DNA/chitosan electrostatic complex

Area of Science:

• Biomaterials Science
• Gene Therapy
• Polymer Chemistry

Background:

• Chitosan is a biocompatible, biodegradable non-viral vector for gene delivery.
• Chitosan protects DNA from degradation and facilitates cellular transfection.
• Viral vectors can elicit immunological reactions, unlike chitosan.

Purpose of the Study:

• To investigate the complexation of high molecular weight DNA with chitosan.
• To characterize the stoichiometry, charge, dimensions, conformation, and thermal stability of DNA-chitosan complexes.
• To explore the influence of salt concentration and chitosan molecular weight on complex formation.

Main Methods:

• DNA compaction with chitosan.
• Determination of complex stoichiometry, net charge, dimensions, and thermal stability.
• Analysis of electrostatic interactions using the ratio of protonated amine groups to phosphate groups ([NH3(+)]/[P(-)]).

Main Results:

• DNA-chitosan complex properties are dependent on stoichiometry and chitosan molecular weight.
• The isoelectric point correlates with the degree of chitosan protonation.
• Stable nanoparticles (average radius ~150nm) are formed at a [NH3(+)]/[P(-)] ratio between 0.35 and 0.80.

Conclusions:

• Electrostatic interactions are the primary driving force in DNA-chitosan complex formation.
• Chitosan is a promising non-viral vector for gene delivery, forming stable nanoparticles.
• Controlling the charge ratio is crucial for achieving stable DNA-chitosan nanoparticles.