Characterization of chitosan thiolation and application to thiol quantification onto nanoparticle surface

Area of Science:

• Materials Science
• Analytical Chemistry
• Polymer Chemistry

Background:

• Thiol group quantification is crucial for characterizing modified nanoparticles.
• The Ellman's assay is widely used but faces challenges with thiolated polymers due to solubility and stability issues.
• Core-shell nanoparticles with poly(isobutyl cyanoacrylates) and thiolated chitosan require reliable surface thiol analysis.

Purpose of the Study:

• To develop a simple and effective method for quantifying thiol groups on the surface of core-shell nanoparticles.
• To critically evaluate the suitability of the Ellman's method for thiolated chitosan-coated nanoparticles.
• To establish an alternative quantification technique for surface thiol groups.

Main Methods:

• Critical analysis of the Ellman's assay for thiol determination in thiolated polymers.
• Development of a novel thiol quantification method based on classical iodine titration.
• Application of the new method to quantify thiol groups on poly(isobutyl cyanoacrylates) nanoparticles coated with thiolated chitosan.

Main Results:

• The Ellman's method demonstrated limited value for quantifying thiol groups in thiolated chitosan due to poor solubility and reaction instability.
• A simple iodine titration method was successfully developed and validated.
• The new method allows for thiol quantification in small sample amounts at acidic pH and kinetic monitoring.

Conclusions:

• Iodine titration provides a superior and simpler alternative to the Ellman's assay for quantifying thiol groups on thiolated chitosan-coated nanoparticles.
• The developed method is effective for analyzing active thiol groups on nanoparticle surfaces.
• This work offers a valuable tool for the characterization of functionalized nanomaterials.