Promotion of initial anti-tumor effect via polydopamine modified doxorubicin-loaded electrospun fibrous membranes

Abstract

Drug-loaded electrospun PLLA membranes are not conducive to adhesion between materials and tissues due to the strong hydrophobicity of PLLA, which possibly attenuate the drugs' effect loaded on the materials. In the present work, we developed a facile method to improve the hydrophilicity of doxorubicin (DOX)-loaded electrospun PLLA fibrous membranes, which could enhance the anti-tumor effect at the early stage after implantation. A mussel protein, polydopamine (PDA), could be easily grafted on the surface of hydrophobic DOX-loaded electrospun PLLA membranes (PLLA-DOX/pDA) in water solution. The morphology analysis of PLLA-DOX/pDA fibers displayed that though the fiber diameter was slightly swollen, they still maintained a 3D fibrous structure, and the XPS analysis certified that pDA had successfully been grafted onto the surface of the fibers. The results of surface wettability analysis showed that the contact angle decreased from 136.7° to 0° after grafting. In vitro MTT assay showed that the cytotoxicity of PLLA-DOX/pDA fibers was the strongest, and the stereologic cell counting assay demonstrated that the adhesiveness of PLLA/pDA fiber was significantly better than PLLA fiber. In vivo tumor-bearing mice displayed that, after one week of implantation, the tumor apoptosis and necrosis of PLLA-DOX/pDA fibers were the most obvious from histopathology and TUNEL assay. The caspase-3 activity of PLLA-DOX/pDA group was the highest using biochemical techniques, and the Bax: Bcl-2 ratio increased significantly in PLLA-DOX/pDA group through qRT-PCR analysis. All the results demonstrated that pDA can improve the affinity of the electrospun PLLA membranes and enhance the drug effect on tumors.

Keywords: Cancer; PLLA; electrospun; hydrophobicity; polydopamine.

Figure 1

SEM photographs of the electrospun PLLA (A), PLLA-DOX (B), PLLA/pDA (C), and PLLA-DOX/pDA fibers (D).

Figure 2

XPS analysis (A) of the electrospun PLLA (a), PLLA-DOX (b), PLLA/pDA (c), and PLLA-DOX/pDA fibers (d). And contact angleanalysis (B) of the electrospun PLLA, PLLA-DOX, PLLA/pDA, and PLLA-DOX/pDA fibers.

Figure 3

(In vitro drug release) In vitro DOX release profiles of the electrospun PLLA-DOX (a) and PLLA-DOX/pDA fibers (b) in pH 7.4 buffer solution.

Figure 4

MTT assay. Cytotoxicity of extracts of different materials tested on MDA-MB-231 cell line. The results are presented as reduction of metabolic activity in percentage when compared with the negative control (cells without extracts of materials, 100%). *P < 0.05 represents significant difference between different groups.

Figure 5

Histopathological analysis of mice with breast residual tumor (50×). The insert images showed the morphology of tumor tissues in the blank dotted box under 200×. The black arrows in the Figures represent the necrosis of tumor tissues.

Figure 6

In vivo TUNEL analysis of mice with breast residual tumor. (A) control group (200×); (B) PLLA group (200×); (C) PLLA-DOX group (200×); (D) PLLA-DOX/pDA group (200×); (E) the number of cells per mm². *P < 0.05 represents significant difference compared to control group; **P < 0.05 represents significant difference compared to control group and PLLA-DOX group.

Figure 7

Caspase-3 activity. A. caspase-3 activity in different groups by the spectrophotometric determination; B. the activation extent of caspase-3 calculated by OD_experiment/OD_{blank control}. *P < 0.05 represents significant difference compared to control group; **P < 0.05 represents significant difference compared to control group and PLLA-DOX group.

Figure 8

qRT-PCR analysis of Bax expression (A); Bcl-2 expression (B); and Bax: Bcl-2 ratio (C) in differently treated groups after one week of operation. Each bar represents the mean values ± SE from experiments performed in triplicate. *P < 0.05 represents significant difference compared to control group; **P < 0.05 represents significant difference compared to control group and PLLA-DOX group.