Pigeon egg white protein-based transparent durable hydrogel via monodisperse ionic surfactant-mediated protein condensation

Abstract

The thermal gelation property of proteins is useful in creating protein-based materials. The gelation of protein solution often proceeds by the random aggregation of denatured proteins, and the protein-based gels are typically brittle or opaque, or both. Improvement in the mechanical and optical properties of protein-based materials are required for them to be practical and functional. This study investigated pigeon egg white, which is semitransparent in its thermally gelled state, as a protein source for creating hydrogel materials. The protein thermal gelation process was initiated from the orderly condensed state of proteins complexed with monodisperse ionic surfactants to suppress random aggregation. The resultant gel showed transparency in the visible light region and was not destroyed at 99% compression under 17.8 MPa compressive stress, 350-fold higher than the compressive fracture strength of typical boiled pigeon egg white. These results showed that durable transparent hydrogels could be fabricated by the rational combination of natural proteins and surfactants.

Facile Fabrication of Transparent and Opaque Albumin Methacryloyl Gels with Highly Improved Mechanical Properties and Controlled Pore Structures

“…Various tough transparent hydrogels have been synthesized as smart windows, as antibacterial coatings, and as optical detectors for tissue engineering and industrial applications [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Similarly tough opaque hydrogels have been utilized more often as bone regeneration or bone tissue engineering scaffolds [ 33 ].…”

Toward Tunable Protein‐Driven Hydrogel Lens

“…While numerous studies have used diverse protein biochemical structures to embed them into polymer hydrogels, [ 25 , 38 , 47 ] a unique feature of our system is that we used BSA to manipulate the microstructure of PEGDA hydrogels to improve their transparency up to ≈95% without compromising the protein secondary structure. [ 26 , 28 , 29 ] In addition, our hydrogel transparency is preserved even under acidic conditions (pH ≈ 2), as the mild denaturing of the BSA molecules (Figures 3f and 4f ) tends to yield a consistent and evenly dispersed arrangement of the denatured BSA molecules, increasing the swelling behavior, and contributing to its transparency. [ 16 ] Additionally, BSA functionalization with PEGDA acted as a spacer between BSA molecules in the hybrid BSA‐PEGDA network.…”

“…[ 26 , 27 ] Recently, a study investigating the gelation of a mixture of pigeon egg white with ionic surfactants at boiling temperatures (≈90 °C) resulted in a transparent hydrogel with 99% light transmittance. [ 28 ] These strategies use experimental processes such as alkyl hydrolysis, high temperatures, and time‐consuming reactions, [ 29 ] which lead to structural alteration and aggregation and conceal the potential of protein‐folded structure and functionality. [ 30 ] An intriguing example is a tunable transparent protein‐based lens, which uses protein nanomechanics to mimic focal accommodation and relaxation in a human lens.…”