Redox-responsive and pH-sensitive nanoparticles enhanced stability and anticancer ability of erlotinib to treat lung cancer in vivo

Figures & data

Figure 1 Synthesis route and ¹H-NMR spectroscopy of PAA-ss-OA.

Abbreviations: ¹H-NMR, hydrogen-1 nuclear magnetic resonance; DMSO, dimethyl sulfoxide; EDC, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide; NHS, N-hydroxysuccinimide; OA, oleic acid; PAA, poly(acrylic acid); ss, cystamine.

Figure 2 Scheme graph of PAA-ETB-NPs.

Abbreviations: ETB, erlotinib; NPs, nanoparticles; OA, oleic acid; PAA, poly(acrylic acid); ss, cystamine.

Table 1 Characterization of NPs

Characteristics	Mean size (nm)	PDI	Zeta potential (mV)	EE (%)	DL (%)
Free NPs	111.8±3.9	0.10±0.02	−21.4±2.9	N/A	N/A
ETB-NPs	112.1±4.3	0.13±0.02	−22.8±3.1	87.6±3.7	4.3±0.5
PAA-ETB-NPs	171.6±4.6	0.18±0.03	−32.3±3.4	84.9±4.3	2.6±0.3

Note: The data is presented as mean ± SD.

Abbreviations: DL, drug loading capacity; EE, encapsulation efficiency; ETB, erlotinib; N/A, not applicable; NPs, nanoparticles; PAA, poly(acrylic acid); PDI, polydispersity index.

Figure 3 The serum stability of NPs in tumor-bearing mouse plasma at 37°C for 72 hours.

Notes: Size (A), PDI (B), and EE (C) changes are illustrated. Data represent mean ± SD (n=3).
Abbreviations: EE, drug encapsulation efficiency; ETB, erlotinib; NPs, nanoparticles; PAA, poly(acrylic acid); PDI, polydispersity index.

Figure 4 In vitro drug release of ETB from the NPs and solution in PBS (A) and GSH-containing PBS (B).

Note: Data represent mean ± SD (n=3).
Abbreviations: ETB, erlotinib; GSH, glutathione; NPs, nanoparticles.

Table 2 IC₅₀ values (μM) of NPs and solution evaluated on A549 cells, NCI-H460 cells, and HUVEC

Cell line	ETB solution	ETB-NPs	PAA-ETB-NPs
A549 cells	36.8±2.3	9.5±0.7	3.3±0.3
NCI-H460 cells	46.5±3.1	17.2±1.1	4.6±0.5
HUVEC	42.3±2.6	40.2±1.9	41.6±2.7

Abbreviations: ETB, erlotinib; HUVEC, human umbilical vein endothelial cell; NPs, nanoparticles; PAA, poly(acrylic acid).

Figure 5 In vitro cytotoxicity of NPs evaluated on A549 cells (A), NCI-H460 cells (B), and HUVEC (C) by MTT assay.

Notes: Data represent mean ± SD (n=3). *p<0.05.
Abbreviations: ETB, erlotinib; HUVEC, human umbilical vein endothelial cell; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; NPs, nanoparticles; PAA, poly(acrylic acid).

Figure 6 In vivo tissue distribution of ETB solution (A), ETB-NPs (B), and PAA-ETB-NPs (C).

Note: Data represent mean ± SD (n=8).
Abbreviations: ETB, erlotinib; NPs, nanoparticles; PAA, poly(acrylic acid).

Figure 7 In vivo tumor inhibition effect evaluated by using a xenograft nude mouse model with human lung cancer cells. Tumor volume (A); body weight (B); and tumor inhibition rate (C).

Notes: Data represent mean ± SD (n=8). *p<0.05, **p<0.01, and ***p<0.001.
Abbreviations: ETB, erlotinib; NPs, nanoparticles; PAA, poly(acrylic acid).