Different types of NPs (nanoparticles) are currently under development for diagnostic and therapeutic applications in the biomedical field, yet our knowledge about their possible effects and fate in living cells is still limited. In the present study, we examined the cellular response of human brain-derived endothelial cells to NPs of different size and structure: uncoated and oleic acid-coated iron oxide NPs (8-9 nm core), fluorescent 25 and 50 nm silica NPs, TiO2 NPs (21 nm mean core diameter) and PLGA [poly(lactic-co-glycolic acid)]-PEO [poly(ethylene oxide)] polymeric NPs (150 nm). We evaluated their uptake by the cells, and their localization, generation of oxidative stress and DNA-damaging effects in exposed cells. We show that NPs are internalized by human brain-derived endothelial cells; however, the extent of their intracellular uptake is dependent on the characteristics of the NPs. After their uptake by human brain-derived endothelial cells NPs are transported into the lysosomes of these cells, where they enhance the activation of lysosomal proteases. In brain-derived endothelial cells, NPs induce the production of an oxidative stress after exposure to iron oxide and TiO2 NPs, which is correlated with an increase in DNA strand breaks and defensive mechanisms that ultimately induce an autophagy process in the cells.

We have tethered epidermal growth factor (EGF) to a solid substrate in a manner permitting the factor to retain its biological activity as assessed by both mitogenic and morphological assays. Mouse EGF was covalently coupled to aminosilane-modified glass via star poly(ethylene oxide) (PEO), which allows the ligand to retain significant mobility and active conformation. Tethered EGF was as effective as soluble EGF in eliciting DNA synthesis and cell rounding responses of primary rat hepatocytes under different surface conditions. In contrast, physically adsorbed EGF at comparable surface concentrations showed no activity. Presentation of growth factors in this manner may help to expedite their clinical use by permitting greater control of temporal and spatial availability in the extracellular environment.

A low molecular weight poly(ethyleneoxide)-poly(butadiene) (PEO-PB) diblock copolymer containing 50 weight percent PEO forms gigantic wormlike micelles at low concentrations (<5 percent by weight) in water. Subsequent generation of free radicals with a conventional water-based redox reaction leads to chemical cross-linking of the PB cores without disruption of the cylindrical morphology, as evidenced by cryotransmission electron microscopy and small-angle neutron scattering experiments. These wormlike rubber micelles exhibit unusual viscoelastic properties in water.

No consensus exists on how to address possible toxicity of nanomaterials as they interfere with most in vitro screening tests based on colorimetric and fluorimetric probes such as the dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay for detection of oxidative species. In the present research, nanomaterial interaction with DCFH-DA was studied in relation to its nature and/or assay conditions (cell-based and time exposure) by incubating Rhodamine (Rhd)-labeled 25nm and 50nm silica (SiO2), naked and oleic acid coated magnetite, (Fe3O4) and maghemite (Fe2O3) iron oxide, titanium dioxide (TiO2) and poly(ethylene oxide)-poly(lactide/glycolide) acid (PLGA-PEO) nanoparticles (NPs) with metabolically active rat hepatocytes for 4 and 24-h periods. Data indicated that nanoparticle uptake correlated with quenching of dye fluorescence emission. In spite of their masking effect, the oxidative potential of NPs could be detected at a limited threshold concentration when exposed for periods of time longer than those frequently used for this test. However, changes in the experimental conditions did not systematically result in free radical formation for all nanomaterials tested. Overall data indicate that despite the quenching effect of nanoparticles on DCFH-DA assay, it can be considered as a useful tool for quantitative measurement of NPs-induced oxidative stress by minor modifications of standardized protocols.

To develop a drug delivery system with enhanced efficacy and minimized adverse effects, we synthesized a novel polymeric nanoparticles, (YCC-DOX) composed of poly (ethylene oxide)-trimellitic anhydride chloride-folate (PEO-TMA-FA), doxorubicin (DOX) and superparamagnetic iron oxide (Fe(3)O(4)) and folate. The efficacy of the nanoparticles was evaluated in rats and rabbits with liver cancer, in comparison with free-DOX (FD) and a commercial liposome drug, DOXIL. YCC-DOX showed the anticancer efficacy and specifically targeted folate receptor (FR)-expressing tumors, thereby increasing the bioavailability and efficacy of DOX. The relative tumor volume of the YCC-DOX group was decreased two- and four-fold compared with the FD and DOXIL groups in the rat and rabbit models, respectively. Furthermore, YCC-DOX showed higher MRI sensitivity comparable to a conventional MRI contrast agent (Resovist), even in its lower iron content. In the immunohistochemical analysis, YCC-DOX group showed the lower expression of CD34 and Ki-67, markers of angiogenesis and cell proliferation, respectively, while apoptotic cells were significantly rich in the YCC-DOX group in terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. These results indicate that YCC-DOX is a promising candidate for treating liver cancer and monitoring the progress of the cancer using MRI.

The low solubility in biological fluids displayed by about 50% of the drugs still remains the main limitation in oral, parenteral, and transdermal administration. Among the existing strategies to overcome these drawbacks, inclusion of hydrophobic drugs into polymeric micelles is one of the most attractive alternatives. Amphiphilic poly(ethylene oxide)-poly(propylene oxide) block copolymers are thermoresponsive materials that display unique aggregation properties in aqueous medium. Due to their ability to form stable micellar systems in water, these materials are broadly studied as hydrosolubilizers for poorly water-soluble drugs. The present review provides a concise description of the most important applications of PEO-PPO-based copolymers in the Pharmaceutical Technology field as means for attaining improved solubility, stability, release, and bioavailability of drugs.

Nanoparticle-based in vivo applications should consider the omnipresence of the phagocytes in the bloodstream and tissue. We have studied the nanoparticle uptake capacities of the most important human primary leukocyte populations using a nanoparticle library encompassing both rod-shaped and spherical gold nanoparticles with diameters between 15 and 50 nm and a variety of surface chemistries. Cetyltrimethylammoniumbromide (CTAB)-stabilized nanoparticles were internalized rapidly within 15 min and in large amounts by macrophages and to a lower extent also by monocytes. Interestingly, we found that the uptake of nanorods by macrophages was more efficient than that of nanospheres. Blocking experiments and electron microscopic studies revealed macropinocytosis as the major uptake mechanism. Grafting of poly(ethylene oxide) (PEO) onto the nanorods was found to significantly delay their internalization for several hours. The long-term uptake of PEO-coated nanoparticles with positively or negatively charged end groups was almost identical. Particle surface chemistry strongly influenced the expression of inflammation-related genes within 1 day. Furthermore, the macrophage phenotype was significantly affected after 7 days of culture with nanorods depending on the surface chemistry. Thus, in vivo application of nanoparticles with certain surface functionalities may lead to inflammation upon particle accumulation. However, our data also suggest that chemical modifications of nanoparticles may be useful for immunomodulation.

Multiple deletions of mitochondrial DNA (mtDNA) have recently been reported in familial progressive external ophthalmoplegia (PEO), in a case of progressive encephalomyopathy, and in inherited recurrent myoglobinuria. The inheritance of familial PEO has been autosomal dominant, which indicates that a mutation in an unknown nuclear gene results in several mtDNA deletions of different sizes in these patients. We report a patient with autosomal dominant PEO, whose major clinical symptom, however, was severe retarded depression. The morphological analyses of the tissue samples derived from autopsy showed various abnormalities in the mitochondria in all the tissues studied. The activities of the respiratory chain enzymes encoded by mtDNA were remarkably reduced in the skeletal muscle. The mtDNA analyses confirmed that besides myopathy, this patient had a multisystem disorder with widespread distribution of multiple deletions of mtDNA. The highest percentage of mutated mtDNA was found in the brain, skeletal muscle and the heart, the relative quantity of mutated mtDNA correlating to the severity of the clinical symptoms.

Integrins play an important role in cellular matrix interactions requisite for cancer cell adhesion, growth, migration and invasion. In this study, we have investigated the expression of integrin subunits alpha3, alpha6, alphav and beta1 in normal ovaries, benign ovarian tumors and ovarian carcinomas of different pathological grades. The expression of these integrins in ovarian cancer cell lines was also investigated, and their role in sustaining proliferation, adhesion, migration and invasion in cohort with the activation of signaling pathways in response to extracellular matrices (ECM) was evaluated. We demonstrate a differential expression pattern of alpha3, alpha6, alphav and beta1 integrin subunits in ovarian carcinomas compared to normal ovaries and benign ovarian tumors. Ovarian cancer cell lines (Hey, Ovcar3 and Peo.36) demonstrated significantly high expression of alpha3, alpha6, alphav and beta1 integrin subunits. A significant increase in proliferation and adhesion (P<0.05) in response to collagen 1 (Coll) and laminin (LM), ligands for integrin receptor alpha3beta1 and alpha6beta1 was observed in ovarian cancer cell lines. On the other hand, fibronectin (FN), a receptor for alphavbeta1 integrin, increased proliferation in all ovarian cancer cell lines studied but only enhanced adhesion in Hey cell line (P<0.05). Neutralizing antibodies against alpha3, alpha6, alphav and beta1 integrin subunits inhibited ECM-induced proliferation, but increased adhesion to ECM was inhibited by beta1 integrin subunit antibody. No suppression of Coll, LM and FN-induced (Hey cells only) adhesion was observed in the presence of alpha3 or alphav subunit antibodies but LM-induced adhesion was inhibited by blocking alpha6 subunit functions. LM, FN and Coll enhanced chemotactic migration in Hey cells, but direct invasion across ECM was observed only in the presence of LM and Coll. Blocking antibodies against alpha3, alpha6 and beta1 integrin subunits inhibited both chemotactic migration and invasion of Hey cells in response to respective ECM. Adhesion of ovarian cancer cells to FN, Coll and LM activated Ras, Erk and Akt pathways. Neutralizing alphav and beta1 functions did not inhibit FN-induced activation of Ras and Erk pathways but inhibited the Akt pathway. On the other hand, antibodies against alpha6 and beta1 subunits, but not alpha3 subunit, inhibited LM-induced activation of Ras but did not inhibit the downstream Akt pathway. Neutralizing beta1 subunit function however, inhibited LM-induced Erk activation. Coll-induced activation of Ras, Erk and Akt pathways was inhibited by alpha3 and beta1 integrin subunit antibodies. These results indicate that alpha3beta1, alphavbeta1 and alpha6beta1 integrin mediate proliferation, adhesion, migration and invasion of ovarian cancer cells in response to ECM and targeting these integrins to modulate integrin-ECM interactions in tumor cells may be a promising tool to reduce the dissemination of ovarian carcinoma in vivo.

OBJECTIVE

Worm-like and spherical micelles are both prepared here from the same amphiphilic diblock copolymer, poly(ethylene oxide)-b-poly (epsilon-caprolactone) (PEO [5 kDa]-PCL [6.5 kDa]) in order to compare loading and delivery of hydrophobic drugs.

METHODS

Worm-like micelles of this degradable copolymer are nanometers in cross-section and spontaneously assemble to stable lengths of microns, resembling filoviruses in some respects and thus suggesting the moniker 'filomicelles'. The highly flexible worm-like micelles can also be sonicated to generate kinetically stable spherical micelles composed of the same copolymer.

RESULTS

The fission process exploits the finding that the PCL cores are fluid, rather than glassy or crystalline, and core-loading of the hydrophobic anticancer drug delivery, paclitaxel (TAX) shows that the worm-like micelles load and solubilize twice as much drug as spherical micelles. In cytotoxicity tests that compare to the clinically prevalent solubilizer, Cremophor EL, both micellar carriers are far less toxic, and both types of TAX-loaded micelles also show fivefold greater anticancer activity on A549 human lung cancer cells.

CONCLUSIONS

PEO-PCL based worm-like filomicelles appear to be promising pharmaceutical nanocarriers with improved solubilization efficiency and comparable stability to spherical micelles, as well as better safety and efficacy in vitro compared to the prevalent Cremophor EL TAX formulation.

The epicardium is the last layer of the vertebrate heart to form, surrounding the heart muscle during embryogenesis and providing signaling cues essential to the continued growth and differentiation of the heart. This outer layer of the heart develops from a transient structure, the proepicardial organ (PEO). Despite its essential roles, the early signals required for the formation of the PEO and the epicardium remain poorly understood. The molecular markers wt1 and tcf21 are used to identify the epicardial layer in the zebrafish heart, to trace its development and to determine genes required for its normal development. Disruption of lateral plate mesoderm (LPM) migration through knockdown of miles apart or casanova leads to cardia bifida with each bilateral heart associated with its own PEO, suggesting that the earliest progenitors of the epicardium lie in the LPM. Using a gene knockdown approach, a genetic framework for PEO development is outlined. The pandora/spt6 gene is required for multiple cardiac lineages, the zinc-finger transcription factor wt1 is required for the epicardial lineage only and finally, the cell polarity genes heart and soul and nagie oko are required for proper PEO morphogenesis.

Efficient entry of synthetic polymers inside cells is a central issue in polymeric drug delivery. Though polymers are widely believed to interact nonspecifically with plasma membrane, we present unexpected evidence that amphiphilic block copolymers, depending on their aggregation state, can distinguish between caveolae- and clathrin-mediated endocytosis. A block copolymer of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), Pluronic P85 (P85), below critical micelle concentration (CMC) exists as single molecule coils (unimers) and above CMC forms 14.6 nm aggregated micelles with a hydrophobic PPO core and hydrophilic PEO shell. The internalization pathways of P85 in mammalian cells were elucidated using endocytosis inhibitors and colocalization with endocytosis markers (clathrin-specific antibodies and transferrin for clathrin and caveolin-1-specific antibodies and cholera toxin B for caveolae). Altogether, our results indicate that P85 unimers internalize through caveolae-mediated endocytosis, while P85 micelles internalize through clathrin-mediated endocytosis. Furthermore, at concentrations above 0.01% P85 inhibits caveolae-mediated endocytosis (cholera toxin B), while having little or no effect on the clathrin-mediated endocytosis (transferrin). Selective interaction of Pluronic with caveolae may explain its striking pharmacological activities including inhibition of drug efflux transport, activation of gene expression, and dose-dependent hyperlipidemia.

In this study, the effect of MDR-1 gene silencing, using small interfering RNA (siRNA), and paclitaxel (PTX) co-therapy in overcoming tumor multidrug resistance was examined. Poly(ethylene oxide)-modified poly(beta-amino ester) (PEO-PbAE) and PEO-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticles were formulated to efficiently encapsulate MDR-1 silencing siRNA and PTX, respectively. Upon administration in multidrug resistant SKOV3(TR) human ovarian adenocarcinoma cells, siRNA-mediated MDR-1 gene silencing was evident at 100 nM dose. Combination of MDR-1 gene silencing and nanoparticle-mediated delivery significantly influenced the cytotoxic activity of PTX in SKOV3(TR) cells similar to what was observed in drug sensitive SKOV3 cells. We speculate that the enhancement in cytotoxicity was due to an increase in intracellular drug accumulation upon MDR-1 gene silencing leading to an apoptotic cell-kill effect. Taken together, these preliminary results are highly encouraging for the development of combination nano-therapeutic strategies that combine gene silencing and drug delivery to provide more potent therapeutic effect, especially in refractory tumors.

Integrins provide the primary link between mesenchymal stem cells (MSCs) and their surrounding extracellular matrix (ECM), with different integrin pairs having specificity for different ECM molecules or peptide sequences contained within them. It is widely acknowledged that the type of ECM present can influence MSC differentiation; however, it is yet to be determined how specific integrin-ECM interactions may alter this or how they change during differentiation. We determined that human bone marrow-derived mesenchymal stem cells (hMSCs) express a broad range of integrins in their undifferentiated state and show a dramatic, but transient, increase in the level of α5 integrin on day 7 of osteogenesis and an increase in α6 integrin expression throughout adipogenesis. We used a nonfouling polystyrene-block-poly(ethylene oxide)-copolymer (PS-PEO) surface to present short peptides with defined integrin-binding capabilities (RGD, IKVAV, YIGSR, and RETTAWA) to hMSCs and investigate the effects of such specific integrin-ECM contacts on differentiation. hMSCs cultured on these peptides displayed different morphologies and had varying abilities to differentiate along the osteogenic and adipogenic lineages. The peptide sequences most conducive to differentiation (IKVAV for osteogenesis and RETTAWA and IKVAV for adipogenesis) were not necessarily those that were bound by those integrin subunits seen to increase during differentiation. Additionally, we also determined that presentation of RGD, which is bound by multiple integrins, was required to support long-term viability of hMSCs. Overall we confirm that integrin-ECM contacts change throughout hMSC differentiation and show that surfaces presenting defined peptide sequences can be used to target specific integrins and ultimately influence hMSC differentiation. This platform also provides information for the development of biomaterials capable of directing hMSC differentiation for use in tissue engineering therapies.

Bone-mimetic electrospun scaffolds consisting of polycaprolactone (PCL), collagen I and nanoparticulate hydroxyapatite (HA) have previously been shown to support the adhesion, integrin-related signaling and proliferation of mesenchymal stem cells (MSCs), suggesting these matrices serve as promising degradable substrates for osteoregeneration. However, the small pore sizes in electrospun scaffolds hinder cell infiltration in vitro and tissue-ingrowth into the scaffold in vivo, limiting their clinical potential. In this study, three separate techniques were evaluated for their capability to increase the pore size of the PCL/col I/nanoHA scaffolds: limited protease digestion, decreasing the fiber packing density during electrospinning, and inclusion of sacrificial fibers of the water-soluble polymer PEO. The PEO sacrificial fiber approach was found to be the most effective in increasing scaffold pore size. Furthermore, the use of sacrificial fibers promoted increased MSC infiltration into the scaffolds, as well as greater infiltration of endogenous cells within bone upon placement of scaffolds within calvarial organ cultures. These collective findings support the use of sacrificial PEO fibers as a means to increase the porosity of complex, bone-mimicking electrospun scaffolds, thereby enhancing tissue regenerative processes that depend upon cell infiltration, such as vascularization and replacement of the scaffold with native bone tissue.

Enzyme-filled polystyrene-b-poly(3-(isocyano-L-alanyl-aminoethyl)thiophene) (PS-b-PIAT) nanoreactors are encapsulated together with free enzymes and substrates in a larger polybutadiene-b-poly(ethylene oxide) (PB-b-PEO) polymersome, forming a multicompartmentalized structure, which shows structural resemblance to the cell and its organelles. An original cofactor-dependent three-enzyme cascade reaction is performed, using either compatible or incompatible enzymes, which takes place across multiple compartments.

To verify the impact of mutations in ANT1, Twinkle, and POLG1 genes in sporadic progressive external ophthalmoplegia associated with multiple mitochondrial DNA (mtDNA) deletions, DNA samples from 15 Italian and 12 British patients were screened. Mutations in ANT1 were found in one patient, in Twinkle in two patients, and in POLG1 in seven patients. Irrespective of the inheritance mode, screening of these genes should be performed in all patients with progressive external ophthalmoplegia with multiple mtDNA deletions.

Progressive external ophthalmoplegia (PEO) is a heritable mitochondrial disorder characterized by the accumulation of multiple point mutations and large deletions in mtDNA. Autosomal dominant PEO was recently shown to co-segregate with a heterozygous Y955C mutation in the human gene encoding the sole mitochondrial DNA polymerase, DNA polymerase gamma (pol gamma). Since Tyr-955 is a highly conserved residue critical for nucleotide recognition among family A DNA polymerases, we analyzed the effects of the Y955C mutation on the kinetics and fidelity of DNA synthesis by the purified human mutant polymerase in complex with its accessory subunit. The Y955C enzyme retains a wild-type catalytic rate (k(cat)) but suffers a 45-fold decrease in apparent binding affinity for the incoming nucleoside triphosphate (K(m)). The Y955C derivative is 2-fold less accurate for base pair substitutions than wild-type pol gamma despite the action of intrinsic exonucleolytic proofreading. The full mutator effect of the Y955C substitution was revealed by genetic inactivation of the exonuclease, and error rates for certain mismatches were elevated by 10-100-fold. The error-prone DNA synthesis observed for the Y955C pol gamma is consistent with the accumulation of mtDNA mutations in patients with PEO.

Using quantitative PCR, we have determined that a human oocyte contains approximately 100,000 mitochondrial genomes (mtDNAs). We have also found that some oocytes harbor measurable levels (up to 0.1%) of the so-called common deletion, an mtDNA molecule containing a 4,977-bp rearrangement that is present in high amounts in many patients with "sporadic" Kearns-Sayre syndrome (KSS) and progressive external ophthalmoplegia (PEO). This is the first demonstration that rearranged mtDNAs are present in human oocytes, and it provides experimental support for the supposition that pathogenic deletions associated with the ontogeny of sporadic KSS and PEO can be transmitted in the female germ line, from mother to child. The relevance of these finding to the accumulation of extremely low levels of deleted mtDNAs in both somatic and germ-line tissues during normal human aging is also discussed.

Type I collagen-PEO fibers and non-woven fiber networks were produced by the electrospinning of a weak acid solution of purified collagen at ambient temperature and pressure. As determined by high-resolution SEM and TEM. fiber morphology was influenced by solution viscosity, conductivity, and flow rate. Uniform fibers with a diameter range of 100-150 nm were produced from a 2-wt% solution of collagen-PEO at a flow rate of 100 microl min(-1). Ultimate tensile strength and elastic modulus of the resulting non-woven fabrics was dependent upon the chosen weight ratio of the collagen-PEO blend. 1H NMR dipolar magnetization transfer analysis suggested that the superior mechanical properties, observed for collagen-PEO blends of weight ratio 1:1, were due to the maximization of intermolecular interactions between the PEO and collagen components. The process outlined herein provides a convenient, non-toxic, non-denaturing approach for the generation collagen-containing nanofibers and non-woven fabrics that have potential application in wound healing, tissue engineering, and as hemostatic agents.

Nanogels are comprised of swollen polymer networks and nearly 95% water and can entrap diverse chemical and biological agents for cancer therapy with very high loading capacities. Here we use diblock copolymer poly(ethylene oxide)-b-poly(methacrylic acid) (PEO-b-PMA) to form nanogels with the desired degree of cross-linking. The nanogels are further conjugated to folic acid (FA) and loaded with different types of drugs (cisplatin, doxorubicin). For the first time we demonstrate a tumor-specific delivery and superior anti-tumor effect in vivo of an anti-cancer drug using these polyelectrolyte nanogels decorated with folate-targeting groups. This reinforces the use of nanogels for the therapy of ovarian and other cancers, where folate receptor (FR) is overexpressed.

To estimate the feasibility of novel containers for drugs, poly(ethylene oxide)-poly(beta-benzyl L-aspartate) (PEO-PBLA) micelles were prepared by dialysis against water using different solvents. The solvent selected is very important because it drastically affects the stability of polymeric micelles. The critical micelle concentration (cmc) of the prepared micelles in distilled water was determined by a fluorescence probe technique using pyrene. Indomethacin (IMC) as a model drug was incorporated into the micelles by dialysis and an oil/water emulsion method. Characteristics of PEO-PBLA micelles without and with the physically trapped IMC in the inner core of the micelles (IMC/PEO-PBLA) were studied by dynamic light scattering and gel permeation chromatography/HPLC as well as an in vitro release test of IMC from the micelles. For the PEO-PBLA block copolymers, N,N-dimethylacetamide (DMAc) was found to be the best of the solvents tested to form stable polymeric micelles with a narrow size distribution and avoid its aggregation, and the cmc of PEO-PBLA micelles thus prepared was determined to be ca. 18 mg/L in water. The diameters of PEO-PBLA micelles and IMC/PEO-PBLA micelles in number averaged scale were observed to be ca. 19 and 25-29 nm, respectively. The release study of IMC from IMC/PEO-PBLA micelles in various buffer solutions at the pH range from 1.2 to 7.4 at 37 degrees C revealed that the release rate of IMC from the micelles was increased by increasing the pH of the medium and indicated that the release rate of IMC from the micelles are controlled by the partition coefficient of IMC based on the pH of the medium and interaction between IMC and the hydrophobic portion of the micelles.

To establish a method for predicting polymer-drug compatibility as a means to guide formulation development, we carried out physicochemical analyses of polymer-drug pairs and compared the difference in total and partial solubility parameters of polymer and drug. For these studies, we employed a range of biodegradable polymers and the anticancer agent Ellipticine as the model drug. The partial and total solubility parameters for the polymer and drug were calculated using the group contribution method. Drug-polymer pairs with different enthalpy of mixing values were analyzed by physicochemical techniques including X-ray diffraction and Fourier transform infrared. Polymers identified to be compatible [i.e., polycaprolactone (PCL) and poly-beta-benzyl-L-aspartate (PBLA)] and incompatible [i.e., poly (d,l-lactide (PLA)], by the above mentioned methods, were used to formulate Ellipticine. Specifically, Ellipticine was loaded into PBLA, PCL, and PLA films using a solvent casting method to produce a local drug formulation; while, polyethylene oxide (PEO)-b-polycaprolactone (PCL) and PEO-b-poly (d,l-lactide) (PLA) copolymer micelles were prepared by both dialysis and dry down methods resulting in a formulation for systemic administration. The drug release profiles for all formulations and the drug loading efficiency for the micelle formulations were also measured. In this way, we compared formulation characteristics with predictions from physicochemical analyses and comparison of total and partial solubility parameters. Overall, a good correlation was obtained between drug formulation characteristics and findings from our polymer-drug compatibility studies. Further optimization of the PEO-b-PCL micelle formulation for Ellipticine was also performed.

A revision (C35r) to the CHARMM ether force field is shown to reproduce experimentally observed conformational populations of dimethoxyethane. Molecular dynamics simulations of 9, 18, 27, and 36-mers of polyethylene oxide (PEO) and 27-mers of polyethylene glycol (PEG) in water based on C35r yield a persistence length lambda = 3.7 A, in quantitative agreement with experimentally obtained values of 3.7 A for PEO and 3.8 A for PEG; agreement with experimental values for hydrodynamic radii of comparably sized PEG is also excellent. The exponent upsilon relating the radius of gyration and molecular weight (R(g) proportional, variantM(w)(upsilon)) of PEO from the simulations equals 0.515 +/- 0.023, consistent with experimental observations that low molecular weight PEG behaves as an ideal chain. The shape anisotropy of hydrated PEO is 2.59:1.44:1.00. The dimension of the middle length for each of the polymers nearly equals the hydrodynamic radius R(h)obtained from diffusion measurements in solution. This explains the correspondence of R(h) and R(p), the pore radius of membrane channels: a polymer such as PEG diffuses with its long axis parallel to the membrane channel, and passes through the channel without substantial distortion.