title: Simple method to measure and analyze the fluctuations of a small particle in biopolymer solutions.
abstract: We developed a simple method to investigate the motion of a small particle in biopolymer solutions. Using optical tweezers with low stiffness, a trapped probe particle fluctuates widely for a long time along the light axis, which reflects the rheological properties of the surrounding environment. We present a convenient technique for three-dimensional position tracking and the analysis focused on the distribution of particle positions and its variance in a given time interval. It allows us to obtain useful information about the dynamics of a small particle in a wide range from a free diffusive motion to a constrained motion with statistical significance. We applied this method to investigate the dynamics in collagen and DNA solutions; it was found that a collagen solution behaves as a simple viscous liquid and a DNA solution has apparent elasticity due to the slow relaxation of the configuration of molecules.
authors.affiliation: Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kuroda
authors.affiliation: Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Murayama
mesh_terms: D001704:Biopolymers / Q000032:analysis* / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D044085:Microfluidics / Q000295:instrumentation*; D053758:Nanoparticles / Q000737:chemistry*; D052898:Optical Tweezers; D010316:Particle Size; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry*
chemical_list: D001704:Biopolymers; D012996:Solutions