Folic Acid-Targeted Etoposide Cubosomes for Theranostic Application of Cancer Cell Imaging and Therapy

Abstract

BACKGROUND The aim of this study was to develop a novel Poloxamer-based drug delivery system featuring a tumor-targeting folate moiety, which was expected to provide better targeting properties and therapeutic effects compared with the traditional cubosomes (Cubs). MATERIAL AND METHODS Both folate-modified Cubs containing etoposide (ETP-Cubs-FA) and normal cubic nanoparticles loaded with etoposide (ETP-Cubs) were prepared through the fragmentation of bulk gels under the homogenization condition of 1500 bar, and a mean particle size of around 180 nm was obtained with a narrow size distribution. The cubosomes were further characterized by differential scanning calorimetry (DSC) and Polarized light microscopy (PLM). The release of ETP in vitro from these nanoparticles was found to be 82.5% at 36 h, showing a sustained release property compared with the free drug administration. RESULTS Folate-modified cubosomes exhibited best anti-proliferative activity followed by normal cubosomes and the free drug. A further cell uptake study of Rhodamine B-loaded Cubs-FA (Rh-B-Cubs-FA) showed a marked increase of cellular accumulation compared with free Rh-B and Rh-B-loaded Cubs (Rh-B-Cubs). In vivo Rh-B-based tumor imaging demonstrated that Cubs-FA specifically targeted the tumor tissue. CONCLUSIONS The folate-modified cubosomes containing ETP may be a promising drug candidate for antitumor treatment.

Figure 1

The DSC thermograms of folate (A), the mixture of folate and P407 (B), P407-FA (C).

Figure 2

¹H-NMR spectrum of P407-FA. Peaks a–c represent aromatic protons in FA.

Figure 3

Size and Zeta distribution of cubosomes. Different colors represent 3 tests (n=3). (A) Size distribution of ETP-Cubs; (B) Size distribution of ETP-Cubs-FA; (C) Zeta distribution of ETP-Cubs; (D) Zeta distribution of ETP-Cubs-FA.

Figure 4

Different states of liquid crystal. (A) and (B) Represent lamellar liquid crystal; (C) No liquid crystal; (D) Cubic liquid crystal.

Figure 5

The DSC thermograms of GMO (A), P407 (B), ETP (C), Their mixture (D), ETP-Cubs (E, prepared with 100% P407), and ETP-Cubs-FA (F, prepared with 100% P407-FA).

Figure 6

Release profile of ETP from ETP solution (●); ETP-Cubs (■); ETP-Cubs-FA (◆).

Figure 7

Cell viability of blank cubosomes and cytotoxicity of ETP and ETP-Cubs -FA. (A) Cell viability of MCF-7 cells after 24-h treatment with Cubs or Cubs-FA was determined by MTT. (B) In vitro cytotoxicity assessment of free ETP, ETP-Cubs, and ETP-Cubs-FA against MCF-7 cell lines.

Figure 8

Rh-B uptake. Uptake of (A) Rh-B; (B) Rh-B-Cubs and (C) Rh-B-Cubs-FA at 4 h in MCF-7 cell lines.

Figure 9

Whole-body and tumor fluorescence images (white circles indicate the inoculated tumor) in MCF-7 tumor-bearing mice after intravenous injection of Rh-B-Cubs and Rh-B-Cubs-FA.