Light Scattering Study of Heat-Induced Aggregation and Gelation of Ovalbumin

Weijers, Mireille; Visschers, Ronald W.; Nicolai, Taco

doi:10.1021/ma0120198

Cited by 90 publications

(89 citation statements)

References 26 publications

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“…3b). These observations indicate that extended interconnected networks are formed in these samples, with networks becoming more rigid with an increasing degree of interconnection, similar to previous observations in colloidal, protein and polymer solutions [27][28][29] . It is likely that the mobility of enzyme clusters within these increasingly rigid interconnected networks is reduced, reducing discontinuities in fibre assembly and thereby favouring the formation of longer fibres, as observed by AFM.…”

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confidence: 89%

Biocatalytic induction of supramolecular order

et al. 2010

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Supramolecular gels, which demonstrate tunable functionalities, have attracted much interest in a range of areas, including healthcare, environmental protection and energy-related technologies. Preparing these materials in a reliable manner is challenging, with an increased level of kinetic defects observed at higher self-assembly rates. Here, by combining biocatalysis and molecular self-assembly, we have shown the ability to more quickly access higher-ordered structures. By simply increasing enzyme concentration, supramolecular order expressed at molecular, nano-and micro-levels is dramatically enhanced, and, importantly, the gelator concentrations remain identical. Amphiphile molecules were prepared by attaching an aromatic moiety to a dipeptide backbone capped with a methyl ester. Their self-assembly was induced by an enzyme that hydrolysed the ester. Different enzyme concentrations altered the catalytic activity and size of the enzyme clusters, affecting their mobility. This allowed structurally diverse materials that represent local minima in the free energy landscape to be accessed based on a single gelator structure.M olecular self-assembly 1-7 can be controlled using a variety of stimuli, including chemical 8,9 and mechanical 10 triggers, as well as X-rays 11 . Although the traditional premise in selfassembly suggests that supramolecular material properties can be fully encoded into molecular building blocks, it is increasingly apparent that the chosen self-assembly pathway is central to the final structure and its material functionality. Biocatalytic control of self-assembly systems is a novel direction for laboratory-based self-assembly 12-17 , although it is omnipresent in the biological world. Indeed, enzymatically controlled self-assembly and disassembly underlies vital processes such as cell movement, intracellular transport and muscle contraction. In chemists' hands, the combination of biocatalysis and molecular self-assembly has recently emerged as a powerful new approach to make novel stimuli-responsive molecular materials [12][13][14][15][16][17] . We believe that catalytic control of self-assembly provides important new methodology beyond such triggering of material transitions. In particular, the combination of biological selectivity, localized action and operation under constant, physiological conditions provides a new methodology for bottomup nanofabrication of future soft materials and devices, allowing for unprecedented control of supramolecular order.Here, we focus on the control of supramolecular order with few defects. In principle, there are two possible approaches to defect reduction-either improving the fidelity of the self-assembly process (avoiding defects) or using fully reversible systems that operate under thermodynamic control (repairing defects). The latter approach is generally slow and only applicable to cases where the desired structure represents the global equilibrium state and where the system is fully reversible, that is, under thermodynamic control 16 . Many structure...

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confidence: 89%

Biocatalytic induction of supramolecular order

et al. 2010

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“…This kind of process was never used for commercial egg white isolates, as they gel at the preheating part of the process at as low as 3% protein solutions (Holt et al, 1984;Croguennec et al, 2002). In some laboratory tests the main M. T.-Mleko et al 1208 crystallized egg white protein -ovalbumin is used or commercial egg white protein is desalinated (Weijers et al, 2002;Weijers et al, 2006). Arntfield (1996) used calcium and magnesium to obtain "cold set" ovalbumin gels.…”

Section: Introductionmentioning

confidence: 99%

Ca2+-Induced Egg White Isolate Gels with Various Microstructure

Tomczyńska‐Mleko

Nishinari

Handa³

2014

FSTR

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Commercially available egg white isolates (EWI) or concentrates can not be used for ions-induced gelationbecause of high mineral content. In the present research new egg white isolate with reduced minerals content was applied for production of calcium induced gel. At 5.5% critical protein concentration no gel was obtained at the preheating process at 80℃ for 30 min. Increased calcium ions concentration formed more elastic gels with higher hardness, adhesiveness and chewiness. There was a linear correlation between (dynamic viscosity) x (density) of the gels and chewiness, hardness and adhesiveness. Higher calcium ions concentration produced more aggregated gels with higher surface roughness. There was a linear correlation between quadratic mean of the surface roughness and maximum roughness height for the gels with different calcium concentration.Keywords: egg white, gelation, salt induced, rheological properties IntroductionEgg white albumin is probably the most popular gelling protein. Heat-induced gelation process involving aggregation and turning translucent egg white into white gel is observed at boiling eggs. Egg white protein is a complete protein with all essential amino acids (Vanniekerk et al., 1993). Together with whey protein it is used as a source of protein in supplements for physically active people. Egg white protein concentrates and isolates have excellent gelling and foaming properties (Foegeding et al., 2000). Heated dispersions form gels and their properties are dependent on the powder composition, pH and ionic composition of solvent and heating conditions (Sun et al., 2002; Broersen et al., 2000).In the beginning of the 1990s a new method of gelation was invented (Foegeding and Barbut 1993). Heating a dispersion of whey protein isolate leads to unfolding and polymerization of proteins and increase in viscosity (Vardhanabhuti and Foegeding 1999). Protein dispersion pH is above isoelectric point of whey proteins (ca. 5) and the repulsion between negatively charged protein molecules prevents them from forming a gel matrix. After cooling to room temperature some ions are added, which neutralize the charges on the surface of proteins. This "shielding effect" enables more intensive interactions between the proteins molecules and at a critical protein concentration a gel is formed (Barbut and Foegeding 1993;Hongsprabhas and Barbut 1997; Bryant and McClements, 2000). This kind of process was never used for commercial egg white isolates, as they gel at the preheating part of the process at as low as 3% protein solutions (Holt et al., 1984;Croguennec et al., 2002). In some laboratory tests the main M. T.-Mleko et al. 1208 crystallized egg white protein -ovalbumin is used or commercial egg white protein is desalinated (Weijers et al., 2002;Weijers et al., 2006). Arntfield (1996) used calcium and magnesium to obtain "cold set" ovalbumin gels. Increased salt concentration causes formation of stronger gels (Artfield 1996;Savoie et al., 1996). Savoie et al. (1996) reported that the fracture stress sh...

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“…16,18,19 Because ATRA is unstable to heat, we employed two-step procedure to prepare complex between OVA NPs and ATRA, i.e., preparing OVA NPs then complexing them with ATRA. In the heat-induced aggregation method, size of resulting protein aggregates depends on heating temperature and solution conditions such as a protein concentration, pH and ionic strength.…”

Section: Preparation and Characterization Of Ova Npsmentioning

confidence: 99%

“…In the heat-induced aggregation method, size of resulting protein aggregates depends on heating temperature and solution conditions such as a protein concentration, pH and ionic strength. 18,19 We aimed to adjust the size of OVA NPs around 100 nm because it is ideal size for uptake by dendritic cells. 20,21 To achieve the aimed size, we screened preparation conditions based on the literature 16 and determined the optimum condition as follows: 10 mg/mL OVA in 50 mM NaCl (pH 7.0), and heating at 85 o C for 5 min.…”

Section: Preparation and Characterization Of Ova Npsmentioning

confidence: 99%