A multifunctional poly(curcumin) nanomedicine for dual-modal targeted delivery, intracellular responsive release, dual-drug treatment and imaging of multidrug resistant cancer cells

A multifunctional anti-cancer nanomedicine PTX/MNPs/QDs@Biotin–PEG–PCDA was developed aiming at overcoming paclitaxel resistance in MCF-7/ADR breast cancer cells with simultaneous imaging.

deionized water for 24 h with a dialysis membrane (MW cut-off of 6000 Da). The product (PEG-PCDA) was obtained by lyophilization and kept under dry conditions

Synthesis of Biotin-PEG-PCDA.
Biotin (0.066 g), PEG6000 (1.350 g), DCC (0.111g), DMAP (9.9 mg) were dissolved in 40 mL anhydrous dichloromethane. The resulting solution was stirred at room temperature for 24 h. After removing the formed DCU, the filtrate was added into an excess of anhydrous ether to produce a precipitate, which was further treated multiple times by dichloromethane with anhydrous ether and then dried under vacuum to yield the Biotin-PEG as a white solid. PCDA (0.90 g), Biotin-PEG (0.337 g), DCC (22 mg) and DMAP (2 mg) were dissolved in 40 mL anhydrous dichloromethane. After stirred at room temperature for 24 h and filtration to remove DCU, the filtrate was added into an excess of anhydrous ether to produce a precipitate, which was dissolved in water and dialyzed against deionized water for 24 h with a dialysis membrane(MW cut-off of 6000 Da). After lyophilization, a dry powder ,the Biotin-PEG-PCDA, was obtained.

The establishment of paclitaxel concentration standard curve
It was supposed that the concentration of the particle was 20~60μg/ml according to previous experiments, so a Paclitaxel concentration curve (1~200μg/mL) was needed when the mobile phase was a mixture of water and acetonitrile in the volume ratio of 50:50 holding the elution rate at 1.0 ml/min, the volume of injected standard samples were 50 μl constantly and the paclitaxel detection wavelength was set at 227nm using a high-performance liquid chromatography (HPLC). Fig. S2 shows the standard calibration curve for PTX where the X is the concentration of paclitaxel and the Y is the peak area of PTX in the HPLC elution profile.

The research of the multiple MCF-7/ADR cells resisting drug
MTT assay was taken to explore the multiple that MCF-7/ADR cancer cell resists drug in contrast of MCF-7 cancer cell. MTT classical method was taken to explore the level that MCF-7/ADR cancer cell resists drug. Human breast cancer cell line MCF-7 and MCF-7/ADR cells in logarithmic growth were washed and digested to be dispersed by culture medium in 96-well plates at a density of 6000 cells/well respectively. Serials of certain concentrate paxlitaxel were added after incubation. The treatments was replaced with MTT assay after 48h.A microplate reader(Bio-Rad 680,USA)was taken to measure the absorbance of each well, when the test wavelength is 570nm.It is necessary to calculate IC 50 values which represents the drug concentration required to inhibit tumor cells growth by 50% relative to controls to explore each group of drugs reversing multidrug resistance effects on MCF-7 / ADR cells by following formulas.

The cytotoxicity of the materials, MNPs, QDs and Biotin-PEG-PCDA
The MTT assay was taken to measure the cytotoxicity against MCF-7/ADR cells of the materials, MNPs, QDs and Biotin-PEG-PCDA. Such experiments were taken to explore whether the materials were obviously cytotoxic without the effect of drug. MCF-7/ADR cells in logarithmic growth were seeded in 96-well plates at a density of 6000 cells/well and