Interstitial fluid pressure (IFP) in tumor is much higher than that in normal tissue, and it constitutes a great obstacle for the delivery of antitumor drugs, thus becoming a potential target for cancer therapy. In this study, cationic nanostructured lipid carriers (NLCs) were modified by low molecular weight gelatin to achieve the desirable reduction of tumor IFP and improve the drug delivery. In this way, the chemotherapy of formulations on tumor proliferation and pulmonary metastasis was further improved. The nanoparticles were used to load three drugs, docetaxel (DTX), quercetin (Qu), and imatinib (IMA), with high encapsulation efficiency of 89.54%, 96.45%, and 60.13%, respectively. GNP-DTX/Qu/IMA nanoparticles exhibited an enzyme-sensitive drug release behavior, and the release rate could be mediated by matrix metalloproteinases (MMP-9). Cellular uptake and MTT assays showed that the obtained GNP-DTX/Qu/IMA could be internalized into human breast 4T1 cells effectively and exhibited the strongest cytotoxicity. Moreover, GNP-DTX/Qu/IMA demonstrated obvious advantages in inducing apoptosis and mediating the expression of apoptosis-related proteins (Caspase 3, Caspase 9, and bcl-2). In the wound-healing assay, GNP-DTX/Qu/IMA exhibited evidently inhibition of cell migration. The benefits of tumor IFP reduction induced by GNP-DTX/Qu/IMA were further proved after a continuous administration to 4T1 tumor-bearing mice. Finally, in the in vivo antitumor assays, GNP-DTX/Qu/IMA displayed stronger antitumor efficiency as well as suppression on pulmonary metastasis. In conclusion, the GNP-DTX/Qu/IMA system might be a promising strategy for metastatic breast cancer treatment.Keywords: imatinib; metastasis; MMP-9; nanoparticles; tumor interstitial fluid pressure;

Although docetaxel (DTX) is an efficient chemotherapeutic drug, its low and variable oral bioavailability restricts its oral applications. In this study, docetaxel–nicotinamide (DTX–NA) complex was prepared using crystallization technology. The DTX–NA complex loaded chitosan nanoparticles (DTX–NA/NPs) were obtained through modified ionic gelation method. Results showed that the saturated solubility of DTX–NA complex increased five-fold compared to DTX in water at 37 °C. The particle size of DTX–NA/NPs was 197.8 ± 16.9 nm. The cumulative drug release of DTX–NA/NPs was 1.88 times higher than that of DTX suspension. DTX–NA/NPs with a zeta potential of +28.12 ± 4.07 mV enhanced cell uptake by 3.85 times and showed a significant cytotoxicity with IC50 decreased from 63.37 ± 6.20 ng mL−1 to 22.06 ± 11.32 ng mL−1. Further analysis indicated that DTX–NA/NPs could down-regulate survivin, caspase-9 and caspase-3 expression, arrest cell cycle at the G2 stage, and induce apoptosis. The oral relative bioavailability of DTX–NA/NPs increased, and was 30.26 times higher than that of free DTX, which was consistent with in vitro permeation results. This study proved that the synergism of the DTX–NA complex and positively charged chitosan NPs could prolong drug residence, facilitate drug absorption, and restrain drug excretion. This novel DTX–NA/NPs drug delivery system exhibits potential for oral, instead of intravenous, administration of DTX.

Multifunctional nanoparticles, Fol/R7 NPs, based on pH-sensitive PLGA-PEG–folate and cell penetrating peptide R7-conjugated PLGA-PEG, were constructed for targeting vincristine sulfate (VCR) to tumor and overcoming multidrug resistance (MDR). In this study, the pH-triggered VCR release was 65.6% during 8 h in pH 5.0, but only 35.8% in pH 7.4, demonstrating that a large amount of VCR released rapidly at weak acidic environment. The VCR-Fol/R7 NPs could significantly enhance cellular uptake and cytotoxicity in MCF-7 and MCF-7/Adr cells when compared to the nanoparticles solely modified by folate or R7. With folate receptor-mediated endocytosis and strong intracellular penetration, VCR-Fol/R7 NPs increased drug accumulation in resistant tumor cells by escaping P-glycoprotein mediated drug efflux. In vivo imaging suggested the active targeting attributed to pH sensitivity and folate receptor-mediated effect could improve tumor targeting efficacy. Indeed, VCR-Fol/R7 NPs exhibited the stongest antitumor efficacy in vivo. Therefore, Fol/R7 NPs are an effective nanocarrier for delivering antitumor drug and overcoming multidrug resistance.Keywords: multidrug resistance; multifunctional; nanoparticles; pH sensitive; vincristine sulfate;

An ultra-performance-liquid-chromatography–quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOF-MS) method was developed and validated for the quantitation of daidzein (DZ) in rat plasma. Ethylparaben was chosen as internal standards (IS). DZ was linear over the range of 0.001–5 μg/mL. The lower limit of quantification (LLOQ) was 0.001 μg/mL and the limit of detection (LOD) was 0.0005 μg/mL. The intra-day and inter-day relative standard deviations (RSDs) were ranged from 3.59% to 6.43% and 5.35% to 7.25%, respectively. This UPLC/Q-TOF-MS method provided good specifity, highly sensitivity, accurate and high-speed detection (6 min), applicable to the pharmacokinetics study in rats in vivo after oral administration of free daidzein solution, daidzein-loaded poly (lactide-co-glycolide) (PLGA) nanoparticles (D-NPs) suspension and D-NPs co-administered with sodium caprate (C10) which as the oral absorption promoter. It was shown that the pharmacokinetics behavior was significantly improved after the oral administration of D-NPs suspension co-administered with absorption promoter C10 by the fact that the relative bioavailability were enhanced about 4.24-fold, compared to that of DZ suspension.Highlights► This UPLC/Q-TOF-MS method is rapid, simple and suitable for pharmacokinetic analysis. ► The absorption promoter C10 could enhance the oral absorption of daidzein. ► It has been identified the pharmacokinetic behavior of three daidzein formulations.

In the present study, the effect of a borneol/menthol eutectic mixture (25:75) and microemulsion on the absorption of daidzein in rat intestinal membrane was evaluated. The microemulsion formulation was composed of ethyl oleate (oil), Cremophor RH40 (surfactant), PEG400 (co-surfactant), and water. The borneol/menthol eutectic mixture and its microemulsion were found to enhance the intestinal absorption of daidzein in vitro. A diffusion chamber system with isolated rat intestinal membranes was used. In contrast, verapamil (0.3 mM), a typical P-glycoprotein inhibitor, showed no effect on the absorption of daidzein by this system. A pharmacokinetic study was conducted in rats. After oral administration of daidzein at a dose of 10 mg/kg in the form of either borneol/menthol eutectic mixtures or suspension, the relative bioavailability of borneol/menthol eutectic mixtures and microemulsion was enhanced by about 1.5- and 3.65-fold, respectively, compared with a daidzein suspension. In conclusion, a borneol/menthol eutectic mixture can enhance the absorption of daidzein, although the mechanism of absorption enhancement is still unclear.

The aim of this study is to develop a simple and applicable HPLC method for the detection of vincristine in rat plasma after administration of poly(lactic-co-glycolic acid)–poly(ethylene glycol) (PLGA–PEG) nanoparticles loaded with vincristine sulfate (VCR). Vincristine was extracted from rat plasma and vinblastine sulfate was chosen as the internal standard (IS). Chromatographic separation of VCR and IS was achieved by a Dikma Dimonsil C18 column (200 mm × 4.6 mm) with the mobile phase consisting of 0.02 M sodium dihydrogen phosphate–methanol (36:64, v/v, pH = 4.7) at a flow rate of 1.0 mL/min. The ultraviolet detection wavelength was set at 276 nm. The calibration curve was linear over a concentration range of 0.05–5.0 μg/mL. The intra-day and inter-day accuracy for three quality controls (QC) samples was 93.48–107.74% and 92.61–96.58%, respectively; the precision was less than 9%. The average method recoveries for vincristine from spiked plasma at all QC levels were over 83%; and extraction recoveries were between 66 and 70%. Vincristine was stable in rat plasma for one month at −80 °C, for 8 h at room temperature, as well as during three freeze–thaw cycles. This HPLC method was applied successfully to the pharmacokinetic study of vincristine in rats after a single intravenous injection of VCR in physiological saline (F-VCR) solution, VCR-loaded PLGA–mPEG nanoparticles with (NP1) and PLGA–PEG–folate nanoparticles (NP2) suspension, respectively. There were significant differences in main pharmacokinetic parameters between F-VCR and the nanoparticles. Both kinds of VCR-loaded nanoparticles displayed improved pharmacokinetic profiles.

This study was aimed at developing a simple HPLC method for the detection of daidzein in rat plasma. Daidzein was extracted from rat plasma with ethylparaben as internal standards (IS). Chromatographic separation of daidzein and IS was achieved by a Dikma Dimonsil C18 column (200 mm × 4.6 mm) with the mobile phase consisting of methanol–water (55:45, v/v) at a flow rate of 1.0 mL/min. The injection volume was 20 μL and the detecting wavelength was 249 nm. The calibration curve was linear over a concentration range from 0.05 to 5 μg/mL, and the accuracy was within a range of 93.4–126.2%. This HPLC method was applied successfully to the pharmacokinetic study of two kinds of daidzein-loaded poly(lactide-co-glycolide) (PLGA) nanoparticles (D-NPs) and daidzein suspension after intravenous injection in rats. Significant differences in main pharmacokinetic parameters of daidzein suspension and D-NPs were observed.

Daidzein is one of the most effective candidates for treating cardiovascular and cerebrovascular disease. However, considering its poor oral absorption and limited bioavailability, daidzein-loaded nanostructured lipid carriers-PLGA nanofibers were designed to handle the drawbacks. Daidzein-NLCs were successfully prepared by an emulsification and low-temperature solidification method. The physicochemical characteristics of NLCs were evaluated afterwards. Based on the preparation of daidzein-loaded NLCs, Daidzein-NLCs-nanofibers were optimized by electrospinning and were observed under Scanning Electron Microscope to capture the appearance. The sustained release profile of daidzein from Daidzein-NLCs-nanofibers in vivo was best fitted to the Kormeyer-Peppas equation. The in vitro skin permeable behavior showed the cumulative amount of daidzein from Daidzein-NLCs-nanofibers reached 21.71 μg cm−2 at 60 h, which was 3.78 times higher than pure daidzein solution. It demonstrated that the Daidzein-NLCs-nanofibers could significantly enhance the transported amount of drug. Confocal Laser Scanning Microscopy resulting images revealed a more effective content accumulation of Daidzein-NLCs-nanofibers than Daidzein-NLCs in epidermis. In vivo study indicated that Daidzein-NLCs-nanofibers had better skin retention than Daidzein-NLCs in the long term. The skin irritation experiment showed a positive result with no obvious stimulus observed. These results suggested that Daidzein-NLCs-nanofibers could be a potential candidate for transdermal delivery.Download high-res image (211KB)Download full-size image

Dual- and multi-functional drug delivery systems, especially ligand-modified nanoparticles (NPs) loaded with chemotherapeutic agents are paid much attention to due to their excellent behavior in vitro and in vivo. Bifunctional NPs (BF-NPs), which were based on PLGA–PEG and modified with folic acid and cell penetrating peptide R7 simultaneously, were developed. BF-NPs loaded with vincristine sulfate (VCR) were prepared via the water–oil–water emulsion solvent evaporation method. BF-NPs showed favorable particle size and zeta potentials, promising drug loading and entrapment efficiency. The release of VCR from BF-NPs exhibited a biphase release manner. Cellular uptake of BF-NPs was found to be higher than that of the NPs merely modified by folic acid or R7. In vitro cytotoxicity, cell apoptosis and cell cycle arrest studies also revealed that BF-NPs were more potent than those of the NPs merely modified by folic acid or R7. Therefore, the results demonstrated that BF-NPs developed in this study could be a potential vehicle for delivering chemotherapeutic agents such as VCR and breast cancer therapy.

Metastasis impedes the successful chemotherapy for breast cancer. In this study, an Akt inhibitor (quercetin, Qu) was co-delivered with a chemotherapeutic agent (docetaxel, DTX) by using hyaluronic acid (HA)-modified nanoparticles (NPs) as vectors to block metastasis. Dual DTX/Qu-loaded HA/polylactic-co-glycolic acid–polyethyleneimine NPs (PP-HA/NPs) were prepared through a modified emulsion solvent evaporation technique. The particle size of PP-HA/NPs with narrow polydispersity was 209.8 ± 10.8 nm. Wound healing assay revealed that Qu co-delivery and HA modification elicited synergistic inhibitory effects on cell motility. The downregulation of p-Akt and matrix metalloproteinase-9 (MMP-9) expression contributed to the significant inhibition of cell migration and invasion with inhibition rates of 95.6% and 99.3%, respectively. Further studies indicated that PP-HA/NPs could be efficiently uptaken by 4T1 breast cancer cells and could further induce cytotoxicity, decrease colony formation and promote cell apoptosis. Biodistribution assay demonstrated PP-HA/NPs also enhanced drug accumulation in the tumor and lungs and predicted that PP-HA/NPs could be employed as an effective therapy for primary tumor and pulmonary metastasis. Therefore, PP-HA/NPs could be a promising delivery system to treat metastatic breast cancer effectively.Download high-res image (232KB)Download full-size image

Nanostructured lipid carriers (NLCs) are a new generation of lipid nanoparticles, which have showed some advantages over traditional lipid nanoparticles, such as improved drug incorporation and release properties. The purpose of this study is to develop an optimized nanostructured lipid carrier formulation for etoposide (VP16), and to estimate the potential of NLCs as oral delivery system. VP16-NLCs were prepared by an emulsification and low-temperature solidification method. The average drug entrapment efficiency, particle size and zeta potential of VP16-NLCs, VP16-PEG40-St-modified NLCs (VP16-PEG40-NLCs) and VP16-DSPE-PE- modified NLCs (VP16-DSPE-NLCs) were 57.9–89.7%, 125.9–91.2 nm and −28.49 to −15.34 mV, respectively. The absorption of VP16-NLCs in the intestine was performed by the diffusion chamber. It was found that VP16-DSPE-NLCs with a smaller particle size made the drug transport easy from mucosal to serosal side. A pharmacokinetic study was conducted in rats. After oral administration of VP16 at a dose of 180 mg/kg in the form of either VP16-NLCs or suspension, the relative bioavailability of VP16-NLCs, VP16-PEG40-NLCs and VP16-DSPE-NLCs were enhanced about 1.8-, 3.0- and 3.5-fold, respectively, compared with VP16 suspension. Furthermore, VP16-DSPE-NLCs displayed the highest cytotoxicity against human epithelial-like lung carcinoma cells. The NLCs formulation remarkably improved the oral bioavailability of VP16 and demonstrated a promising perspective for oral delivery of VP16.