Quantitative determination of fucoidan using polyion-sensitive membrane electrodes.

Area of Science:

• Analytical Chemistry
• Marine Biotechnology
• Biochemistry

Background:

• Fucoidans are sulfated polysaccharides from brown algae with complex, branched structures and variable charge densities.
• Existing electrochemical sensors are often designed for linear polyanions, limiting their application to complex molecules like fucoidans.
• Accurate quantification of fucoidan is crucial for understanding its biological activities and applications.

Purpose of the Study:

• To develop and validate sensitive membrane electrodes for the detection and quantification of fucoidan.
• To investigate the use of polyanion-sensitive electrodes for analyzing highly branched, sulfated polysaccharides.
• To assess the applicability of these methods for determining fucoidan content in nutritional supplements and biological fluids.

Main Methods:

• Utilized polyanion-sensitive membrane electrodes with tridodecylmethylammonium (TDMA) for direct EMF response measurement.
• Employed potentiometric titration with polycationic protamine and a dinonylnaphthalene sulfonate (DNNS)-doped electrode for endpoint detection.
• Determined the binding ratio between protamine and fucoidan to quantify fucoidan content.

Main Results:

• A significant, non-equilibrium EMF response was observed for fucoidan over a concentration range of 0.5-50 μg mL(-1) using TDMA-based electrodes.
• Potentiometric titration successfully determined the binding ratio of protamine to fucoidan for various preparations.
• Fucoidan content was accurately determined in commercial nutritional supplements.
• Successful measurement of fucoidan in undiluted blood serum was achieved.

Conclusions:

• Polyanion-sensitive membrane electrodes offer a viable method for quantifying complex, branched fucoidans.
• The developed potentiometric titration method allows for accurate fucoidan determination in diverse matrices.
• These findings suggest potential clinical applications for fucoidan measurement in biological samples like blood serum.