Soft solution growth of magnetite-maghemite nanocrystals in crosslinked chitosan templates and their superparamagnetic properties

Figures & data

Figure 1. Preparation of crosslinked chitosan/iron oxide nanocomposites (CC/IO).

Figure 2. DSC thermograms: (a) CC0.3, (b) CC0.4, (c) CC0.5 and (d) CC0.6 templates.

Figure 3. XRD patterns: (a) CC0.3/IO-R, (b) CC0.4/IO-R and (c) CC0.5/IO-R nanocomposites.

Table 1. Parameters for synthesis of CC/IO nanocomposites and XRD and TEM data.

Sample	Synthesis conditions			XRD		TEM
	% TPP (%w/v)	Synthesis method	Heating Method	Phase	D(311)* (nm)	Shape of IO	Size of IO** (nm)
CC0.3/IO-R	0.3	Adsorption	Reflux	Fe3O4, / γ-Fe2O3	12.4	Quadrilateral	D 10.3
CC0.4/IO-R	0.4	Adsorption	Reflux	Fe3O4, / γ-Fe2O3	11.2	Quadrilateral	D 13.5
CC0.5/IO-R	0.5	Adsorption	Reflux	Fe3O4, / γ-Fe2O3	14.1	Quadrilateral	D 12.5
CC0.4/IO-HT	0.4	Adsorption	Hydrothermal	Fe3O4, / γ-Fe2O3	11.7	Quadrilateral	D 10.7

* D₍₃₁₁₎ was calculated by Scherrer equation.

** IO nanocrystal size was analyzed by ImageJ software.

Figure 4. TEM images: (a) CC0.3/IO-R, (b) CC0.4/IO-R and (c) CC0.5/IO-R nanocomposites.

Figure 5. Particle size distributions of magnetite-maghemite nanocrystals: (a) CC0.3/IO-R, (b) CC0.4/IO-R and (c) CC0.5/IO-R nanocomposites.

Figure 6. TGA thermograms: (a) CC0.3/IO-R, (b) CC0.4/IO-R and (c) CC0.5/IO-R nanocomposites under N₂ and O₂ atmospheres.

Table 2. TGA, DSC, VSM and cell viability of synthesized CC/IO nanocomposites.

Sample	TGA					DSC				VSM			Cell viability (%)
	Td1 of chitosan* (°C)	Weight loss at Td1** (%)	Td2 of chitosan* (°C)	Weight loss at Td2** (%)	Residual** (%)	Tm (°C)	ΔHm (J/g)	Td (°C)	ΔHd (J/g)	Mmax (emu/g)	Mr (emu/g)	Hc (Oe)
CC0.3/IO-R	256.2	30	431.6	27	28	184.0	133.3	251.2	129.5	8.6	<0.1	<3.0	82
CC0.4/IO-R	252.9	28	412.3	25	35	183.1	111.6	249.8	100.2	15.2	<0.1	<3.0	81
CC0.5/IO-R	250.6	29	409.2	27	34	187.7	67.5	249.4	95.9	14.8	<0.1	<3.0	80
CC0.4/IO-HT	252.9	31	482.0	36	21	185.4	104.1	258.0	118.3	12.7	0.4	11.6	89

* T_d values of chitosan were determined from TGA profiles under N₂.

** Weight losses at T_d and residuals were determined from the TGA profiles under O₂. The remaining proportion out of the weight loss at T_d and residuals was considered to be the amount of water and organic solvent.

Figure 7. DSC thermograms: (a) CC0.3/IO-R, (b) CC0.4/IO-R and (c) CC0.5/IO-R nanocomposites.

Figure 8. Magnetization curves: (a) CC0.3/IO-R, (b) CC0.4/IO-R and (c) CC0.5/IO-R nanocomposites.

Figure 9. (a) XRD pattern, (b) TEM image and (c) particle size distribution of CC0.4/IO-HT nanocomposite.

Figure 10. TGA thermograms of (a) CC0.4/IO-R and (b) CC0.4/IO-HT nanocomposites under N₂ and O₂ atmospheres.

Figure 11. DSC thermograms of (a) CC0.4/IO-R and (b) CC0.4/IO-HT nanocomposites.

Figure 12. Magnetization curves of (a) CC0.4/IO-R and (b) CC0.4/IO-HT nanocomposites.