Effect of enzymatic hydrolysis on surface activity and surface rheology of type I collagen

Deepening in the understanding of the role of collagen subunits on the differential molecular arrangement of P. glauca and M. merluccius marine collagens

Decades of extensive efforts on marine collagen extraction and characterization allowed to recognize the unique and excellent characteristics of marine collagen offering advantages over that obtained from terrestrial sources. However, not all marine collagens have the same biochemical characteristics; understanding those at molecular and supramolecular level, is crucial for optimal design of applications. One relevant aspect of collagen characterization is the analysis of its different subunits (α-chains) and their intermolecular cross-links (β- and γ-components), which ultimately determine the specific functions of a particular collagen. Collagens from a teleost and an elasmobranch species were analyzed to understand the influence of their subunit composition and intermolecular crosslinking pattern on their different physicochemical behaviour. For comparative purposes a commercial mammal collagen was included in the study. Although electrophoretic profiles showed the typical composition of type I collagen for hake, blue shark and calf collagen, molar ratios of their α-chains were different indicating a different degree of dimerization of their α2-chains with implications in the presence of a different crosslinking degree pattern. Electrophoresis, amino acid composition, hydrophobicity (RP-HPLC) and molecular weight analysis (GPC-HPLC) results, besides a peptide mapping and an antioxidant activity study of the resultant peptides, would help to understand the role of different subunit collagen composition and different crosslinking pattern in the conformation of a differential quaternary supramolecular structure within different species and its biofunctional implications. The experiments developed would allow to progress in the valorization potential of fish discards and byproducts to explore commercial uses of collagens from marine origin.

Investigation of the effects of bovine collagen peptides and mixed berries on rheological properties and biological activity of egg white-based beverage via central composite design

Modern consumer expectations have become highly diversified: they want more opportunities to meet diverse family needs (diversity of family members in age, gender, physical activity, etc. ,) and individual health goals with a huge variety of sensorial preferences. Our research is aimed to develop a protein-dense, highly bioactive, lactose- and whey protein-free beverage applying a central composite rotational design (CCRD) with 2 factors. For this purpose, an egg white-based beverage was flavored with mixed berries (factor A) and enriched with bovine collagen peptides (factor B). After suitable sample preparation, the rheological properties were investigated by an Anton Paar MCR 92 rheometer (with CC 27 system, and flow behavior was analyzed with a Herschel-Bulkley (H-B) model). The antioxidant capacity of samples was investigated by Ferric Reducing Antioxidant Power (FRAP) method, the total anthocyanin content was estimated based on a spectrophotometric method, and the total phenolic content was determined by the Folin Ciocalteu method. Our results are figured on response surfaces demonstrating that both factors and their interactions show a positive correlation with the examined parameters. Based on the CCRD, all investigated parameters are significantly influenced by at least one aspect and can be adequately estimated for further product development.

Photocatalytic Synthesis of Materials for Regenerative Medicine Using Complex Oxides with β-pyrochlore Structure

Graft copolymerization of methyl methacrylate onto cod collagen was carried out under visible light irradiation (λ = 400-700 nm) at 20-25 °C using the RbTe_1.5W_0.5O₆, CsTeMoO₆, and RbNbTeO₆ complex oxides with β-pyrochlore structure as photocatalysts. The as-prepared materials were characterized by X-ray diffraction, scanning electron microscopy, and UV-Vis diffuse reflectance spectroscopy. It was also found that RbNbTeO₆ with β-pyrochlore structure was not able to photocatalyze the reaction. Enzymatic hydrolysis of the obtained graft copolymers proceeds with the formation of peptides with a molecular weight (MW) of about 20 and 10 kDa. In contrast to collagen, which decomposes predominantly to peptides with MW of about 10 kDa, the ratio of fractions with MW of about 10 kDa and 20 kDa differs much less, their changes are symbatic, and the content of polymers with MW of more than 20 kDa is about 70% after 1 h in the case of graft copolymers. The data obtained indicate that synthetic fragments grafted to the collagen macromolecule do not prevent the hydrolysis of the peptide bonds but change the rate of polymer degradation. This is important for creating network matrix scaffolds based on graft copolymers by cross-linking peptides, which are products of enzymatic hydrolysis.

Collagen Alignment via Electro-Compaction for Biofabrication Applications: A Review

As the most prevalent structural protein in the extracellular matrix, collagen has been extensively investigated for biofabrication-based applications. However, its utilisation has been impeded due to a lack of sufficient mechanical toughness and the inability of the scaffold to mimic complex natural tissues. The anisotropic alignment of collagen fibres has been proven to be an effective method to enhance its overall mechanical properties and produce biomimetic scaffolds. This review introduces the complicated scenario of collagen structure, fibril arrangement, type, function, and in addition, distribution within the body for the enhancement of collagen-based scaffolds. We describe and compare existing approaches for the alignment of collagen with a sharper focus on electro-compaction. Additionally, various effective processes to further enhance electro-compacted collagen, such as crosslinking, the addition of filler materials, and post-alignment fabrication techniques, are discussed. Finally, current challenges and future directions for the electro-compaction of collagen are presented, providing guidance for the further development of collagenous scaffolds for bioengineering and nanotechnology.

Surface tension of native and modified plant seed proteins

The present review, dedicated to Prof. Zbigniew Adamczyk on the occasion of his 70th anniversary, covers the literature data on surface tension and surface compression (dilational) rheology of the adsorbed layers of 21 plant seed proteins (10 leguminous and 11 non-leguminous plants). They are typically analyzed as protein concentrates or isolates, the latter usually obtained by isoelectric precipitation or diafiltration. Despite generally lower solubility, as compared to their animal counterparts (lactoglobulins, caseins, albumins, etc.), the plant seed proteins are also capable of lowering surface tension and forming viscoelastic adsorbed layers. Many seed proteins serve mostly as amino acids reservoirs for the future seedling (storage proteins), hence their instantaneous amphiphilicity is not always sufficient to induce strong adsorption at the aqueous-air interface. They can be, however, conveniently unfolded, hydrolyzed and/or chemically/enzymatically modified to expose more hydrophilic or hydrophobic patches. As shown in numerous contributions reviewed below, the resulting shift of the hydrophilic-lipophilic balance can boost their surface activity to the level comparable to that of many animal proteins or low molecular weight surfactants. An important advantage of the plant seed proteins over the animal ones is their much lower environmental cost and abundance in many plants (e.g. ~40% in sunflower or soybean seeds).

Characterization Methods of Acellularized Tissue and Organs

The extracellular matrix (ECM) of mammalian organs and tissues has been applied as a substitute scaffold to simplify the restoration and reconstruction of several tissues. Such scaffolds are prepared in various arrangements including sheets, powders, and hydrogels. One of the more applicable processes is using natural scaffolds, for this purpose discarded tissues or organs are naturally derived by processes that comprised decellularization of following tissues or organs. Protection of the complex structure and 3D (three dimensional) ultrastructure of the ECM is extremely necessary but it is predictable that all protocols of decellularization end in disruption of the architecture and potential loss of surface organization and configuration. Tissue decellularization with conservation of ECM bioactivity and integrity can be improved by providing well-designed protocols regarding the agents and decellularization techniques operated during processing. An overview of the characterization of decellularized scaffolds and the role of reagnets can validate the applied methods' efficacy.

Enzymatic Hydrolysis of Marine Collagen and Fibrinogen Proteins in the Presence of Thrombin

: Enzymatic hydrolysis of native collagen and fibrinogen was carried out under comparable conditions at room temperature. The molecular weight parameters of proteins before and after hydrolysis by thrombin were monitored by gel-penetrating chromatography (GPC). An analysis of the experiment results shows that the molecular weight parameters of the initial fibrinogen (Fn) and cod collagen (CC) are very similar. High molecular CC decays within the first minute, forming two low molecular fractions. The main part (~80%) falls on the fraction with a value of Mw less than 10 kDa. The initial high molecular fraction of Fn with Mw ~320-340 kDa is not completely hydrolyzed even after three days of control. The presence of low molecular fractions with Mw ~17 and Mw ~10 kDa in the solution slightly increases within an hour and noticeably increases for three days. The destruction of macromolecules of high molecular collagen to hydrolysis products appears almost completely within the first minute mainly to the polymer with Mw ~10 kDa, and enzymatic hydrolysis of fibrinogen proceeds slower than that of collagen, but also mainly to the polymer with Mw ~10 kDa. Comparative photos of the surfaces of native collagen, fibrinogen and the scaffold based on them were obtained.

Hydrolyzed Collagen-Sources and Applications

Hydrolyzed collagen (HC) is a group of peptides with low molecular weight (3-6 KDa) that can be obtained by enzymatic action in acid or alkaline media at a specific incubation temperature. HC can be extracted from different sources such as bovine or porcine. These sources have presented health limitations in the last years. Recently research has shown good properties of the HC found in skin, scale, and bones from marine sources. Type and source of extraction are the main factors that affect HC properties, such as molecular weight of the peptide chain, solubility, and functional activity. HC is widely used in several industries including food, pharmaceutical, cosmetic, biomedical, and leather industries. The present review presents the different types of HC, sources of extraction, and their applications as a biomaterial.

Generation of shrimp waste-based dispersant for oil spill response

In this study, shrimp waste was enzymatically hydrolyzed to generate a green dispersant and the product was tested for crude oil dispersion in seawater. The hydrolysis process was first optimized based on the dispersant effectiveness (DE) of the product. The functional properties of the product were identified including stability, critical micelle concentration, and emulsification activity. Water was confirmed as a good solvent for dispersant generation when compared with three chemical solvents. The effects of salinity, mixing energy, and temperature on the dispersion of the Alaska North Slope (ANS) crude oil were examined. Microtox acute toxicity test was also conducted to evaluate the toxicity of the produced dispersant. In addition, DE of the product on three different types of crude oil, including ANS crude oil, Prudhoe Bay crude oil (PBC), and Arabian Light crude oil (ALC) was compared with that of the Corexit 9500, respectively. The research output could lead to a promising green solution to the oil spill problem and might result in many other environmental applications.

Collagen Hydrolysates of Skin Shavings Prepared by Enzymatic Hydrolysis as a Natural Flocculant and Their Flocculating Property

A series of collagen hydrolysates (CHs) were prepared from pigskin shavings by using pepsin (PCH), trypsin (TCH), Alcalase (ACH), HCl (HCH), and NaOH (NCH). Their physicochemical properties, including degree of collagen hydrolysis, molecular weight distribution, electric charge, and microstructure, were investigated, and their flocculation performance was evaluated in a kaolin suspension, at varied pHs and concentrations. PCH exhibited high flocculation capability under acidic and neutral conditions, and its efficiency for removing suspended particles was approximately 80% at a concentration of 0.05 g/L. TCH, ACH, HCH, and NCH showed almost no flocculation capability. The flocculation capability of PCH could be mainly due to a combination of optimal molecular weight distribution and electric charge. This study could provide an environment-friendly natural flocculant and also proposes a promising approach for the reuse of collagen wastes. Graphical Abstract ᅟ.

Effect of surfactants on surface activity and rheological properties of type I collagen at air/water interface

We describe the effect of three synthetic surfactants (anionic - sodium dodecyl sulfate (SDS), cationic - cetyltrimethylammonium bromide (CTAB) and nonionic - Triton X-100 (TX-100)) on surface properties of the type I calf skin collagen at the air/water interface in acidic solutions (pH 1.8). The protein concentration was fixed at 5×10^-6molL^-1 and the surfactant concentration was varied in the range 5×10^-6molL^-1-1×10^-4molL^-1, producing the protein/surfactant mixtures with molar ratios of 1:1, 1:2, 1:5, 1:10 and 1:20. An Axisymmetric Drop Shape Analysis (ADSA) method was used to determine the dynamic surface tension and surface dilatational moduli of the mixed adsorption layers. Two spectroscopic techniques: UV-vis spectroscopy and fluorimetry allowed us to determine the effect of the surfactants on the protein structure. The thermodynamic characteristic of the mixtures was studied using isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). Modification of the collagen structure by SDS at low surfactant/protein ratios has a positive effect on the mixture's surface activity with only minor deterioration of the rheological properties of the adsorbed layers. The collagen/CTAB mixtures do not show that pronounced improvement in surface activity, while rheological properties are significantly deteriorated. The mixtures with non-ionic TX-100 do not show any synergistic effects in surface activity.