Directed 2-dimensional organisation of collagen: Role of cross-linking and denaturing agents

Abstract

The effect of additives like curcumin and surfactants on the self-assembly of collagen from a simple 2-dimensional system of Langmuir films of the protein at air/solution interface has been attempted in this study using quartz crystal microbalance (QCM) and dynamic surface tensiometer. Though pure curcumin is not surface active, a synergistic effect of collagen with curcumin seems to lead to enhanced surface activity in the protein. In general, the presence of additives, increases the surface activity of collagen even for the lowest concentration and the largest change in surface activity is seen for collagen with sodium dodecyl sulfate (SDS). The results suggest interplay between the unexposed hydrophobic groups, and the opening out and solvation of the more charged or polar groups at the surface leading to aggregation followed by self-assembly. Modulation of aggregation at interface in collagen due to these additives may be an approach that could be explored for possible applications in bio-materials and for delivery of protein-drug complexes.

Engineered Coiled-Coil Protein Microfibers

“…Morphology and aggregation of α-helical protein fibers results from an energetically favorable balance between the burial of the hydrophobic residues and the solvation of the surface-facing polar groups. 56 Our CD studies have confirmed that increasing molar ratios of curcumin affects only helical packing, not protein conformation. Curcumin increases the surface activity of collagen as a result of local restructuring of water, leading to some exposure of nonpolar groups.…”

“…With curcumin being fully protonated at pH 4, the interaction of curcumin with negative charges on the protein is likely. 56 Indeed, as curcumin concentration increases, the zeta potential exhibits a slight increase as well, indicating a neutralization of any negative charges through binding to curcumin (Figure 4a). For Q, zeta potential in the absence of curcumin is 19.1 ± 2.5 mV, with a steady increase up to a maximum value of 25.2 ± 0.8 mV at a curcumin concentration of 40 μM (Figure 4a).…”

“…5 We have engineered proteins that can hierarchically assemble into mesofibers with the assistance of small molecules through encapsulation and aggregation (Figure S13). While studies have been performed on controlling aggregation of coiled-coil protein fibers through macromolecular crowding 50 and adjusting solvent conditions such as pH 60 and ionic strength, 11 save a few exceptions, 56,57,61 comparatively little work has been done on inducing aggregation of α-helical protein fibers through additives. In such examples, change on the order of the nanometer to micrometer scale of de novo designed α-helical protein fibers has not been previously reported.…”

Collagen films with stabilized liquid crystalline phases and concerns on osteoblast behaviors

“…The relatively stiff collagen molecules can self-assemble at the level of microfibrils, fibrils, and suprafibrillar networks [20]. Moreover, solutions of the filament-shaped protein exhibit a lyotropic LC behavior, that undergoes a spontaneous phase transition from isotropic to crystalline state with increasing concentration.…”

Hydration dynamics of collagen/PVA composites: Thermoporometric and impedance analysis

“…Porous scaffolds are gaining importance in tissue engineering applications and organ regeneration. Collagen, a significant component of the extracellular matrix (ECM), provides principal structural and mechanical support to the connective tissues [3].…”