Preparation of ferric ion crosslinked acrylamide grafted poly (vinyl alcohol)/sodium alginate microspheres and application in controlled release of anticancer drug 5-fluorouracil

Figures & data

Table 1. The elemental analysis results.

Polymer	N (%)	C (%)	H (%)	Grafting percentage
AAm-g-PVA	3 (52)	51 (15)	7 (94)	18

Figure 1. Schematic representation of synthesis of semi-IPN.

Table 2. Preparation conditions of the 5-FU-loaded PVA-g-AAm/NaAlg semi-IPN microspheres.

Formulation code	Drug/polymer ratio (w/w)	PVA-g-AAm/NaAlg ratio (w/w)	Concentration of crosslinking agent (M)	Exposure time to crosslinking agent (Min)	Entrapment efficiency (%)	Microsphere yield (%)	Microsphere diameter (mm)
A1	1:8	1:4	0.05	10	20.17	71.2	0.75 ± 0.01
A2	1:8	1:3	0.05	10	13.65	62.36	0.67 ± 0.003
A3	1:8	1:2	0.05	10	39.6	61.91	1.08 ± 0.007
A4	1:8	1:1	0.05	10	30.17	47.4	0.71 ± 0.002
A1.1	1:8	1:4	0.2	10	17.56	80.69	0.79 ± 0.04
A1.2	1:8	1:4	0.1	10	13.25	78.85	0.78 ± 0.005
A1.3	1:8	1:4	0.05	15	28.63	77.04	1.17 ± 0.04
A1.4	1:8	1:4	0.05	20	7.72	71.42	1.20 ± 0.04
A1.5	1:4	1:4	0.05	10	32.2	60.69	1.12 ± 0.01
A1.6	1:2	1:4	0.05	10	52.60	58.94	1.20 ± 0.02
A1.7	1:1	1:4	0.05	10	53.68	55.15	1.28 ± 0.01
A1.0		1:4	0.05	10
A2.0		1:3	0.05	10
A3.0		1:2	0.05	10
A4.0		1:1	0.05	10

Figure 2. FTIR spectra of (a) PVA and (b) PVA-g-AAm.

Figure 3. FTIR spectra of (a) 5-FU and (b) 5-FU-loaded semi-IPN microspheres.

Figure 4. Microscopic pictures of (a) empty (b) 5-FU-loaded microspheres.

Figure 5. Effect of PVA-g-AAm/NaAlg ratio on the 5-FU release. Concentration of FeCl₃: 0.05 M, exposure time to FeCl₃: 10 min, drug/polymer ratio: 1:8 (diamond indicates 1:1; square, 1:2; triangle, 1:3; circle, 1:4).

Table 3. Equilibrium swelling degree of microspheres.

Formulation Code	pH = 1.2	pH = 6.8	pH = 7.4
A1.0	171.8 ± 3.4	720.3 ± 3.5	1093.2 ± 8.9
A2.0	138.6 ± 2.9	677.1 ± 4.7	960.3 ± 4.7
A3.0	134.6 ± 6.2	529.3 ± 3.2	844.5 ± 3.6
A4.0	129.6 ± 1.1	480.4 ± 1.0	530.8 ± 1.2

Figure 6. Effect of crosslinker concentration on the 5-FU release. PVA-g-AAm NaAlg ratio: 1:4, exposure time to FeCl₃: 10 min; drug/polymer ratio: 1:8 (diamond indicates 0.2 M, triangle: 0.1 M, circle: 0.05 M).

Figure 7. Effect of exposure time to crosslinker on the 5-FU release. PVA-g-AAm/NaAlg ratio: 1:4, concentration of FeCl₃: 0.05 M, drug/polymer ratio: 1/8. (square: 5 min, circle: 10 min, multiplication symbol: 15 min).

Figure 8. Effect of drug/polymer ratio on 5-FU release. PVA-g-AAm/NaAlg ratio: 1:4, concentration of FeCl₃: 0.05 M, exposure time to FeCl₃: 10 min. (circle, 1:8; triangle, 1:4; diamond, 1:2; square, 1:1).

Table 4. The results of k, n, r and D calculated from Equations (3) and (4).

Formulation code	k (min^−^n)	n	r	D (cm^2/s) × 10^−13
A1	0.0275	0.6641	0.904	7.877
A2	0.0487	0.5533	0.935	5.770
A3	0.1330	0.3719	0.904	8.760
A4	0.1350	0.3477	0.873	2.470
A1.1	0.0032	0.9482	0.951	4.330
A1.2	0.0190	0.6844	0.864	4.225
A1.3	0.0029	0.9509	0.939	7.700
A1.4	0.0074	0.7469	0.977	6.400
A1.5	0.2350	0.2361	0.930	4.028
A1.6	0.1130	0.3695	0.927	8.464
A1.7	0.0523	0.5016	0.909	10.930