Guangpu Liu

Synergistic effect of folate-mediated targeting and verapamil-mediated P-gp inhibition with paclitaxel -polymer micelles to overcome multi-drug resistance

Multidrug resistance (MDR) in tumor cells is a significant obstacle for successful cancer chemotherapy. Overexpression of drug efflux transporters such as P-glycoprotein (P-gp) is a key factor contributing to the development of tumor drug resistance. Verapamil (VRP), a P-gp inhibitor, has been reported to be able to reverse completely the resistance caused by P-gp. For optimal synergy, the drug and inhibitor combination may need to be temporally colocalized in the tumor cells. Herein, we investigated the effectiveness of simultaneous and targeted delivery of anticancer drug, paclitaxel (PTX), along with VRP, using DOMC-FA micelles to overcome tumor drug resistance. The floate-functionalized dual agent loaded micelles resulted in the similar cytotoxicity to PTX-loaded micelles/free VRP combination and co-administration of two single-agent loaded micelles, which was higher than that of PTX-loaded micelles. Enhanced therapeutic efficacy of dual agent micelles could be ascribe to increased accumulation of PTX in drug-resistant tumor cells. We suggest that the synergistic effect of folate receptor-mediated internalization and VRP-mediated overcoming MDR could be beneficial in treatment of MDR solid tumors by targeting delivery of micellar PTX into tumor cells. As a result, the difunctional micelle systems is a very promising approach to overcome tumor drug resistance.

Galactose-decorated pH-responsive nanogels for hepatoma-targeted delivery of oridonin.

Nanogels based on the polymers of galactosylated chitosan-graft-poly (N-isopropylacrylamide) (Gal-CS-g-PNIPAm) were used as carriers of oridonin (ORI) for tumor targeting. Three ORI-loaded nanogels with various degrees of galactose substitution were prepared, and their characteristics were evaluated. The release behavior of ORI from these nanogels was pH-dependent, and the release could be accelerated under mildly acidic conditions. The cytotoxicity of ORI-loaded nanogels was pH-sensitive. ORI-loaded nanogels exhibited a higher antitumor activity than drug-loaded nanogels without galactosylation, and the anticancer activity increased in relation to increases in the number of galactose moieties of the nanogels in HepG2 cells. In contrast, the cytotoxicity of ORI-loaded nanogels against MCF-7 cells decreased compared with that of drug-loaded nanogels without galactosylation. Results demonstrated that these nanogels could enhance the uptake of ORI into HepG2 cells via asialoglycoprotein receptor-mediated endocytosis. These galactose-decorated pH-responsive nanogels were well-suited for targeted drug delivery to liver cancer cells.

Folate-mediated targeted and intracellular delivery of paclitaxel using a novel deoxycholic acid- O -carboxymethylated chitosan–folic acid micelles

Background A critical disadvantage for successful chemotherapy with paclitaxel (PTX) is its nontargeting nature to cancer cells. Folic acid has been employed as a targeting ligand of various anticancer agents to increase their cellular uptake within target cells since the folate receptor is overexpressed on the surface of such tumor cells. In this study, a novel biodegradable deoxycholic acid-O-carboxymethylated chitosan–folic acid conjugate (DOMC-FA) was used to form micelles for encapsulating the anticancer drug PTX. Methods and results The drug-loading efficiency, encapsulation efficiency, in vitro drug release and physicochemical properties of PTX-loaded micelles were investigated in detail. In vitro cell culture studies were carried out in MCF-7 cells, a human breast carcinoma cell line, with folate receptor overexpressed on its surface. An increased level of uptake of folate-conjugated micelles compared to plain micelles in MCF-7 cells was observed, and the enhanced uptake of folate-micelles mainly on account of the effective process of folate receptor-mediated endocytosis. The MTT assay, morphological changes, and apoptosis test implied that the folate-conjugated micelles enhanced the cell death by folate-mediated active internalization, and the cytotoxicity of the FA-micellar PTX (DOMC-FA/PTX) to cancer cells was much higher than micelles without folate (DOMC/PTX) or the commercially available injectable preparation of PTX (Taxol). Conclusion Results indicate that the PTX-loaded DOMC-FA micelle is a successful anticancertargeted drug-delivery system for effective cancer chemotherapy.

In vitro and in vivo evaluation of silybin nanosuspensions for oral and intravenous delivery

In this study, we evaluate the effect of particle sizes on the physicochemical properties of silybin and identify the influence of silybin nanosuspensions on its permeation across the Caco-2 cell monolayer. In vivo pharmacokinetic evaluation of silybin nanosuspensions was also carried out in beagle dogs. TEM, AFM and SEM analyses revealed the effect of homogenization pressure on particle size and morphology, and confirmed the existence of a surfactant-stabilizer film on the surface of nanoparticles. DSC and XRPD experiments manifested that the crystalline state was maintained as particle size was reduced and the enhanced dissolution property was due to the increased surface area. Nanosuspensions had a significant influence on drug transport across the Caco-2 cell monolayer and the enhanced dissolution velocity was responsible for the increased permeability. A pharmacokinetics study in beagle dogs further confirmed the in vitro results and demonstrated that oral administration of silybin nanosuspensions significantly increase its bioavailability compared to the coarse powder. Nanosuspensions of silybin with smaller particle size reveal a higher potential to increase their oral bioavailability; while for intravenous infusion the lower pressure produced silybin nanosuspensions appeared to maintain a more sustained drug release profile.

In vitro and in vivo evaluation of paclitaxel-loaded mesoporous silica nanoparticles with three pore sizes

In the present study, mesoporous silica nanoparticles (MSNs) with three pore size were manufactured by the etch method. A typical chemotherapeutic agent, paclitaxel (PTX) was loaded into these MSNs. The in vitro drug release behavior, the in vitro anti-tumor activity, the morphological apoptosis cell changes, cell apoptosis rate and pharmacokinetics were extensively evaluated to clarify the biomedical roles of these MSNs in the application of drug delivery. The results showed that paclitaxel-loaded MSNs not only demonstrated effective drug loading but also exhibited pore-size-dependent drug release performance in vitro. In addition, MSNs exhibited pore-size-dependent anti-tumor activity against breast cancer MCF-7 cells. The apoptosis mechanism study demonstrated that the percentage of early and late apoptosis of all PTX-loaded MSNs treated MCF-7 cells were significantly higher than that of free PTX, and additionally the percentage of apoptosis for PTX-loaded MSNs increased as the pore size of carriers enlarged. The pharmacokinetics results showed that PTX-loaded MSNs with the largest pore size exhibited the pharmacokinetic property similar to the PTX solution and the other drug loaded MSNs displayed sustained release behavior. These results demonstrate that MSNs could be a very promising drug delivery system for pore-size controllable drug release and enhancing the anti-tumor activity.

Redox-responsive catiomer based on PEG-ss-chitosan oligosaccharide-ss-polyethylenimine copolymer for effective gene delivery

The chitosan oligosaccharide-based disulfide-containing polyethylenimine derivative PEG-ss-COS-ss-PEI was synthesized and evaluated as a nonviral gene delivery carrier. The structure of the obtained polymers was confirmed by 1H NMR and FTIR. PEG-ss-COS-ss-PEI copolymers could effectively condense DNA into small particles with average diameters less than 120 nm and the zeta potential of +15.7 mV at the N/P ratio of 15/1. Additionally, the resultant polyplexes showed excellent colloidal stability against 150 mM NaCl and had a better buffering capacity of ∼44%, which was more than double the buffering capacity of PEI1.8k (∼20%). In the presence of 10 mM glutathione (GSH), however, polyplexes of PEG-ss-COS-ss-PEI were rapidly unpacked, as revealed by significant increase of particle sizes to over 800 nm. In vitro experiments revealed that the PEG-ss-COS-ss-PEI copolymers not only had much lower cytotoxicity, but also displayed high transfection efficiency as compared to the control branch 25 kDa PEI. This study indicates that a reducibly degradable copolymer PEG-ss-COS-ss-PEI composed of low molecular weight PEI, chitosan oligosaccharide and PEG via disulfide-containing linkages can be a promising gene delivery carrier.

Self-assembled nanoparticles based on galactosylated O-carboxymethyl chitosan-graft-stearic acid conjugates for delivery of doxorubicin.

A novel polymer, i.e. galactosylated O-carboxymethyl chitosan-graft-stearic acid (Gal-OCMC-g-SA) was synthesized for liver targeting delivery of doxorubicin. The chemical structure was characterized by FT-IR, (1)H NMR and elemental analysis. Gal-OCMC-g-SA could self-assemble into nanoparticles with diameter of 160 nm by probe sonication in aqueous medium and exhibited a low critical aggregation concentration of 0.047 mg/mL. The DOX-loaded Gal-OCMC-g-SA (Gal-OCMC-g-SA/DOX) self-assembled nanoparticles were almost spherical in shape with an average diameter of less than 200 nm and zeta potential of around -10 mV. In vitro release revealed that the Gal-OCMC-g-SA/DOX nanoparticles exhibited a sustained and pH-dependent drug release manner. Furthermore, the hemolysis test demonstrated the good safety of Gal-OCMC-g-SA in blood-contacting applications. These results indicated that Gal-OCMC-g-SA/DOX nanoparticles were highly potential to be applied in cancer therapy.

Preparation and characterization of galactosylated bovine serum albumin nanoparticles for liver-targeted delivery of oridonin

In this study, galactosylated bovine serum albumin (GB), which could be developed for a liver targeting carrier was synthetized and it was identified by Fourier transform infrared (FT-IR) spectrometer. Oridonin loaded bovine serum albumin nanoparticle (ORI-BSA-NP) and oridonin loaded GB nanoparticle (ORI-GB-NP) were prepared and optimized by the desolvation technique. During the preparation of ORI-GB-NP, galactosamine was introduced to end-cap the free aldehyde groups on nanoparticles. The characteristics of ORI-GB-NP such as particle size, zeta potential, particle morphologie, entrapment efficiency and drug loading were evaluated. The nearly spherical nanoparticles, with a narrow size distribution below 200 nm, were negatively charged with zeta potential of about -30 mV. Meanwhile, differential scanning calorimetry (DSC) and X-ray diffraction confirmed the amorphous state of ORI in ORI-GB-NP. The in vitro drug release of ORI from ORI-GB-NP presented a biphasic pattern with an initial burst effect and consequently sustained release. These results implied that the nanoparticles possessed fine physicochemical characteristics and seemed to be a stable delivery system for poorly soluble oridonin.

In vitro antitumor activity of silybin nanosuspension in PC-3 cells

The present study aims to evaluate the antitumor activity of silybin nanosuspension on human prostatic carcinoma PC-3 cell line in vitro. Silybin nanosuspension was prepared by the high pressure homogenization (HPH) method. MTT assay, observation of morphological changes and apoptotic body showed that silybin nanosuspension could significantly enhance the in vitro cytotoxicity against PC-3 cells compared to the silybin solution. Flow cytometric (FCM) analysis demonstrated that silybin nanosuspension induced G1 cycle arrest and apoptosis in PC-3 cells. Thereby, the overall results suggest that the silybin nanosuspension represents a potential source of medicine for the treatment of human prostate cancer.

Successfully tailoring the pore size of mesoporous silica nanoparticles: Exploitation of delivery systems for poorly water-soluble drugs

A novel approach was applied to fabricate mesoporous silica nanoparticles (MSNs) with different pore size in this study. The pore size of MSNs can be modulated conveniently from 3 nm to 10nm by controlling the etching time of MSNs with the NaBH(4) solution. The as-synthesized MSNs were investigated as carriers for loading and delivery of the model drug paclitaxel (PTX). The characteristics, drug loading capacity, in vitro drug release behavior, anti-tumor activity and the mechanism of cell uptake were systematically studies. The resultant MSNs showed uniform and mono-dispersed sphere with high drug loading capacity (12-21%). The in vitro drug release exhibited that the released rate of PTX from MSNs could be controlled by the pore size and the larger the pore size, the faster the release rate of PTX. The in vitro anti-tumor studies demonstrated that PTX-loaded MSNs produced higher cytotoxicity than free PTX. Besides, the PTX-loaded MSNs with largest pore size showed the highest anti-tumor activity. These results indicated that these MSNs could provide a promising platform for delivering water-insoluble drugs, controlling the release rate of drugs and increasing the anti-tumor activity.