**7. Preparation of PBNDDS of plant extracts and its phytoconstituents**

Phospholipid based nano drug delivery systems using liposomes & phytosomes were prepared for plant extracts and phytoconstituents. Phospholipid based nano drug delivery systems (PBNDDS) batches of plant extracts and its phytoconstituents showed average particle size of 50–250 nm, PDI value of 0.02–0.5 and entrapment efficiency up to 90% (**Figures 5** and **6**). It was observed that the average size, polydispersity and entrapment efficiency of PBNDDS were markedly affected by the process and formulation factors used in different studies.

**Figure 5.** *TEM images for PBNDDS of phytoconstituents.*

**Figure 6.** *DLS data of PBNDDS of phytoconstituents.*

Entrapment efficiency of black seed oil loaded liposomes was increased markedly while cryoprotectant (sugar) and cholesterol were used in the preparation of liposomes. It was also observed that entrapment efficiency of liposomes was high for larger sized liposomes compared to small average size of liposomes.
