A novel method to prepare magnetite chitosan microspheres conjugated with methotrexate (MTX) for the controlled release of MTX as a magnetic targeting drug delivery system

Figures & data

Figure 1.  Schematic representation of the preparation process of the magnetic chitosan–MTX microspheres.

Figure 2.  A typical SEM image of magnetite chitosan–MTX microspheres.

Figure 3.  FTIR spectra of chitosan (a), MTX (b), Chitosan–MTX (c), and magnetite chitosan–MTX microspheres (d).

Table 1.  Assignments of the characteristic FTIR absorption bands presented in Figure 3.

Samples	IR absorption bands/cm^−1	Description^a
(a) chitosan	3448	ν(N-H···H) and ν(O-H···H)
	2925, 2877	νas(C-H) and νs(C-H) of –CH2
	1654, 1603,1323	amide band I, II, and III
	1120, 1013	ν(C3-OH) and ν(C6-OH)
	894	β-glycosidic bond
(b) MTX	3380, 3216	νas(N-H···H), νs(N-H···H), and ν(O-H···H)
	2961,2924	νas(C-H) and νs(C-H) of –CH2
	1607	stretching vibration of the skeleton of aromatic ring
	1561,1407	νas(COO^−) and νs(COO^−)
	1508	δ(N-H)
	1449,1356	δ(CH2), δ(CH3)
	1208	ν(C-N)
	827, 767	Absorption band from methotrexate
(c) chitosan-MTX	3423	ν(N-H···H) and ν(O-H···H)
	2920, 2876	νas(C-H) and νs(C-H) of –CH2
	1607	stretching vibration of the skeleton of aromatic ring, a broad band coupled with amide band I
	1562, 1407	νas(COO^−) and νs(COO^−)
	1508	δ(N-H)
	1450, 1378	δ(CH2), δ(CH3)
	1322	ν(C-O)
	1208	ν(C-N)
	1123, 1020	ν(C3-OH) and ν(C6-OH)
	894	β–glycosidic bond
	827, 767	Absorption band from methotrexate
(d) magnetite chitosan–MTX microspheres	3409	ν(N-H···H) and ν(O-H···H)
	2954, 2924, 2854	νas(C-H) and νs(C-H) of –CH2
	1634	Absorption band of shiff base
	1606	stretching vibration of the skeleton of aromatic ring, a broad band coupled with amide band I
	1565, 1407	νas(COO^−) and νs(COO^−)
	1504	δ(N-H)
	1462, 1377	δ(CH2), δ(CH3)
	1066	ν(C-O-C)
	632, 582	Absorption bands of Fe-O bond
	446	Absorption band of Fe-O bond

^aν_s = symmetric stretching vibration; ν_as = asymmetric stretching vibration; δ = bending vibration or deformation.

Figure 4.  XRD patterns of the prepared magnetite nanoparticles (a) and magnetite chitosan–MTX microspheres (b).

Figure 5.  TGA curves of the prepared magnetite nanoparticles (a) and magnetite chitosan–MTX microspheres (b).

Figure 6.  Release profiles of methotrexate from magnetic chitosan–MTX microspheres in the presence of 0.1 mg/ml crude protease from bovine pancreas with various pH values at 37°C.

Figure 7.  Release profiles of methotrexate from magnetic chitosan–MTX microspheres (a) and chitosan-MTX conjugations (b) at pH = 7.4 in the presence of 0.1 mg/ml crude protease from bovine pancreas at 37°C.

Figure 8.  Magnetization curves for the prepared magnetite nanoparticles (solid) and magnetite chitosan-MTX microspheres (dash dot) at room temperature.