Lipid-coated gold nanocomposites for enhanced cancer therapy

Abstract

The aim of the work reported here was to develop lipid-coated multifunctional nanocomposites composed of drugs and nanoparticles for use in cancer therapy. We incorporated thermosensitive phospholipids onto the surface of anisotropic gold nanoparticles (AuNPs) to further enhance drug delivery, with possible additional applications for in vivo imaging and photothermal cancer therapy. Lipid-coated nanohybrids loaded with the drug docetaxel (DTX) were prepared by a thin-film formation, hydration, and sonication method. Nanoparticles and their composites were characterized using particle-size analysis, zeta potential measurements, transmission electron microscopy, UV-visible spectroscopy, and reverse-phase high-performance liquid chromatography, demonstrating successful loading of DTX into the lipid bilayer on the surface of the gold nanoparticles. Initial in vitro studies using breast-cancer (MCF-7) and melanoma (B16F10) cell lines demonstrated that the drug-containing nanocomposites at equivalent drug concentrations caused significant cytotoxicity compared to free DTX. Differential flow cytometry analysis confirmed the improved cellular uptake of lipid-coated nanocomposites. Our preliminary results show that DTX-loaded anionic lipid-coated gold nanorod (AL_AuNR_DTX) and cationic lipid-coated gold nanoparticle (CL_AuNP_DTX) possess effective tumor cell-suppression abilities and can therefore be considered promising chemotherapeutic agents. Further evaluation of the therapeutic efficacy of these hybrid nanoparticles combined with external near-infrared photothermal treatment is warranted to assess their synergistic anticancer actions and potential bioimaging applications.

Keywords: anticancer; docetaxel; drug-containing nanocomposites; gold nanorods; thermosensitive lipids.

Figure 1

The gold nanocomposite formulations were prepared by a thin-film hydration-sonication technique. Abbreviations: AuNR, gold nanorod; AuNP, spherical gold nanoparticle.

Figure 2

Characterization data of gold nanocomposites as determined by transmission electron microscopy (TEM) and UV-visible spectrophotometry. Notes: (A) UV-visible spectroscopy of (a) AuNR, (b) AuNP, and (c) CL_AuNP_DTX and AL_AuNR_DTX. (B) TEM images of (a) AuNP, (b) CL_AuNP_DTX, (c) AuNR, and (d) AL_AuNR_DTX. Abbreviations: AL_AuNR_DTX, docetaxel-loaded anionic lipid-coated gold nanorod; AuNP, spherical gold nanoparticle; AuNR, gold nanorod; CL_AuNP_DTX, cationic lipid-coated gold nanoparticle.

Figure 3

In vitro release profiles of DTX from AL_AuNR_DTX, CL_AuNP_DTX, and free DTX in phosphate-buffered saline (pH 7.4, 0.14 M NaCl) at 37°C. Abbreviations: AL_AuNR_DTX, docetaxel-loaded anionic lipid-coated gold nanorod; CL_AuNP_DTX, cationic lipid-coated gold nanoparticle; DTX, docetaxel.

Figure 4

Quantitative cellular uptake analysis by B16F10 and MCF-7 cells. In vitro cellular uptake of gold nanoparticles and nanocomposite formulations into B16F10 (A and B) and MCF-7 cells (C and D), assessed using fluorescence-activated cell sorting analysis. Notes: Unlabeled and fluorescently labeled histograms of (A) CL_AuNP_DTX and (B) AL_AuNR_DTX for B16F10 cells, and (C) CL_AuNP_DTX and (D) AL_AuNR_DTX for MCF-7 cells. Control, gray; nanoparticles, green; formulations, pink. Abbreviations: AL_AuNR_DTX, docetaxel-loaded anionic lipid-coated gold nanorod; CL_AuNP_DTX, cationic lipid-coated gold nanoparticle; FL2-H, fluorescence2-height; SSC-H, side-scattered light-height.

Figure 5

Qualitative study of gold nanocomposites uptake in B16F10 cells. Notes: Confocal laser scanning microscopy analysis of live cell imaging of B16F10 cells after treatment with CL_AuNP_DTX (A) and AL_AuNR_DTX (B). Blue, DAPI; red, gold nanocomposites. The scale bars indicate 10 μM. Abbreviations: AL_AuNR_DTX, docetaxel-loaded anionic lipid-coated gold nanorods; CL_AuNP_DTX, cationic lipid-coated gold nanoparticles; DAPI, 4′,6-diamidino-2-phenylindole.

Figure 6

Quantitative cellular uptake measured by liquid chromatography–tandem mass spectrometry (LC-MS/MS). Abbreviations: AL_AuNR_DTX, docetaxel-loaded anionic lipid-coated gold nanorod; CL_AuNP_DTX, cationic lipid-coated gold nanoparticle.

Figure 7

Dose effects study of gold nanocomposites on the cytotoxicity by MTT assay. Notes: In vitro cytotoxicity of uncoated and lipid-coated drug-containing gold nanocomposites in B16F10 and MCF-7 cells after 24 hours. Each value represents the mean ± standard error (n=8). Statistical significance was determined using two-way analysis of variance with Bonferroni post-tests using free DTX as control (*P<0.05; **P<0.01; ***P<0.001). Abbreviations: AL_AuNR_DTX, docetaxel-loaded anionic lipid-coated gold nanorod; AL_B, anionic liposomes; AuNP, spherical gold nanoparticle; AuNR, gold nanorod; CL_AuNP_DTX, cationic lipid-coated gold nanoparticle; CL_B, cationic liposomes; DTX, docetaxel; MTT, 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl-2H-tetrazolium bromide.

Figure 8

Cell-cycle analysis and the corresponding microscopy images of B16F10 and MCF-7 cells after control treatments and 24-hour incubations with AuNP, CL_AuNP_DTX, AuNR, and AL_AuNR_DTX. Abbreviations: AuNR, gold nanorod; AuNP, spherical gold nanoparticle; AL_AuNR_DTX, docetaxel-loaded anionic lipid-coated gold nanorod; CL_AuNP_DTX, cationic lipid-coated gold nanoparticle; G1, Gap 1; G2/M, Gap 2/Mitosis; S, Synthesis; Sub-G1, Gap 1.