Influence of CaCl2, poly(NIPAM), poly(N-vinylpyrrolidone), pluronic F-127 and ultrasound on viscosity of rat tail collagen solutions

Abstract

A convenient approach from a practical point of view is proposed for assessing rheology of aqueous acetic acid rat tail collagen solutions by determining the kinematic viscosity (v), which depends only on the solution outflow time and is directly measured on cheap and affordable capillary viscometers. In this case, it is irrelevant to take into account the solvent outflow time and temperature correction, unlike relative, specific, reduced and intrinsic viscosities. Influence of the temperature as well as duration and periodicity of ultrasonic treatment on v of 0.3 wt.% solution of rat tail collagen in 0.02 M aqueous CH₃COOH was studied for the first time. Additionally, the influence of a temperature on v of mixtures of this collagen solutions with CaCl₂, poly(NIPAM), poly(N-vinylpyrrolidone), pluronic F-127 as well as with CaCl₂+poly(NIPAM), CaCl₂+poly(N-vinylpyrrolidone) and with CaCl₂+pluronic F-127 in a similar acetic acid aqueous solutions was studied. Linear regression dependences of the influence of a temperature on v of collagen solutions and its above-mentioned mixtures (R² is closest to 1) up to 40°C have been found, which make it possible to predict the viscosity characteristics of these solutions at the temperature of interest. It was found that shorter initial sonication periods at 20°C followed by relaxation stages minimize the decrease in v of pure collagen solutions. Results of the research can be useful for scientists, doctors and tissue engineers who carry out research in the field of regenerative medicine in predicting and selecting a temperature as well as ultrasonic parameters for bioprinting with collagen bioinks.