Novel gelatin-polyoxometalate based self-assembled pH responsive hydrogels: formulation and in vitro characterization

Figures & data

Figure 1. Presumptive structure of the acrylic acid-gelatin-POM self-assembled hydrogel.

Figure 2. Sol form (right) and developed hydrogel disc (left).

Figure 3. Effect of gelatin concentration on [P₂W₁₅O₅₆]^12- release.

Table 1. Mechanism of encapsulated POM release in dissolution experiments.

Formulation code	Zero order R^2	First order R^2	Higuchi model R^2	Peppas model R^2	n
GP1	0.978	0.913	0.745	0.996	1.235
GP 2	0.983	0.981	0.856	0.990	0.892
GP 3	0.992	0.945	0.785	0.996	1.103
GP 4	0.992	0.939	0.790	0.995	1.081
GP 5	0.991	0.939	0.805	0.991	1.027
GP 6	0.993	0.920	0.804	0.994	1.036
GP 7	0.994	0.948	0.784	0.999	1.111
GP 8	0.999	0.951	0.781	0.998	1.121
GP 9	0.992	0.954	0.778	0.999	1.126

Figure 4. Effect of gelatin concentration on swelling of hydrogels.

Figure 5. Effect of acrylic acid concentration on [P₂W₁₅O₅₆]^12- release.

Figure 6. Effect of acrylic acid concentration on swelling of hydrogels.

Figure 7. Effect of [P₂W₁₅O₅₆]^12- concentration on cumulative % release.

Figure 8. Effect of [P₂W₁₅O₅₆]^12- concentration on swelling of hydrogel.

Table 2. Composition of the various hydrogel formulations.

S. No	Formulation code	Gelatin/100 g	AA/100 g	SHS/APS/100 g	POM salt (mg) per hydrogel disk
1	GP1	1	10	0.3/0.3	20
2	GP2	2	10	0.3/0.3	20
3	GP3	3	10	0.3/0.3	20
4	GP4	1	08	0.3/0.3	20
5	GP5	1	12	0.3/0.3	20
6	GP6	1	16	0.3/0.3	20
7	GP7	1	10	0.3/0.3	25
8	GP8	1	10	0.3/0.3	30
9	GP9	1	10	0.3/0.3	35

Figure 9. SEM photomicrographs of powdered hydrogel (a, b, c) and (d) cross sectional.

Figure 10. FT-IR spectra of (a) gelatin (b) tungstophosphate sodium salt (c) hydrogel (d) acrylic acid.

Figure 11. TGA plots of gelatin, tungstophosphate sodium salt and hydrogel.

Figure 12. DSC thermograms of tungstophosphate sodium salt, gelatin and hydrogel.