Thiolated polymers: An overview of mucoadhesive properties and their potential in drug delivery via mucosal tissues

Thiolated polymers, or thiomers, are a class of polymers that exhibit unique mucoadhesive properties, allowing them to form strong covalent bonds with cysteine-rich subdomains of mucus glycoproteins. This property makes them ideal for developing drug delivery systems (DDSs) for various dry mucosal surface diseases. Compared to their non-thiolated counterparts, thiomers offer higher adhesion and retention time, leading to increased bioavailability and reduced patient noncompliance. They can also inhibit certain enzymes, increase permeability, and shield protein and peptide drugs from digestive enzymes. Thiomers have been investigated for use in various routes of administration, and different types of polymers have been thiolated using different thiolation moieties. Thiolated polymers have great application potential, including mucoadhesive and controlled drug release, and tissue engineering. This review explores the impacts of thiolation and the function of thiomers in different administration routes, highlighting their potential to empower drug delivery via mucosal tissues for improved therapeutic outcomes.