Chitosan Phthalate Microspheres for Oral Delivery of Insulin: Preparation, Characterization, and In Vitro Evaluation

Figures & data

FIG. 1 FTIR spectra of (a) chitosan phthalate microspheres and (b) chitosan microspheres.

FIG. 2 Photomicroscopy of chitosan phthalate microspheres.

FIG. 3 SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of insulin. Lane 1: supernatant plain microspheres; Lane 2: supernatant after insulin-loading process; Lane 3 and 4: released samples from the insulin-loaded microspheres in PBS (pH 7.4); Lane 5: insulin standard.

TABLE 1 Degradation of insulin and insulin-loaded chitosan phthalate microspheres in pepsin and trypsin solution

	Pure insulin		Insulin-loaded microspheres
Time (min)	Pepsin (%)	Trypsin (%)	Pepsin (%)	Trypsin (%)
0	100	100	100	100
15	94 ± 3.5	92 ± 1.6	99 ± 2.6	98 ± 2.4
30	89 ± 2.8	84 ± 2.8	97 ± 3.4	95 ± 1.8
45	76 ± 1.9	78 ± 3.2	95 ± 1.5	94 ± 3.4
60	72 ± 2.6	65 ± 2.3	92 ± 3.1	91 ± 2.7
90	64 ± 1.4	58 ± 1.2	91 ± 2.8	88 ± 1.4
120	53 ± 2.5	49 ± 1.5	88 ± 1.6	86 ± 2.0

Results are the mean of triplicate observations, n = 3. Mean ± SD.

FIG. 4 In vitro release of insulin from microspheres in the presence of PBS (pH 7.4) and 0.1N HCl (pH 2.0).