Protein microparticles visualize the contact network and rigidity onset in the gelation of model proteins

Abstract

Protein aggregation into gel networks is of immense importance in diverse areas from food science to medical research; however, it remains a grand challenge as the underlying molecular interactions are complex, difficult to access experimentally, and to model computationally. Early stages of gelation often involve protein aggregation into protein clusters that later on aggregate into a gel network. Recently synthesized protein microparticles allow direct control of these early stages of aggregation, decoupling them from the subsequent gelation stages. Here, by following the gelation of protein microparticles directly at the particle scale, we elucidate in detail the emergence of a percolating structure and the onset of rigidity as measured by microrheology. We find that the largest particle cluster, correlation length, and degree of polymerization all diverge with power laws, while the particles bind irreversibly indicating a nonequilibrium percolation process, in agreement with recent results on weakly attractive colloids. Concomitantly, the elastic modulus increases in a power-law fashion as determined by microrheology. These results give a consistent microscopic picture of the emergence of rigidity in a nonequilibrium percolation process that likely underlies the gelation in many more systems such as proteins, and other strongly interacting structures originating from (bio)molecules.

Physicochemical Properties and in vitro Digestibility of Myofibrillar Proteins From the Scallop Mantle (Patinopecten yessoensis) Based on Ultrahigh Pressure Treatment

“…It might be induced by the depolymerization of actin and actomyosin under UHP treatment. It was in accordance with the previous report that the increase of protein solubility resulted from the increase of shear treatment, which could disrupt newly formed polymers and prompt the interaction of unfolded protein and water molecules ( 33 ). The solubility reduction of MP from scallop mantle might be attributed to the fact that high-pressure treatment (≥300 MPa) promoted the formation of insoluble protein aggregates through non-disulfide and disulfide bonds relying on the exposure of the interior hydrophobic resides and sulfhydryl groups ( 34 ).…”

Polyphenol-Enriched Protein Oleogels as Potential Delivery Systems of Omega-3 Fatty Acids

“…This microscopic insight allows us to propose the possible interparticle attraction behind oleogelation. For WPM-GA, WPM-EGCG, and WPM-TA oleogels, protein particles stick to form strand-like and relatively fine clusters with large fractal dimensions, which might be associated with the high interparticle attraction . We have demonstrated the enhanced particle–particle interaction and strengthened structural rigidity of the Pickering emulsion gels due to the increased hydrogen-bonding interaction between polyphenol-functionalized protein particles …”

Rigidity-Induced Controlled Aggregation of Binary Colloids

“…The irreversible system mimics the recent experimentally realized protein microparticle aggregation process. 4 By tuning the bond flexibility in only one species of the binary system, we demonstrate that the kinetics of colloidal aggregation can be altered. The change in kinetics is observed only in one species and in both species depending upon the combination of packing volume fraction and critical concentration.…”

“…As a proof-of-concept, we model the binary system with irreversible bond formation in both species of the colloidal mixture. The irreversible system mimics the recent experimentally realized protein microparticle aggregation process . By tuning the bond flexibility in only one species of the binary system, we demonstrate that the kinetics of colloidal aggregation can be altered.…”