Statistical Physics in Biology

Ionic Interactions

1. Ionic solutions:
   • Why do electrolytes dissociate (ionize) in water?
   • The bare Coulomb interaction and the Bjerrum length
   • Acids, bases, and salts
   • The importance of Coulomb repulsion in biological systems
   • Macroions, counterions, salt ions
   • Restricted partition function
2. Statistical treatments of ionic solutions:
   • ‘Mean-field’ potential and charge density via the self-consistent Poisson-Boltzmann equation
   • Screening in salt solutions
     • Linearized Poisson-Boltzman
     • Debye-Hückel theory
   • Dissociation from a charged membrane
     • Solution of the 1d equation
     • The Gouy-Chapman layer
   • Interaction between charged parallel plates
   • Importance of fluctuations; like charges can attract

Some Related Links

• Gelbart, et al. DNA-Inspired Electrostatics. Physics Today 53, no. 9 (2000): 38.
• Electrostatics in DNA-peptide complexes; from a course on Principles of Protein Structure.
• Bustamante, et al. Ten Years of Tension: Single-molecule DNA Mechanic. Nature 421 (2003): 423–7.
• On Electrostatic Screening; John Marko at Northwestern.
• On DNA elasticity; Philip Nelson at UPenn.
• The residual potential; Bruce Tidor at MIT.

(Detailed Lecture Notes (PDF))