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Original Research

Formation of ion pairing as an alternative to improve encapsulation and anticancer activity of all-trans retinoic acid loaded in solid lipid nanoparticles

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Pages 6011-6020 | Published online: 12 Dec 2012

Figures & data

Figure 1 Chemical structure of RA (A), benethamine (B), stearylamine (C), and triethylamine (D).

Abbreviation: RA, all-trans retinoic acid.

Figure 1 Chemical structure of RA (A), benethamine (B), stearylamine (C), and triethylamine (D).Abbreviation: RA, all-trans retinoic acid.

Table 1 Influence of the amine type on the particle size, polydis-persion index, zeta potential and EE of RA in SLNs

Figure 2 Stability of encapsulation efficiency (EE) of RA in SLNs prepared with triethylamine (TA) or benethamine (BA).

Note: Data represent mean ± SD (n = 3).

Abbreviations: RA, all-trans retinoic acid; SD, standard deviation; SLN, solid lipid nanoparticle.

Figure 2 Stability of encapsulation efficiency (EE) of RA in SLNs prepared with triethylamine (TA) or benethamine (BA).Note: Data represent mean ± SD (n = 3).Abbreviations: RA, all-trans retinoic acid; SD, standard deviation; SLN, solid lipid nanoparticle.

Figure 3 Cell viability studies, as evaluated by MTT assay, of blank SLNs, RA-SA-loaded SLNs, and free RA in cancer and normal cells, MCF-7 (A), Jurkat (B), HCT-116 (C), and PBMCs (D), after 48 hours of exposure.

Notes: Data were expressed as mean ± SD of three independent experiments. The blank SLNs were diluted at the same proportion as RA-loaded SLNs.

Abbreviations: MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; RA, all-trans retinoic acid; PBMC, peripheral blood mononuclear cells; SA, stearylamine; SD, standard deviation; SLN, solid lipid nanoparticle.

Figure 3 Cell viability studies, as evaluated by MTT assay, of blank SLNs, RA-SA-loaded SLNs, and free RA in cancer and normal cells, MCF-7 (A), Jurkat (B), HCT-116 (C), and PBMCs (D), after 48 hours of exposure.Notes: Data were expressed as mean ± SD of three independent experiments. The blank SLNs were diluted at the same proportion as RA-loaded SLNs.Abbreviations: MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; RA, all-trans retinoic acid; PBMC, peripheral blood mononuclear cells; SA, stearylamine; SD, standard deviation; SLN, solid lipid nanoparticle.

Figure 4 Cell viability studies, as evaluated by MTT assay, of blank SLNs, RA-TA-loaded SLNs, RA-BA-loaded SLNs and free RA in MCF-7 cells after 48-hour exposure.

Notes: Data were expressed as mean ± SD of three independent experiments. The data for blank SLNs, which were diluted at the same proportion as RA-loaded SLNs, represent overlapping values for TA-based SLNs and BA-based SLNs. aSignificant difference compared to free RA; bsignificant difference between TA-based SLNs and BA-based SLNs.

Abbreviations: MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; BA, benethamine; RA, all-trans retinoic acid; SLN, solid lipid nanoparticle; TA, triethylamine.

Figure 4 Cell viability studies, as evaluated by MTT assay, of blank SLNs, RA-TA-loaded SLNs, RA-BA-loaded SLNs and free RA in MCF-7 cells after 48-hour exposure.Notes: Data were expressed as mean ± SD of three independent experiments. The data for blank SLNs, which were diluted at the same proportion as RA-loaded SLNs, represent overlapping values for TA-based SLNs and BA-based SLNs. aSignificant difference compared to free RA; bsignificant difference between TA-based SLNs and BA-based SLNs.Abbreviations: MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; BA, benethamine; RA, all-trans retinoic acid; SLN, solid lipid nanoparticle; TA, triethylamine.

Table 2 Effects of different treatments of MCF-7 cancer cells on DNA fragmentation and cell-cycle stage distribution

Figure 5 DNA fluorescence histograms of PI-stained MCF-7 cells after 48 hours of incubation under various experimental conditions: medium alone (A), blank SLNs (B), free RA (C), or BA-RA-loaded SLNs (D).

Notes: RA was used at 25 μM. BA-RA-loaded SLNs induce cell-cycle arrest accompanied by reduction in the S phase in MCF-7 cells. Data from one representative experiment that represents 20,000 events (cells) are shown.

Abbreviations: BA, benethamine; PI, propidium iodide; RA, all-trans retinoic acid; SLN, solid lipid nanoparticle.

Figure 5 DNA fluorescence histograms of PI-stained MCF-7 cells after 48 hours of incubation under various experimental conditions: medium alone (A), blank SLNs (B), free RA (C), or BA-RA-loaded SLNs (D).Notes: RA was used at 25 μM. BA-RA-loaded SLNs induce cell-cycle arrest accompanied by reduction in the S phase in MCF-7 cells. Data from one representative experiment that represents 20,000 events (cells) are shown.Abbreviations: BA, benethamine; PI, propidium iodide; RA, all-trans retinoic acid; SLN, solid lipid nanoparticle.