N-Hydroxysulfosuccinimide Esters versus Thiomers: A Comparative Study Regarding Mucoadhesiveness

AIM: The objective of the study was to compare polyacrylic acid-N-hydroxysulfosuccinimide reactive esters (PAA-Sulfo-NHS) and polyacrylic acid-cysteine conjugates (PAA-Cys) regarding their mucoadhesiveness. METHODS: Polymer conjugates were synthesized in a water free environment and characterized by UV/VIS spectroscopy and FTIR. Water uptake studies were performed and the polymers were further examined for their mucoadhesive properties and cohesiveness using the rotating cylinder method. Tensile force measurements were conducted to define the strength of adhesion to porcine intestinal mucosa. Additionally, polymer-mucus mixtures were assessed for rheological synergism by measuring the increase in dynamic viscosity. RESULTS: Both modifications led to a prolonged adhesion time compared to unmodified PAA. Fast dissolution of PAA-Sulfo-NHS derivatives was monitored, whereas PAA-Cys tends to extensively swell while exhibiting high cohesive properties. Measurements of tensile force revealed up to 2.7-fold (PAA-...