Liposomes are spherical vesicles of phospholipid bilayers which are used in advanced drug delivery systems. An additive such as cholesterol is often used for achieving better elasticity, fluidity and stability in liposomes. However, an alternative to cholesterol for this purpose is necessary, not only for the associated health hazards but also for enhancing the efficiency of the drug carrier. In our earlier studies, β-sitosteryl sulfate (PSO₄) was found to interact favourably with the DPPC (dipalmitoylphosphatidylcholine)^[1]and soy lecithin^[2]bilayers, which motivated us to investigate the properties of the corresponding liposomes.
For this study, suspensions of the multilamellar vesicles (MLV) of DPPC, containing varying mole fractions of PSO₄, were prepared. Two portions of this suspension were sonicated with a bath sonicator and a probe sonicator, respectively, while the third portion was studied as such. Analysis of the samples was carried out with the help of spectrofluorometry, DLS, and ζ-potential measurements.
The addition of even a small quantity of PSO₄caused a significant decrease in the size of the multilamellar liposomes of DPPC. The liposomes containing up to 0.5 mole fraction (x) of PSO₄are more stable against agglutination compared to the liposomes without it. Similarly, fluorescence anisotropy of the membranes decreases with increasing x indicating an increased membrane fluidity. The negative value of the ζ-potential increases significantly with the addition of PSO₄ensuring a higher stability and dispersibility of the liposomal particles. A combination of saturated PC and PSO₄can be suitable for formulating liposomes with enhanced efficiency, dispersibility and stability.
References:
[1] Kafle, A.; Misono, T.; Bhadani, A.; Sakai, K.; Kaise, C.; Kaneko, T.; Sakai, H.,Colloids Surf., B, 161,59 (2018).
[2] Kafle, A.; Akamatsu, M.; Bhadani A.; Sakai, K.; Kaise, C.; Kaneko, T.; Sakai, H., Langmuir, doi/10.1021/acs.langmuir.0c00472.

Chihiro Kaise

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