Effective oral delivery of gp100 plasmid vaccine against metastatic melanoma through multi-faceted blending-by-blending nanogels.

Plasmid DNA gp100 is able to act as an available vaccine against metastatic melanoma, but its administration is usually limited to parenteral route. Since oral delivery of plasmid DNA is intervened by various physical obstacles, here we constructed a nanogel (Alg-Tat-gp100) with multi-faceted functions through blending-by-blending method. Due to the cooperation of alginate and Tat peptide, Alg-Tat-gp100 demonstrated the significant improvement of stability in the stomach, mucus penetration ability in intestine, and transport across mucus layer and MDCK cells. Moreover, the bone marrow-derived cells were activated with an enhanced co-stimulatory molecule expression. Following immunization using Alg-Tat-gp100 nanogels in C57BL/6 mice, the secretion of IFN-γ and the activation of cytotoxic T cells were significantly improved. Benefiting from those cases, the B16F10 tumor inhibition rate achieved 42.5% by this oral DNA vaccine, suggesting that this multi-faceted nanogel prepared by simple blending-by-blending method may provide a new strategy for oral DNA vaccine delivery.

Effective intracellular delivery and Th1 immune response induced by ovalbumin loaded in pH-responsive polyphosphazene polymersomes.

A polymersome system for delivering protein antigen ovalbumin (OVA) based on amphiphilic polyphosphazene grafting with N,N-diisopropylethylenediamine (DPA) and poly(ethylene glycol) (PEG) groups (poly[(DPA)m (PEG)n phosphazene], PEDP) was designed and constructed. The 200-240 nm-size OVA-loaded polymersomes displayed high stability at physiological pH, slow internalization through clathrin-mediated endocytosis pathway, and then a pH-triggered sustained OVA release in acidic environment, leading to extensive antigen access to cytosol. Prime-boost vaccine kept high antibody titers for 8 weeks and the subcutaneous vaccine of OVA polymersomes biased the immune response towards a type 1 T helper (Th1) response. Animal experiment results showed that the antigen-specific prophylactic vaccination by PEDP polymersomes delivery was much more rapid and efficient in depressing tumor growth and progress when compared with the therapeutic vaccination. These results suggested that PEDP-based polymersomes are very promising in controlled cytosolic delivery of protein antigens, and enhanced Th1 specific immune response.

Reversal of P-glycoprotein-mediated multidrug resistance by doxorubicin and quinine co-loaded liposomes in tumor cells.

Multidrug resistance (MDR) is a major obstacle to successful clinical cancer chemotherapy. Currently, there is still unsatisfactory demand for innovative strategies as well as effective and safe reversing agent to overcome MDR. In this study, we developed a novel nanoformulation, in which doxorubicin hydrochloride (DOX) and quinine hydrochloride (QN) were simultaneously loaded into liposomes by a pH-gradient method for overcoming MDR and enhancing cytotoxicity in a doxorubicin-resistant human breast cancer cell line (MCF-7/ADR). The various factors were investigated to optimize the formulation and manufacturing conditions of DOX and QN co-loaded liposomes (DQLs). The DQL showed uniform size distribution and high encapsulation efficiency (over 90%) for both the drugs. Furthermore, DQLs significantly displayed high intracellular accumulation and potential of MDR reversal capability in MCF-7/ADR cells through the cooperation of DOX with QN, in which QN played the role as a MDR reversing agent. The IC50 of DQL0.5:1 with the DOX/QN/SPC weight ratio of 0.5:1:50 was 1.80 ± 0.03 µg/mL, which was 14.23 times lower than that of free DOX in MCF-7/ADR cells. And the apoptotic percentage induced by DQL0.5:1 was also increased to 62.2%. These findings suggest that DQLs have great potential for effective treatment of MDR cancer.

Sensitization of multidrug-resistant malignant cells by liposomes co-encapsulating doxorubicin and chloroquine through autophagic inhibition.

Adenosine triphosphate (ATP)-binding cassette (ABC) transporters play a key role in the development of multidrug resistance (MDR) in cancer cells. P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1) are important proteins in this superfamily which are widely expressed on the membranes of multidrug resistance (MDR) cancer cells. Besides, upregulation of cellular autophagic responses is considered a contributing factor for MDR in cancer cells. We designed a liposome system co-encapsulating a chemotherapeutic drug (doxorubicin hydrochloride, DOX) and a typical autophagy inhibitior (chloroquine phosphate, CQ) at a weight ratio of 1:2 and investigated its drug resistance reversal mechanism. MTT assay showed that the IC50 of DOX/CQ co-encapsulated liposome in DOX-resistant human breast cancer cells (MCF7/ADR) was 4.7 ± 0.2 µM, 5.7-fold less than that of free DOX (26.9 ± 1.9 µM), whereas it was 19.5-fold in doxorubicin-resistant human acute myelocytic leukemia cancer cells (HL60/ADR) (DOX/CQ co-encapsulated liposome 1.2 ± 0.1 µM, free DOX 23.4 ± 2.8 µM). The cellular uptake of DOX increased upon addition of free CQ, indicating that CQ may interact with P-gp and MRP1; however, the expressions of P-gp and MRP1 remained unchanged. In contrast, the expression of the autophagy-related protein LC3-II increased remarkably. Therefore, the mechanism of MDR reversal may be closely related to autophagic inhibition. Evaluation of anti-tumor activity was achieved in an MCF-7/ADR multicellular tumor spheroid model and transgenic zebrafish model. DOX/CQ co-encapsulated liposome exerted a better anti-tumor effect in both models than that of liposomal DOX or DOX alone. These findings suggest that encapsulating CQ with DOX in liposomes significantly improves the sensitivity of DOX in DOX-resistant cancer cells.

Cationic Polyphosphazene Vesicles for Cancer Immunotherapy by Efficient in Vivo Cytokine IL-12 Plasmid Delivery.

To circumvent the severe toxicity of the systemic delivery of IL-12 protein and the limits of local administration of IL-12 gene, we constructed a polymersome system for systemic delivery of recombinant murine IL-12 plasmid (pmIL-12) based on amphiphilic polyphosphazenes containing weakly cationic N,N-diisopropylethylenediamine (DPA) as hydrophobic groups and monomethoxy poly(ethylene glycol) (mPEG) as hydrophilic tails. By simple dialysis method, pmIL-12 was successfully loaded into polymersomes due to the combination effect of physical encapsulation and electrostatic interaction. This pmIL-12 polymersome delivery system was validated with good biocompatibility and stability despite of serum protein and DNase challenging. The results of in vivo antitumor experiments showed that intravenous injection of pmIL-12 polymersomes achieved significant suppression of tumor growth in BALB/c mice bearing CT-26 colon carcinoma. The analysis revealed that the mechanism was related to the antitumor immune response induced by efficient transfection of pmIL-12 polymersomes, which maybe involved lymphocytes infiltration and angiogenic inhibition at the tumor site.

Polymersomes via Self-Assembly of Amphiphilic ß-Cyclodextrin-Centered Triarm Star Polymers for Enhanced Oral Bioavailability of Water-Soluble Chemotherapeutics.

To date, improving oral bioavailability of water-soluble drugs with poor membrane permeability is still challenging. An example of this includes doxorubicin hydrochloride (DOX·HCl), a widely used chemotherapeutic. We therefore developed a novel DOX·HCl-loaded polymersome (Ps-DOX·HCl) self-assembled by amphiphilic ß-cyclodextrin-centered triarm star polymer (mPEG(2k)-PLA(3k))3-CD with the considerable drug loading capability. Using Madin-Darby canine kidney (MDCK) cells trans-well models, it was found that the cellular uptake and absorptive transport of DOX·HCl was significantly increased and the efflux was attenuated when delivered through polymersomes than free drugs. This phenomenon was further verified in mechanistic studies, which was attributed to the change in membrane transport pathway from paracellular route (free DOX·HCl) to active transcellular transport (drug-loaded polymersomes). Moreover, in vivo pharmacokinetic studies in mice demonstrated a significant increase in the oral bioavailability of Ps-DOX·HCl compared with free DOX·HCl (7.32-fold), as well as extended half-life (8.22-fold). This resulted in a substantial anticancer efficacy against mouse sarcoma 180 (S180) tumor in vivo. The cardiotoxicity, which is intrinsically induced by DOX·HCl, and toxicity toward gastrointestinal tissues were avoided according to histological studies. These findings indicate that (mPEG(2k)-PLA(3k))3-CD copolymer displays great potential as a vehicle for the effective oral delivery of water-soluble drugs with low permeability.

Optimizing particle size of docetaxel-loaded micelles for enhanced treatment of oral epidermoid carcinoma.

Understanding how the size of nanocarriers affects their fate in biological systems in vivo is of fundamental importance for rational design of drug delivery systems. In this study, five docetaxel (DTX)-loaded methoxy poly(ethylene glycol)-poly(lactide) micelles of different sizes (30-230nm) were prepared. It was observed that the permeation of micelles within both the multicellular tumor spheroids and tumor xenografts in mice was dependent on the size of the micelle. In addition, the size of micelles influenced their pharmacokinetic behavior. DTX-loaded pH-sensitive micelle based on poly(ethylene glycol)-poly(lactide)-poly(ß-amino ester) (DTX-pHPM) was constructed to further illustrate the effect of particle size. As expected, DTX-pHPM improved tumor penetration, uptake by tumor cells, and prolonged circulation time, consequently demonstrating the highest inhibition of in vivo tumor growth (84.4%) in oral epidermoid carcinoma. Taken together, our findings can aid in designing nano-scale drug delivery systems for cancer therapy by optimizing the particle size.

Targeted delivery of anticancer drugs by aptamer AS1411 mediated Pluronic F127/cyclodextrin-linked polymer composite micelles.

Aptamers are single-stranded RNA or DNA ligands that can specifically bind to various molecular targets with high affinity. Owing to this unique character, they have become increasingly attractive in the field of drug delivery. In this study, we developed a multifunctional composite micelle (CM) with surface modification of aptamer AS1411 (Ap) for targeted delivery of doxorubicin (DOX) to human breast tumors. This binary mixed system consisting of AS1411 modified Pluronic F127 and beta-cyclodextrin-linked poly(ethylene glycol)-b-polylactide could enhance DOX-loading capacity and increase micelle stability. Cellular uptake of CM-Ap was found to be higher than that of untargeted CM due to the nucleolin-mediated endocytosis effect. In vivo study in MCF-7 tumor-bearing mice demonstrated that the AS1411-functionalized composite micelles showed prolonged circulation time in blood, enhanced accumulation in tumor, improved antitumor activity, and decreased cardiotoxicity. In conclusion, aptamer-conjugated multifunctional composite micelles could be a potential delivery vehicle for cancer therapy.

High loading of hydrophilic/hydrophobic doxorubicin into polyphosphazene polymersome for breast cancer therapy.

Breast cancer remains one of the most common cancers for females. Drug delivery based on cancer nanotechnology could improve the performance of some chemotherapeutic medicines already used in clinic. The emergence of polymersomes provided the potential to encapsulate hydrophobic/hydrophilic drugs. By modifying the weight ratio of methoxy-poly (ethylene glycol) (mPEG) chain to ethyl-p-aminobenzoate (EAB) side group, a series of amphiphilic graft polyphosphazenes (PEPs) was prepared. PEP can be tuned from micelles to polymersomes with the decrease of mPEG content via dialysis. Either hydrophilic doxorubicin hydrochloride (DOX·HCl) or hydrophobic doxorubicin base (DOX) could be encapsulated into PEP polymersomes with high payload and high encapsulation efficiency due to the strong intermolecular interaction with PEP. Compared with free DOX·HCl administration, in vivo investigation in growth inhibition of MCF-7 xenograft tumors in nude mice demonstrated that PEP polymersomes could enhance life safety without compromise of therapeutic efficacy, especially DOX·HCl loaded delivery system. FROM THE CLINICAL EDITOR: In this preclinical study, polymerosomes based on PEPs were investigated as doxorubicin delivery systems, demonstrating similar efficacy but less toxicity compared to standard delivery methods.

Mechanisms of drug resistance reversal in Dox-resistant MCF-7 cells by pH-responsive amphiphilic polyphosphazene containing diisopropylamino side groups.

pH-responsive drug carriers derived from polymers containing weak base groups have been shown to improve the antitumor effect of chemotherapeutics. The common interpretation is that a "proton sponge effect" caused by pH-responsive polymers facilitates endosomal membrane destruction and accelerates cytoplasmic drug release in tumor cells. However, the mechanisms by which pH-responsive weak base polymers disrupt membranes have not been expatiated clearly. Herein, we synthesized a series of pH-responsive amphiphilic polyphosphazenes containing diisopropylamino (DPA) side groups with various contents and investigated the effect of DPA content on the actions of polymers with cell membranes. In a certain pH range, the polymers with elevated DPA content showed enhanced membrane disruptive activity. Electrical interactions between the protonated DPA groups of polymers and the cell lipid bilayer are critical for pH-dependent membrane disruption, which can be competitively prevented by serum proteins. On the other hand, the hydrophobic unprotonated DPA moieties can insert into lipophilic regions of cell membrane. These synergic actions caused the alteration of biomembrane permeability consequently. More interestingly, it was also found that DPA-rich polymers exhibit higher P-glycoprotein (P-gp) inhibition activity as compared with the polymer containing only low levels of DPA by efficiently blocking the internal epitope of P-gp. These findings strongly provide rational support for pH-responsive amphiphilic polyphosphazenes containing DPA side groups to be quite promising drug carriers for intracellular drug delivery applications, especially the treatment of P-gp overexpressing, drug-resistant tumors.

Doxorubicin and chloroquine coencapsulated liposomes: preparation and improved cytotoxicity on human breast cancer cells.

Doxorubicin, as a widely used chemotherapeutic, always causes multidrug resistance in human cancer cells. To circumvent drug resistance, we developed a novel formulation where doxorubicin hydrochloride (DOX) and chloroquine phosphate (CQ) were simultaneously loaded into liposomes by a pH-gradient method where CQ played the role of a chemical sensitizer. The various factors were investigated to optimize the formulation and manufacturing conditions of DOX and CQ coencapsulated liposomes (DCL). The resultant DCLs achieved the high encapsulation efficiency of both drugs over 90%. Further, DCLs significantly displayed resistance reversal action on a doxorubicin-resistant human breast cancer cell line (MCF-7/ADR) through the cooperation of CQ with DOX. The reversal fold of DCL with the DOX/CQ/soybean phosphatidylcholine weight ratio of 0.5:1:50 was 5.7, compared to free DOX. These results demonstrate that DCL is a promising formulation for the treatment of DOX-resistant breast cancer.

Application of liposome encapsulation technique to improve anti-carcinoma effect of resveratrol.

AIM: The promising anti-tumor effect of resveratrol (RES) has aroused much interest in recent years, but its clinical application was seriously hindered due to its poor solubility in water. The aim of this study was to improve the water solubility of RES by liposome encapsulation technique for effective tumor treatment. METHODS: This study develops two liposomal formulations to solubilize RES by reverse-phase evaporation method with or without poly(ethylene glycol-2000)-grafted distearolyl phosphatidylethanolamine (DSPE-PEG(2000)). The effect of different formulation factors on the encapsulation efficiency (EE) and the particle sizes were investigated. These factors included the mass ratio of drug to soybean phosphatidylcholine (drug/SPC), the mass ratio of cholesterol to soybean phosphatidylcholine (chol/SPC), the volume ratio of water phase/organic phase and the microfluidization process. The drug release studies were performed in various media, simulating the desired application conditions. The cytotoxicity study was carried out by MTT assay on HeLa and Hep G2 cell lines. RESULTS: The RES EE of 95% was obtained when using drug/SPC (1:40 mass ratio), Chol/SPC (1:10 mass ratio), water phase/oil phase (1:2 volume ratio), microfluidization process (entrance pressure 6 kpa, two times of cycle time). The addition of DSPE-PEG(2000) into the formulation showed little effect on the formation and properties of RES liposome. The release of RES was pH-independent. RES liposomes and PEG-modified liposomes performed significant inhibition effects on both cells growth due to the solubilized RES. CONCLUSION: RES can be effectively loaded into liposomes and its anti-cancer effect was evidently improved by the application of liposome encapsulation technique.

Near infrared light triggered ternary synergistic cancer therapy via L-arginine-loaded nanovesicles with modification of PEGylated indocyanine green.

L-arginine (L-Arg) is an important nitric oxide (NO) donor, and its exploration in NO gas therapy has received widespread attention. Application of nano-platforms that can efficiently deliver L-Arg and induce its rapid conversion to NO becomes a predominant strategy to achieve promising therapeutic effects in tumor treatment. Herein, an enhanced nano-vesicular system of ternary synergistic treatment combining NO therapy, photodynamic therapy (PDT) along with mild photothermal therapy (MPTT) was developed for cancer therapy. We integrated photosensitizer PEGylated indocyanine green (mPEG-ICG) into polyphosphazene PEP nano-vesicles through co-assembly and simultaneously encapsulated NO donor L-Arg into the vesicle center chambers to form mPEG-ICG/L-Arg co-loaded system IA-PEP. The unique nanostructure of vesicle provided considerable loading capacity for mPEG-ICG and L-Arg with 15.9% and 17.95% loading content, respectively, and efficiently prevented mPEG-ICG and L-Arg from leaking. Significantly, the reactive oxygen species (ROS) was produced by IA-PEP under 808 nm laser irradiation to perform PDT against tumors, which concurrently reacted with L-Arg to release NO and arouse gas therapy effectively. Moreover, the mild heat produced by IA-PEP could exhibit cooperative anti-tumor effect with minimal damage. As a consequence, in vivo antitumor investigation on nude mice bearing xenograft MCF-7 tumors verified the potent anti-tumor efficacy of IA-PEP under 808 nm laser irradiation with complete tumor elimination. Taken together, the IA-PEP nano-vesicle system designed in this work may provide a promising treatment paradigm for synergistic cancer treatment. STATEMENT OF SIGNIFICANCE: Nitric oxide (NO) gas therapy has drawn widespread attention due to its "green" treatment paradigm with negligible side effects. L-arginine (L-Arg) is an important NO donor. However, how to efficiently deliver L-Arg and induce NO generation remains a big challenge since L-Arg is a water-soluble small molecule. Herein, we developed a nano-vesicle system IA-PEP to integrate photosensitizer PEGylated indocyanine green and L-Arg with high loading content and to produce a ternary synergistic treatment combining NO therapy, photodynamic therapy (PDT) along with mild-temperature photothermal therapy (MPTT) under 808 nm laser irradiation. The in vivo investigation on nude mice bearing xenograft MCF-7 tumors verified its potent anti-tumor efficacy with complete tumor elimination.

Development of a successive targeting liposome with multi-ligand for efficient targeting gene delivery.

BACKGROUND: A successful gene delivery system needs to breakthrough several barriers to allow efficient transgenic expression. In the present study, successive targeting liposomes (STL) were constructed by integrating various targeting groups into a nanoparticle to address this issue. METHODS: Polyethylenimine (PEI) 1800-triamcinolone acetonide (TA) with nuclear targeting capability was synthesized by a two-step reaction. Lactobionic acid was connected with cholesterol to obtain a compound of [(2-lactoylamido) ethylamino]formic acid cholesterol ester (CHEDLA) with hepatocyte-targeting capability. The liposome was modified with PEI 1800-TA and CHEDLA to prepare successive targeting liposome (STL). Its physicochemical properties and transfection efficiency were investigated both in vitro and in vivo. RESULTS: The diameter of STL was approximately 100 nm with 20 mV of potential. The confocal microscopy observation and potential assay verified that lipid bilayer of STL was decorated with PEI 1800-TA. Cytotoxicity of STL was significantly lower than that of PEI 1800-TA and PEI 25K. The transfection efficiency of 10% CHEDLA STL in HepG2 cells was the higher than of the latter two with serum. Its transfection efficiency was greatly reduced with excessive free galactose, indicating that STL was absorbed via galactose receptor-mediated endocytosis. The in vivo study in mice showed that 10% CHEDLA STL had better transgenic expression in liver than the other carriers. CONCLUSIONS: STL with multi-ligand was able to overcome the various barriers to target nucleus and special cells and present distinctive transgenic expression. Therefore, it has a great potential for gene therapy as a nonviral carrier.

6-Aminocaproic acid as a linker to improve near-infrared fluorescence imaging and photothermal cancer therapy of PEGylated indocyanine green.

Clinical extensive application of indocyanine green (ICG) is limited by several drawbacks such as poor bioenvironmental stability, aggregate propensity, and rapid elimination from the body, etc. In this study, we construct a novel amphiphilic mPEG-ACA-ICG conjugate by modifying synthetic heptamethine cyanine derivative ICG-COOH with a hydrophobic linker 6-aminocaproic acid (ACA) and amino-terminal poly(ethylene glycol) (mPEG-NH2). The as-prepared mPEG-ACA-ICG conjugate has the ability to self-assemble into micellar aggregates in an aqueous solution with a lower CMC value than mPEG-ICG conjugate without ACA linker. More importantly, compared with free ICG and mPEG-ICG conjugate, mPEG-ACA-ICG nanomicelles exhibited better stability and higher photothermal conversion efficiency upon near-infrared light irradiation due to the intramolecular introduction of a hydrophobic ACA segment. In our in vivo experiment, mPEG-ACA-ICG nanomicelles ensured the formidable effect on tumor photothermal therapy (PTT) and the maximum tumor inhibition rate reached 72.6 %. In addition, real-time determination ability for fluorescence image-guided surgery (FIGS) of mPEG-ACA-ICG nanomicelles was also confirmed on tumor xenograft mice model. Taken together, mPEG-ACA-ICG conjugate may hold great promise for non-invasive cancer theranostics.

Investigation of polyethylenimine-grafted-triamcinolone acetonide as nucleus-targeting gene delivery systems.

BACKGROUND: Nuclear membrane is one of the main barriers in polymer mediated intracellular gene delivery. To improve the transgenic activity and safety of nonviral vector, triamcinolone acetonide (TA) as a nuclear localization signal was conjugated with different molecular weight polyethylenimine (PEI). METHODS: Different molecular weight PEI [600, 1800, 25,000 (25k)] was conjugated with TA to synthesize PEI-TA by two-step reaction. Their physicochemical characteristics, in vitro cytotoxicity and transfection efficiency were evaluated. To investigate the difference of transfection efficiency of various molecular weight PEI-TA, their transfection mechanism was further investigated by confocal microscopy and competition assay. Transgenic expression in vivo was evaluated by injection into hepatic portal vein of mice. RESULTS: All PEI-TA could form nanosize polyplexes with DNA and their physicochemical properties resemble each other. Their cytotoxicities were negligible compared to PEI 25k. The order of transfection efficiency was PEI 1800-TA > PEI 600-TA > PEI 25k-TA. A transfection mechanism study displayed that TA could inhibit considerably the transgenic activity of PEI 1800-TA and PEI 600-TA, but that of PEI 25k-TA was not inhibited. It was suggested that PEI 1800-TA and PEI 600-TA might translocate into the nucleus. Confocal microscopy investigation verified this suggestion. The data strongly suggested that the transfection efficiency of PEI 1800-TA in vivo was much higher than that of PEI 25k, which was consistent with the results obtained in vitro. CONCLUSIONS: Low molecular weight PEI-TA could translocate into the nucleus efficiently. PEI 1800-TA presented higher transgenic activity and it has a great potential for gene therapy as a nonviral carrier.

Nano-vesicles based on phospholipid-like amphiphilic polyphosphazenes to orally deliver ovalbumin antigen for evoking anti-tumor immune response.

Aimed at evoking an adequate anti-tumor immune response via oral administration route, this study constructed functionally and structurally mimicking-bacteria-membrane (MBM) nano-vesicle (RGD-PEOP) to orally deliver ovalbumin (OVA) antigen. In terms of simulating bacterial membrane structure, we creatively designed this nano-vesicle to have phospholipid-like octadecylphosphoethanolamine groups in vesicle membrane to improve OVA loading by means of specific interactions including salt bridge and hydrogen bond interaction. For simulating bacterial membrane function, the RGD peptide was modified onto the nano-vesicle surface, and the resulting vector displayed a good transport ability with a 3.4-fold higher than free OVA. In vitro and in vivo assay showed that the expression of co-stimulatory molecules and MHC class II complexes was significantly enhanced by MBM nano-vesicle. IFN-γ and IL-4 levels also increased several folds in the MBM nano-vesicle group. Consequently, MBM nano-vesicle achieved the highest in vivo inhibition rate of 69% against E.G7-OVA tumors among all the oral groups. These results suggest that this MBM nano-vesicle may be a promising vector to orally deliver OVA antigen for cancer immunotherapy. STATEMENT OF SIGNIFICANCE: Developing an effective non-bacterial carrier for oral cancer immunotherapy remains challenging. This work constructed a mimicking-bacteria-membrane nano-vesicle based on phospholipid-like amphiphilic polyphosphazenes for oral delivery of ovalbumin antigen. With the considerable capability to load ovalbumin antigen and target M cells, the nano-vesicle produced remarkable tumor suppression in vivo by evoking anti-tumor immune response.

Polymeric nanoparticles of cholesterol-modified glycol chitosan for doxorubicin delivery: preparation and in-vitro and in-vivo characterization.

OBJECTIVES: Polymeric nanoparticles have been extensively studied as drug carriers. Chitosan and its derivatives have attracted significant attention in this regard but have limited application because of insolubility in biological solution. In this work, we attempted to utilize cholesterol-modified glycol chitosan (CHGC) self-aggregated nanoparticles to increase aqueous solubility, and to reduce side effects and enhance the antitumour efficacy of the anticancer drug doxorubicin. Methods CHGC nanoparticles were loaded with doxorubicin by a dialysis method, and their characteristics were determined by transmission electron microscopy examination, light-scattering study, in-vitro drug-release study, pharmacokinetic study in rats and in-vivo antitumour activity in mice. KEY FINDINGS: The resulting doxorubicin-loaded CHGC nanoparticles (DCNs) formed self-assembled aggregates in aqueous medium. From the observation by transmission electron microscopy, DCNs were almost spherical in shape. The mean diameters of these nanoparticles determined by dynamic light scattering were in the range of 237-336 nm as the doxorubicin-loading content increased from 1.73% to 9.36%. In-vitro data indicated that doxorubicin release from DCNs was much faster in phosphate-buffered saline at pH 5.5 than at pH 6.5 and 7.4, and the release rate was dependent on the loading content of doxorubicin in these nanoparticles. It was observed that DCN-16 (drug loaded content: 9.36%) exhibited prolonged circulation time in rat plasma and showed higher antitumour efficacy against S180-bearing mice than free doxorubicin. CONCLUSIONS: These results indicated that CHGC nanoparticles had potential as a carrier for insoluble anticancer drugs in cancer therapy.

Polymersomes: Preparation and Characterization.

Polymersomes, also called polymeric vesicles, are self-assembled by amphiphilic copolymers. Due to their unique characters, polymersomes are attracting more and more interest as an important class of vehicles for nanopharmaceuticals. In this chapter, various methods to prepare and characterize polymersomes are introduced systematically with several applicable examples. In addition, the advantages and disadvantages of each method were compared and analyzed with the aim to help readers choose the appropriate method in the process of experiments. Although some methods we introduced here are effective in preparing and characterizing polymersomes, the remaining challenge in this filed is to develop new tools. The reason is that polymersome is a kind of complex nanostructure, and some minor factors can affect the formation of polymersome. Meanwhile, more advanced technology should be developed to precisely determine the structure of some complex polymersomes such as multilayer polymersomes.

Preparation and in vitro evaluation of liposomal chloroquine diphosphate loaded by a transmembrane pH-gradient method.

This study developed an active loading method for encapsulating chloroquine diphosphate (CQ) into liposomes. The effects of different formulation factors on the encapsulation efficiency (EE) and the size of CQ liposomes were investigated. These factors included the internal phase of liposomes, the external phase of liposomes, the ratio of drug to soybean phosphatidylcholine (drug/SPC), the ratio of cholesterol to soybean phosphatidylcholine (Chol/SPC), and the incubation temperature and time. The EE (93%) was obtained when using drug/SPC (1:50 mass ratio), SPC/Chol (1:5 mass ratio) at 0.10 M citrate-sodium citrate buffer (pH 3.6). As 5 mol% methoxypoly(ethylene glycol)(2,000) cholesteryl succinate (CHS-PEG(2000)) or distearoyl phosphatidylethanolamine-poly (ethylene glycol)(2,000) (DSPE-PEG(2000)) was added, the size of particle was reduced and the EE was improved. Freeze-drying with 5% trehalose as a cryoprotectant was carried out to achieve long-term stability. The drug release studies were performed in vitro simulating the desired application conditions, such as physiological fluids (pH 7.4), tumor tissues (pH 6.5) and endosomal compartments (pH 5.5). The release of CQ from the liposomes prepared via remote loading showed the significant pH-sensitivity and retention properties, which favored the application of liposomal CQ at tumor tissues and endosomal compartments.