DNA gelation in concentrated solutions

Michael G. Fried, Victor A. Bloomfield

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Sonicated calf‐thymus DNA (200 ± 30 base pairs) spontaneously forms viscoelastic gels over a wide range of concentration, temperature, and buffer conditions. Quasielastic light scattering (QLS) can be used to monitor this process, because the ratio of dynamic‐to‐static scattering intensity decreases dramatically as gelation occurs. Using QLS, we have explored the effects of DNA concentration and mono‐ and divalent cations on the thermal stability of DNA gels. We found that the gel–sol transition temperature (Tgel) varies linearly with [DNA] from 7.5 to 17 mg/mL. Both Na+ and Mg2+ strongly stabilize the gel state. The sharpness of the transition increases with increasing ionic and DNA concentrations. Analysis of the Na+‐dependent gelation indicates that the process requires the association of one Na+ per 118 base pairs. Mg2+ effectively stabilizes the gel at concentrations 10‐fold below those required for Na+. The unexpectedly large effect of Mg2+ suggests that ion‐specific interactions may play an important role in determining gel stability.

Original languageEnglish
Pages (from-to)2141-2155
Number of pages15
Issue number11
StatePublished - Nov 1984

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Biomaterials
  • Organic Chemistry


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