Silicones with enhanced protein resistance were prepared by introducing poly(ethylene oxide) (PEO) chains via siloxane tethers (a-c) of varying lengths. Three unique ambifunctional molecules (a-c) having the general formula alpha-(EtO)3Si(CH2)2-oligodimethylsiloxanen-block-poly(ethylene oxide)8-OCH3 (n = 0 (a), 4, (b), and 13 (c)) were prepared via regioselective Rh-catalyzed hydrosilylation. Nine films were subsequently produced by the H3PO4-catalyzed sol-gel cross-linking of a-c each with alpha,omega-bis(Si-OH)polydimethylsiloxane (P, Mn = 3000 g/mol) in varying ratios (1:1, 1:2, and 2:3 molar ratio a, b, or c to P). Films prepared with a 2:3 molar ratio (a-c to P) contained the least amount of un-cross-linked materials, which may migrate to the film surface. For this set of films, surface hydrophilicity and protein resistance increased with siloxane tether length (a-c). These results indicate that PEO was more effectively mobilized to the surface if incorporated into silicones via longer siloxane tethers.

Block copolymers consisting of poly (gamma-benzyl L-glutamate) and poly (ethylene oxide) as the hydrophobic and hydrophilic components, respectively were prepared. Cell attachment onto the surfaces of block copolymers fabricated either as well-defined ordered Langmuir-Blodgett (LB) films or solvent cast microphase-separated structures was studied. On ordered LB surfaces, adherent fibroblasts were larger than on the microphase-separated cast surfaces within 15 min. The difference in cell adhesion between LB films and cast surfaces increased with increasing PEO contents in block copolymer. Adherent cells increased with an increase in surface pressure of LB films in any polymer. Phase-contrast microphotographs of adherent cells showed rapid and extensive morphologic changes associated with the LB surface as compared to cast film surfaces. The number of cells grown on the LB surface is greater than that on the cast film.

Natural source poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (PHBV) with a low hydroxyvalerate (HV) content ( approximately 8wt.%) was modified by blending it with poly[(R)-3-hydroxybutyrate]-alt-poly(ethylene oxide) (HE) alternating block copolymer. We hypothesized that the adjoining PHB segments could improve the miscibility of the poly(ethylene oxide) segments of HE with the PHBV matrix and therefore improve the physical properties of the PHBV/HE blends. A differential scanning calorimetry study revealed the improved miscibility of PEO segments of HE characterized by the interference of the crystallization of PHBV. The decrease in water contact angle and the increase in equilibrium water uptake of the PHBV/HE blends indicated that both the surface and bulk hydrophilicity of PHBV could be improved through blending HE. The mechanical properties of the hydrated PHBV/HE blends were assessed by measuring their tensile strength. In contrast to the hydrated natural source PHBV, which failed in a brittle manner, the hydrated PHBV/HE blends were ductile. Their strain at break increased with increasing HE content, reaching a maximum of 394% at an HE content of 15wt.%. The excellent integrity of the PHBV/HE blends in water is attributed to the strong affinity between the PHB segments of HE and the PHBV matrix. Platelet adhesion on the film surface of the PHBV/HE blends was investigated in vitro to evaluate their blood compatibility. The results demonstrated that the PHBV/HE blends effectively resisted the adhesion of platelets due to the anchored PEO segments from HE on the film surface.

The same reasons that prompt older people to give up driving can also result in difficulties with accessing public transport. Difficulties using public transport can limit older people's participation in society, thereby impacting negatively on their health. Focusing on public buses, this review explicates the link between bus usability and the health of older people and frames existing evidence on bus usability issues. The Person-Environment-Occupation (PEO) model offers a framework by which bus usability can be assessed. A combination of person-centred, environmental, and occupation-related factors, including bus design, service provision and performance, information, and the attitudes of staff and the community, impact on older people's ability to catch buses. More systematic research needs to take place in order to develop a comprehensive understanding of bus usability. Occupational therapy has a key role to play in conceptualizing, implementing, and evaluating improvements in bus usability for older people.

The rapid degradation of magnesium-based implants in physiological environments in vivo not only will quickly deteriorate their mechanical strengths but will also lead to a severe change of the micro-environment around the implants, which may cause the final failure of magnesium-based implants. In this work, a polycaprolactone (PCL) layer was prepared to seal the plasma electrolytic oxidization coating (PEO) to form a PEO/PCL composite coating on a biodegradable AZ31 magnesium alloy, followed by further surface functionalization with polydopamine. The in vitro degradation behaviors of the bare AZ31 alloy and coated samples were evaluated in a simulated body fluid (SBF) using the potentiodynamic polarization curve test and the static immersion test. The bioactivity of the samples was investigated using the SBF soaking test. The cytocompatibility of all samples was evaluated using the cytotoxicity test and analysis of the adhesion and proliferation of osteoblast cells (MC3T3-E1) directly cultivated on the sample surface. The results showed that the PCL layer successfully sealed the pores of the PEO coating, and then the polydopamine layer formed on its surface. The in vitro degradation tests showed that the PEO/PCL composite coating improved the corrosion resistance of the AZ31 alloy in SBF with a more positive corrosion potential and a lower corrosion current density. Due to the protection of the PEO/PCL composite coating, the surrounding environment showed nearly no influence on the degradation of the coated sample, which led to no obvious local alkalization and hydrogen evolution. Moreover, compared with the AZ31 alloy and PEO coating, the PEO/PCL composite coating was more suitable for cell adhesion and proliferation. After further surface functionalization by polydopamine, the corrosion resistance of the composite coating was maintained, while its bioactivity was significantly enhanced with a large amount of hydroxyapatite (HA) formed on its surface after immersion in SBF. The initial cell adhesion and spread were also improved by the polydopamine. By further immobilizing polyhexamethylene biguanidine (PHMB) onto the coating surface via the assistance of polydopamine, good antibacterial ability was obtained. This feasible method for fabricating a cytocompatible and antibacterial composite coating on a biodegradable AZ31 alloy may be promising in implant applications due to the osteointegration and anti-infection properties of these materials post operation.

Sustained release (SR) tablets containing solid dispersions (SD) granules of a poorly water-soluble drug were prepared to investigate the controlled pH-independent release of the drug. Losartan potassium (LST), an anti-hypertensive agent was chosen as a model drug because of its pH-dependent solubility and short elimination half-life. Poloxamer 188 was used as an SD carrier. A free-flowing SD granule was prepared by adsorbing the melt of the drug and poloxamer 188 onto the surface of an adsorbent, Aerosil 300 (fumed silicon dioxide), followed by direct compression with polyethylene oxide (PEO, 5 × 10(6)) to obtain an SD-loaded SR (SD-SR) matrix tablet. Differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) revealed partially amorphous structures of the drug in the SD granules. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) images indicated adsorption of SD granules onto the surface of the adsorbent. The SD granules dissolved completely within 10 min, a dissolution rate much higher than that of pure LST. Moreover, pH-independent sustained release of LST from the SD-SR tablet was achieved for 2h in gastric fluid (pH 1.2) and for 10h in intestinal fluid (pH 6.8). A combination of SD techniques using surface adsorption and SR concepts is a promising approach to control the release rate of poorly water-soluble drugs in a pH-independent manner.

Core/shell wormlike polymer brushes with densely grafted poly(ϵ-caprolactone)-b-poly(ethylene oxide) (PCL-b-PEO) are synthesized via grafting an alkynyl terminated PCL-b-PEO (ay-PCL(17) -b-PEO(113) ) onto a well-defined azido functionalized polymethacrylate (PGA(940) ) and are evaluated preliminarily as a single molecular cylindrical vehicle for drug delivery. Water soluble molecular worms of ca. 230 nm are obtained and then the anticancer drug doxorubicin (DOX) is loaded into its PCL core by hydrophobic interaction. Compared with spherical micelles from linear PCL(17) -b-PEO(113) , the brushes demonstrate a lower loading efficiency but a faster release rate of DOX. Confocal laser scanning microscopy measurements show that DOX-loaded cylindrical molecular brushes can easily enter into HeLa and HepG2 cells in 1 h.

OBJECTIVE

Muscle is one of the most commonly affected organs in mitochondrial disorders, and the symptoms are often exercise related. The cardiopulmonary exercise test with the determination of lactic acid formation could give supplementary information about the exercise-induced metabolic stress and compensatory mechanisms used in these disorders. The aim of this study was to evaluate the exercise capacity and lactate kinetics related to exercise in subjects with two genetically characterized mitochondrial disorders (multiple mitochondrial DNA deletions with PEO, MELAS) compared with lactate kinetics in subjects with metabolic myopathy (McArdle's disease) and in the healthy controls.

METHODS

The subjects were consecutive, co-operative patients of Department of Neurology of Helsinki University Hospital. Molecular genetic analyses were used for group classification of the mitochondrial myopathy.

METHODS

The study groups consisted of 11 patients with multiple deletions (PEO) and five patients with a point mutation in the mitochondrial DNA (MELAS), four patients with a muscle phosphorylase enzyme deficiency (McArdle's disease) and 13 healthy controls. The clinical disease of the patients was relatively mild.

RESULTS

A graded exercise test with ventilatory gas analyses and venous blood lactic acid analyses was performed. The main finding was the prolonged accumulation of blood lactate after the exercise in the PEO and MELAS groups compared with the controls. An overcompensation in ventilation was found in the MELAS and PEO group.

CONCLUSIONS

The blood lactate accumulation after exercise occurs in patients with multiple mitochondrial DNA deletions or MELAS even in patients with only mild exercise intolerance. Cardiopulmonary exercise can be used in the diagnostic process of patients with mitochondrial myopathies.

DNA polymerase gamma (POLG) is the replicative polymerase responsible for maintaining mitochondrial DNA (mtDNA). Disorders related to its functionality are a major cause of mitochondrial disease. The clinical spectrum of POLG syndromes includes Alpers-Huttenlocher syndrome (AHS), childhood myocerebrohepatopathy spectrum (MCHS), myoclonic epilepsy myopathy sensory ataxia (MEMSA), the ataxia neuropathy spectrum (ANS) and progressive external ophthalmoplegia (PEO). We have collected all publicly available POLG-related patient data and analyzed it using our pathogenic clustering model to provide a new research and clinical tool in the form of an online server. The server evaluates the pathogenicity of both previously reported and novel mutations. There are currently 176 unique point mutations reported and found in mitochondrial patients in the gene encoding the catalytic subunit of POLG, POLG. The mutations are distributed nearly uniformly along the length of the primary amino acid sequence of the gene. Our analysis shows that most of the mutations are recessive, and that the reported dominant mutations cluster within the polymerase active site in the tertiary structure of the POLG enzyme. The POLG Pathogenicity Prediction Server (http://polg.bmb.msu.edu) is targeted at clinicians and scientists studying POLG disorders, and aims to provide the most current available information regarding the pathogenicity of POLG mutations.

OBJECTIVE

To investigate if the cross-linking of transferrin receptor (TfR) induced by Tf-oligomers alters the endocytosis of receptor-ligand complexes in cultured tumor cells and hence increases intracellular drug release.

METHODS

An average of 3.5 Tf molecules per aggregate were cross-linked either by using homobifunctional linker (1, 11-bis-maleimidotetraethyleneglycol) [Tf(3.5-BM(PEO)4)] or heterobifunction linker [succinimidyl 4-(-p-maleimidophenyl)-butyrate] (Tf(3.5-SMPB)). Cell surface binding and competition experiments with 125I-Tf for TfR binding were studied to demonstrate that Tf-oligomers maintain specificity of the TfR-binding. To determine the degradation of Tf-oligomers in TfR-mediated endocytosis, cultured tumor cells were pulsed for 15 min with 125I-Tf-oligomers and chased for 2 h at 37 degrees C in the presence of excess unlabeled Tf. The chase medium was subjected to TCA precipitation to separate the intact and degraded Tf. To investigate if the alteration of TfR-trafficking facilitates the intracellular release of the drug from the Tf-conjugated form, methotrexate (MTX) was conjugated to Tf-oligomer (Agg-Tf-MTX) and its antiproliferative activity was compared with monomeric-Tf-MTX (Mono-Tf-MTX) in human colon carcinoma (Caco-2) cells, human breast adenocarcinoma (MCF-7) cells, wild-type Chinese hamster ovary (CHO) cells, and MTX-resistant CHO (CHO-MTX-RII) cells.

RESULTS

TfR-mediated degradation of Tf-oligomers was higher than that of monomeric Tf in both Caco-2 and MCF-7 cells. The IC50 of Agg-Tf-MTX was lower than that of Mono-Tf-MTX in both tumor cell lines. The IC50 of MTX and Mono-Tf-MTX in CHO-MTX-RII cells was higher than that in wild-type CHO cells, whereas the Agg-Tf-MTX was almost identical in both the resistant and wild-type cells.

CONCLUSIONS

Cross-linking of TfR induced by oligomeric Tf binding alters the intracellular trafficking of Tf-TfR complexes, redirects them out of the recycling pathway, and targets them to intracellular degradation in cultured tumor cells. The alteration of TfR-trafficking facilitates the intracellular release of the drug from the Tf-conjugated form. Consequently, Agg-Tf-MTX is more effective than Mono-Tf-MTX as a TfR-mediated antiproliferative agent in tumor cells, as well as in MTX-resistant transport deficient cells. Therefore, Tf-oligomers are potentially effective TfR-targeting carriers for intracellular delivery of anticancer drugs.

A potential anti-cancer drug-delivery polymeric micelle system with an in vitro degradation half-life of about 48 h that releases its drug upon application of ultrasound was synthesized. This vehicle was composed of an amphiphilic co-polymer, poly(ethylene oxide)-b-poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate-lactate(n)). The degree of polymerization of the lactate side group, n, was 0, 3 or 5. The molar ratio of NIPAAm to HEMA-lactate(n) to PEO in polymerization was optimized to produce an in vitro polymeric micelle half-life of about 48 h at 40 degrees C. 1,6-Diphenyl-1,3,5-hexatriene (DPH) was used as a fluorescent probe to study the hydrophobicity of the cores of the polymeric micelles. The results showed that the cores of the polymeric micelles were hydrophobic enough to sequester DPH and the anti-cancer drug doxorubicin (Dox). Dox was encapsulated into the polymeric micelles having a molar feed ratio of NIPAAm to HEMA-lactate3 to PEO equal to 20:5:1; this drug was released upon the application of low-frequency ultrasound. The Dox release was about 2% at room temperature and 4% at body temperature, and the drug returned to the polymeric micelles when insonation ceased.

Propolis has a broad spectrum of biological activities; however, whether its essential oils have neuroprotective effects is unknown. In this study, we found that propolis essential oil (PEO) could significantly reverse the anxiety-like behavior of restraint-stressed mice, and has no effect on locomotor activity. Furthermore, PEO significantly decreased the plasma levels of cortisol (CORT), adrenocorticotropic hormone (ACTH) and malondialdehyde (MDA), whereas it increased the activity of superoxide dismutase (SOD) in restraint-stressed mice. These results strongly suggest that PEO has therapeutic effects on anxiety through antagonizing the hyperfunction of hypothalamic-pituitary-adrenal (HPA) axis and improving the ability of antioxidation in brain tissue.

OBJECTIVE

The aim of the study was to evaluate the effect of binding hydrophilic polyethylene oxide (PEO) onto Dacron fibers in the sewing ring of a mechanical heart valve (MHV), in terms of thrombogenicity of the prosthesis.

METHODS

The study was performed in blinded fashion. Six Yorkshire-cross pigs (bodyweight 35-45 kg) were implanted with MHVs, in the mitral annulus, with the PEO-treated sewing ring. An additional five pigs implanted with identical MHVs, but with untreated sewing rings, served as controls. PEO of chain-length 10,000 Da was grafted to Dacron fibers using gamma irradiation. PEO-bonded Dacron fibers (diameter 100 microns) were used to weave the sewing ring, which was then assembled on a titanium stent (OD 25 mm). Autologous platelets were labeled with 111In-tropolone and injected intravenously (850-1250 microCi per injection) into the pigs on removal from cardiopulmonary bypass (CPB). At 20-24 h after surgery, platelet thrombi adherent to MHV components, and shed emboli trapped in the brain, lung, heart, kidneys and other organs/connective tissues were imaged using a gamma camera. The animals were killed and the amounts of thrombi adherent to MHV components and organ-trapped emboli quantified using an ionization chamber and gamma counter.

RESULTS

There was no statistically significant difference in the adhesion of 111In-labeled platelets to either control sewing rings (0.08 +/- 0.06% dose) or PEO-treated rings (0.19 +/- 0.21% dose). The thrombogenicity of MHV components in both animal groups was in the ascending order: Dacron ring>> Teflon pledgets>> polypropylene sutures>> titanium housing>> pyrolytic carbon. The number of platelet-emboli trapped in the organs was not significantly different between the two groups.

CONCLUSIONS

Simple modifications may not reduce platelet thrombosis or wound-healing of the sewing ring in the acute phase, at which time several complex processes are activating and inactivating platelets and coagulant factors during CPB and implantation of MHVs.

OBJECTIVE

To assess the efficacy of Oxiplex (FzioMed, Inc., San Luis Obispo, CA) barriers.

METHODS

Film of polyethylene oxide and carboxymethylcellulose (Oxiplex) were tested for strength and tissue adherence. Films were selected for evaluation in models for biocompatability and adherence. Three films were selected for evaluation in efficacy studies, and one was evaluated for effects on bacterial peritonitis. Handling characteristics of Oxiplex film were evaluated via laparoscopy.

METHODS

University laboratory.

METHODS

Rabbits, rats, pigs.

METHODS

Placement of Oxiplex prototypes at the site of injury.

METHODS

Mechanical properties, biocompatibility, tissue adherence, adhesion development, infection potentiation, and device handling.

RESULTS

Mechanical tests indicated that tensile strength and elongation were inversely correlated. All films tested had excellent tissue adherence properties. Selected films, based on residence time and biocompatibility, prevented adhesion formation in all animals and were highly efficacious in preventing adhesion reformation. The optimal Oxiplex prototype prevented adhesion reformation in 91% of the animals. This Oxiplex film, dyed to allow visualization, prevented adhesion reformation and did not affect bacterial peritonitis. In a laparoscopic model, the Oxiplex film, delivered in FilmSert forceps, via a 5.0-mm trocar, rapidly unfurled and could be easily applied to tissue with strong adherence.

CONCLUSIONS

These data show development of an adhesion prevention material that is tissue adherent, can be placed via laparoscopy, and does not affect host resistance.

A novel cubic bicontinuous morphology is found in polymer-ceramic nanocomposites and mesoporous aluminosilicates that are derived by an amphiphilic diblock copolymer, poly(isoprene-b-ethylene oxide) (PI-b-PEO), used as a structure-directing agent for an inorganic aluminosilicate. Small-angle X-ray scattering (SAXS) was employed to unambiguously identify the Im(-)3m crystallographic symmetry of the materials by fitting individual Bragg peak positions in the two-dimensional X-ray images. Structure factor calculations, in conjunction with results from transmission electron microscopy, were used to narrow the range of possible structures consistent with the symmetry and showed the plumber's nightmare morphology to be consistent with the data. The samples are made by deposition onto a substrate that imposes a strain field, generating a lattice distortion. This distortion is quantitatively analyzed and shown to have resulted in shrinkage of the crystallites by approximately one-third in a direction perpendicular to the substrate, in both as-made composites and calcined ceramic materials. Finally, the observation of the bicontinuous block-copolymer-derived hybrid morphology is discussed in the context of a pseudo-ternary morphology diagram and compared to existing studies of ternary phase diagrams of amphiphiles in a mixture of two solvents. The calcined mesoporous materials have potential applications in the fields of catalysis, separation technology, and microelectronics.

Novel, controlled-release formulations for high drug load, highly water soluble compound niacin based on polyethylene oxide (PEO) and hydroxypropylmethyl cellulose (HPMC) matrices were developed and investigated. The effect of sodium bicarbonate as a modulator of swelling, erosion, and drug release and its impact on changes in the kinetics of axial swelling and gel strength were evaluated by textural analysis during dissolution study. The drug release rate from PEO-based matrices was faster and correlated with lower gel strength, greater water uptake, and greater matrix erosion. Slower release rate and greater release duration correlated significantly with greater matrix swelling with negligible matrix erosion for the HPMC-based matrix system. Inclusion of sodium bicarbonate in the polymeric matrix salted out the macromolecules and increased gel strength and gel viscosity, especially in the vicinity of the swelling fronts. An in vivo study in human subjects after administration of the formulations and a commercial product exhibited similar plasma concentrations. For the formulation of interest, the mean drug fraction absorbed by the body was calculated by the Wagner-Nelson technique, and a level A "in vitro-in vivo correlation" was observed between the percent released in vitro and percent absorbed in vivo. The developed formulations appear to be robust and easy to manufacture with maximum flexibility with respect to drug dose, polymeric carriers, duration, and kinetics of drug release.

Electrospun hybrid nanofibers have been extensively regarded as drug carriers. This study tries to introduce a nano fibrous wound dressing as a new strategy for a topical drug-delivery system. The vancomycin (VCM)-loaded hybrid chitosan/poly ethylene oxide (CH/PEO) nanofibers were fabricated by the blend-electrospinning process. Morphological, mechanical, chemical, and biological properties of nanofibers were examined by SEM, FTIR, release profile study, tensile assay, Alamar Blue cytotoxicity evaluation, and antibacterial activity assay. In vivo wound healing activity of hybrid CH/PEO/VCM nanofibers was evaluated in full-thickness skin wounds of rats. The hybrid CH/PEO/VCM nanofibers were successfully fabricated in a nanometer. The CH/PEO/VCM 2.5% had higher Young's Modulus, better tensile strength, smaller fiber diameter with sustained-release profiles compared to CH/PEO/VCM 5%. All nanofibers did not show any significant cytotoxicity (P < 0.05) on the normal fibroblast cells. Also, VCM-load hybrid CH/PEO nanofibers successfully inhibited bacterial growth. The wound area in the rats treated with CH/PEO/VCM 2.5% was less than CH/PEO/VCM 5% treated group. According to histological evaluation, the CH/PEO/VCM 2.5% group showed the fastest wound healing than other treatment groups. Results of this study proposed that CH/PEO/VCM nanofibers could promote the wound healing process by reducing the side effects of VCM as a topical antimicrobial agent.

Keywords: Chitosan nanofibers; Vancomycin; Wound dressing.

Quaternary ammonium chitosan (HACC)/polyvinyl alcohol (PVA)/polyethylene oxide (PEO) hydrogels were prepared using gamma radiation. The chemical structure of the hydrogels was characterized using FT-IR. The results revealed that HACC, PVA and PEO were perfectly compatible and interacted via the hydrogen bonds. As revealed by SEM, scaffolds with a homogeneous interconnected pore structure were obtained after lyophilizing the hydrogels. The influence of different radiation doses and weight ratios on properties including gel content, swelling ability, water evaporation rate and mechanical properties were investigated. It indicated that the hydrogels had the good swelling ability, water evaporation rate and mechanical properties. In vitro antibacterial activity assessment, the hydrogels exhibited a pronounced inhibitory effect against two bacteria (Staphylococcus aureus and Escherichia coli). Therefore, the hydrogels showed a promising potential to be applied as wound dressing.

An increase in the degree of chemical compatibility between drug and polymeric structure in the core has been shown to raise the encapsulation efficiency and lower the rate of drug release from polymeric micelles. In this study, to achieve an optimized polymeric micellar delivery system for the solubilization and controlled delivery of cucurbitacin I (CuI), the Flory-Huggins interaction parameter (chi(sc)) between CuI and poly(epsilon-caprolactone) (PCL), poly(alpha-benzylcarboxylate-epsilon-caprolactone) (PBCL) and poly(alpha-cholesteryl carboxylate-epsilon-caprolactone) (PChCL) structures was calculated by group contribution method (GCM) as an indication for the degree of chemical compatibility between different micellar core structures and CuI. The results pointed to a better compatibility between CuI and PChCL core rationalizing the synthesis of self-associating methoxy poly(ethylene oxide)-b-poly(alpha-cholesteryl carboxylate-epsilon-caprolactone) block copolymer (MePEO-b-PChCL). Novel block copolymer of MePEO-b-PChCL was synthesized through, first, preparation of substituted monomer, that is, alpha-cholesteryl carboxylate-epsilon-caprolactone, and further ring opening polymerization of this monomer by methoxy PEO (5000 g mol(-1)) using stannous octoate as catalyst. Synthesized block copolymers were characterized for their molecular weight and polydispersity by (1)H NMR and gel permeation chromatography. Self-assembled MePEO-b-PChCL micelles were characterized for their size, morphology, critical micellar concentration (CMC), capacity for the physical encapsulation of CuI, and mode of CuI release in comparison to MePEO-b-PCL and MePEO-b-PBCL micelles. Overall, the experimental order for the level of CuI encapsulation in different polymeric micellar formulations was consistent with what was predicted by the Flory-Huggins interaction parameter. Although MePEO-b-PChCL micelles exhibited the highest level of CuI loading, this structure did not show any significant superiority over MePEO-b-PCL in controlling CuI release. The most efficient control over the rate of CuI release was achieved by MePEO-b-PBCL micelles that had more viscous cores than that of MePEO-b-PChCL, instead. The results point to a potential for MePEO-b-PChCL micelles for the solubilization of cholesterol compatible drugs. It also highlights the inadequacy of the Flory-Huggins interaction parameter calculated by GCM in predicting the order of drug release from different polymeric micellar structures.

Non-woven mats of Bombyx mori silk fibroin were fabricated using electrospinning with an all aqueous solution at <10wt% without any co-existing water soluble polymer such as PEO. The fibroin aqueous solution electrospinnability was affected by the fibroin molecular weight and the spinning solution pH. Hot-water treatment without any alkaline reagent or soap produced higher molecular weight fibroin than the typical degumming process did. The higher molecular weight fibroin provided good electrospinnability. Results show that the basic solution (pH10-11) is important for electrospinning at low concentrations of 5wt%. Evaluation of structural and mechanical properties of the non-woven mat fabricated with water solvent revealed that it is safe for use in the human body. It is anticipated for wider use in medical materials such as cellular scaffolds for tissue engineering.

Blends based on plasticized-wheat starch (as matrix or rich phase) and poly(ethylene oxide) (PEO) (as dispersed phase) were prepared by melt processing in a twin-screw extruder. The extrusion of the plasticized-starch is significantly facilitated by blending with PEO. Plasticized-starch and PEO are immiscible in the range of the investigated blend ratios (90/10-50/50). The phase inversion takes place when the PEO content is 50 wt.% in the blend. Both the thermal stability and the tensile properties of plasticized-starch are improved by blending with PEO. Also, a synergistic effect between plasticized-starch and PEO is noticed at 25-40 wt.% PEO content in the blend, the Young's modulus of the materials obtained being the highest and higher than both neat polymer components at those blending ratios.

An ordered mesoporous WO3 material with a highly crystalline framework was synthesized by using amphiphilic poly(ethylene oxide)-b-polystyrene (PEO-b-PS) diblock copolymers as a structure-directing agent through a solvent-evaporation-induced self-assembly method combined with a simple template-carbonization strategy. The obtained mesoporous WO3 materials have a large uniform mesopore size (ca. 10.9 nm) and a high surface area (ca. 121 m(2) g(-1)). The mesoporous WO3-based H2S gas sensor shows an excellent performance for H2S sensing at low concentration (0.25 ppm) with fast response (2 s) and recovery (38 s). The high mesoporosity and continuous crystalline framework are responsible for the excellent performance in H2S sensing.

This article presents a systematic study of the effect of pH on the rheological properties of aqueous micellar gels formed from 10.0 wt % aqueous solutions of a thermo- and pH-sensitive ABA triblock copolymer, poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid)-b-poly(ethylene oxide)-b-poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid) (P(DEGEA-co-AA)-b-PEO-b-P(DEGEA-co-AA)). The block copolymer was synthesized by atom transfer radical polymerization of DEGEA and tert-butyl acrylate with a molar ratio of 100:5 from a difunctional PEO macroinitiator and subsequent removal of tert-butyl groups using trifluoroacetic acid. PDEGEA is a thermosensitive water-soluble polymer with a cloud point of 9 °C in water. The thermo-induced sol-gel transition temperature (T(sol-gel)) of the 10.0 wt % aqueous solution of P(DEGEA-co-AA)-b-PEO-b-P(DEGEA-co-AA) can be continuously and reversibly tuned over a wide temperature range by varying the solution pH. The sol-gel transition became broader with the increase of pH, which stemmed from the weaker and broader LCST transition of P(DEGEA-co-AA) blocks at higher pH values. The maximum value of dynamic storage modulus, obtained from heating ramp, and the plateau storage moduli (G(N)), evaluated from frequency sweeps at three normalized temperatures (T/T(sol-gel) = 1.025, 1.032, and 1.039), decreased with the increase of pH from 3.00 to 5.40 with the sharpest drop observed at pH = ∼4.7. The decrease in G(N) reflects the reduction of the number of bridging polymer chains and simultaneously the increase of the numbers of loops and dangling polymer chains. The ionization of carboxylic acid groups at higher pH values introduced charges onto the thermosensitive blocks and made the polymer chains more hydrophilic, facilitating the formation of loops and dangling chains in the gels. The increase in the number of dangling polymer chains with the increase of pH was supported by fluorescence spectroscopy studies, which showed that the critical micelle concentration of P(DEGEA-co-AA)-b-PEO-b-P(DEGEA-co-AA) at a temperature corresponding to T(sol-gel) was higher at a higher pH. The results reported in this article showed that both T(sol-gel) and gel strength can be tuned by varying the solution pH, providing greater design flexibility for potential applications.

Different types of gels were prepared by combining poloxamines (Tetronic), i.e. poly(ethylene oxide)/poly(propylene oxide) (PEO/PPO) octablock star copolymers, and cyclodextrins (CD). Two different poloxamines with the same molecular weight (ca. 7000) but different molecular architectures were used. For each of their four diblock arms, direct Tetronic 904 presents PEO outer blocks while in reverse Tetronic 90R4 the hydrophilic PEO blocks are the inner ones. These gels were prepared by combining α-CD and poloxamine aqueous solutions. The physicochemical properties of these systems depend on several factors such as the structure of the block copolymers and the Tetronic/α-CD ratio. These gels were characterized using differential scanning calorimetry (DSC), viscometry and X-ray diffraction measurements. The 90R4 gels present a consistency that makes them suitable for sustained drug delivery. The resulting gels were easily eroded: these complexes were dismantled when placed in a large amount of water, so controlled release of entrapped large molecules such as proteins (Bovine Serum Albumin, BSA) is feasible and can be tuned by varying the copolymer/CD ratio.