Sonication-assisted drug encapsulation in layer-by-layer self-assembled gelatin-poly (styrenesulfonate) polyelectrolyte nanocapsules: process optimization

Figures & data

Table I. Layout of design actual.

Run	Factor 1 A: deposition temperature	Factor 2 B: number of bilayer coating	Percentage drug diffused in 8 h	Percentage drug loading
1	20	20	19.79	63.70
2	50	20	19.14	61.8
3	50	15	21.07	63.46
4	35	20	20.57	61.09
5	50	10	22.64	76.02
6	20	15	21.71	74.36
7	35	10	25.86	77.20
8	20	10	23.5	82.42
9	35	15	21.93	68.67
Fopt	25.78	10	23.82	80.00

Figure 1. In-vitro release pattern: (a) In-vitro diffusion graph of pure LXM and Fopt; (b) In-vitro dissolution graph of pure LXM and Fopt.

Table II. Composition of factorial batches using 3² full factorial design.

	Variable level
Batch	X1(°C)	X2
F1	20	20
F2	50	20
F3	50	15
F4	35	20
F5	50	10
F6	20	15
F7	35	10
F8	20	10
F9	35	15
Fopt	25.78	10

Independent Variable	Low	Medium	High
Temperature (X1)	20°C	35°C	50°C
Number of bilayer (X2)	10	15	20

Figure 2. (a) Contour plot showing effect of deposition temperature and number of bilayer coating on percentage drug release; (b) Surface response curve showing effect of deposition temperature and number of bilayer coating on percentage drug release.

Figure 3. (a) Contour plot of percentage drug loading; (b) Surface response curve of percentage drug loading with respect to deposition temperature and number of bilayer coating.

Table III. The ANOVA for percentage drug diffusion at 8 h.

Source	Sum of squares	Df	Mean square	F value	p-value probe > F
Model	20.47	5	4.09	110.39	0.00013 (significant)
Deposition temperature (A)	0.77	1	0.77	20.77	0.0198
Number of bilayers (B)	18.38	1	18.38	495.34	0.0002
AB	0.011	1	0.011	0.30	0.6236
Residual	0.11	3	0.037
Core total	20.59	8

DF = Degrees of freedom; SS = Sum of squares; MS = Mean sum of squares; F = Fischer's ratio.

Table IV. The ANOVA for percentage drug loading.

Source	Sum of squares	Df	Mean square	F value	p- value probe > F
Model	462.42	2	231.21	46.87	0.0002 (significant)
Deposition temperature (A)	61.44	1	61.40	12.45	0.0124
Number of bilayers (B)	400.98	1	400.98	81.28	0.0001
Residual	29.60	6	4.93
Core total	492.02	8

DF = Degrees of freedom; SS = Sum of squares; MS = Mean sum of squares; F = Fischer's ratio.

Figure 4. Desirability plot (a) Contour plot; (b) Overlay plot.

Figure 5. Plot showing correlation between predicted and observed value of response.

Table V. Predicted and observed value of response of Fopt and prediction error.

		Y1		Y2		Error
X1	X2	Predicted	Observed	Predicted	Observed	Y1	Y2
25.78	10	23.82	24.20	80	78.85	0.38	−1.15

*Error = (observed−predicted).

Figure 6. FTIR spectrum of pure drug LXM.

Figure 7. FTIR spectra of (a) LXM and Physical mixture and (b) Fopt.

Figure 8. DSC spectrum of pure LXM, physical mixture and Fopt.

Figure 9. SEM of (a) pure nanocrystaline LXM particles (b) LbL-encapsulated LXM nanocrystaline particles.

Figure 10. Zeta potential curve of pure drug, pure drug with Gelatin and PSS coating.

Figure 11. (a) pure nanocrystaline LXM particles (b) LbL-encapsulated LXM nanocrystaline particles.

Table VI. Zeta potential of LXM nanocrystals at various experimental steps.

Layer number	ζ potential
0	−31
1	0.83
2	−25.78
3	2.08