Fusion of phosphatidylcholine liposomes induced by polyethylene glycol

Fusion of small unilamellar vesicles of L-alpha-phosphatidylcholihne (PC) was carried out in the presence of polyethylene glycol (PEG, Mr 6000-7500). The fusion of liposomes was detected by (i) monitoring the efficiency of energy transfer from chlorophyll b (Chl b) to chlorophyll a (Chl a), (ii) formation of fluorescent complex Tb (DPA)3(3-) between terbium chloride (TbCl3) and dipicolinic acid (DPA), (iii) light scattering at 520 nm and (iv) PMR spectroscopy. The changes in the proton magnetic resonance (PMR) signal intensities and increase in the linewidths of the fatty acyl chain methylenes and terminal methyl group in presence of PEG are discussed in relation to fusion.