Liposomes with polyribonucleotides as model of precellular systems

Area of Science:

• Biochemistry
• Origin of Life Studies
• Materials Science

Background:

• Liposomes are crucial for drug delivery and as model systems for cell membranes.
• Prebiotic chemistry explores the formation of complex molecules and systems under early Earth conditions.
• Polyribonucleotides like poly(U) and poly(C) are essential components in understanding early genetic material.

Purpose of the Study:

• To investigate the encapsulation efficiency of polyribonucleotides within different liposome formulations.
• To evaluate the impact of condensing agents (urea, cyanamide, Zn++) on liposome formation and encapsulation.
• To explore the potential of these liposome-polyribonucleotide systems as precellular models.

Main Methods:

• Liposomes were prepared using the reverse-phase evaporation method under anoxic conditions.
• Liposome formulations included dipalmitoylphosphatidyl choline (DPPC), egg yolk phosphatidyl choline (PC), and PC with cholesterol (CHOL).
• Encapsulation efficiency was measured with and without the addition of urea, cyanamide, and zinc ions (Zn++).

Main Results:

• Liposome formation was observed with DPPC and PC:CHOL in 1.0 M urea, but not with PC alone.
• Urea and cyanamide at tested concentrations did not enhance polyribonucleotide encapsulation.
• Zinc ions (0.001–0.01 M) significantly increased poly(U) and poly(C) encapsulation, with a 15–25 fold enhancement for DPPC liposomes at 0.01 M Zn++.

Conclusions:

• Dipalmitoylphosphatidyl choline liposomes demonstrate significant potential for encapsulating polyribonucleotides.
• Zinc ions act as effective agents for enhancing polyribonucleotide encapsulation in liposomes.
• These findings support the utility of DPPC-polyribonucleotide liposomes as viable precellular systems in origin of life research.