PEG-calf thymus DNA interactions: conformational, morphological and spectroscopic thermal studies

Area of Science:

• Biochemistry
• Biophysics
• Materials Science

Background:

• Understanding the interaction between polymers and DNA is crucial for developing novel biomedical materials.
• Polyethylene glycol (PEG) is a widely used biocompatible polymer with potential applications in drug delivery and gene therapy.
• Calf thymus DNA (ctDNA) serves as a model system for studying DNA interactions.

Purpose of the Study:

• To elucidate the interaction modes and binding affinity between PEG 400 and ctDNA.
• To investigate the influence of various factors (PEG-to-ctDNA ratio, pH, incubation time, thermal stability) on PEG-ctDNA biocomplex formation.

Main Methods:

• UV-vis-NIR absorption spectroscopy to analyze complex formation.
• Thermal denaturation studies to assess DNA stability.
• Fourier-transform infrared (FTIR) spectroscopy to identify interaction types.
• Transmission electron microscopy (TEM) to visualize structural changes.

Main Results:

• UV-vis-NIR analysis suggests PEG-ctDNA complex formation occurs through non-intercalative mechanisms.
• Thermal denaturation studies indicate stabilization of the ctDNA helix upon PEG binding, evidenced by an increased melting temperature.
• FTIR analysis reveals hydrophilic and hydrophobic interactions between PEG and ctDNA base pairs.
• TEM micrographs show PEG-induced condensation of ctDNA into irregular aggregates.

Conclusions:

• PEG 400 interacts with ctDNA via non-intercalative hydrophilic and hydrophobic interactions, leading to DNA structural stabilization.
• The formation of PEG-ctDNA biocomplexes, characterized by DNA condensation and stabilization, suggests potential utility in biomedical applications.