Published online by Cambridge University Press: 23 May 2012
How the molecular structure of proteins in solution correlates with the mechanical properties of the solution at different length scales is not known. Using optical-tweezers based microrheology, we investigate a key physical property, viscoelasticity, of collagen solutions. To do this, we measure short-range thermal fluctuations of probe particles to obtain elastic and viscous moduli of their surrounding medium, and validate our measurement and analysis techniques using the previously studied system of polyethylene oxide. Probing the concentration dependence of viscoelasticity, we find that collagen solutions exhibit elasticity of comparable strength to viscosity when the concentration reaches ∼5 mg/ml. We also find that the presence of telopeptides alters the viscoelasticity of collagen solutions, particularly at high frequencies