ABSTRACT
Protein denaturation is under intensive research, since it leads to neurological disorders of severe con-sequences. Avoiding denaturation and stabilizing the proteins in their native state is of great importance, especially when proteins are used as drug molecules or vaccines. It is preferred to add pharmaceutical excipients in protein formulations to avoid denaturation and thereby stabilize them. The present study aimed at using bile salts (BSs), a group of well-known drug delivery systems, for stabilization of proteins. Bovine serum albumin (BSA) was taken as the model protein, whose association with two BSs, namely sodium cholate (NaC) and sodium deoxycholate (NaDC), was studied. Denaturation studies on the pre-formed BSA-BS systems were carried out under chemical and physical denaturation conditions. Urea was used as the chemical denaturant and BSA-BS systems were subjected to various temperature conditions to understand the thermal (physical) denaturation. With the denaturation conditions prescribed here, the data obtained is informative on the association of BSA-BS systems to be hydrophobic and this effect of hydrophobicity plays an important role in stabilizing the serum albumin in its native state under both chemical and thermal denaturation.
ABSTRACT
Objective To test the hypothesis that collagen is a significant determinant of skin viscoelasticity,with particular attention paid to the thermomechanical properties of skin under dynamic loading.Methods Differential scanning calorimetry (DSC) was used to detect the denaturation of dermal collagen and assess its thermal stability.The DSC results obtained with various heating rates were used to derive the Arrhenius parameters in burn damage integration,which were subsequently used to calculate the degree of denatured collagen in the skin.The dynamic mechanical analyzer (DMA) was employed to evaluate the changes in skin viscoelastic properties as a function of temperature and collagen damage.Results The results showed remarkable changes in storage modulus,possibly due to the release of water,whilst there was no significant change in loss factor.Conclusion These results suggest that at a fixed frequency the denaturation of collagen molecules has a large effect on the viscoelastic behavior of skin tissue.
ABSTRACT
Objective This paper aims to characterize the tensile and compressive behaviors of skin tissue under different temperatures and to study the effect of temperature and corresponding dermal collagen denaturation on the mechanical properties of skin tissue.Methods The uniaxial tensile and compressive tests of fresh pig ear skin under different temperatures have been performed by using two specifically-designed hydrothermal experimental systems.Results In tensile tests,the skin stiffness decreases with increased temperature,while a contrary trend is observed in compressive tests.Conclusion The results show that temperature has a great influence on both tensile and compressive properties of skin tissue,but the mechanisms are different.The variation of skin tensile properties is caused by the thermal denaturation of skin collagen with increased temperature,while the variation of skin compressive behavior of skin tissue may be due to the hydration change with thermal denaturation.