Size and Shape of Primary (Bio)Polyelectrolyte Complexes Chitosan/Gelatin: Study Using Small-Angle X-Ray Scattering...

Area of Science:

• Biopolymer science
• Materials science
• Physical chemistry

Background:

• Chitosan and gelatin are biocompatible polyelectrolytes with potential applications in various fields.
• Understanding their self-assembly behavior is crucial for designing novel biomaterials.
• Polyelectrolyte complexation is influenced by pH, concentration, and ratio of components.

Purpose of the Study:

• To investigate the macromolecular structure and self-assembly of chitosan and gelatin polyelectrolyte mixtures.
• To determine the size, shape, and formation of supramolecular complexes at different pH values and ratios.
• To elucidate the role of polyelectrolyte associative interactions in complex formation.

Main Methods:

• Small-angle X-ray scattering (SAXS) from synchrotron radiation.
• Pair distance function analysis.
• Ab initio shape reconstruction.

Main Results:

• Individual chitosan and gelatin molecules formed oblate spheroid structures.
• Below the isoelectric point, mixtures showed minimal structural changes.
• Above the isoelectric point, mixtures (ratio > 1:5) formed elongated, cylinder-like supramolecular complexes, indicating enhanced polyelectrolyte interactions.

Conclusions:

• The pH-dependent associative interactions between chitosan and gelatin significantly influence their self-assembly.
• Supramolecular complex formation, particularly above the isoelectric point, leads to distinct structural changes and potential applications in biomaterials.
• SAXS is an effective technique for characterizing the nanoscale structure of biopolymer complexes.