Design and Developement of a low-cost heating stage to enable tensile tests of microscale fibers under precise temperature control

Abstract

Collagens are the primary components building extracellular matrix in mammalian tissues. The most abundant is fibrillar collagen type I, which can be found in tissues such as tendons, bones, skin, blood vessels, and influences the mechanical strength of those tissues. Mechanical testing of individual collagen fibrils is typically conducted at room temperature. However, in the physiological environment, collagen “operates” at body temperature (~ 37 °C in mammals). Moreover, collagenous tissue is often treated with even higher temperatures either during medical treatment or in collagen-based tissue engineering. Therefore, there is a need for developing a method for tensile testing of single collagen fibrils at higher temperatures to better understand temperature–dependent behavior of collagen. In this thesis a low–cost heating stage was developed to enable tensile tests of collagen fibrils at temperatures higher than room temperature. The heating stage–temperature measurement setup was designed and developed to accommodate limitations set by the tensile testing device for nanofibers-NanoTens, and to expand its current functionality. As proof-of-concept collagen fibrils from one, BALB/c, 18-week-old mouse tail tendon were pulled to rupture at: 9 fibrils at room temperature, 8 at 37 °C and 3 at temperature close to denaturation (50 °C). Additionally, a thorough analysis of the influence of temperature on the NanoTens force readout was conducted. The developed heating and temperature measurement setup fulfilled the requirements set for its development. However, with heating of the sample, possible new error sources, such as temperature related force drift and higher sensitivity to contamination of the sample were recognized. Conducted tensile tests did not bring conclusive results but showed potential for successful experiments in the future.