Interaction between polylysine monolayer and DNA at the air-water interface

Area of Science:

• Biophysical Chemistry
• Polymer Science
• Materials Science

Background:

• Polylysine amphiphiles, featuring poly-L- or -D-lysine segments and alkyl chains, self-assemble into organized structures.
• Understanding polylysine behavior at interfaces is crucial for biomaterial and drug delivery applications.

Purpose of the Study:

• To investigate the interfacial behavior and polynucleotide interactions of polylysine amphiphiles.
• To elucidate the influence of polylysine secondary structure on DNA binding.

Main Methods:

• Surface pressure-area isotherm measurements to assess monolayer stability.
• Circular dichroism and Fourier transform infrared spectroscopies to determine secondary structure.
• Studies on interactions with various polynucleotides (DNA, polyadenylic acid).

Main Results:

• Both poly-L-lysine (1L) and poly-D-lysine (1D) formed stable monolayers at neutral pH.
• Helical structures were maintained at the interface, unlike in bulk solution.
• Protonated 1L monolayers interacted electrostatically with DNA, inducing alpha-helix formation.
• Helical monolayers showed specific interactions with double-stranded DNA, preferring right-handed 1L over left-handed 1D.

Conclusions:

• Polylysine amphiphiles exhibit unique interfacial properties and secondary structure stability.
• The secondary structure and chirality of polylysine influence DNA binding affinity and complex stability.
• These findings have implications for designing functionalized interfaces and DNA-based nanostructures.