Using Optical Tweezers for the Characterization of Polyelectrolyte Solutions with Very Low Viscoelasticity

ABSTRACT: Recently, optical tweezing has been used to provide a method for microrheology addressed to measure the rheological properties of small volumes of samples. In this work, we corroborate this emerging field of microrheology by using these optical methods for the characterization of polyelectrolyte solutions with very low viscoelasticity. The influence of polyelectrolyte (i.e., polyacrylamide, PAM) concentration, specif-ically its aging, of the salt concentration is shown. The close agreement of the technique with classical bulk rheological measurements is demonstrated, illustrating the advantages of the technique. The study of the rheological properties of polyelectrolytes, which in nature include nucleic acids, some proteins, and carbohydrates, has important consequences with respect to both an understanding of fundamental biological fluid dynamic