Preparation and characterization of biodegradable nanospheres composed of methoxy poly(ethylene glycol) and DL-lactide block copolymer as novel drug carriers

We synthesized amphiphilic diblock copolymer based on methoxy poly(ethylene glycol) (MePEG) and dl-lactide with different molar composition in bulk without catalyst. Using the resulting amphiphilic diblock copolymers, we prepared drug-loaded polymeric nanospheres by micelle formation through solution behavior of amphiphilic copolymer in selective solvents. The structure of MePEG/dl-lactide diblock copolymers was identified by IR, WAXD, GPC, 1H-NMR. The size of nanosphere measured by dynamic light scattering showed a narrow monodisperse size distribution and average diameter less than 200 nm. From the surface chemical composition of nanosphere by ESCA, the presence of MePEG chains on the nanosphere layers was confirmed. The critical micelle concentration of ML50 sample investigated by fluorescence spectroscopy was 1.44x10-7 mol/l which is lower than common low molecular weight surfactants. In addition, we could obtain nanospheres having a relatively high drug-loading of about 33.0% when the feed weight ratio of indomethacin to polymer was 1:1. In vitro release experiments of the indomethacin-loaded MePEG/dl-lactide nanospheres exhibited sustained release behavior without any burst effects. The results of cytotoxicity tests showed that the MePEG/dl-lactide nanospheres didn't induce any relevant cell damage.     

Effect of electrolytes and surfactants on the thermoseparation of an ethylene oxide-propylene oxide random copolymer in aqueous solution

A total of 59 strains of Pseudomonas, isolated from meat products, were grown in micro-titer plates in a meat medium over a range of pH (5.8-7.0), alpha w (0.97-1.00) and temperature (7-25 degrees C). Growths were performed in a meat broth with an automated turbidimeter (Bioscreen C, Labsystem, France). The growth curves obtained in this study did not have sigmoidal shapes making it impossible to calculate growth parameters using the Gompertz equation. The medium was weakly oxygenated in the micro-titer plates and reached 0%-dissolved oxygen at the beginning of the exponential phase. Strains were separated into two groups: P. fragi and P. fluorescens. Strains of P. fragi had shorter lag times than those of P. fluorescens. The impact of such results is interesting in that these could assist to explain the succession of flora that is observed during the processing of meat: P. fluorescens is the dominant bacteria among Pseudomonas spp. at the beginning of a slaughter line and P. fragi becomes dominant during the chilling process.     

Development of novel chitosan derivatives as micellar carriers of taxol

PURPOSE: To develop an intravenous injectable carrier composed of chitosan derivatives for taxol. METHODS: A chitosan with lauryl groups attached to amino groups to provide the hydrophobic moieties and, carboxymethyl groups attached to hydroxy groups to provide the hydrophilic moieties (N-lauryl-carboxymethyl-chitosan = LCC), was newly synthesized. The solubility of taxol in LCC micelles in aqueous solution was examined. The hemolysis test of LCC and the growth inhibition experiment of taxol-loading micelle using KB cells were also performed as in vitro assay. RESULTS: It was found that LCC solubilized taxol by forming micelles with particle sizes less than 100nm. This particle size was considered effective for passive targeting for tumors. The concentration of taxol in the micellar solution was very high, with a maximum of 2.37mg/mL. This maximum was 1000 times above that in a saturated solution of taxol at pH 7.4. Hemolysis testing as an in vitro assay indicated that LCC was safer than Polysorbate 80 (TO-10M) as intravenous surfactant in terms of induction of membrane damage. As judged by cytostatic activity against KB cells, taxol retained activity even when included in LCC micelles. LCC-entrapped taxol was more effective in cytostatic activity than free taxol in low concentrations. CONCLUSIONS: The results of solubilization capacity examination, hemolysis testing, and cytostatic activity suggest that LCC may be useful as a carrier of taxol.     

Poly (DL-lactide-co-glycolide) microspheres as carriers for peptide vaccines

Peptides carrying an immunodominant T-helper cell epitope delineated from the rabies virus nucleoprotein either alone or in combination with a linear B-cell epitope from the same protein were incorporated into three different formulations of poly(DL-lactide-co-glycolide) (PLG) which were distinct in their composition, and consequently in their peptide release rates. In vitro peptides incorporated into any of the PLG formulations stimulated a peptide-specific T-cell line. Upon subcutaneous immunization of mice, the PLG formulation that showed the fastest peptide release rate induced the best immune response. This immune response was in magnitude comparable or even superior to that induced by peptide emulsified in complete Freund's adjuvant.     

Conjugation of classic Bowman-Birk soy inhibitor with a copolymer of ethylene oxide and propylene oxide

A classical soybean inhibitor of the Bowman-Birk type (BBI) with a copolymer of ethylene oxide and propylene oxide (PE) has been synthesized. The BBI-PE conjugate contain five covalently bound polymeric chains per one protein molecule and retains its capacity to inhibit trypsin (Ki = 10(-10) M), alpha-chymotrypsin (Ki = 7 x 10(-8) M) and human granulocyte elastase (Ki = 3 x 10(-8) M). The preservation of the antiproteinase activity in the antichymotrypsin center creates a prerequisite for the manifestation of the anticarcinogenic effect of the inhibitor.     

Long circulating biodegradable poly(phosphazene) nanoparticles surface modified with poly(phosphazene)-poly(ethylene oxide) copolymer

The biodistribution of biodegradable poly(organo phosphazene) nanoparticles surface modified by adsorption of a novel poly(organo phosphazene)-poly(ethylene oxide) copolymer with a 5000 M(W) PEO chain (PF-PEO[5000]), following intravenous administration in rats and rabbits, is described. The data are compared to the biodistribution of poly(organo phosphazene) and poly(lactide-co-glycolide) nanoparticles coated with a tetrafunctional copolymer of poly(ethylene oxide)-poly(propylene oxide) ethylenediamine, commercially available as Poloxamine 908. This copolymer has a PEO chain of the same size as the poly(organo phosphazene)-PEO derivative used. The results in the rat model reveal that poly(organo phosphazene) nanoparticles with a Poloxamine 908 coating were mainly captured by the liver, although a retardation in clearance from the systemic circulation was seen. In contrast, the poly(organo phosphazene) nanoparticles coated with PF-PEO(5000) showed a prolonged blood circulating profile, with only a small amount of the nanoparticles sequestered by the liver. This indicates the importance of the nature of both the anchoring group and the particle surface on the biological performances of the system. Study of the biodistribution of the PF-PEO(5000)-coated poly(organo phosphazene) nanoparticles in the rabbit model also indicated a prolonged systemic circulation lifetime and reduced liver uptake, whereby a significant amount of the administered nanoparticles was targeted to the bone marrow.     

Water-soluble polyion complex associates of DNA and poly(ethylene glycol)-poly(L-lysine) block copolymer

Complex formation of poly(ethylene glycol)-poly(L-lysine) (PEG-PLL) AB type block copolymer with salmon testes DNA or Col E1 plasmid DNA in aqueous milieu was studied. The PLL segment of PEG-PLL interacts with nucleic acid through an electrostatic force to form a water-soluble complex associate with a diameter of ca. 50 nm. PEG segments surrounding the core of the polyion complex prevented the complex from precipitation even under stoichiometric conditions, at which the unit ratio of L-lysine in PEG-PLL and phosphate in the DNA is equal. The profile of the thermal melting curve revealed a higher stabilization of DNA structure in PEG-PLL/DNA complexes compared to that in the complex made from DNA and PLL homopolymer with the same molecular weight as the PLL segment in PEG-PLL. This stabilizing effect on the DNA structure may be due to the compartmentalization of DNA into the microenvironment of PEG with low permittivity. The reversible nature of the PEG-PLL/DNA complex was further verified through the addition of polyanion [poly-(L-aspartic acid)]: Poly(L-aspartic acid) replaced DNA in the complex with PEG-PLL, resulting in the release of free DNA in the medium. Furthermore, the PEG-PLL/DNA complex showed high resistance against DNase I attack, suggesting DNA protection through the segregation into the core of the associate having PEG palisade.     

N-acylated alpha-amino acids as novel oral delivery agents for proteins

A series of N-acylated alpha-amino acids were synthesized and shown to improve the oral delivery of two protein drugs, salmon calcitonin (sCT) and interferon-alpha. Forty-five compounds in this series were tested in vivo in rats and primates. A significant positive correlation was found between the log P of the acylated amino acids and the decrease in serum calcium following oral dosage of sCT in rats. Such a correlation was not found for interferon-alpha. These derivatized amino acids only weakly inhibited the activity of trypsin or leucine aminopeptidase. Histological examinations of rat intestinal tissue after oral dosing of acylated amino acid/protein combinations revealed no detectable pathology.     

Characterization and assessment of a novel poly(ethylene oxide)/polyurethane composite hydrogel (Aquavene) as a ureteral stent biomaterial

Although endothelium-derived hyperpolarizing factor (EDHF) activity has been demonstrated in arteries from various species, EDHF has not been chemically identified, nor its mechanism of action characterized. To elucidate this mechanism, we tested the effect of EDHF on large-conductance Ca2+-activated K+ (K(Ca)) channels in porcine coronary artery smooth muscle cells. By using a patch-clamp technique, single-channel currents were recorded in cultured smooth muscle cells; the organ bath also contained a strip of porcine coronary with endothelium, which served as the source of endothelium-derived relaxing factor(s) including EDHF. Exposure of endothelium to 10(-6) M bradykinin activated K(Ca) channels in cultured smooth muscle cells in cell-attached patches. When the experiment was performed in the presence of 10 microM indomethacin and 30 microM N(G)-nitro-L-arginine (L-NNA), which block the generation of prostaglandin I2 (PGI2) and NO, respectively, K(Ca) channel activity was stimulated by bradykinin, indicating the direct involvement of EDHF in K(Ca) channel stimulation. Neither 10 microM methylene blue nor 25 microM Rp-cAMPS inhibited bradykinin-induced K(Ca) channel activity. In inside-out patches, the addition of bradykinin to the solution was without effect on K(Ca) channel activation. However, in the presence of 0.5 mM guanosine triphosphate (GTP) and 1.0 mM adenosine triphosphate (ATP) in the bath solution, K(Ca) channels was activated by bradykinin. In outside-out patches, the addition of bradykinin also increased K(Ca) channel activity, when GTP and ATP were added to the pipette solution. The addition of GDP-beta-S (100 microM) in the cytosolic solution completely blocked the activation K(Ca) channels induced by bradykinin in inside-out and outside-out patches. Pretreatment with 30 microM quinacrine, a phospholipase A2 inhibitor, or 3 microM 17-octadecynoic acid (17-ODYA), a cytochrome P450 inhibitor, in addition to indomethacin and L-NNA, abolished bradykinin-stimulated K(Ca) channel activity in cell-attached patches. Both 14,15-epoxyeicosatrienoic acid (EET) and 11,12-EET increased the open probabilities of K(Ca) channels in cell-attached patches. These results suggest that EDHF, released from endothelial cells in response to bradykinin, hyperpolarizes smooth muscle cells by opening K(Ca) channels. Furthermore, our data suggest that EDHF is an endothelium-derived cytochrome P450 metabolite of arachidonic acid. The effect of EDHF on K(Ca) channels is not associated with an increase of cAMP and cGMP. The activation of K(Ca) channels appears to be due to the activation of GTP-binding protein.     

Iron incorporated porous cerium oxide nanoparticles as an efficient photocatalyst for different hazardous elimination

Po rous ceria（CeO₂） nanoparticles and iron-doped porous ceria with different iron co ntents（1 wt%,2.5 wt%,5 wt% and 10 wt%） were prepared using a one-pot simple process.Several characterization techniques were applied to characterize the prepared materials,including inductively coupled plasma（ICP）ele mental analysis,X-ray diffraction（XRD）,Fourier transform infrared（FTIR）,N₂ sorption measure ments,scanning electron microscopy（SEM）,high resolution-transmission electron microscopy（HR-TEM）,and DR-UV-Vis.The obtained results confirm the incorporation of iron ions in the CeO₂ lattice,with no evidence for the formation of iron oxide as a separate phase.More importantly,the light absorption property of Fe-doped porous ceria samples is found to be red-shifted and the calculated bandgap decreases from 3.08 to 2.66 eV for pure porous ceria and 10 wt% Fe-doped ceria,respectively.Under the illumination of visible light,the photocatalytic activity of Fe-doped porous ceria was investigated through the decolourization reaction of methyl green aqueous solution as a model contaminant in industrial wastewater.The obtained photocatalytic data show a remarkable increase in activity by almost4.8 times higher compared to a pure ceria sample.Furthermore,the prepared Fe-doped ceria sample exhibits good reusability up to the fourth consecutive reaction without treatment.Moreover,the bestperforming sample was further investigated in two additional photocatalytic reactions;the first is the elimination of phenol in an aqueous solution,while the second is the degradation of a gas mixture containing four short-chain hydrocarbon gases.The results of both reactions confirm the great improvement in the photocatalytic performance of Fe-doped porous ceria compared to a pure porous ceria sample.     

The fibronectin type III domain as a scaffold for novel binding proteins

The fibronectin type III domain (FN3) is a small autonomous folding unit which occurs in many animal proteins involving in ligand binding. The beta-sandwich structure of FN3 closely resembles that of immunoglobulin domains. We have prepared a phage display library of FN3 in which residues in two surface loops were randomized. We have selected mutant FN3s which bind to a test ligand, ubiquitin, with significant affinities, while the wild-type FN3 shows no measurable affinity. A dominant clone was expressed as a soluble protein and its properties were investigated in detail. Heteronuclear NMR characterization revealed that the selected mutant protein retains the global fold of FN3. It also has a modest conformational stability despite mutations at 12 out of 94 residues. These results clearly show the potential of FN3 as a scaffold for engineering novel binding proteins.     

Niosomes as carriers for ophthalmic drugs: in vitro/in vivo evaluation

This report provides X-ray diffraction and Raman spectral evidence that, when 2,6-dichlorobenzonitrile is present in the culture medium, Acetobacter xylinum, which is a model system for investigation of the biosynthesis of native cellulose, produces cellulose II, as well as cellulose I. The significance of the observations with respect to the mechanism of biosynthesis of cellulose is discussed briefly.     

A comparative study of ethylene oxide and ionizing radiation for sterilizing bone grafts

To find a good way for sterilization and disinfection of bone grafts, we compared the sterilization capacity of gaseous ethylene oxide (EO) and cobalt-60 gamma radiation. The bone chips were contaminated with 10(7) bacteria per milliliter of Staphylococcus aureus ATCC 25923, Bacillus subtilis globigii 8017 and Bacillus cereus 4001, then sterilized with various doses of gaseous EO or cobalt- 60 gamma radiation. The sterilization effect of EO was more stronger and faster than that of 60Co gamma radiation. The application of moderate doses of EO for sterilizing particulate bone grafts was recommended.     

Effects of ions on partitioning of serum albumin and lysozyme in aqueous two-phase systems containing ethylene oxide/propylene oxide co-polymers

To examine the influence of dietary polyunsaturated fatty acids (PUFA) on the lipid composition of the pineal organ and its production of prostaglandins, Atlantic salmon were fed diets containing either fish oils rich in long-chain n-3 polyunsaturated fatty acids, or plant oils with high levels of 18:2(n-6) (sunflower oil) or 18:3(n-3) (linseed oil) for 12 weeks. Lipid content and lipid class composition of the pineal organ were not greatly influenced by the type of oil fed to the fish: choline phosphoglycerides were always the predominant lipid class and the proportion of polar lipids exceeded that of neutral lipids. The pattern of PUFA present in total lipid and individual lipid classes was, however, related to that of the dietary oil. The major PUFA in pineal total lipid from all four dietary groups was 22:6(n-3) and the proportion of n-6 PUFA present was highest in lipid from salmon fed sunflower oil. Both PGE and PGF analogues of the 2- and 3-series were detected in pineal homogenates from all dietary groups with the former prostaglandin being the most abundant. The ratio of PGE2/PGE3 was greatest in fish fed sunflower oil and lowest in those fed linseed oil. The results provide further evidence that despite its anatomical location the pineal organ resembles non-neural tissues more than brain in terms of lipid composition and prostaglandin production.     

Preparation and characterization of collagen coated cholesterol-free liposome nanoparticles matrix for drug carriers and tissue engineering application

The collagen coated cholesterol (CH)-free liposome nanoparticle (CCLNP) matrix has been prepared and characterized for use as therapeutic drug carriers, tissue engineering and regenerative medicinal applications. The CH-free liposome nanoparticle (LNP) was prepared by heating method under the N2 atmosphere and CCLNP matrix was prepared by incubation of bovine Achilles tendon collagen with preformed CH-free LNP. The results indicate that collagen stabilizes the original liposomal structure, and CCLNP are more stable in vitro than control liposome. This mineralized collagen composite matrix could be useful to bone and dental implants.     

Chitosan as a nasal delivery system: the effect of chitosan solutions on in vitro and in vivo mucociliary transport rates in human turbinates and volunteers

In these studies, we examined the effect on mucociliary transport rates (MTR) of various 0.25% (w/v) chitosan solutions applied to human nasal tissue both ex vivo and in vivo. In the first study a range of chitosans with different molecular weights were applied to freshly amputated human nasal turbinates, and their effect on MTR was recorded. The transient inhibitory effect on turbinate MTR that was found for most of the chitosan preparations showed a marked dependence on the volume of chitosan solution applied and the molecular weight of the chitosan tested. The higher the molecular weight of the chitosan and the more chitosan applied, the longer the original MTR was depressed. A small scale human trial, investigating the effect of chitosan glutamate, on saccharin clearance times, was also undertaken. The study showed that a once daily application of a 0.25% solution of the chitosan for 7 days had no effect on either saccharin clearance times or nasal histology as examined by light microscopy.     

Comparison of liquid chemical sterilization with peracetic acid and ethylene oxide sterilization for long narrow lumens

The aim of this study was to determine how well peracetic acid liquid chemical sterilization (LCPAS) killed test organisms in the presence of 10% fetal bovine serum and 0.65% salt challenge (RPMI-S) compared with a 100% ethylene oxide (ETO) sterilizer and an ETO hydrochlorofluorocarbon (ETO-HCFC) sterilization method with long (125 cm), narrow (3-mm internal diameter) flexible lumens as the test carrier. The inoculated lumens were dried overnight before processing. The test organisms included Mycobacterium chelonei, Enterococcus faecalis, and Bacillus subtilis. For all 3 organisms tested, the LCPAS process resulted in a 6 log10 reduction in bacterial load compared with a 2.5 log10 to 6 log10 reduction for the 100% ETO and ETO-HCFC sterilizers. Sterilization was achieved for 100%, 61%, and 67% of the lumen test carriers for the LCPAS, 100% ETO, and ETO-HCFC sterilizers, respectively. The data indicate that of the sterilization methods evaluated, LCPAS was the most effective for sterilizing narrow flexible lumens in the presence of residual inorganic and organic soil. This effectiveness was achieved through a combination of organism wash-off and peracetic acid sterilant killing of organisms. Salt was the major compounding factor for effective ETO gas sterilization, because carriers inoculated with organisms in 10% fetal bovine serum alone all were sterilized by both 100% ETO and ETO-HCFC sterilization methods. Our data support the critical need to ensure adequate precleaning of narrow flexible lumen endoscopes before any sterilization method.     

NdFeO3 as anode material for S/O2 solid oxide fuel cells

Sulfur-oxygen solid oxide fuel cells (S/O2-SOFCs) can improve the utilization ratio of energy via converting the combustion heat of sulfur into electrical energy directly, and sulfur trioxide which is an intermediate in sulfuric acid industry can be obtained directly via S/O2-SOFCs. The anode material NdFeO3 was prepared via sol-gel method, the phase stability of NdFeO3 in sulfur vapor or sulfur dioxide atmosphere was investigated. The single cell, consisting of NdFeO3-SDC/SDC/LSM-SDC structure, was fabricated by the screen-printing method and tested by the home-built equipment with sulfur vapor or sulfur dioxide as the fuel. As indicated by X-ray diffraction (XRD) analysis, NdFeO3 was stable in sulfur vapor or sulfur dioxide atmosphere at 800℃, the phase composition of the mixture of NdFeO3 and SDC (Sm doped CeO2) did not change after the mixture was calcined at 800℃ for 4 h. The transmission electron microscope (TEM) photograph revealed that the average grain size of NdFeO3 powder was about 80 nm. With sulfur vapor or SO2 as the fuel, the maximum open circuit voltages (OCVs) of the single cell were 409 mV at 620℃ and 474 mV at 650℃, respectively; the maximum power densities of single cell were 0.154 mW/cm2 at 620℃ and 0.265 mW/cm2 at 650℃, respectively.     

Comparison of tethered star and linear poly(ethylene oxide) for control of biomaterials surface properties

BACKGROUND: Breast carcinoma in males is infrequent, and information regarding the results of modern treatment is limited. Cases of breast carcinoma in males were accrued from multiple hospitals in one region to determine treatment, survival, and prognostic factors. METHODS: A retrospective review was performed of 217 cases of breast carcinoma in males accessioned at tumor registries of 18 health care institutions in eastern Wisconsin between 1953 and 1995. RESULTS: Of the 217 cases, 215 (99.1%) were carcinomas. The majority of carcinomas were of invasive ductal type and presented as masses. Carcinoma in situ accounted for 5.5% of cases. The 5- and 10-year observed survivals for men were 50.6% and 23.7%, respectively. A high rate of post-treatment mortality from comorbid disease was found. Stage, axillary lymph node status, number of lymph nodes with metastases, and tumor hormone receptors were significant indicators of prognosis. Adjuvant systemic chemotherapy and hormone therapy improved the prognosis of patients with axillary lymph node metastases and hormone receptor positive tumors. Earlier stage at presentation and improved 5-year survival were found in cases occurring between 1986-1995 compared with those occurring in earlier years. Use of modified radical mastectomy and systemic adjuvant therapy also increased since 1986. CONCLUSIONS: The clinical, pathologic, and prognostic features of breast carcinoma in men are similar to those reported for women. The poorer prognosis of men is related to older age at diagnosis, more advanced stage of disease at presentation, and high mortality from comorbid disease. Earlier diagnosis, less radical surgery, and use of systemic adjuvant therapy are coincident with an improved prognosis for men.     

Protein-resistant coatings for glass and metal oxide surfaces derived from oligo(ethylene glycol)-terminated alkytrichlorosilanes

This paper describes the preparation of oligo(ethylene glycol)-terminated alkyltrichlorosilanes, Cl3Si(CH2)11(OCH2CH2)(n)OCH3 (n = 2, 3), and their use in the formation of self-assembled monolayers on an oxide surface. The adsorption of the trichlorosilanes from solution produces densely packed, oriented monolayer films that are 2-3 nm in thickness. The trichlorosilyl group anchors the molecules to the surface, and the resulting film exposes the ethylene glycol units at its surface, as noted by its moderate hydrophilicity (theta2(H2O) approximately 68 degrees). The films are robust with stabilities similar to those of other alkylsiloxane coatings. These oligo(ethylene glycol)-terminated silane reagents produce films that notably exhibit resistances against the non-specific adsorption of proteins from solution that are better than for films prepared from octadecyltrichlorosilane. With insulin, tysozyme, albumin, and hexokinase, no adsorption was observed with the oligo(ethylene glycol)-siloxane coatings whereas protein films of approximately a monolayer formed on surfaces-treated with octadecyltrichlorosilane. With fibrinogen, complete resistance was not possible with either coating; however, the oligo(ethylene glycol)-siloxane coatings exhibited greater resistance against non-specific adsorption. The oligo(ethylene glycol)-siloxane coatings offer performance advantages over available systems and could easily provide a direct and superior replacement in protocols that presently use silane reagents to generate hydrophobic, 'inert' surfaces.