Alternate Polyelectrolyte Coating of Chitosan Beads for Extending Drug Release

Figures & data

TABLE 1 Composition and physical characteristics of the prepared multilayered chitosan beads

	Coagulation fluid (% w/v)		Post-treatment (% w/v)			Bead size (mm)
Batch	TPP	Alginate	Chitosan	Alginate	EE (% w/w)	Wet bead	Dry bead
TP1	2	—	—	—	67.21 ± 1.95	2.23 ± 0.19	0.60 ± 0.09
SA1	2	0.5	—	—	75.32 ± 2.67	2.69 ± 0.13	0.77 ± 0.12
SA2	2	1	—	—	78.08 ± 3.06	2.89 ± 0.07	0.81 ± 0.15
SA3	2	2	—	—	78.14 ± 2.84	2.98 ± 0.16	0.83 ± 0.13
SA4^a	2	1	—	—	77.83 ± 2.31	2.91 ± 0.21	0.81 ± 0.11
SA5^b	2	1	—	—	76.95 ± 2.94	2.97 ± 0.13	0.79 ± 0.09
CT1	2	1	0.2	—	78.11 ± 2.43	3.10 ± 0.20	0.91 ± 0.21
CT2	2	1	0.4	—	78.52 ± 2.99	3.09 ± 0.15	0.92 ± 0.14
CT3	2	1	0.2	1	78.04 ± 2.31	3.15 ± 0.27	0.95 ± 0.20

EE = encapsulation efficiency; TPP = tripolyphosphate.

TP-uncoated beads; SA = single layered beads; CT1 and CT2 = double layered beads; CT3 = triple layered beads.

^aSA2 hardened with calcium chloride (0.5% w/v, 30 min); ^b SA2 hardened with glutaraldehyde (0.5% v/v, 30 min).

FIG. 1 Scanning electron microscope images of (A) alginate coated chitosan bead (batch SA2). Magnified view of bead surface: (B) before alginate coating (batch TP1); (C) after alginate coating (batch SA2).

FIG. 2 Water uptake study of the beads (n = 3).

FIG. 3 Effect of polyelectrolyte coating and cross-linking on chitosan bead on the drug release rate: TP1 = (-•-), SA1 = (-ˆ-), SA2 = (-∇-), SA3 = (-▵-), SA4 = (-▪-) and SA5 = (-□-). (n = 3).

FIG. 4 Drug release from multiple-coated beads. SA2 = (-•-), CT1 = (-ˆ-), CT2 = (-∇-), and CT3 = (-▵-),. (n = 3).

TABLE 2 Correlation coefficient, release exponent, and t_50% of various batches

	Correlation coefficient (r^2)
Batch	Higuchi model	Release exponent (n)	t50%(h)
TP1	0.9797	0.53	2.52
SA1	0.9803	0.54	3.98
SA2	0.9761	0.55	4.27
SA3	0.9797	0.58	4.94
SA4	0.9496	0.59	5.71
SA5	0.9564	0.57	6.46
CT1	0.8380	1.05	7.31
CT2	0.8383	1.10	> 8
CT3	0.7669	1.18	> 8