Optimization, Characterization and in vivo Evaluation of Paclitaxel-Loaded Folate-Conjugated Superparamagnetic Iron Oxide Nanoparticles

Figures & data

Table 1 Levels of the Factors in RSM Design

Variable	Code	Levels
		−1.682	−1	0	1	1.682
m(SPTX): m(FA@PEG/PEI-SPIONs)	X1	0.33	0.5	1	2	3
V(ethanol-chloroform): V(H2O)	X2	0.2	0.33	0.5	1	2
Dropping speed of SPTX (mL/min)	X3	0.1	0.5	1	2	3

Figure 1 Synthesis schematic of SPTX@FA@PEG/PEI-SPIONs.

Abbreviations: PEG, polyethylene glycol; PEI, polyethyleneimine; FA, folic acid; SPTX, 2ʹ-succinate paclitaxel.

Figure 2 3D response surface diagram for particle size (A1–A3) and EE (B1–B3) of SPTX@FA@PEG/PEI-SPIONs showing interaction between (A1 and B1) X₁ and X₂; (A2 and B2) X₁ and X₃; (A3 and B3) X₂ and X₃.

Abbreviations: m_(SPTX), m_{(FA@PEG/PEI-SPIONs)} (X₁); V_{(ethanol-chloroform)}, V_(H2O) (X₂), dropping speed of SPTX (X₃).

Table 2 Results of Certification Optimization

Number	Particle Size (nm)	Zeta Potential (mV)	EE of SPTX (%)	LE of SPTX (%)
1	174.5	−10.24	81.3	13.6
2	180.3	−11.62	79.6	16.4
3	177.4	−10.64	82.3	14.3
Mean ± SD	178.1 ± 3.12	−10.8 ± 0.71	81.1 ± 1.66	14.8 ± 1.46

Figure 3 Particles size (A), zeta potential (B), TEM images and size distributions of PEG/PEI-SPIONs (C1), FA@PEG/PEI-SPIONs (C2), SPTX@FA@PEG/PEI-SPIONs (C3) under optimal conditions.

Figure 4 (A) The ultraviolet (UV) and (B) Fourier transform infrared (FTIR) spectra of SPTX@FA@PEG/PEI-SPIONs.

Figure 5 (A) The stability and (B) drug content of SPTX@FA@PEG/PEI-SPIONs in 0.01 mol/L PBS solution, FBS-containing PBS solution (10% FBS) and complete cell culture medium (10% FBS) at 37°C for 72 h (A1 and B1) or at 4°C for 28 days (A2 and B2). Data were represented as mean ± SD (n=3).

Figure 6 Release profiles of SPTX from SPTX@FA@PEG/PEI-SPIONs at pH 7.3, 6.0 and 5.0, respectively.

Figure 7 IC₅₀ of PTX and SPTX treated with at 24 h (A) and 48 h (B). Concentration-dependent survival curves of CNE-1 and HNE-1 cells treated by PEG/PEI-SPIONs (C) and FA@PEG/PEI-SPIONs (D) for 24 h. In vitro cytotoxicity of SPTX@FA@PEG/PEI-SPIONs against CNE-1 and HNE-1 cells after treatment for 24 h (E) or 48 h (F). Data were expressed as means ± SD (n=3). *P<0.05, **P<0.01; ^##P<0.01; ^&&P<0.01.

Figure 8 (A) Plasma concentration–time curves of free PTX, SPTX and SPTX@FA@PEG/PEI-SPIONs in vivo, data are expressed as the mean ± SD (n=4). Tissue distributions of free PTX, SPTX and SPTX@FA@PEG/PEI-SPIONs at 1 h (B), 4 h (C) and 12 h (D) post-intravenous injection (n=4), *P<0.05.