Air-ozonolysis activation of polyolefins versus use of laden finishing to form contact-active nonwoven materials.

Two synthetic approaches were explored for modification of the polyolefins polyethylene/polypropylene (PE/PP) to form contact-active nonwoven materials. In the first approach, polymer surfaces were activated by O2-free air-ozonolysis, and then the active agent (trimethoxysilyl) propyl-octadecyl-dimethyl-ammonium chloride (C18-TSA) was covalently bound. In the second approach, the active agent was directly conjugated to the commercial 'finishing' that was then applied to the polymer. The chemical, physical and microscopic properties of the modified polymers were comprehensively studied, and their active site density was quantified by fluorescein sodium salt-cetyltrimethylammonium chloride reaction. The antimicrobial activity of the prepared nonwovens against Bacillus subtilis (Gram-positive) and Salmonella enterica (Gram-negative), and their stability at various pHs and temperatures were examined. The two approaches conferred antimicrobial properties to the modified polymers and demonstrated stable linkage of C18-TSA. However, the performance of the nonwovens formed by the first approach was superior. The study suggests two feasible and safe pathways for the modification of polyolefins to form contact-active nonwoven materials that can be further applied in various fields, such as hygiene products, medical fabrics, sanitizing wipes, and more.

Synthesis and characterization of a photo-cross-linked bioactive polycaprolactone-based osteoconductive biocomposite.

In this study, a light cross-linkable biocomposite scaffold based on a photo-cross-linkable poly (propylene fumarate) (PPF)-co-polycaprolactone (PCL) tri-block copolymer was synthesized and characterized. The developed biodegradable scaffold was further modified with ß-tricalcium phosphate (ß-TCP) bioceramic for bone tissue engineering applications. The developed biocomposite was characterized using H nuclear magnetic resonance and Fourier transform infrared spectroscopy. Moreover, the bioceramic particle size distribution and morphology were evaluated using Brunauer-Emmett-Teller method, X-ray diffraction, and scanning electron microscopy. The mechanical properties and biodegradation of the scaffolds were also evaluated. Cytotoxicity and mineralization assays were performed to analyze the biocompatibility and bioactivity capacity of the developed biocomposite. The characterization data confirmed the development of a biodegradable and photo-cross-linkable PCL-based biocomposite reinforced with ß-TCP bioceramic. In vitro analyses demonstrated the biocompatibility and mineralization potential of the synthesized bioceramic. Altogether, the results of the present study suggest that the photo-cross-linkable PCL-PPF-PCL tri-block copolymer reinforced with ß-TCP is a promising biocomposite for bone tissue engineering applications. According to the results, this newly synthesized material has a proper chemical composition for further clinically-relevant studies in tissue engineering.

Synthesis of a novel tannic acid-functionalized polypropylene as antioxidant active-packaging materials.

This work focuses on the synthesis of novel tannin-functionalized polypropylene copolymers that are designed to inhibit the oxidation of vegetable oils for potential use as packaging materials. An empty glass Petri dish (control), a chlorinated polypropylene-coated glass Petri dish (control) and a series of the tannin-functionalized polypropylene coated glass Petri dishes overlaid with linseed oil were exposed to air and additional white light. Oligomerization of the oxidized linseed oil was assessed by measuring the flow properties of the exposed oil using a viscometer. The antioxidant effect of the tannic acid grafted polypropylene copolymers (PP-Tann) retarded oligomerization of the linseed oil. The molar mass of the linoleic acid overlaid onto the PP-Tann films was the lowest among the tested samples after each time period indicating that tannin-grafted polypropylene may be a promising packaging material for vegetable oils.

Features of In Vitro Degradation and Physical Properties of a Biopolymer and In Vivo Tissue Reactions in Comparison with Polypropylene.

We compared in vitro degradation and physical properties of polypropylene and a biodegradable polymer synthesized by electrospinning and consisting of 65% polycaprolactone and 35% polytrimethylene carbonate as a possible alternative material for use in surgery for pelvic floor muscle failure. Samples of the studied polymers were implanted to 10 male Wistar rats into the interfascial space on the back (polypropylene on the right side and biodegradable polymer on the left side). The synthesized biopolymer was characterized by elongation and tear resistance, similar to those of polypropylene. During the period from the third to the sixth month after implantation, the area of fibrosis around individual polypropylene and biopolymer fibers increased by 16.7 and 107.9%, respectively, while remaining reduced compared to polypropylene. The total fibrosis area in 6 months after implantation of polypropylene and biopolymer samples significantly increased by 18% (p=0.0097) and 48% (p=0.05), respectively, i.e. fibrosing processes were more intense in case of biopolymer. Induction of more pronounced fibrosis can be an advantage of the synthesized biopolymer when choosing the material for fabrication of implants and their use for correction of incompetence of the ligamentous and muscular apparatus.

Homopolymer self-assembly of poly(propylene sulfone) hydrogels via dynamic noncovalent sulfone-sulfone bonding.

Natural biomolecules such as peptides and DNA can dynamically self-organize into diverse hierarchical structures. Mimicry of this homopolymer self-assembly using synthetic systems has remained limited but would be advantageous for the design of adaptive bio/nanomaterials. Here, we report both experiments and simulations on the dynamic network self-assembly and subsequent collapse of the synthetic homopolymer poly(propylene sulfone). The assembly is directed by dynamic noncovalent sulfone-sulfone bonds that are susceptible to solvent polarity. The hydration history, specified by the stepwise increase in water ratio within lower polarity water-miscible solvents like dimethylsulfoxide, controls the homopolymer assembly into crystalline frameworks or uniform nanostructured hydrogels of spherical, vesicular, or cylindrical morphologies. These electrostatic hydrogels have a high affinity for a wide range of organic solutes, achieving >95% encapsulation efficiency for hydrophilic small molecules and biologics. This system validates sulfone-sulfone bonding for dynamic self-assembly, presenting a robust platform for controllable gelation, nanofabrication, and molecular encapsulation.

Polypropylene mesh for hernia repair with controllable cell adhesion/de-adhesion properties.

Herein, a versatile bilayer system, composed by a polypropylene (PP) mesh and a covalently bonded poly(N-isopropylacrylamide) (PNIPAAm) hydrogel, is reported. The cell adhesion mechanism was successfully modulated by controlling the architecture of the hydrogel in terms of duration of PNIPAAm grafting time, crosslinker content, and temperature of material exposure in PBS solutions (below and above the LCST of PNIPAAm). The best in vitro results with fibroblast (COS-1) and epithelial (MCF-7) cells was obtained with a mesh modified with a porous iPP-g-PNIPAAm bilayer system, prepared via PNIPAAm grafting for 2 h at the lowest N,N'-methylene bis(acrylamide) (MBA) concentration (1 mM). Under these conditions, the detachment of the fibroblast-like cells was 50% lower than that of the control, after 7 days of cell incubation, which represents a high de-adhesion of cells in a short period. Moreover, the whole system showed excellent stability in dry or wet media, proving that the thermosensitive hydrogel was well adhered to the polymer surface, after PP fibre activation by cold plasma. This study provides new insights on the development of anti-adherent meshes for abdominal hernia repair.

Quantification of poisons for Ziegler Natta catalysts and effects on the production of polypropylene by gas chromatographic with simultaneous detection: Pulsed discharge helium ionization, mass spectrometry and flame ionization.

This article describes a new simultaneous method for the analysis of sulfur-type poisons, hydrocarbons and permanent gases affecting the productivity of the Ziegler Natta catalyst during the synthesis of polypropylene on an industrial scale in a fluidized-bed reactor. The identification was achieved employing a configuration of the seven-valve chromatographic system, with events at different times, allowing distribution of the sample through multiple columns, and finally reaching the helium ionization detectors of pulsed discharge, flame ionization and mass spectrometry. The results obtained show a good precision of the method used because the variability was less than 1.02% in area and 0.49% in retention time for short term precisión and longer term precision . The quantification of these species was successful after performing the calibration curve with the dynamic mixer showing an r2 higher than 0.9945 and excellent linearity. The lowest LOD value was 0.01 mg kg-1 for carbonyl sulphide, hydrogen sulfide, ethylmercaptan and propylmercaptan and the lowest LOQ was 0.03 mg kg-1 for hydrogen sulfide. The highest LOD and LOQ values were for oxygen and carbon dioxide with 0.40 and 0.93 mg kg-1 respectively. With this configuration, the correlation of data between the three detectors was simplified, having almost identical retention times for the analytes studied. The poisons detected and quantified in the samples were: hydrogen sulfide (0.1-0.5 mg kg-1), carbonyl sulphide (0.012-0.06 mg kg-1), carbon disulphide (0.04-0.22 mg kg-1), methylmercaptan (0.12-12.51 mg kg-1), ethylmercaptan (0.9-5.5 mg kg-1), carbon dioxide (0.10-3.0 mg kg-1), oxygen (0.55-6.1 mg kg-1), acetylene (0.15-3.5 mg kg-1) and methylacetylene (0.04-0.2 mg kg-1). The productivity losses were between 5 and 22%.

Application of Biocides and Super-Absorbing Polymers to Enhance the Efficiency of Filtering Materials.

Studies on the functionalization of materials used for the construction of filtering facepiece respirators (FFRs) relate to endowing fibers with biocidal properties. There is also a real need for reducing moisture content accumulating in such materials during FFR use, as it would lead to decreased microorganism survival. Thus, in our study, we propose the use of superabsorbent polymers (SAPs), together with a biocidal agent (biohalloysite), as additives in the manufacturing of polypropylene/polyester (PP/PET) multifunctional filtering material (MFM). The aim of this study was to evaluate the MFM for stability of the modifier's attachment to the polymer matrix, the degree of survival of microorganisms on the nonwoven, and its microorganism filtration efficiency. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were used to test the stability of the modifier's attachment. The filtration efficiency was determined under conditions of dynamic aerosol flow of S. aureus bacteria. The survival rates (N%) of the following microorganisms were assessed: Escherichia coli and Staphylococcus aureus bacteria, Candida albicans yeast, and Aspergillus niger mold using the AATCC 100-2004 method. FTIR spectrum analysis confirmed the pre-established composition of MFM. The loss of the active substance from MFM in simulated conditions of use did not exceed 0.02%, which validated the stability of the modifier's attachment to the PP/PET fiber structure. SEM image analysis verified the uniformity of the MFM structure. Lower microorganism survival rates were detected for S. aureus, C. albicans, and E. coli on the MFM nonwoven compared to control samples that did not contain the modifiers. However, the MFM did not inhibit A. niger growth. The MFM also showed high filtration efficiency (99.86%) against S. aureus bacteria.

Injectable Catalyst-Free Poly(Propylene Fumarate) System Cross-Linked by Strain Promoted Alkyne-Azide Cycloaddition Click Chemistry for Spine Defect Filling.

A new PPF-BCN/hyPCL32-N3 injectable system that can be cross-linked by catalyst-free, strain promoted alkyne-azide cycloaddition (SPAAC) click chemistry was developed for tissue engineering applications. The system consisted of two components: PPF-BCN, poly(propylene fumarate) (PPF) functionalized with (1R,8S,9s)-bicyclo[6.1.0]non-4-yn-9-ylmethanol (BCN-OH), and hyPCL32-N3, a hyper-branched 32-arm poly(ε-caprolactone) (PCL) dendrimer functionalized with azide as the cross-linker core. Fast SPAAC click reaction allowed the desired gelation of the system without using any toxic initiator or catalyst. Compared to the conventional injectable formulation, e.g., poly(methyl methacrylate) (PMMA), our PPF-BCN/hyPCL32-N3 (abbreviated as PFCL-Click) injectable system showed enhanced biocompatibility and low heat generation during cross-linking. After reaction, the cross-linked PFCL-Click scaffolds supported excellent proliferation and differentiation of preosteoblast cells on the surface. The PFCL-Click system can be successfully injected into vertebral bodies of rabbit spine and can be monitored by X-ray imaging after incorporating zirconium dioxide (ZrO2) powder. With these unique advantages, this injectable system has promising potential for bone defect repair and other tissue engineering and regenerative medicine applications.

Molecular Mass-Dependent Resorption and Bone Regeneration of 3D Printed PPF Scaffolds in a Critical-Sized Rat Cranial Defect Model.

The emergence of additive manufacturing has afforded the ability to fabricate intricate, high resolution, and patient-specific polymeric implants. However, the availability of biocompatible resins with tunable resorption profiles remains a significant hurdle to clinical translation. In this study, 3D scaffolds are fabricated via stereolithographic cDLP printing of poly(propylene fumarate) (PPF) and assessed for bone regeneration in a rat critical-sized cranial defect model. Scaffolds are printed with two different molecular mass resin formulations (1000 and 1900 Da) with narrow molecular mass distributions and implanted to determine if these polymer characteristics influence scaffold resorption and bone regeneration in vivo. X-ray microcomputed tomography (µ-CT) data reveal that at 4 weeks the lower molecular mass polymer degrades faster than the higher molecular mass PPF and thus more new bone is able to infiltrate the defect. However, at 12 weeks, the regenerated bone volume of the 1900 Da formulation is nearly equivalent to the lower molecular mass 1000 Da formulation. Significantly, lamellar bone bridges the defect at 12 weeks with both PPF formulations and there is no indication of an acute inflammatory response.

Propylene Polymerization Catalyzed by Metallocene /Methylaluminoxane Systems on Rice Husk Ash.

Silica generated from agricultural waste is more cost effective and environmentally friendly than silica from traditional commercial processes. In this study, spherical silica particles with a diameter of around 120 nm were fabricated from rice husk ash (RHA), and were used to support two bridged zirconcene complexes ((I) Me2Si(Ind)2ZrCl2 and (II) C2H4(Ind)2ZrCl2 ) for catalyzing propylene polymerization to produce polypropylene (PP) in a temperature range of 40-70 C and in a solution methylaluminoxane (MAO) range of 0.1-0.6 wt%. Due to its small particle size, RHA-supported catalyst exhibited much higher activity than micro-sized commercial silica-supported catalyst. At the optimum polymerization temperature of 55 C and with increasing MAO concentration, polymer yield increased proportionally with the increase of number average molecular weight. Compared to (I), (II) produced more polymer molecules but with much shorter chain length, ascribed to the differences of Zr loading and bridge structure. With increasing polymerization temperature, polymer molecular weight decreased rapidly and resulted in a significant change of PP assembly morphology (shape and size). At 55 C, (I) produced uniform PP assemblies which had dumbbell-like structure with a smooth middle section and two fibrillar ends, while (II) produced spherical PP particles. The dumbbell middle part width was essentially identical to the Batchelor microscale proposed in turbulent mixing theory.

Set of Highly Stable Amine- and Carboxylate-Terminated Dendronized Au Nanoparticles with Dense Coating and Nontoxic Mixed-Dendronized Form.

The synthesis of a novel poly(propyleneimine) (PPI) dendron in gram scale as well as its use in the formation of a highly stable, dendronized gold nanoparticle (AuNP)-based drug delivery platform is described herein. The AuNP-based platform is composed of three complementary parts: (i) a 15 nm AuNP core, (ii) a heterofunctional thioctic acid-terminated tetraethylene glycol spacer, and (iii) a third-generation PPI dendron with a unique protonation profile and diverse end-group functionalization that allows for further derivatization. The prepared dendronized AuNPs are able to withstand several rounds of lyophilization cycles with no sign of aggregation, are stable in phosphate-buffered saline and Hanks' buffer as well as in serum, and are resistant to degradation by glutathione exchange reactions. This nanocarrier platform displays a dense coating, with >1400 dendrons/AuNPs, which will enable very high payload. Furthermore, while amine-terminated AuNPs expectedly showed cytotoxicity against the MCF-7 breast cancer cell line from a NP concentration of 1 nM, the mixed monolayer AuNPs (coated with 40/60 amine/carboxylate dendrons) interestingly did not exhibit any sign of toxicity at concentrations as high as 15 nM, similar to the carboxylate-terminated AuNPs. The described dendronized AuNPs address the current practical need for a stable NP-based drug delivery platform which is scalable and easily conjugable, has long-term stability in solution, and can be conveniently formulated as a powder and redispersed in desired buffer or serum.

Development of Valsartan Floating Matrix Tablets Using Low Density Polypropylene Foam Powder: In vitro and In vivo Evaluation.

The main purpose of the study was to develop valsartan floating tablets (VFT) via non-effervescent technique using low density polypropylene foam powder, carbopol, and xanthan gum by direct compression. Before compression, the particulate powdered mixture was evaluated for pre-compression parameters. The prepared valsartan tablets were evaluated for post-compression parameters, swelling index, floating lag time, in vitro buoyancy studies, and in vitro and in vivo X-ray imaging studies in albino rabbits. The result of all formulations for pre- and post-compression parameters were within the limits of USP. FTIR and DSC studies revealed no interaction between the drug and polymers used. The prepared floating tablets had good swelling and floating capabilities for more than 12 h with zero floating lag time. The release of valsartan from optimized formulation NF-2 showed sustained release up to 12 h; which was found to be non-Fickian release. Moreover, the X-ray imaging of optimized formulation (NF-2) revealed that tablet was constantly floating in the stomach region of the rabbit, thereby indicating improved gastric retention time for more than 12 h. Consequently, all the findings and outcomes have showed that developed valsartan matrix tablets could be effectively used for floating drug delivery system.

Synthesis, characterization and evaluation of transfection efficiency of dexamethasone conjugated poly(propyleneimine) nanocarriers for gene delivery#.

CONTEXT: Polypropylenimine (PPI), a cationic dendrimer with defined structure and positive surface charge, is a potent non-viral vector. Dexamethasone (Dexa) conveys to the nucleus through interaction with its intracellular receptor. OBJECTIVE: This study develops efficient and non-toxic gene carriers through conjugation of Dexa at various percentages (5, 10 and 20%) to the fourth and the fifth generation PPIs (PPIG4s and PPIG5s). MATERIALS AND METHODS: The 21-OH group of Dexa (0.536 mmol) was modified with methanesulfonyl chloride (0.644 mmol) to activate it (Dexa-mesylate), and then it was conjugated to PPIs using Traut's reagent. After dialysis (48 h) and lyophilization, the physicochemical characteristics of products (PPI-Dexa) including zeta potential, size, buffering capacity and DNA condensing capability were investigated and compared with unmodified PPIs. Moreover, the cytotoxicity and transfection activity of the Dexa-modified PPIs were assessed using Neuro2A cells. RESULTS: Transfection of PPIG4 was close to PEI 25 kDa. Although the addition of Dexa to PPIG4s did not improve their transfection, their cytotoxicity was improved; especially in the carrier to DNA weight ratios (C/P) of one and two. The Dexa conjugation to PPIG5s enhanced their transfection at C/P ratio of one in both 5% (1.3-fold) and 10% (1.6-fold) Dexa grafting, of which the best result was observed in PPIG5-Dexa 10% at C/P ratio of one. DISCUSSION AND CONCLUSIONS: The modification of PPIs with Dexa is a promising approach to improve their cytotoxicity and transfection. The higher optimization of physicochemical characteristics, the better cell transfection and toxicity will be achieved.

Preparation of New Risperidone Depot Microspheres Based on Novel Biocompatible Poly(Alkylene Adipate) Polyesters as Long-Acting Injectable Formulations.

Risperidone (RIS)-loaded microspheres based on poly(alkylene adipate)s derived from dicarboxylic acids and different aliphatic diols were prepared by the oil in water emulsion and solvent evaporation method. Specifically, 3 polyesters, namely poly(ethylene adipate), poly(propylene adipate), and poly(butylene adipate), were prepared with the aid of a 2-stage melt-polycondensation method and characterized by gel permeation chromatography, proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry, and X-ray diffraction analysis. Results showed that the molecular weight of the polyesters increased as the diol molecular weight increased, while all polymers were of semi-crystalline nature and the melting temperature was varying from 49.1°C to 51.8°C and 65.9°C for poly(propylene adipate), poly(ethylene adipate), and poly(butylene adipate), respectively. The particle size of the RIS-loaded microspheres varied from 10 to 100 µm depending on the polyester type and the drug loading, while X-ray diffraction analysis revealed amorphous active pharmaceutical ingredient in the cases of high drug-loaded microspheres. In vitro drug release studies along with scanning electron microscopy images of microspheres after the completion of dissolution process showed that in all cases RIS release was controlled by the glass transition temperature of polyesters and physical state of active pharmaceutical ingredients via diffusion.

Ring-Opening Copolymerization of Maleic Anhydride with Functional Epoxides: Poly(propylene fumarate) Analogues Capable of Post-Polymerization Modification.

Three functional epoxides were copolymerized with maleic anhydride to yield degradable poly(propylene fumarate) analogues. The polymers were modified post-polymerization and post-printing with either click-type addition reactions or UV deprotection to either attach bioactive species or increase the hydrophilicity. Successful dye attachment, induced wettability, and improved cell spreading show the viability of these analogues in biomaterials applications.

Oriented Overgrowths of Poly(l-Lactide) on Oriented Isotactic Polypropylene: A Sequence of Soft and Hard Epitaxies.

The crystallization behavior of an amorphous poly(l-lactide) (PLLA) layer deposited on uniaxially oriented isotactic polypropylene (iPP) substrate is been studied by atomic force microscopy (AFM) and electron microscopy combined with electron diffraction. A patterned PLLA structure with two fixed lamella and chain orientations is observed. Electron diffraction demonstrates that the major lamellar set is oriented with molecular chains perpendicular to the chain direction of the iPP. The minor lamellar set is inclined at ≈64° to both the iPP chain axis direction and the lamellae of the major set as judged from both the bright field electron micrograph and the AFM image. The orientation of the main set is explained in terms of "soft" epitaxy or graphoepitaxy, in which PLLA chains oriented parallel to the ditches of the iPP substrate caused by alternatively arranged crystalline and amorphous regions. The minor set is due to a homoepitaxy of PLLA with parallelism of the helical paths. The orientation of this minor set of lamellae therefore depends on and can help determine the chirality-l or d-of the PLA investigated.

Three-dimensional porous poly(propylene fumarate)-co-poly(lactic-co-glycolic acid) scaffolds for tissue engineering.

Three-dimensional structural scaffolds have played an important role in tissue engineering, especially broad applications in areas such as regenerative medicine. We have developed novel biodegradable porous poly(propylene fumarate)-co-poly(lactic-co-glycolic acid) (PPF-co-PLGA) scaffolds using thermally induced phase separation, and determined the effects of critical parameters such as copolymer concentration (6, 8, and 10 wt %) and the binary solvent ratio of dioxane:water (78/22, 80/20, 82/18 wt/wt %) on the fabrication process. The cloud-point temperatures of PPF-co-PLGA changed in parallel with increasing copolymer concentration, but inversely with increasing dioxane content. The compressive moduli of the scaffolds increased with greater weight composition and dioxane:water ratio. Scaffolds formed using high copolymer concentrations and solvent ratios exhibited preferable biomineralization. All samples showed biodegradation capability in both accelerated solution and phosphate-buffered saline (PBS). Cell toxicity testing indicated that the scaffolds had good biocompatibility with bone and nerve cells, which adhered well to the scaffolds. Variations in the copolymer concentration and solvent ratio exercised a remarkable influence on morphology, mechanical properties, biomineralization, and biodegradation, but not on the cell viability and adhesion of the cross-linked scaffolds. An 8 to 10 wt % solute concentration and 80/20 to 82/18 wt/wt dioxane:water ratio were the optimum parameters for scaffold fabrication. PPF-co-PLGA scaffolds thus possess several promising prospects for tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A:2507-2517, 2018.

Phasor-Fluorescence Lifetime Imaging Microscopy Analysis to Monitor Intercellular Drug Release from a pH-Sensitive Polymeric Nanocarrier.

The design of highly efficient drug carriers, and the development of appropriate techniques to monitor their mechanism of action and therapeutic effect, are both critical for improving chemotherapy. Herein, a polymeric nanoparticle, PAH-Cit/DOX (poly(allylamine)-citraconic anhydride/doxorubicin), was synthesized and used as a nanodrug system for the efficient delivery and pH-responsive release of doxorubicin (DOX) into cancer cells. The PAH-Cit/DOX nanoparticles were stable at physiological pH but effectively released DOX under weakly acidic conditions. The release efficiency was 90.6% after 60 h of dialysis in phosphate-buffered saline at pH 5.5. Confocal images showed the rapid movement of the drug from the cytoplasm to the nucleus, indicating the effective drug release MCF-7 cells. Notably, the combination of fluorescence lifetime imaging microscopy (FLIM) and phasor analysis (phasor-FLIM) provides an approach to monitor the dynamic change of DOX fluorescence lifetime in intercellular environments. Phasor-differentiated lifetime pixel intensity in FLIM images was quantified and used to evaluate the DOX release from nanocarriers, making it possible to detect the dynamics of intracellular release and transport of DOX.

Quasi-Living Polymerization of Propene with an Isotactic-Specific Zirconocene Catalyst.

Propene polymerization with isotactic (iso)-specific C2-symmetric rac-Me2Si(2-Me-Benz(e)-Ind)2ZrCl2 (1) and rac-Me2Si(2-Me-4-Ph-1-Ind)2ZrCl2 (2) were conducted under various conditions for achieving iso-specific living polymerization of propene. When Complex 1 was activated with trialkylaluminum-free modified methylaluminoxane (dMMAO) at -40 °C, the number-average molecular weight (Mn) linearly increased against the polymerization time to reach Mn = 704,000 within 15 min of polymerization, although the molecular weight distributions was broad (Mw/Mn < 3). Thus, it was found that quasi-living polymerization of propene proceeded in the 1-dMMAO system. The living nature of iso-polypropene was confirmed by the block copolymerization, where the Mn value increased from 221,000 to 382,000 after the addition of 1-octene to yield the block copolymer with a melting point of 150 °C.