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Gene therapy using small interfering RNA (siRNA) is a novel strategy for effective anticancer therapies. However, low gene transfection efficiency and technical difficulties linked to siRNA delivery limit their practical application for gene delivery. Therefore, development of effective siRNA carriers is required. Overexpression of osteopontin (OPN) and its association with tumorigenesis has been reported in a majority of breast cancers. In this study, we used siRNA against OPN (siOPN) and investigated the possible OPN-dependent signaling pathway and the potential use of poly(amino ester) (PAE) based on glycerol propoxylate triacrylate (GPT) and spermine (SPE) for siRNA delivery. The GPT-SPE could effectively condense siRNA and protect the siRNA from RNaseA enzyme degradation. GPT-SPE/siRNA complexes showed good intracellular uptake and high gene silencing efficiency in vitro. Furthermore, in the breast cancer xenograft model, intratumoral injection of GPT-SPE/siOPN significantly inhibited tumor growth. These results demonstrated that silencing of OPN effectively suppressed the growth of breast cancer cells and further suggested that delivery of siRNA using GPT-SPE may act as an effective gene carrier for cancer therapy., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Polyethylenimine (PEI) has been commonly used as a cationic polymeric gene carrier due to high transfection efficiency, however, its cytotoxicity has hindered the practical application. In this study, we report the development of poly(amino ester) (PAE) based on glycerol propoxylate triacrylate (GPT) and spermine (SPE) as an alternative gene carrier for lung cancer therapy. GPT-SPE copolymer was prepared by Michael addition reaction between GPT and SPE, and the efficacy was evaluated using shAkt1 as a model therapeutic gene. The molecular weight and composition were characterized using gel permeability chromatography (GPC) and (1)H-nuclear magnetic resonance ((1)H-NMR), respectively. The GPT-SPE could effectively condense DNA with about 163 nm size and protect the DNA from nucleases. GPT-SPE/DNA complexes showed excellent transfection with low toxicity both in vitro and in vivo. Furthermore, aerosol delivery of GPT-SPE/Akt1 shRNA complexes significantly suppressed lung tumorigenesis in K-ras(LA1) lung cancer model mice. These results suggest that GPT-SPE can be used in shRNA-based lung cancer gene therapy., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Experiments were designed to evaluate the in vitro cytotoxic interactions of anticancer drugs in combination, evaluate synergistic activity in vivo and utilize micelle-forming polymeric drugs as drug carriers in a murine cancer model. Antitumor effects of 5-fluorouracil, cisplatin, CPT-11, oxaliplatin, etoposide, mitomycin-C, doxorubicin and paclitaxel were evaluated by determination of in vitro cytotoxicity to CT-26 colorectal tumor cells or in vivo following a subcutaneous transplant in BALB/c mice. Single agent and combination in vivo studies were also performed using drug-loaded polymeric micelles composed of poly(gamma-benzyl L-glutamate) and poly(ethylene oxide) (GEG) or poly(L-lactide)/poly(ethylene glycol) (LE) diblock copolymer. After 3 days exposure, the mean IC(50) (microg/mL) for 5-fluorouracil, cisplatin, CPT-11, oxaliplatin, etoposide, mitomycin-C, doxorubicin and paclitaxel were 0.95, 2.01, 4.47, 3.34, 3.5, 1.96, 1.8 and 2.1, respectively. When tumor cells were exposed to doxorubicin concurrently with etoposide or paclitaxel, evidence of synergy was observed in CT-26 cells in vitro. Doxorubicin and paclitaxel loaded into GEG or LE copolymers at a high concentration (19.5 and 16.7 wt%, respectively) were almost completely released (83.2% and 93.7%, respectively) by day 3. When tumor-bearing mice were treated in combination with doxorubicin-paclitaxel or doxorubicin-etoposide, substantial antitumor activity was evident compared with single therapy. These data suggest that in vitro cytotoxicity of anticancer drugs is related to in vivo results, and chemotherapy using micelle-loaded anticancer drugs represents a promising potential as a carrier system in modulating drug delivery.

Efficient delivery of small interfering RNA (siRNA) remains a challenging task in RNA interference (RNAi) studies. In this study, we used chitosan-graft-polyethylenimine (CHI-g-PEI) copolymer composed of chitosan and low molecular weight polyethylenimine (PEI) for the delivery of siRNA. The CHI-g-PEI carrier formed stable complexes with siRNA with compact spherical morphology. CHI-g-PEI delivered EGFP siRNA (siGFP) silenced EGFP expression nearly 2.5 folds higher than PEI25K at 50 pM siGFP concentration. Cell viability was found to be 2 folds high with CHI-g-PEI carrier than PEI25K. Also, our CHI-g-PEI carrier efficiently delivered Akt1 siRNA (siAkt) and thereby silenced onco-protein Akt1. Silencing of this crucial cell survival protein significantly reduced the lung cancer cell survival and proliferation. Additionally, Akt1 protein knock-down decreased A549 cell malignancy and metastasis. These findings suggest that the CHI-g-PEI carrier efficiently and safely delivered siRNA. Moreover, CHI-g-PEI mediated Akt1 siRNA delivery may emerge as a viable approach for lung cancer treatment.

Gene transfer using non-viral vectors is a promising approach for the safe delivery of therapeutic genes. Among non-viral vectors, chitosans have been proposed as alternative, biocompatible cationic polymers for non-viral gene delivery. However, the low transfection efficiency and low specificity of chitosan needs to be addressed prior to clinical application. In this study, mannosylated chitosan-graft-polyethylenimine (Man-CHI-g-PEI) copolymer was prepared by thiourea reaction between the isothiocyanate group of mannopyranosylphenylisothiocyanate and the amine groups of chitosan-graft-PEI (CHI-g-PEI) for targeting into antigen presenting cells (APCs) having mannose receptors. The composition and molecular weight were characterized using (1)H NMR and GPC, respectively. The copolymer was complexed with plasmid DNA in various copolymer/DNA (N/P) charge ratios, and the complexes were characterized. Man-CHI-g-PEI showed good DNA binding ability and high protection of DNA from nuclease attack and had low cytotoxicity compared with PEI 25K. The transfection efficiency of Man-CHI-g-PEI/DNA complexes into the Raw 264.7 macrophage cell line, which has mannose receptors, was higher than CHI-g-PEI itself as well as PEI 25K, indicating Man-CHI-g-PEI can be used as an APCs' targeting gene delivery carrier.

The multiblock copolymer composed of poly(gamma-benzyl L-glutamate) (PBLG) and poly(ethylene oxide) (PEO) was synthesized to prepare polymeric micelles as an anticancer drug carrier. Adriamycin (ADR) used as an anticancer drug was incorporated into the polymeric micelles prepared by the multiblock copolymer. The higher the drug feeding ratio, the higher the drug loading contents and the lower the drug loading efficiency. The increased drug feeding ratio resulted in increased particle sizes. At all of the formulations, particle sizes were less than 150 nm. The particles were observed as spherical shapes. ADR release from ADR-loaded polymeric micelles in vitro was decreased with an increased drug loading contents. In in vitro antitumor activity test using CT 26 tumor cells, polymeric micelles showed almost similar cytotoxicity when compared to ADR itself while polymeric micelles themselves did not affect cytotoxicity. In in vivo antitumor activity test using mice tumor xenograft model, the polymeric micelles showed improved survivability of mice with minimized weight changes and excellent tumor growth suppression efficacy. Polymeric micelles of the multiblock copolymer suggested to be a good candidate for anticancer drug delivery carrier.

Organic-inorganic nanohybrids have been studied for their use as non-viral transfection agents. The purpose of this study was to examine the ability of mesoporous silica nanoparticles (MSN) coupled with mannosylated polyethylenimine (MP) to transfect plasmid DNA in vitro. Although MSN is biocompatible and has low cytotoxicity, it is not easily transfected into a variety of cell types. To overcome this barrier, MP was coupled to MSN (abbreviated as MPS) to target macrophage cells with mannose receptors and enhance transfection efficiency. The DNA conveyance ability of MPS was examined by evaluating properties such as particle size, zeta potential, complex formation, protection of plasmid DNA against DNase-I, and the release of DNA upon cell entry. Particle sizes of the MPS/DNA complexes decreased with increasing weight ratio of MPS to DNA, while the zeta potential increased. Complete MPS/DNA complexes were formed at a weight ratio of five, and their resistance to DNase-I was evaluated. Cytotoxicity studies showed that MPS/DNA complexes resulted in a high percentage of cell viability, compared with PEI 25K as a vector. The transfection efficiency of MPS/DNA complexes was evaluated on Raw 264.7 and HeLa cell lines. It was found that MPS/DNA complexes showed enhanced transfection efficiency through receptor-mediated endocytosis via mannose receptors. These results indicate that MPS can be employed in the future as a potential gene carrier to antigen presenting cells.

The aim of this study was using Eudragit-cysteine conjugate to coat on chitosan microspheres (CMs) for developing an oral protein drug delivery system, having mucoadhesive and pH-sensitive property. Bovine serum albumin (BSA) as a protein model drug was loaded in thiolated Eudragit-coated CMs (TECMs) to study the release character of the delivery system. After thiolated Eudragit coating, it was found that the release rate of BSA from BSA-loaded TECMs was observably suppressed at pH 2.0 PBS solution, while at pH 7.4 PBS solution the BSA can be sustainingly released for several hours. The structural integrity of BSA released from BSA-loaded TECMs was guaranteed by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and circular dichroism (CD) spectroscopy. The mucoadhesive property of TECMs was evaluated and compared with CMs and Eudragit-coated chitosan microspheres (ECMs). It was confirmed that after coating thiolated Eudragit, the percentage of TECMs remained on the isolated porcine intestinal mucosa surface was significantly higher than those of CMs and ECMs. Likewise, gamma camera imaging of Tc-99m labeled microsphere distribution in rats after oral administration also suggested that TECMs had comparatively stronger mucoadhesive characters. Therefore, our results indicated that TECMs have potentials to be an oral protein drug carrier.

A ruman bypass delivery system was investigated to improve the delivery efficiency of L-carnitine in biological samples of cows. Highly water-soluble L-carnitine used for dietary supplement in ruminants was chosen. L-Carnitine-loaded compact pellets were prepared by extrusion method and then coated with various coating materials such as ethylcellulose (EC), Eudragit E100 (E100), Eudragit RS100 (RS100), stearyl alcohol and glyceryl monostearate, for single-layered coated pellets (SCP). Two types of dual-layered coated pellets (DCP) were also designed as DCP-A (inner E100/outer EC) or DCP-B (inner EC/outer E100). Preparation of compact pellet and methods of polymeric coatings are the most important strategies for modulated release and rumen bypass efficiency based on chewing behaviors and physiology of veterinary species. DCPs were more efficient in retarding L-carnitine release in rumen fluid (pH 6.8) than the SCP but DCP-B gave much faster release in abomasums fluid (pH 1.2). Both DCP-A and DCP-B showed high in vivo rumen bypass efficiency in cows compared with the nonprotected preparation and most of l-carnitine was readily absorbed. DCP-B was also efficient for delivering L-carnitine in biological samples of cows, mainly in muscle but no statistical differences were observed among the tested preparations after the multiple oral feeding to cows for 3 months. Interestingly, DCP-B produced higher L-carnitine levels in milk in a dose-dependent manner. However, delivery efficiency of L-carnitine preparations in biological samples of cows would rather be more dependent on feeding schedules.

We have elsewhere reported the work on the preparation of semi-interpenetrating polymer networks (SIPNs) composed of chitosan (CS) and poloxamer to improve the mechanical strength of CS sponge. This study focuses on evaluation of the CS/poloxamer SIPNs to intend for wound dressing application and the efficacy of dehydroepiandrosterone (DHEA)-loaded CS/poloxamer SIPNs in the wound model studies. The properties required for ideal wound dressing, such as equilibrium water content (EWC), water absorption (A(w)), water vapor transmission rate (WVTR), and evaporative water loss, were examined. The CS/poloxamer SIPNs were found to have a water content of 90% of their weight which could prevent the wound bed from accumulation of exudates and also have excellent water adsorption. The WVTR of CS/poloxamer SIPNs was found to be 2,508.2+/-65.7gm(-2)day(-1), indicating that the SIPNs can maintain a moist environment over wound bed in moderate to heavily exuding wound which enhances epithelial cell migration during the healing process. Also, the CS/poloxamer SIPNs in vitro assessment showed proper biodegradation and low cytotoxicity for wound dressing application. The wound healing efficacy of CS/poloxamer SIPNs as a wound dressing was evaluated on experimental full thickness wounds in a mouse model. It was found that the wounds covered with CS/poloxamer SIPNs or DHEA-loaded CS/poloxamer SIPNs were completely filled with new epithelium without any significant adverse reactions after 3 weeks. The results thus indicate that CS/poloxamer SIPNs could be employed in the future as potential wound dressing materials.

Transforming growth factor (TGF)-beta1 is a pleiotropic cytokine with many functions, including those related to growth modulation, immunosuppression, and pro-inflammation, in a wide variety of cell types. In this study, we investigated the ability of TGF-beta1 to regulate RANTES production by activated rheumatoid synovial fibroblasts. Fibroblast-like synoviocytes (FLS) were cultured in the presence of TGF-beta1 and IL-1beta, IL-15, TNFalpha, or IL-17, and the secretion of RANTES into culture supernatants was measured by enzyme-linked immunosorbent assay (ELISA). Expression of RANTES encoded mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR), and NF-kappaB binding activity for RANTES transcription was determined by electrophoretic mobility shift assay (EMSA). We found that the concentrations of RANTES in synovial fluid (SF) from rheumatoid arthritis (RA) patients were lower than in SF from osteoarthritis (OA) patients, whereas the concentrations of TGF-beta1 were higher in RA SF than in OA SF. TGF-beta1 dose-dependently inhibited TNFalpha-induced production of RANTES protein and mRNA from RA FLS. Addition of RA SF with high-level TGF-beta1 mimicked the effect of TGF-beta1 on TNFalpha-induced RANTES production, which was inhibited by treatment with anti-TGF-beta1 neutralizing antibody. TGF-beta1 blocked the degradation of cytosolic IkappaB-alpha and the translocation of activated NF-kappaB to the nucleus. EMSA showed that the inhibitory effect of TGF-beta1 was associated with decreased binding of NF-kappaB to the RANTES promoter. These results suggest that elevated TGF-beta1 in rheumatoid synovial tissue may suppress joint inflammation by inhibiting RANTES secretion from synovial fibroblasts, thus blocking the infiltration of immune cells. These findings may provide an explanation for the mechanism by which TGF-beta1 regulates immune function in RA.

Interleukin-18 (IL-18) is a novel pro-inflammatory cytokine which has been implicated to play a pathogenic role in rheumatoid arthritis (RA). Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis in rheumatoid synoviocytes. In present study, we examined the effect of IL-18 on VEGF production in fibroblast-like synoviocytes (FLS) isolated from the patients with RA. FLS were prepared from the synovial tissues of patients with RA and osteoarthritis (OA) and cultured in the presence of IL-18. The production of VEGF from FLS was measured in culture supernatants by enzyme-linked immunosorbent assay (ELISA). The VEGF messenger RNA (mRNA) expression and AP-1 binding activity of VEGF transcript were determined by reverse transcription-polymerase chain reaction (RT-PCR) and electrophoretic mobility shift assay (EMSA). IL-18 and VEGF levels of sera and synovial fluids (SF) of RA patients (n=30) were significantly higher than those of OA patients (n=20). IL-18 dose-dependently increased the production of VEGF. The effect of IL-18 on VEGF production appeared to be as potent as IL-1beta, whereas tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma showed little effects on VEGF production. AP-1-specific inhibitor Curcumin dose-dependently abrogated the effect of IL-18 on VEGF production. The VEGF enhancement of IL-18 was associated with increased AP-1 binding activity to the VEGF promoter site. These findings suggest IL-18 as an angiogenic factor in RA and down-regulation of IL-18 activity or AP-1 signal pathway can be potential therapeutic targets for RA.

Poly(gamma-benzyl L-glutamate) (PBLG)/poly(ethylene glycol) (PEG) diblock copolymer endcapped with galactose moiety (abbreviated as GEG) was synthesized and characterized for study of liver-specific targeting. From dynamic light scattering measurement, particle sizes of copolymeric nanoparticles were decreased with an increase of PEG in the copolymer. The morphology of GEG-3 nanoparticles observed by transmission electron micrograph was observed as almost spherical shapes and ranged about 50-300 nm. From the structural characterization using 1H nuclear magnetic resonance, both characteristic peaks of PBLG and PEG were visible in CDCl3 but the characteristic peaks of PBLG were invisible in D2O, indicating that GEG block copolymers are found to the core-shell type nanoparticles in water with PBLG innercore and PEG outershell, exposing that galactose moiety of GEG block copolymers are outerwards oriented on the nanoparticle surfaces. By galactose-specific aggregation test of particles using beta-galactose specific lectin, and flow cytometry measurement, specific interaction between asialoglycoprotein receptors (ASGPR) of HepG2, human hepatoma cell line, and galactose moieties of the GEG nanoparticles was confirmed. From cell cytotoxicity test, HepG2 cells with ASGPR are more sensitive to paclitaxel (TX)-loaded nanoparticles than free TX whereas, P388 cells, murine leukemia cell line, and SK-Hep 01, human hepatoma cell line, without ASGPR is less sensitive to TX-loaded nanoparticles than free TX, suggesting that specific interaction between HepG2 cells and galactose moiety of the nanoparticles occurred.

Mucoadhesive microspheres were prepared to increase gastric residence time using an interpolymer complexation of poly(acrylic acid) (PAA) with poly(vinyl pyrrolidone) (PVP) and a solvent diffusion method. The complexation between poly(acrylic acid) and poly(vinyl pyrrolidone) as a result of hydrogen bonding was confirmed by the shift in the carbonyl absorption bands of poly(acrylic acid) using FT-IR. A mixture of ethanol/water was used as the internal phase, corn oil was used as the external phase of emulsion, and span 80 was used as the surfactant. Spherical microspheres were prepared and the inside of the microspheres was completely filled. The optimum solvent ratio of the internal phase (ethanol/water) was 8/2 and 7/3, and the particle size increased as the content of water was increased. The mean particle size increased with the increase in polymer concentration. The adhesive force of microspheres was equivalent to that of Carbopol. The release rate of acetaminophen from the complex microspheres was slower than the PVP microspheres at pH 2.0 and 6.8.

Recently, in situ gel formation has extensively been studied to enhance ocular bioavailability and duration of the drug activity. In this study, we report grafting of poloxamer onto the hyaluronic acid for application of tissue engineering oriented ophthalmic drug delivery system. Graft copolymers were prepared by coupling mono amine-terminated poloxamer (MATP) with hyaluronic acid (HA) backbone using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxylsuccinimide (NHS) as coupling agents. The coupling of MATP with HA was clarified by 1H NMR and FT-IR spectroscopy. The gelation temperature of graft copolymers was dependent on the content of HA and the concentration of poloxamer. From drug release studies in vitro, ciprofloxacin was sustainedly released from the poloxamer-g-hyaluronic acid hydrogel due to the in situ gel formation of the copolymer and viscous properties of HA.

Dual-labeled galactosylated chitosan-graft-poly(ethylene glycol) (PEG) (GCP)/DNA complexes were prepared and their hepatocyte-specific delivery and cellular distribution were investigated by confocal laser scanning microscopy (CLSM). The complexes were transfected into hepatocyte through specific interaction of galactose moiety of the GCP and asialoglycoprotein receptors (ASGPR) of the hepatocytes. The GCP/DNA complexes taken up by the hepatocytes were rapidly released into the cytoplasm, but nuclear trafficking of the released complexes was slow and rate-limiting process. The more efficient transfection of the complex occurred in the human-derived HepG2 cells than in primary hepatocytes.

The release behavior of albumin from chitosan-coated pectin beads in vitro was investigated. The factors, such as concentration of CaCl(2), molecular weight of chitosan, pH of chitosan solution, and pH of release medium, which can have a significant effect on the release behavior from the beads, were discussed in this study. The loading efficiency (LE) of albumin showed maximum value when the concentration of CaCl(2) and the weight ratio of pectin to albumin were 2 wt.% and 2, respectively. The release of albumin from pectin beads could be retarded by coating with chitosan at various pH medium. The increase of the concentration of CaCl(2) induced the decrease of albumin release for uncoated-pectin beads, but not much difference of release for coated-pectin ones. The higher molecular weight of chitosan showed less albumin release than the lower one. The release of albumin from the chitosan-coated pectin beads was dependent on pH of coating solution and release medium, which might affect the degree of swelling of pectin beads.

Although the etiology of rheumatoid arthritis (RA) has not been clearly understood to date, the hyperplasia of the synovial membrane imposed by pro-inflammatory cytokines has been suggested to play a crucial role in the progression of this disease. TNF-alpha, a potent pro-inflammatory cytokine, was detected at highly enhanced concentrations in the blood and synovial fluids of patients with RA relative to those of patients with osteoarthritis and normal subjects. To evaluate the role of TNF-alpha in the synovial hyperplasia during the pathogenic state, we investigated cellular outcomes and molecular mechanisms of synoviocytes in response to TNF-alpha. Following TNF-alpha treatment, fibroblast-like synoviocytes (FLS) obtained from patients with RA proliferated, unlike the cells from a normal subject that were unaffected. This TNF-alpha induced proliferation of synoviocytes obtained from RA patients coincided with down-regulation of TNFR1 and up-regulation of TNFR2 and TRAF1-6, as well as NF-kappaB activation. TNF-alpha-induced proliferation of synoviocytes was inhibited by transfection with a dominant negative mutant form of I-kappaBalpha cDNA (I-kappaBalphadN). Moreover, following TNF-alpha treatment, transfectants with I-kappaBalphadN underwent apoptosis, whereas mock-transfectants did not. Taken together, these results suggest that high levels of TNF-alpha present in RA synovium play an important role in the synovial hyperplasia of RA by suppressing apoptosis and promoting proliferation of synoviocytes through NF-kappaB-dependent signaling pathways mediated by up-regulated TNFR2 and TRAF1-6 molecules.

Poly(L-lactic acid)/poly(N-isopropylacrylamide) (abbreviated as LN) block copolymers were synthesized and the LN nanoparticles were prepared by simple diafiltration method. The thermal transition of the LN nanoparticles was at 32.3 degrees C, the lower critical solution temperature (LCST) of the polymer. The fluorescence spectroscopy data showed that LN was self-assembled in water to form core-shell structure nanoparticles, and the critical association concentration (CAC) value was estimated as 1.3x10(-2) g/l. From the transmission electron microscope observations, the LN nanoparticles were spherically shaped and ranged in size between 30 and 50 nm below the LCST. The hydrated size was measured by photon correlation spectroscopy, and reversible size changes were investigated by the factor of temperature. The release of indomethacin from the LN nanoparticles was thermo-sensitive due to the unique characteristic of poly(N-isopropylacrylamide).

Cholic acid (CA) was coupled with amine-terminated poly (N-isopropylacrylamide) (ATPNIPAAm) using N,N'-dicyclohexyl carbodiimide as a coupling agent. Self-assembled CA/PNIPAAm conjugate (abbreviated as CN) micelles were prepared by diafiltration method in water. The CN micelles exhibited the lower critical solution temperature (LCST) at 31.5 degrees C. The CN micelles were observed as spherical shapes and their dried sizes were ranged between 30 and 50 nm by the transmission electron microscope (TEM) images. Hydrated micelle sizes measured by photon correlation spectroscopy (PCS) were ranged 337.5+/-67.8 nm. And reversible size changes of CN micelles were observed with two point temperature 10 and 40 degrees C, respectively. From the fluorescence spectra, fluorescence intensity of pyrene in the CN micelles was increased and red-shifted as the concentration of CN increased, indicating the formation of self-assembled polymeric micelles in water. The critical micelle concentration (CMC) was evaluated as 8.9 x 10(-2) g/l. Much more indomethacin (IN) was released from th CN micelles at 10 than at 40 degrees C due to the thermo-sensitivity of the PNIPAAm in the CN polymer.

Star-block copolymer based on PBLG as the hydrophobic part and PEO as the hydrophilic one (as abbreviated GEG) was synthesized and characterized. Polymeric micelle was prepared by the diafiltration method. From the measurement of photon correlation spectroscopy, the nanoparticle sizes of GEG-1, GEG-2 and GEG-3 were 106.5+/-59.2, 43.8+/-0.7 and 13.5+/-1.0 nm in number average, respectively, indicating of the formation of polymeric micelle. Also, the nanoparticle sizes were dependent on the PBLG chain length, i.e. the more PBLG content in the copolymer, the larger the particle size. From the observation of transmission electron microscope(TEM), GEG-2 block copolymer had almost spherical shapes with size range about 20-70 nm, that was similar to particle size measurement. Fluorescence spectroscopy measurement indicated that GEG block copolymers associated in water to form polymeric micelles and critical micelle concentration (CMC) values of the block copolymers decreased with increasing PBLG chain length in the block copolymer. Characteristic peaks of the protons of the benzyl group in the PBLG and the methylene protons adjacent to the benzyl group of the PBLG segment in the GEG-2 nanoparticles appeared in 7.2 approximately 7.4 and 5.0 approximately 5.2 ppm, respectively, and disappeared in D(2)O, indicating the restricted motions of these protons within the micellar core and the very rigid structure of the PBLG core in the GEG polymeric micelles. Release of ADR from the polymeric micelles in vitro was slower in longer PBLG chain length and higher loading contents of ADR.

Poly(ethylene glycol)(PEG) macromers terminated with acrylate groups and semi-interpenetrating polymer networks (SIPNs) composed of poly(epsilon-caprolactone)(PCL) and PEG macromer were synthesized to obtain a bioerodible hydrogel. Polymerization of PEG macromer resulted in the formation of cross-linked gels due to the multifunctionality of macromer. Glass transition temperature (Tg) and melting temperature (Tm) of PEG networks and PCL in the SIPNs were inner-shifted, indicating an interpenetration of PCL and PEG chains. Water content in the SIPNs increased with increasing PEG weight fraction due to the hydrophilicity of PEG. The amount of clonazepam (CNZ) released from the SIPNs increased with higher content in the SIPNs, lower drug loading, lower concentration of PEG macromer during the SIPNs preparation, and higher molecular weight of PEG. In particular, a combination with low PEG content and low CNZ solubility in water led to long-term constant release from these matrices in vitro and in vivo., (Copyright.)

Prolonged circulation of anticancer agent in blood is expected to decrease the host toxicity and enhance the anticancer activity. The purpose of this study is to develop and characterize the prolonged and sustained release formulation of anticancer agent using biodegradable poly(gamma-benzyl-L-glutamate)/poly(ethylene oxide) (PBLG/PEO) polymer nanoparticles. PBLG/PEO polymer is a hydrophilic/hydrophobic block copolymer and forms a micelle-like structure in solution. Spherical nanoparticles incorporating adriamycin were prepared by a dialysis method. The fluorescence intensity of adriamycin in the nanoparticles was increased when sodium dodecylsulfate was added. It is one of the evidences of entrapment of adriamycin in the polymer nanoparticles. Only 20% of entrapped drug was released in 24 h at 37 degrees C a and the release was dependent on the molecular weight of hydrophobic polymer. The endothermic peak of adriamycin at 197 degrees C disappeared in the nanoparticles system, suggesting the inhibition of a crystallization of adriamycin by polymer adsorption during the precipitation process. The mean residence time of adriamycin from the nanoparticles was more than threefold that from a free adriamycin. These results suggest usefulness of PBLG/PEO nanoparticles as a sustained and prolonged release carrier for adriamycin.