Comparison of chemical treatments on the chain dynamics and thermal stability of bovine pericardium collagen

Abstract

A new approach for the replacement of heart valves consists of obtaining an acellular matrix from animal aortic valves that performs mechanically, is nonantigenic, and is free from calcification and fibroblast proliferation. Novel biochemical treatments must be developed for this purpose. In this work, we focus on the characterization of collagen in acellular bovine cardiovascular tissues, fresh or glutaraldehyde treated, and stored in different solutions [phosphate-buffered saline (PBS), ethanol, octanol, and glutaraldehyde], to determine whether the resulting fibrous material is structurally preserved. The preservation of the triple helical structure of collagen is checked by differential scanning calorimetry (DSC), which is a well suited technique to analyze thermal transitions in proteins, such as denaturation. To get insight into the molecular dynamics of collagen in the nanometric range, we used thermally stimulated currents, a dielectric technique running at low frequency, that measure the dipolar reorientations in proteins submitted to a static electrical field. The combined use of these two techniques allowed us to evaluate the physical structure and conformation of collagen after the different chemical treatments. We have found that the glutaraldehyde treatment followed by octanol storage preserves the triple helical conformation of the polypeptidic chains of collagen, contrary to the ethanol and PBS storage that induce drastic changes in the thermal and dielectric behavior of the protein. Moreover, this particular chemical treatment stabilizes the collagen structure (shift toward high temperature of the collagen denaturation and stiffening of the chains by a cross-linking action) when compared to the control sample, and so could provide interesting fibrous material for the conception of bioprosthetic heart valve.

Development of Composite Porous Scaffolds Based on Collagen and Biodegradable Poly(ester urethane)urea

“…This could be due to hydrogen bond interactions between collagen and PEUU decreasing collagen chain interactions, which would facilitate the conformational change at denaturation relative to collagen alone. The existence of the endothermic denaturation peak in the composite implies that collagen in the composite maintained a triple helical structure and did not substantially change conformation during scaffold processing (21). Further evidence that would strengthen this conclusion in future studies might include transmission electron imaging to demonstrate characteristic collagen banding or analysis of circular dichroism patterns from the composite scaffolds.…”

In vivo xenogeneic scaffold fate is determined by residual antigenicity and extracellular matrix preservation

“…ECM thermal stability was determined using an adaptation of a method previously described [23]. Briefly, 5 mm diameter discs (punched from an initial 0.2 g piece, n = 6 per group) were lyophilized (0.8–5.7 mg in dry weight), crimped in aluminum pans, and heated (30–280 °C at 20 °C/min and 10 min hold at 120 °C) using a differential scanning calorimeter (DSC 6000; Perkin Elmer, Waltham, MA).…”

Evaluation of peritoneal tissue by means of differential scanning calorimetry (DSC)

“…Thermally induced transformations of collagen reflect the overall condition of the structure, cross-links in the collagen network and interactions with the surrounding molecules [8][9][10]. Differential scanning calorimetry (DSC) provides a powerful method for examining conditions in which the stabilization of protein breaks down, and has been proved to be sensitive to the amount of cross-links as well as to the hydration and the molecular environment of the collagen molecules [10][11][12][13][14][15].…”