Affiliations: National Institute of Standards and Technology, Material Measurement Laboratory, Applied Chemicals and Materials Division, Boulder, CO, USA
Note: [] Address for correspondence: Dr. Arno Laesecke, NIST, Mailstop 647.07, 325 Broadway, Boulder, CO 80305-3337, USA. Tel.: +1 303 497-3197; Fax: +1 303 497-6682; E-mail: [email protected]
Abstract: Aqueous solutions calf thymus DNA at three concentrations were studied by viscosity measurements at ambient pressure. A gravitational capillary viscometer and a rotating cylinder viscometer were employed. Three polycations were tested as viscosity-reducing agents with measurements from 25°C to 50°C. The most significant viscosity reduction was achieved with spermine in a solution of DNA at 2 mg/ml concentration. Measurements of DNA solutions without agents from 10°C to 90°C revealed concentration-dependent viscosity maxima in the range from 50°C to 65°C. The associated increases in viscosity were as high as 400%. A two-liquids model for solutions of double- and single-stranded DNA was developed that closely represented the experimental data.
