*2.6. Nanoemulgel Formulation*

*2.6. Nanoemulgel Formulation* Even though the formulations were discovered to be in the range suitable for na‐ nosize, their poor viscosities hampered their application and were thus deemed unsuita‐ ble for cutaneous usage. To improve the nanoemulsion application, respective viscosities were increased by inserting nanoemulsions within the gel matrix of 940 carbomers, lead‐ ing to formations of nanoemulgel that were appropriate, homogenous, yet extremely vis‐ Even though the formulations were discovered to be in the range suitable for nanosize, their poor viscosities hampered their application and were thus deemed unsuitable for cutaneous usage. To improve the nanoemulsion application, respective viscosities were increased by inserting nanoemulsions within the gel matrix of 940 carbomers, leading to formations of nanoemulgel that were appropriate, homogenous, yet extremely viscous enough to be dermally administered.

### 2.6.1. Nanoemulgel pH Determination and Concentration of Drug

Values of pH for all nanoemulgels separately were observed at 6.5 ± 0.15 to 6.9 ± 0.47 in the neutral range. This allowed the formulated mixture to be used on the skin easily.

### 2.6.2. Ability to Spread

Due to the utilization of the formulated mixture, the spreading ability of nanoemulgel preparation was assessed. Its texture is pleasant for skin inflammation as it distributes quickly, with maximal drag and slip. The spreading ability of the formulations was determined to be from the 5.6 ± 0.21 to 6.2 ± 0.12 gcm/S ranges. The increased radius indicates a greater ability to spread.

### 2.6.3. Measurement of Rheological Behaviour

The ability to spread and flow along with the release of oil is all governed by rheological properties. The release of oil and its substances through the formulated mixture is primarily regulated by the components present in it. The index used for measuring the consistency was 1 s−<sup>1</sup> at the shear rate and it equaled the apparent viscosity. The index of consistency of the formulated mixture was observed to be 0.33. The index of flow was defined as the measurement of the system's divergence from Newtonian behavior (n = 1). The value of "n" lesser than 1 implies pseudoplastic flow or narrowing of shear, whereas a value greater than 1 suggests a narrowing of shear or dilatants. The index of flow indicated the ability to flow the formulated mixture from the container.

In general, a lesser index of flow results in a thick base. The index of flow for nanoemulgel was 0.33, presenting characteristics of pseudoplastic flow. Pseudoplasticity is usually caused by a network of colloidal structures which align themselves in the shear direction. This lowers the viscosity and increases the rate of shear. The flow characteristic of pseudoplastic nature validates the designed system's need to exert some force of expulsion.

### *2.7. Applying Central Composite Rotatable Design for Formulation*

Effect of Independent Variables on Particle Size (nm), Zeta Potential, and Time Phases

Three-dementional response surface graphs present the effect of Babchi oil and Smix concentration on particle size (nm), zeta potential (mV), and entrapment efficiency of 91.298% EE and are presented in Figure 3 and Table 1. The zeta potential of Babchi oil was observed to be −24.93 mV at 25 ◦C with water as a dispersant, viscosity as 0.887 cP, and material absorption as 0.01 nm as observed in Figure 3a,b. The zeta potential distribution conductivity observed was 0.03359 mS/cm. Figure 3c shows the size distribution of 108 nm by intensity. Figure 4a depicts the phase time graph of zeta potential and Figure 4b,c depict the total counts of zeta potential distribution graph and Babchi size distribution and intensity graph, respectively.

Particle size (nm) (Y1) = 194.03 + 63.96A <sup>−</sup> 10.75B <sup>−</sup> 5.40AB + 9.80A<sup>2</sup> <sup>−</sup> 1.80B<sup>2</sup> ;

Zeta Potential (mV) (Y2) = <sup>−</sup>22.91 <sup>−</sup> 0.91A + 5.13B <sup>−</sup> 0.13AB + 2.89A<sup>2</sup> + 0.63B<sup>2</sup> ;

Entrapment Efficiency (%) (Y3) = 88.78 + 11.59A + 0.46B <sup>−</sup> 0.15AB <sup>−</sup> 5.84A<sup>2</sup> <sup>−</sup> 5.33B<sup>2</sup> .
