Light-Responsive Polymeric Micellar Nanoparticles with Enhanced Formulation Stability.

Light-sensitive polymeric micelles have recently emerged as promising drug delivery systems for spatiotemporally controlled release of payload at target sites. Here, we developed diazonaphthoquinone (DNQ)-conjugated micellar nanoparticles that showed a change in polarity of the micellar core from hydrophobic to hydrophilic under UV light, releasing the encapsulated anti-cancer drug, doxetaxel (DTX). The micelles exhibited a low critical micelle concentration and high stability in the presence of bovine serum albumin (BSA) solution due to the hydrophobic and π-π stacking interactions in the micellar core. Cell studies showed enhanced cytotoxicity of DTX-loaded micellar nanoparticles upon irradiation. The enhanced stability would increase the circulation time of the micellar nanoparticles in blood, and enhance the therapeutic effectiveness for cancer therapy.

Preclinical studies of ropivacaine extended-release from a temperature responsive hydrogel for prolonged relief of pain at the surgical wound.

Postoperative pain is a common form of acute pain that has been treated commonly by local anesthetics through regional nerve blocking. In this study, a series of experiments were conducted using rats to investigate the pharmacokinetic, distribution, and efficacy of a temperature responsive hydrogel-based drug delivery device (PF-72) containing ropivacaine (0.75%) for extended relief of postoperative pain by allowing the prolonged release of ropivacaine. When the ropivacaine was administered using PF-72, its concentration-time curve (AUClast) and peak concentration (Cmax) were 577.0 h*ng/mL and 271.9 ng/mL, respectively. In contrast when the ropivacaine solution was administered using saline solution, its AUClast and Cmax were 982.8 h*ng/mL and 423.6 ng/mL, respectively. In the tissue distribution study, the peak concentration and mean area under the curve of the ropivacaine in injection area (target tissue) were found about 2-fold higher in the case of PF-72 compared with the case of conventional ropivacaine solution. These results clearly demonstrate the capability of PF-72 hydrogel to retain the ropivacaine at the injection site for an extended period. Effective extended (at least 24 h) pain relief of ropivacaine administered using PF-72 was found in the pharmacodynamic study of prolonged analgesic effect. The results of this study indicated that local drug delivery by PF-72 hydrogel formulation may be an effective method to achieve extended relief of pain. Other advantages of ropivacaine administration using PF-72 include reduced systemic side effects and high localization of a drug in target tissues.

Synthesis and characterization of bioreducible cationic biarm polymer for efficient gene delivery.

We synthesized a new cationic AB2 miktoarm block copolymer consisting of one poly (ethylene glycol) (PEG) block and two cationic poly (l-lysine) (PLL) blocks, wherein the PLL blocks were conjugated to the PEG blocks with or without a bioreducible linker (disulfide bonds). Bioreducible and non-bioreducible miktoarm block copolymers (mPEG-(ss-PLL)2 and mPEG-PLL2) were prepared for efficient gene delivery as a non-viral gene delivery approach. Both cationic copolymers (bioreducible and nonbioreducible) efficiently formed the nanopolyplexes with plasmid DNA (pDNA) through electrostatic interaction at different weight ratio of polymer and pDNA. Gene condensation ability of the polymers and release of the DNA under reduction condition were measured by gel electrophoresis. Dynamic light scattering (DLS) and field-emission transmission electron microscopy (FE-TEM) were used to measure the average hydrodynamic diameter and morphology of the nanoparticles, respectively. The bioreducible nanopolyplexes showed lower cytotoxicity and higher gene expression than the non-reducible nanopolyplexes in cancer cells.

Assembly of polymer micelles through the sol-gel transition for effective cancer therapy.

Photo-induced apoptosis-targeted chemotherapy (PIATC) was designed and characterized to propose a new protocol for improved chemotherapy. Intratumoral injection was selected as the mode of administration of the anticancer drug, doxorubicin (DOX). To extend the retention time of DOX at the tumor parenchyma, in-situ gel formation was induced through the sol-gel transition of the Pluronic NPs containing a prodrug of DOX or a photosensitizer. The prodrug (DEVD-S-DOX) was designed to be inactive with a peptide moiety (Aspartic acid-Glutamic acid-Valine-Aspartic acid: DEVD) linked to DOX and to be cleaved into free DOX by caspase-3 expressed with apoptosis. For reactive oxygen species (ROS)-mediated apoptosis, photo-irradiation with methylene blue (MB, photosensitizer) was utilized. The sol-gel transition of the Pluronic NPs containing reactive species, DEVD-S-DOX or MB, was examined by measuring the cloud point and the gel strength in response to temperature change. ROS-mediated apoptosis was observed by measuring the ROS and membrane integrity with induced apoptosis. The in vivo antitumor efficacy of PIATC was measured with a cardiotoxicity assay in tumor-bearing mice.

Polysaccharide-based Nanoparticles for Gene Delivery.

Nanoparticles based on nanotechnology and biotechnology have emerged as efficient carriers for various biopharmaceutical agents including proteins and genes. In particular, polysaccharides have attracted interest of many researchers in the drug delivery field due to their advantages such as biocompatibility, biodegradability, low toxicity, and ease of modification. A number of polysaccharides including chitosan, hyaluronic acid, and dextran, and their derivatives have been widely used as polymeric backbones for the formation of nanoparticles, which can be provided as valuable gene delivery carriers. In this review, we introduce the chemical and physical natures of different polysaccharides particularly used in biomedical applications, and then discuss recent progress in the development of polysaccharide-based nanoparticles for gene delivery.

The multilayer nanoparticles for deep penetration of docetaxel into tumor parenchyma to overcome tumor microenvironment.

Deep penetration of the anticancer drug, docetaxel (DTX), into tumor parenchyma was demonstrated to achieve improved chemotherapy. For this purpose, a multistage nanostructure was designed and characterized using the multilayer nanoparticles (NPs). The multilayer NPs had a core/shell structure. The core was composed of the DTX-loaded Pluronic NPs (diameter: 12nm) that were transferred into the inner side of vesicles to form the vesicle NPs. Förster resonance energy transfer (FRET) in the NPs was observed to verify the incorporation of the DTX-loaded Pluronic NPs into the inner side of the vesicles during the formation of the vesicle NPs. Subsequently, the vesicle NPs were stabilized through Pluronic-lipid bilayer interaction to form the multilayer NPs. To examine the morphology and size distribution of the multilayer NPs, transmittance electron microscopy and dynamic light scattering were used. In vitro release behavior and toxicity were observed to verify the functionality of the multilayer NPs as nanocarriers for cancer therapy. Multistage functionality was evaluated by cellular uptake and tissue distribution behaviors of the multilayer NPs. The biodistribution of the multilayer NPs and their antitumor efficacy were also observed to understand the role of multistage functionality for improved chemotherapy.

Doxorubicin/heparin composite nanoparticles for caspase-activated prodrug chemotherapy.

Caspase-activated prodrug chemotherapy is introduced and demonstrated using the composite nanoparticles (NPs), which deliver doxorubicin (DOX) and DEVD-S-DOX together to the tumor tissue. DEVD-S-DOX, DOX linked to a peptide moiety (DEVD), is a prodrug that is cleaved into free DOX by caspase-3 upon apoptosis. DEVD-S-DOX has no therapeutic efficacy, but it changes into free DOX with the expression of caspase-3. With the accumulation of the composite NPs in the tumor tissue by the enhanced permeation and retention (EPR) effect, a small exposure of DOX in the tumor cells initiated apoptosis in a localized area of the tumor tissue, which induced caspase-3 activation. Cleavage of DEVD-S-DOX into free DOX by caspase-3 continued with repetitive activation of caspase-3 and cleavage of DEVD-S-DOX at the tumor site. The composite NPs were characterized with transmittance electron microscopy (TEM) and particle size analyzer. We then evaluated the nanoparticle drug release, therapeutic efficacy, and in vivo biodistribution for tumor targeting using a non-invasive live animal imaging technology and the quantification of DOX with high performance liquid chromatography. DOX-induced apoptosis-targeted chemotherapy (DIATC) was verified by in vitro/in vivo DEVD-S-DOX response to free DOX and cellular uptake behavior of the composite NPs with flow cytometry analysis. Significant antitumor efficacy with minimal cardiotoxicity was also observed, which supported DIATC for improved chemotherapy.

Docetaxel-loaded multilayer nanoparticles with nanodroplets for cancer therapy.

A mixture of docetaxel (DTX) and Solutol(®) HS 15 (Solutol) transiently formed nanodroplets when it was suspended in an aqueous medium. However, nanodroplets that comprised DTX and Solutol showed a rapid precipitation of DTX because of their unstable characteristics in the aqueous medium. The incorporation of nanodroplets that comprised DTX and Solutol through vesicle fusion and subsequent stabilization was designed to prepare multilayer nanoparticles (NPs) with a DTX-loaded Solutol nanodroplet (as template NPs) core for an efficient delivery of DTX as a chemotherapeutic drug. As a result, the DTX-loaded Solutol nanodroplets (~11.7 nm) were observed to have an increased average diameter (from 11.7 nm to 156.1 nm) and a good stability of the hydrated NPs without precipitation of DTX by vesicle fusion and multilayered structure, respectively. Also, a long circulation of the multilayer NPs was observed, and this was due to the presence of Pluronic F-68 on the surface of the multilayer NPs. This led to an improved antitumor efficacy based on the enhanced permeation and retention effect. Therefore, this study indicated that the multilayer NPs have a considerable potential as a drug delivery system with an enhanced therapeutic efficacy by blood circulation and with low side effects.

Doxorubicin/gold-loaded core/shell nanoparticles for combination therapy to treat cancer through the enhanced tumor targeting.

A combination therapy consisting of radiotherapy and chemotherapy is performed using the core/shell nanoparticles (NPs) containing gold NPs and doxorubicin (DOX). Gold NPs in the core/shell NPs were utilized as a radiosensitizer. To examine the morphology and size distribution of the core/shell NPs, transmittance electron microscopy and dynamic light scattering were used. The in vitro release behavior, cellular uptake and toxicity were also observed to verify the functionality of the core/shell NPs as a nanocarrier. To demonstrate the advantage of the core/shell NPs over traditional gold NPs reported in the combination therapy, we evaluated the accumulation behavior of the core/shell NPs at the tumor site using the biodistribution. Antitumor efficacy was observed with and without radiation to evaluate the role of gold NPs as a radiosensitizer.

Sol-gel transition of nanoparticles/polymer mixtures for sustained delivery of exenatide to treat type 2 diabetes mellitus.

The sol-gel transition of nanoparticles (NPs)/polymer mixture in aqueous medium was investigated for the sustained delivery of exenatide to treat type 2 diabetes mellitus. Exenatide-loaded multilayer NPs were prepared using a layer-by-layer approach which utilized the interaction between Pluronics and lipid bilayers as the main driving force for the construction of the multilayer. Pluronic F-127 was the polymer used, and it forms a gel at body temperature. Although the antidiabetic effects of exenatide-loaded multilayer NPs have been demonstrated previously in an animal model, in this work, the attempt was made to demonstrate the extended duration of antidiabetic effects, which was accomplished by localizing the exenatide-loaded NPs in muscular areas in the body through the gelation of Pluronic F-127. Transmittance electron microscopy and dynamic light scattering were used to examine the morphology of the multilayer NPs/polymer mixture. A change in the release pattern of exenatide was observed after gel formation at body temperature, and Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis was performed using native exenatide and a reference biomarker as control to observe whether exenatide extracted from the multilayer NPs and the multilayer NPs/Pluronic F-127 mixture degraded or not. We then observed the antidiabetic effect of exenatide-loaded multilayer NPs/Pluronic F-127 mixture by monitoring blood-glucose levels in db/db mice. In vitro and in vivo correlation was discussed regarding structural variation in the delivery vehicles.

Effect of HIFU treatment on tumor targeting efficacy of docetaxel-loaded Pluronic nanoparticles.

Numerous studies have been performed to identify the microenvironment of solid tumors, which is responsible for the insufficient delivery of anticancer drugs to tumor cells due to the poorly organized vasculature and the increased interstitial fluid pressure. As a result, the extravasation of convection-dependent agents including NPs is severely limited. Therefore, we have demonstrated the feasibility of targeting an enhancement of docetaxel-loaded Pluronic nanoparticles (NPs) using high-intensity focused ultrasound (HIFU) as an external stimulus-induced clinical system in tumor tissue. The efficient extravasation of NPs into the interior cells in tumor tissue was induced by relatively low HIFU exposure without apparent acute tissue damage. The enhanced targeting of NPs with near-infrared fluorescence dye was observed in tumor-bearing mice with various HIFU exposures. As a result, the greatest accumulation of NPs at the tumor tissue was observed at an HIFU exposure of 20 W/cm(2). However, the tumor tissue above at 20 W/cm(2) appeared to be destroyed and the tumor targetability of NPs was significantly decreased owing to thermal ablation with necrosis, resulting in the destruction of the tumor tissue and the blood vessels. In particular, a cross-sectional view of the tumor tissue verified that the NPs migrated into the middle of the tumor tissue upon HIFU exposure. The preliminary results here demonstrate that HIFU exposure through non-thermal mechanisms can aid with the extravasation of NPs into the interior cells of tumors and increase the therapeutic effect in enhanced and targeted cancer therapy.

Accurate sequential detection of primary tumor and metastatic lymphatics using a temperature-induced phase transition nanoparticulate system.

Primary tumor and tumor-associated metastatic lymphatics have emerged as new targets for anticancer therapy, given that these are difficult to treat using traditional chemotherapy. In this study, docetaxel-loaded Pluronic nanoparticles with Flamma (FPR-675, fluorescence molecular imaging dye; DTX/FPR-675 Pluronic NPs) were prepared using a temperature-induced phase transition for accurate detection of metastatic lymphatics. Significant accumulation was seen at the primary tumor and in metastatic lymph nodes within a short time. Particle size, maximum drug loading capacity, and drug encapsulation efficiency of the docetaxel-loaded Pluronic NPs were approximately 10.34±4.28 nm, 3.84 wt%, and 94±2.67 wt%, respectively. Lymphatic tracking after local and systemic delivery showed that DTX/FPR-675 Pluronic NPs were more potent in tumor-bearing mice than in normal mice, and excised mouse lymphatics showed stronger near-infrared fluorescence intensity on the tumor-bearing side than on the non-tumor-bearing side at 60 minutes post-injection. In vivo cytotoxicity and efficacy data for the NPs demonstrated that the systemically administered NPs caused little tissue damage and had minimal side effects in terms of slow renal excretion and prolonged circulation in tumor-bearing mice, and rapid renal excretion in non-tumor-bearing mice using an in vivo real-time near-infrared fluorescence imaging system. These results clearly indicate that docetaxel-loaded Pluronic NPs could provide a strategy to achieve effective cancer therapy by simultaneous delivery to primary tumors, tumor lymphatics, and tumor-associated metastatic lymphatics.

Multilayer nanoparticles for sustained delivery of exenatide to treat type 2 diabetes mellitus.

A method for the sustained delivery of exenatide was proposed using nanoparticles (NPs) with a core/shell structure. The interactions between lipid bilayers and Pluronics were utilized to form various NPs using a layer-by-layer approach. Transmittance electron microscopy and dynamic light scattering were used to examine the morphology of the NPs. The in vitro release pattern was observed as a function of changes in the structure of the NPs, and the structural integrity of exenatide released was examined by SDS-PAGE analysis. Pharmacokinetics and antidiabetic effects were also observed with the structural change of NPs using in vivo animal models. In vitro-in vivo correlation was discussed in relation to manipulation of the NP structures.

Pluronic-based core/shell nanoparticles for drug delivery and diagnosis.

Pluronic-based core/shell nanoparticles (NPs) were formed using various strategies such as self-assembly and temperature induced-phase transition. To improve their functionality as a nanomedicine for diagnosis and therapy, the vesicle fusion and layer by layer approach were employed. Because of the hydrophilic nature of the Pluronic shell and the relatively small size, Pluronic-based core/shell NPs were used in order to improve their pharmacokinetic behaviors in drugs and in imaging agents. This review will introduce various types of Pluronic-based core/shell NPs according to their preparation method and formation mechanism. The focus will be on the Pluronic-based core/shell NPs for tumor targeting, stimulated release of proteins, and cancer imaging capabilities.

The multilayer nanoparticles formed by layer by layer approach for cancer-targeting therapy.

The multilayer nanoparticles (NPs) were prepared for cancer-targeting therapy using the layer by layer approach. When drug-loaded Pluronic NPs were mixed with vesicles (liposomes) in the aqueous medium, Pluronic NPs were incorporated into the vesicles to form the vesicle NPs. Then, the multilayer NPs were formed by freeze-drying the vesicle NPs in a Pluronic aqueous solution. The morphology and size distribution of the multilayer NPs were observed using a TEM and a particle size analyzer. In order to apply the multilayer NPs as a delivery system for docetaxel (DTX), which is a model anticancer drug, the release pattern of the DTX was observed and the tumor growth was monitored by injecting the multilayer NPs into the tail veins of tumor (squamous cell carcinoma)-bearing mice. The cytotoxicity of free DTX (commercial DTX formulation (Taxotere®)) and the multilayer NPs was evaluated using MTT assay. We also evaluated the tumor targeting ability of the multilayer NPs using magnetic resonance imaging. The multilayer NPs showed excellent tumor targetability and antitumor efficacy in tumor-bearing mice, caused by the enhanced permeation and retention (EPR) effect. These results suggest that the multilayer NPs could be a potential drug delivery system for cancer-targeting therapy.

Phthalocyanine-aggregated polymeric nanoparticles as tumor-homing near-infrared absorbers for photothermal therapy of cancer.

Phthalocyanine-aggregated Pluronic nanoparticles were constructed as a novel type of near-infrared (NIR) absorber for photothermal therapy. Tiny nanoparticles (~ 60 nm, FPc NPs) were prepared by aqueous dispersion of phthalocyanine-aggregated self-assembled nanodomains that were phase-separated from the melt mixture with Pluronic. Under NIR laser irradiation, FPc NPs manifested robust heat generation capability, superior to an individual cyanine dye and cyanine-aggregated nanoparticles. Micro- and macroscopic imaging experiments showed that FPc NPs are capable of internalization into live cancer cells as well as tumor accumulation when intravenously administered into living mice. It is shown here that continuous NIR irradiation of the tumor-targeted FPc NPs can cause phototherapeutic effects in vitro and in vivo through excessive local heating, demonstrating potential of phthalocyanine-aggregated nanoparticles as an all-organic NIR nanoabsorber for hyperthermia.

Blood-pool multifunctional nanoparticles formed by temperature-induced phase transition for cancer-targeting therapy and molecular imaging.

Multifunctional nanoparticles (NPs) were prepared based on temperature-induced phase transition in a molten mixture of Lipiodol(®), Tween 80, paclitaxel (PTX), and Pluronic F-68, wherein the Lipiodol(®)/Tween 80 mixture is used as a solubilizer for PTX, and Pluronic F-68 is used for the stabilization of the molten mixture. The morphology and size distribution of optimized multifunctional NPs were observed using transmittance electron microscopy (TEM) and a particle size analyzer. In the optical imaging of tumor-bearing mice using a near-infrared fluorescence (NIRF) imaging system, the multifunctional NPs were evaluated in terms of a time-dependent excretion profile, in vivo biodistribution and tumor-targeting capability compared to free fluorescence dye. In addition, the prolonged circulation of multifunctional NPs was confirmed by enhancement of the blood-pool in live animals using a micro-CT imaging system, because iodine-containing Lipiodol(®) has an X-ray enhancement property. Finally, the anti-tumor efficacy of multifunctional NPs was monitored by injecting the multifunctional NPs into the tail veins of tumor-bearing mice. The multifunctional NPs showed excellent tumor targetability and anti-tumor efficacy in tumor-bearing mice, caused by the enhanced permeation and retention (EPR) effect.

Enhancement of the targeting capabilities of the Paclitaxel-loaded pluronic nanoparticles with a glycol chitosan/heparin composite.

An enhancement of tumor-targeting capability was demonstrated with paclitaxel (PTX)-loaded Pluronic nanoparticles (NPs) with immobilized glycol chitosan and heparin. The PTX-loaded Pluronic NPs were prepared as described in our previous report by means of a temperature-induced phase transition in a mixture of Pluronic F-68 and liquid polyethylene glycol (PEG; molecular weight: 400) containing PTX. The liquid PEG is used as the solubilizer of PTX, and Pluronic F-68 is the polymer that encapsulates the PTX. The glycol chitosan and heparin were immobilized on the surface of the Pluronic NPs in an aqueous medium, and a powdery form of the glycol chitosan/heparin immobilized Pluronic NPs (composite NPs) was obtained by freeze-drying. Field emission scanning electron microscopy and a particle size analyzer were used to observe the morphology and size distribution of the prepared NPs. To apply the composite NPs as a delivery system for the model anticancer drug PTX, the release pattern and pharmacokinetic parameters were observed, and the tumor growth was monitored by injecting the composite NPs into the tail veins of tumor-bearing mice. An enhancement of tumor-targeting capability of NPs was verified by using noninvasive live animal imaging technology to observe the time-dependent excretion profile, the in vivo biodistribution, circulation time, and the tumor-targeting capability of composite NPs.

Paclitaxel-loaded poly(lactide-co-glycolide)/poly(ethylene vinyl acetate) composite for stent coating by ultrasonic atomizing spray.

The mixture of poly(lactide-co-glycolide) (PLGA) and poly(ethylene vinyl acetate) (PEVA) forms a homogeneous liquid in an organic solvent such as tetrahydrofuran, and a phase-separated PLGA/PEVA composite can be prepared from it by evaporating the organic solvent. Exploiting this phenomenon, we designed a novel method of preparing a drug-loaded PLGA/PEVA composite and used it for coating drug-eluting stents (DESs). Paclitaxel (PTX), an anticancer drug, was chosen as a model drug. PLGA acts as a microdepot for PTX, and PEVA provides mechanical strength to the coating material. The presence of PLGA in the PLGA/PEVA composite suppressed PTX crystallization in the coating material, and PTX showed a sustained release rate over more than 30 days. The mechanical strength of the PLGA/PEVA composite was better than that of PEVA used as a control. After coating the stent with a PLGA/PEVA composite using ultrasonic atomizing spray, the morphology of the coated material was observed by scanning electron microscopy, and the release pattern of PTX was measured by high-performance liquid chromatography.

Multi-core vesicle nanoparticles based on vesicle fusion for delivery of chemotherapic drugs.

The Pluronic nanoparticles (NPs) composed of Pluronic (F-68) and liquid polyethylene glycol (PEG, molecular wt: 400) containing docetaxel (DTX) were stabilized with the vesicle fusion. When DTX-loaded Pluronic NPs were mixed with vesicles in the aqueous medium, DTX-loaded Pluronic NPs were incorporated into vesicles to form multi-core vesicle NPs. The morphology and size distribution of multi-core vesicle NPs were observed using FE-SEM, cryo-TEM and a particle size analyzer. To apply multi-core vesicle NPs as a delivery system for DTX, a model anti-cancer drug, the release pattern of DTX was observed and the tumor growth was monitored by injecting the DTX-loaded multi-core vesicle NPs into the tail veins of tumor-bearing mice. We also evaluated the time-dependent excretion profile, in vivo biodistribution, circulation time, and tumor targeting capability of multi-core vesicle NPs using a non-invasive live animal imaging technology.