Author Contributions
Conceptualization, F.Z., G.A., G.K.J. and S.M.A.Z.; methodology, P.P.N.; formal analysis, P.P.N. and M.S.K.; investigation, A.S.; data curation, F.Z. and A.S.; writing—original draft preparation, S.M.A.Z.; writing—review and editing, F.Z.; supervision, F.Z., G.A. and G.K.J.; project administration, G.A.; funding acquisition, P.P.N. and M.S.K. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Pseudo-ternary phase diagrams of the developed nanoemulsion formulations using different oil:Smix ratios: (a) 1:9, (b) 2:8, (c) 3:7, (d) 4:6, (e) 5:5, (f) 6:4, (g) 7:3, (h) 8:2, (i) 1:2, (j) 1:3, (k) 1:5, (l) 1:6, (m) 1:7, and (n) 1:8. The figure shows oil, surfactant:cosurfatant, and water in each corner with 100% of each component. The blue dots indicate clear dispersion, whereas red crosses denote turbidity. It can be seen that the nanoemulsion forming zone (represented by blue dots) is larger in images (k–n), suggesting stable formulation.
Figure 1.
Pseudo-ternary phase diagrams of the developed nanoemulsion formulations using different oil:Smix ratios: (a) 1:9, (b) 2:8, (c) 3:7, (d) 4:6, (e) 5:5, (f) 6:4, (g) 7:3, (h) 8:2, (i) 1:2, (j) 1:3, (k) 1:5, (l) 1:6, (m) 1:7, and (n) 1:8. The figure shows oil, surfactant:cosurfatant, and water in each corner with 100% of each component. The blue dots indicate clear dispersion, whereas red crosses denote turbidity. It can be seen that the nanoemulsion forming zone (represented by blue dots) is larger in images (k–n), suggesting stable formulation.
Figure 2.
(a) Droplet size distribution by intensity; (b) zeta potential graph.
Figure 2.
(a) Droplet size distribution by intensity; (b) zeta potential graph.
Figure 3.
Transmission electron microscope images of nanoemulsion droplets at a magnification of (a) 11,000× (scale in the image represents 500 nm) and (b) 45,000× (scale in the image represents 500 nm).
Figure 3.
Transmission electron microscope images of nanoemulsion droplets at a magnification of (a) 11,000× (scale in the image represents 500 nm) and (b) 45,000× (scale in the image represents 500 nm).
Figure 4.
Fourier transform infrared spectra of (a) pure chamomile oil and (b) chamomile oil-loaded nanoemulsion.
Figure 4.
Fourier transform infrared spectra of (a) pure chamomile oil and (b) chamomile oil-loaded nanoemulsion.
Figure 5.
Viscosity vs. shear rate graph of the developed chamomile nanogel.
Figure 5.
Viscosity vs. shear rate graph of the developed chamomile nanogel.
Figure 6.
Texture profile analysis graph of the developed chamomile oil nanogel. Line 2 indicates the firmness value when pointing up, and when pointing down, it indicates cohesiveness. The area between 1 and 2 is consistency and between 2 and 3 is cohesiveness.
Figure 6.
Texture profile analysis graph of the developed chamomile oil nanogel. Line 2 indicates the firmness value when pointing up, and when pointing down, it indicates cohesiveness. The area between 1 and 2 is consistency and between 2 and 3 is cohesiveness.
Figure 7.
Cumulative percent drug release vs. time graph of the chamomile oil nanogel (COG) vs. chamomile oil nanoemulsion (CON) in a phosphate buffer of pH 6.
Figure 7.
Cumulative percent drug release vs. time graph of the chamomile oil nanogel (COG) vs. chamomile oil nanoemulsion (CON) in a phosphate buffer of pH 6.
Figure 8.
Graph depicting the cumulative amount of pure chamomile oil (CO) and chamomile oil from nanogel (COG) penetrating excised rat skin vs. time.
Figure 8.
Graph depicting the cumulative amount of pure chamomile oil (CO) and chamomile oil from nanogel (COG) penetrating excised rat skin vs. time.
Figure 9.
Anxiolytic effect via the light and dark box model. The duration of stay ofthe rats in both light and dark compartments was tested for different treatment groups. The data represented are mean ± SEM. Where *** p < 0.001, ** p < 0.01, and * p < 0.05. A two-way ANOVA with Tukey’s post hoc test was used for statistical analysis.
Figure 9.
Anxiolytic effect via the light and dark box model. The duration of stay ofthe rats in both light and dark compartments was tested for different treatment groups. The data represented are mean ± SEM. Where *** p < 0.001, ** p < 0.01, and * p < 0.05. A two-way ANOVA with Tukey’s post hoc test was used for statistical analysis.
Figure 10.
The in vitro skin irritation test expressed as percentage viability for different treatment groups; NC, negative control; PC, positive control; CO, pure chamomile oil; COG, chamomile oil nanogel.
Figure 10.
The in vitro skin irritation test expressed as percentage viability for different treatment groups; NC, negative control; PC, positive control; CO, pure chamomile oil; COG, chamomile oil nanogel.
Table 1.
Thermodynamic stability studies of selected nanoemulsion formulations.
Table 1.
Thermodynamic stability studies of selected nanoemulsion formulations.
Oil:Smix | Heating–Cooling Cycles | Centrifugation | Freeze–Thaw | Inference |
---|
1:5 | Clear | Clear | Clear | Stable |
1:6 | PS | PS | PS | Unstable |
1:7 | PS | PS | PS | Unstable |
1:8 | PS | PS | PS | Unstable |
Table 2.
FT-IR spectra peaks of chamomile oil and nanoemulsion. The figures represent the wave number values for different functional groups.
Table 2.
FT-IR spectra peaks of chamomile oil and nanoemulsion. The figures represent the wave number values for different functional groups.
S. No | Groups | Actual Value (cm−1) | Observed Values |
---|
Chamomile Oil | Nanoemulsion |
---|
1. | -CH2- (aliphatic asymmetric) | 2926 | 2929.21 | 2925.55 |
2. | C=O | 1730–1750 | 1731.81 | 1732.42 |
3. | =C-H (Scissor) | Approx. 1465 | 1456.51 | 1457.14 |
4. | C-O | 1000–1300 | 1374.96 | 1355.23 |
Table 3.
Drug-release kinetic analysis of the nanogel formulation using different models.
Table 3.
Drug-release kinetic analysis of the nanogel formulation using different models.
Zero-Order | First-Order | Higuchi | Korsmeyer–Peppas | Hixson–Crowell |
---|
K0 (intercept) | R2 | K1 (intercept) | R2 | KH (intercept) | R2 | KKP (intercept) | N | R2 | KHC | R2 |
0.054 | 0.1065 | 0.001 | 0.1124 | 0.237 | 0.8763 | 0.290 | 0.417 | 0.9051 | 0.000 | 0.1104 |
Table 4.
The time for latency before treatment and post-treatment using different formulations during the tail flick test.
Table 4.
The time for latency before treatment and post-treatment using different formulations during the tail flick test.
Groups | Dose | Time (S) | Percent Inhibition |
---|
Pre-Treatment | Post-Treatment |
---|
Control (saline) | 1 mL/kg, IP | 2.88 ± 0.75 | 2.81 ± 1.12 | - |
Standard treatment (diclofenac) | 20 mg/kg, IP | 2.77 ± 0.31 | 7.21 ± 0.97 | 36.3 |
Test treatment (COG) | 100 mg/rat, topical | 2.58 ± 0.93 | 6.88 ± 0.81 | 34.62 |
Table 5.
The writhing count exhibited as a result of treatment with different formulations during the acetic acid-induced writhing test.
Table 5.
The writhing count exhibited as a result of treatment with different formulations during the acetic acid-induced writhing test.
Groups | Dose | No. of Writhes | % Protection |
---|
Control (saline) | 0.3%, 10 mL/kg Ip | 24.88 ± 0.98 | |
Standard (diclofenac sodium) | 20 mg/kg Ip | 11.27 ± 1.1 | 54.7% |
Test (COG) | 100 mg/rat, topical | 14.75 ± 0.95 | 40.71% |
Table 6.
Stability studies of optimized nanogel at different time intervals and temperature/humidity conditions.
Table 6.
Stability studies of optimized nanogel at different time intervals and temperature/humidity conditions.
Storage Conditions | Parameters |
---|
Time | Temperature/Relative Humidity | Appearance | Phase Separation | pH | Percent Transmittance |
---|
0 day | 25 ± 2 °C/60 ± 5% RH | Good | No | 5.9 | 96.33% |
40 ± 2 °C/75 ± 5% RH | Good | No | 5.9 | 96.41% |
30 days | 25 ± 2 °C/60 ± 5% RH | Good | No | 5.8 | 95.18% |
40 ± 2 °C/75 ± 5% RH | Good | No | 6.0 | 95.12% |
60 days | 25 ± 2 °C/60 ± 5% RH | Good | No | 6.1 | 95.89% |
40 ± 2 °C/75 ± 5% RH | Good | No | 6.0 | 95.93% |