*2.1.5 Fourier transform infrared (FTIR) spectra of hydrogel*

Fourier transform infrared (FTIR) spectra of the chitosan, oxidized chitosan, CS/OCS hydrogel, CS/drug/OCS lyophilized hydrogel, Fe3O4 NPs and the

**Figure 5.**

*Representation of superparamagnetic magnetite nanoparticles synthesis technique.*

**9**

*A Novel Drug Delivery System Based on Nanoparticles of Magnetite Fe3O4 Embedded in an Auto…*

freeze-dried CS/Fe3O4/OCS ferrogel were obtained from discs containing 2.0 mg dry sample in approximately 198 mg potassium bromide (KBr). The measurements were recorded by a Perkin–Elmer FTIR spectrophotometer at the resolution of

The thermal properties of lyophilized hydrogel, pure chitosan, oxidized chitosan, Fe3O4 NPs and CS/Fe3O4/OCS lyophilized ferrogel were investigated by thermogravimetric analysis (TGA). Samples were placed in the balance system and heated from 40 to 800°C at a heating rate of 10°C/min using a TA Instruments TGA

The saturation magnetization of Fe3O4 NPs, CS-Fe3O4-OCS ferrogel was measured by vibrating sample magnetometer VSM (SQUID model MPMS XL 7) from Quantum at room temperature between magnetic fields of −14,000 (Oe) to

The chitosan-based hydrogels cross-linked with oxidized chitosan was frozen at −75°C for 24 h and then lyophilized (by Alpha 1–2 LDplus) for 48 h. The lyophilized sample was obtained and then examined by a scanning electron microscopy (SEM)

Freeze-dried CS/OCS hydrogel were immersed in phosphate-buffered saline (PBS) at 37°C (pH = 1.2, pH = 5.8 and pH = 7.4). The samples were weighed before being put into PBS (W0). After the vial was sealed and held at 37°C for 24 h, and the excess solution on the surface of the hydrogels was quickly absorbed with filter paper [55]. The equilibrium-swelling ratio (SR) was calculated using the following

> % , <sup>−</sup> <sup>=</sup> **s d d**

where, Wd is the weight of dry hydrogel after lyophilization and Ws is the weight

(5-FU, caffeine or ascorbic acid) was selected and used as a model drug in the release experiments. In vitro drug release test was performed in a phosphate buffer solution PBS (pH 7.4 at 37°C) under shaking. The hydrogels and ferrogels (m = 1.14 g) (3 cm x 4 cm) were placed in a cartouche before immersing in 1000 mL of phosphate-buffered saline (PBS). At predetermined time intervals, 5 mL of release medium was withdrawn. Then 5 mL of fresh buffer was added to the original to maintain the total volume. The drug release was determined by

**<sup>W</sup>** (1)

**W W SR**

*2.1.10 In vitro drug release from the hydrogels and ferrogels*

*DOI: http://dx.doi.org/10.5772/intechopen.94873*

*2.1.6 Thermogravimetric (TGA) analysis*

(Q500) device.

14,000 (Oe).

4 cm−1 in the wave number region 400–4000 cm−1.

*2.1.7 Magnetization studies using (SQUID) analysis*

*2.1.8 Scanning electron microscopy (SEM)*

(Mini SEM Hirox SH-4000).

*2.1.9 Hydrogel swelling*

of swollen hydrogel.

equation:

**Figure 6.**

*Representation of superparamagnetic drug delivery hydrogel.*

*A Novel Drug Delivery System Based on Nanoparticles of Magnetite Fe3O4 Embedded in an Auto… DOI: http://dx.doi.org/10.5772/intechopen.94873*

freeze-dried CS/Fe3O4/OCS ferrogel were obtained from discs containing 2.0 mg dry sample in approximately 198 mg potassium bromide (KBr). The measurements were recorded by a Perkin–Elmer FTIR spectrophotometer at the resolution of 4 cm−1 in the wave number region 400–4000 cm−1.
