{"title":"Effect of urea on the linear and nonlinear rheological properties of human serum albumin hydrogels","authors":"Tochukwu Olunna Nnyigide, Osita Sunday Nnyigide, Kyu Hyun","doi":"10.1007/s00397-024-01467-7","DOIUrl":null,"url":null,"abstract":"<div><p>We report the linear and nonlinear rheological properties of human serum albumin (HSA) hydrogels with and without urea using small (SAOS) and large (LAOS) amplitude oscillatory shear tests. In SAOS tests, pure HSA and HSA-urea hydrogels exhibited a predominantly solid-like behavior (G' ≫ G''), with viscoelastic properties proportional to HSA concentrations. As urea concentration increased, the viscoelastic properties of the hydrogels decreased and the frequency dependence declined, indicating a sparser cross-linking network. Under LAOS flow, both pure HSA and HSA-urea hydrogels exhibited intra- and inter-cycle strain-stiffening, which became more pronounced with increasing urea concentration. The presence of urea delayed the onset of the nonlinear behavior in HSA-urea hydrogels, in proportion to the urea concentration, decreasing the hydrogel strength. The degree of nonlinearity, quantified by the intrinsic nonlinear parameter Q<sub>0</sub> from Fourier-transform rheology, decreased with increasing urea concentration. Additionally, critical strain amplitudes obtained from LAOS tests indicated that the yield strain of the HSA-urea hydrogels increased with urea concentration. The intracycle behavior was analyzed by sequence of physical processes methods. Molecular dynamics simulations were performed to analyze the hydrogels behavior at the atomic level. Significant changes in the hydrogel network were attributed to the efficient insertion of urea into the HSA hydrogen bond network, which forms the cross-linking network. Thus, the hydrogen bonding between urea and HSA, as well as urea’s contribution to HSA denaturation, affects the gelation, linear, and nonlinear viscoelastic properties of the HSA hydrogels.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":null,"pages":null},"PeriodicalIF":2.3000,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Rheologica Acta","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s00397-024-01467-7","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MECHANICS","Score":null,"Total":0}
引用次数: 0
Abstract
We report the linear and nonlinear rheological properties of human serum albumin (HSA) hydrogels with and without urea using small (SAOS) and large (LAOS) amplitude oscillatory shear tests. In SAOS tests, pure HSA and HSA-urea hydrogels exhibited a predominantly solid-like behavior (G' ≫ G''), with viscoelastic properties proportional to HSA concentrations. As urea concentration increased, the viscoelastic properties of the hydrogels decreased and the frequency dependence declined, indicating a sparser cross-linking network. Under LAOS flow, both pure HSA and HSA-urea hydrogels exhibited intra- and inter-cycle strain-stiffening, which became more pronounced with increasing urea concentration. The presence of urea delayed the onset of the nonlinear behavior in HSA-urea hydrogels, in proportion to the urea concentration, decreasing the hydrogel strength. The degree of nonlinearity, quantified by the intrinsic nonlinear parameter Q0 from Fourier-transform rheology, decreased with increasing urea concentration. Additionally, critical strain amplitudes obtained from LAOS tests indicated that the yield strain of the HSA-urea hydrogels increased with urea concentration. The intracycle behavior was analyzed by sequence of physical processes methods. Molecular dynamics simulations were performed to analyze the hydrogels behavior at the atomic level. Significant changes in the hydrogel network were attributed to the efficient insertion of urea into the HSA hydrogen bond network, which forms the cross-linking network. Thus, the hydrogen bonding between urea and HSA, as well as urea’s contribution to HSA denaturation, affects the gelation, linear, and nonlinear viscoelastic properties of the HSA hydrogels.
期刊介绍:
"Rheologica Acta is the official journal of The European Society of Rheology. The aim of the journal is to advance the science of rheology, by publishing high quality peer reviewed articles, invited reviews and peer reviewed short communications.
The Scope of Rheologica Acta includes:
- Advances in rheometrical and rheo-physical techniques, rheo-optics, microrheology
- Rheology of soft matter systems, including polymer melts and solutions, colloidal dispersions, cement, ceramics, glasses, gels, emulsions, surfactant systems, liquid crystals, biomaterials and food.
- Rheology of Solids, chemo-rheology
- Electro and magnetorheology
- Theory of rheology
- Non-Newtonian fluid mechanics, complex fluids in microfluidic devices and flow instabilities
- Interfacial rheology
Rheologica Acta aims to publish papers which represent a substantial advance in the field, mere data reports or incremental work will not be considered. Priority will be given to papers that are methodological in nature and are beneficial to a wide range of material classes. It should also be noted that the list of topics given above is meant to be representative, not exhaustive. The editors welcome feedback on the journal and suggestions for reviews and comments."