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

The IR spectrum of CS, OCS, (CS/OCS) and (CS/drug/OCS) lyophilized hydrogel are listed in (**Figures 9** and **10**) and major functional moieties are labeled with wavenumbers was recorded in the region of 4000–40 cm−1. The FTIR spectrum of pure chitosan (**Figure 9(a)**) shows wide band around 3450 cm−1 corresponding to amine N–H symmetrical vibration and H bonded O–H group. The peak observed between 3400 and 3700 cm−1 corresponding to combination of the band O-H, NH2 intra and intermolecular hydrogen bonding. The peaks at 2920 and 2320 cm−1 are assigned to the symmetric and asymmetric may be attributed to –CH vibrations of carbohydrate ring [59]. The bands at 1650 cm−1 and 1545 cm−1 may be attributed to C=O stretching (amide I vibration) and N-H bending (–NH2 bending of amide II) in amide group, respectively and 1390 cm−1 (N–H stretching or C–N bond stretching vibrations, amide III vibration) [60]. The peak observed at 1050 cm−1 has the contribution to the symmetric stretching of C–O–C groups. The absorption peaks in the range 900–1200 cm−1 are due to the antisymmetric C–O stretching of saccharide structure of chitosan. In order to understand the oxidation of oxidized chitosan (OCS), the FTIR spectra results for (OCS) in (**Figure 9(b)**) verified successful oxidation, while a new absorption peak appeared around 1725 cm−1 [55], which was assigned to an aldehyde group (-C=O) bond, indicating that the CS has been successfully oxidized by the NaIO4 [61]. Furthermore, the peak (**Figure 9(c)** at 1637 cm−1 caused by C=O and C=N is reduced significantly. These differences indicate that the aldehyde groups of OCS reacted with the amino groups of CS to generate a Schiff base"imine" [62]. FTIR analysis was performed (**Figure 9(d)**) exhibits the IR spectra of the prepared nanoparticles. The spectrum of Fe3O4 magnetic nanoparticles shows the formation of two strong absorption bands between 636 cm−1 and 592 cm−1. Furthermore, the band at 592 cm−1 was confirmed as the Fe-O stretching vibration of tetrahedral sites of spinel structure. The absorption bands at 459 cm−1, assigned to tetrahedral and octahedral sites, peaks at 3400 cm−1 due to the O-H stretching model adsorbed on the surface of the Fe3O4 nanoparticles [63].

**13**

**Figure 10.**

*(c) CS/5FU/OCS lyophilized hydrogel.*

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

For the spectra of three drugs (5-FU, caffeine and ascorbic acid) loaded (CS/OCS) in hydrogels (**Figure 10**); exhibited the characteristic absorption of imine stretching vibration (-C=N–) at 1637 cm−1 [54, 64], suggests that the coupling

*FTIR spectra of (a) CS/a.AS/OCS lyophilized hydrogel, (b) CS/CAF/OCS lyophilized hydrogel;* 

The measurements of the magnetic field-dependence of the magnetization of the uncoated and coated magnetite nanoparticles at 25°C are presented in (**Figure 11**). The plots indicate that both samples exhibit superparamagnetic behavior with zero remanence and coercivity. (**Figure 11**) shows the magnetic curves as a function of applied field at room temperature obtained for Fe3O4 and CS-Fe3O4-OCS ferrogel, respectively. The magnetization saturations were found to be 60.57 emu/g for Fe3O4, 17.25 emu/g for CS-Fe3O4-OCS ferrogel [65]. The magnetization value decreased after coating due to the existence of oxidized chitosan and chitosan, which formed polymerized multilayers. It can be concluded that the Ms. value of CS/Fe3O4/OCS ferrogel is less than the Fe3O4 (NPs) that can be attributed to the creation of a non-magnetic polymer layer around Fe3O4 (NPs) in the hydrogel [66]. Taking into account the magnetic properties of the prepared by ferrogel, it may be able to deliver the drug to the target area in

A perfect injectable hydrogel must have pores in the range of 50–100 μm and a high degree of interconnectivity to facilitate nutrient and oxygen transport, as well as cell adhesion and migration. By using SEM, we studied the pore size distribution in hydrogels (**Figure 12**). In this study, morphology of freeze-dried hydrogel (CS/ OCS) were observed with scanning electron microscope (SEM). As can be seen in (**Figure 12**), the (CS/OCS) lyophilized hydrogel had continuous and porous structures with interconnecting pores, pores diameter ranging from several tens to

reaction was occurred between –CHO of OCS and –NH2 of CS.

**3.3 Magnetization studies using (SQUID) analysis**

the presence of an external magnetic field.

**3.4 Scanning electron microscopy (SEM)**

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

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

#### **Figure 10.**

*Chitin and Chitosan - Physicochemical Properties and Industrial Applications*

The IR spectrum of CS, OCS, (CS/OCS) and (CS/drug/OCS) lyophilized hydrogel are listed in (**Figures 9** and **10**) and major functional moieties are labeled with wavenumbers was recorded in the region of 4000–40 cm−1. The FTIR spectrum of pure chitosan (**Figure 9(a)**) shows wide band around 3450 cm−1 corresponding to amine N–H symmetrical vibration and H bonded O–H group. The peak observed between 3400 and 3700 cm−1 corresponding to combination of the band O-H, NH2 intra and intermolecular hydrogen bonding. The peaks at 2920 and 2320 cm−1 are assigned to the symmetric and asymmetric may be attributed to –CH vibrations of carbohydrate ring [59]. The bands at 1650 cm−1 and 1545 cm−1 may be attributed to C=O stretching (amide I vibration) and N-H bending (–NH2 bending of amide II) in amide group, respectively and 1390 cm−1 (N–H stretching or C–N bond stretching vibrations, amide III vibration) [60]. The peak observed at 1050 cm−1 has the contribution to the symmetric stretching of C–O–C groups. The absorption peaks in the range 900–1200 cm−1 are due to the antisymmetric C–O stretching of saccharide structure of chitosan. In order to understand the oxidation of oxidized chitosan (OCS), the FTIR spectra results for (OCS) in (**Figure 9(b)**) verified successful oxidation, while a new absorption peak appeared around 1725 cm−1 [55], which was assigned to an aldehyde group (-C=O) bond, indicating that the CS has been successfully oxidized by the NaIO4 [61]. Furthermore, the peak (**Figure 9(c)** at 1637 cm−1 caused by C=O and C=N is reduced significantly. These differences indicate that the aldehyde groups of OCS reacted with the amino groups of CS to generate a Schiff base"imine" [62]. FTIR analysis was performed (**Figure 9(d)**) exhibits the IR spectra of the prepared nanoparticles. The spectrum of Fe3O4 magnetic nanoparticles shows the formation of two strong absorption bands between 636 cm−1 and 592 cm−1. Furthermore, the band at 592 cm−1 was confirmed as the Fe-O stretching vibration of tetrahedral sites of spinel structure. The absorption bands at 459 cm−1, assigned to tetrahedral and octahedral sites, peaks at 3400 cm−1 due to the O-H stretching model

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

adsorbed on the surface of the Fe3O4 nanoparticles [63].

*FTIR spectra of (a) chitosan, (b) oxidized chitosan, (c) CS/OCS lyophilized hydrogel, (d) Fe3O4 NP.*

**12**

**Figure 9.**

*FTIR spectra of (a) CS/a.AS/OCS lyophilized hydrogel, (b) CS/CAF/OCS lyophilized hydrogel; (c) CS/5FU/OCS lyophilized hydrogel.*

For the spectra of three drugs (5-FU, caffeine and ascorbic acid) loaded (CS/OCS) in hydrogels (**Figure 10**); exhibited the characteristic absorption of imine stretching vibration (-C=N–) at 1637 cm−1 [54, 64], suggests that the coupling reaction was occurred between –CHO of OCS and –NH2 of CS.

#### **3.3 Magnetization studies using (SQUID) analysis**

The measurements of the magnetic field-dependence of the magnetization of the uncoated and coated magnetite nanoparticles at 25°C are presented in (**Figure 11**). The plots indicate that both samples exhibit superparamagnetic behavior with zero remanence and coercivity. (**Figure 11**) shows the magnetic curves as a function of applied field at room temperature obtained for Fe3O4 and CS-Fe3O4-OCS ferrogel, respectively. The magnetization saturations were found to be 60.57 emu/g for Fe3O4, 17.25 emu/g for CS-Fe3O4-OCS ferrogel [65]. The magnetization value decreased after coating due to the existence of oxidized chitosan and chitosan, which formed polymerized multilayers. It can be concluded that the Ms. value of CS/Fe3O4/OCS ferrogel is less than the Fe3O4 (NPs) that can be attributed to the creation of a non-magnetic polymer layer around Fe3O4 (NPs) in the hydrogel [66]. Taking into account the magnetic properties of the prepared by ferrogel, it may be able to deliver the drug to the target area in the presence of an external magnetic field.

#### **3.4 Scanning electron microscopy (SEM)**

A perfect injectable hydrogel must have pores in the range of 50–100 μm and a high degree of interconnectivity to facilitate nutrient and oxygen transport, as well as cell adhesion and migration. By using SEM, we studied the pore size distribution in hydrogels (**Figure 12**). In this study, morphology of freeze-dried hydrogel (CS/ OCS) were observed with scanning electron microscope (SEM). As can be seen in (**Figure 12**), the (CS/OCS) lyophilized hydrogel had continuous and porous structures with interconnecting pores, pores diameter ranging from several tens to

**Figure 11.**

*The magnetic hysteresis loops for Fe3O4 NPs and CS@Fe3O4@OCS hydrogel measured by SQUID at room temperature.*

**Figure 12.** *Micrographs of chitosan cross-linked oxidized chitosan hydrogel at low and high magnification.*

several thousands of micrometers [55]. Moreover, the more crosslinking between amino group and aldehyde group, the diameter of the pores are decreased and the compactness of pores increased. The micrographs of CS/OCS hydrogel it was clearly observed that the hydrogel had a three-dimensional porous structure, which was beneficial for drug delivery systems.
