Bovine Serum Albumin Hydrogel Formation: pH Dependence and Rheological Analyses.

Area of Science:

• Biopolymer science
• Materials science
• Protein chemistry

Background:

• In vitro evaluation of biopolymer-based hydrogels aids understanding of phenomena like liquid-liquid phase separation.
• Bovine serum albumin (BSA) hydrogels are investigated for their physical properties across a pH range.

Purpose of the Study:

• To investigate the formation of BSA hydrogels in the pH range of 1.0 to 4.0.
• To analyze the structural changes of BSA under acidic conditions.
• To establish a reproducible method for measuring hydrogel viscoelasticity with minimal sample volume.

Main Methods:

• Hydrogel formation was studied across a pH range of 1.0 to 4.0.
• Circular dichroism spectroscopy was used to determine α-helix content at various pH values.
• Dynamic viscoelastic properties were measured using a traditional rheometer with small sample volumes (200 and 350 μL).

Main Results:

• BSA hydrogels formed between pH 3.0 and 4.0, with viscous solutions forming between pH 1.5 and 2.5.
• Unexpectedly, BSA hydrogel formed at pH 1.0.
• α-helix content decreased with decreasing pH, indicating BSA denaturation, yet α-helix content at pH 1.0 and 3.0 was similar.
• BSA hydrogels at pH 1.0 and 3.5 exhibited comparable dynamic viscoelastic properties.
• A reproducible procedure for measuring hydrogel viscoelasticity using minimal sample volumes was developed.

Conclusions:

• BSA hydrogel formation at pH 1.0 is linked to stereo structural changes from denatured E-isoform to partially denatured F-isoform.
• The study provides insights into BSA hydrogel formation and denaturation under extreme acidic conditions.
• A reliable method for assessing hydrogel viscoelasticity with limited sample amounts was successfully established.