model drug (thiolated dye) was grafted onto free thiols via disulfide bonds under mild oxidizing conditions.
• Reversible release and regrafting of the dye were achieved through redox stimulation.

Conclusions:

• Thiolactone-containing copolymers offer a stable precursor strategy for preparing redox-responsive polythiol layers.
• These layers facilitate controlled and reversible drug conjugation and release.
• The developed system holds promise for advanced drug delivery applications.