zetapotential indicates the stability of formulation interms of the particle agglomeration capacity if liposome shows zetapotential  above +/-  30  indicates the good atbility generally the zetapotential was depend up on

                                     1. The polymer concentration

                                     2. Medium surrounding liposomes during measurement

Thank for the reply. Can you please provide any links regarding effect of polymer concentration on zetapotential?

Zeta potential provides repulsion to the vesicles and thereby prevents the aggregation of the vesicles.

This helps in improving the physical stability of the liposomes.

surface charge of vesicular systems have great advantage over stability of system as well as enhanced systemic uptake. An excess of  ±25-30 zeta value was reported to play a prominent role in improving the stability of vesicular systems and more over encapsulation of charged molecules was influenced by surface charge induced by charge inducers and pH of the medium which they are formed/present. More over route of delivery demands the extent and quality  of surface charge for better systemic exposure. Find the attached link which would really help in this concern i believe. All the very best.

http://www.ncbi.nlm.nih.gov/pubmed/18770073

http://www.ncbi.nlm.nih.gov/pubmed/9380447

Thanks a lot Kartik..

The more surface charge resulting better emulsion stability. but in higher surface charge (more than 40) particles causes some effect on suspension medium and may result to aggregation of particles.