Narrow Dispersity Research Articles

Synthesis and Analysis of Well‐Defined Copolymers via by Combination ROP Technique

AbstractHerein, the poly(ɛ‐caprolactone)‐poly(ethylene glycol)‐poly(ɛ‐caprolactone) (PCL‐PEG‐PCL) macro xanthate reversible addition–fragmentation chain‐transfer agent is obtained on the polyethylene glycol (PEG) (600, 1000, and 1500 g mol−1) block, after the addition of ɛ‐caprolactone via ring‐opening polymerization. Then, poly (styrene‐b‐ɛ‐caprolactone‐b‐PEG‐b‐ɛ‐caprolactone‐b‐styrene) pentablock copolymer is synthesized reversible addition–fragmentation chain‐transfer (RAFT) solution polymerization technique via mediated PCL‐PEG‐PCL xanthate macro‐RAFT agents and 2,2′‐azobisisobutyronitrile as initiator. The products are demonstrated using Fourier transform infrared spectrophotometer (FT‐IR), proton nuclear magnetic resonance (1H‐NMR), carbon nuclear magnetic resonance (13C‐NMR), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC) analyses. First‐order linear kinetic graphs of the reaction mechanism are observed with an increase in molecular weights (MW) between 16 000 and 36 000 g mol−1. The narrow dispersity (Đ = 1.40–1.48) polymer formation of styrene (St) controlled by RAFT polymerization confirms the increase in molecular weight according to the polymerization time. The reaction kinetics are first order and the rate constants are found to be k1 = 6.16 × 10−4s−1, k2 = 6.91 × 10−4 s−1 and k3 = 7.33 × 10−4 s−1. Thermal and spectroscopic analyses prove that the reactions are carried out successfully.

Fabrication and characterisation of poly(sulfonated) and poly(sulfonic acid) dissolving microneedles for delivery of antibiotic and antifungal agents

Skin and soft tissue infections (SSTIs) arise from microbial ingress into the skin. In this study, poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (polyAMPS), which has been reported to exhibit antimicrobial properties was synthesised for the manufacture of microarray patches (MAPs). The free acid and sodium salt of polyAMPS with controlled molar masses and narrow dispersity were synthesised via reversible addition − fragmentation chain-transfer (RAFT) polymerisation reaction with a monomer conversion of over 99%, as determined by 1H NMR. The polymers were shown to be biocompatible when evaluated using a fibroblast dermal cell line while agar plating assay using cultures of C. albican demonstrated that the acid form of polyAMPS exhibited antimicrobial inhibition, which is potentiated in the presence of antimicrobial agents. The synthesised polymers were then used to fabricate dissolving MAPs, which were loaded with either ITRA or levofloxacin (LEV). The MAPs displayed acceptable mechanical resistance and punctured ex vivo skin to a depth of 600 µm. Skin deposition studies revealed that the MAPs were able to administer up to ∼ 1.9 mg of LEV (delivery efficiency: 94.7%) and ∼ 0.2 mg of ITRA (delivery efficiency: 45.9%), respectively. Collectively, the synthesis and development of this novel pharmaceutical system may offer a strategy to manage SSTIs.

Cytotoxic Screening and Enhanced Anticancer Activity of Lippia alba and Clinopodium nepeta Essential Oils-Loaded Biocompatible Lipid Nanoparticles against Lung and Colon Cancer Cells.

Plant and herbal essential oils (EOs) offer a wide range of pharmacological actions that include anticancer effects. Here, we evaluated the cytotoxic activity of EO from Lippia alba (chemotype linalool), L. alba (chemotype dihydrocarvone, LaDEO), Clinopodium nepeta (L.) Kuntze (CnEO), Eucalyptus globulus, Origanum × paniculatum, Mentha × piperita, Mentha arvensis L., and Rosmarinus officinalis L. against human lung (A549) and colon (HCT-116) cancer cells. The cells were treated with increasing EO concentrations (0-500 µL/L) for 24 h, and cytotoxic activity was assessed. LaDEO and CnEO were the most potent EOs evaluated (IC50 range, 145-275 µL/L). The gas chromatography-mass spectrometry method was used to determine their composition. Considering EO limitations as therapeutic agents (poor water solubility, volatilization, and oxidation), we evaluated whether LaDEO and CnEO encapsulation into solid lipid nanoparticles (SLN/EO) enhanced their anticancer activity. Highly stable spherical SLN/LaDEO and SLN/CnEO SLN/EO were obtained, with a mean diameter of 140-150 nm, narrow size dispersion, and Z potential around -5mV. EO encapsulation strongly increased their anticancer activity, particularly in A549 cells exposed to SLN/CnEO (IC50 = 66 µL/L CnEO). The physicochemical characterization, biosafety, and anticancer mechanisms of SLN/CnEO were also evaluated in A549 cells. SLN/CnEO containing 97 ± 1% CnEO was highly stable for up to 6 months. An increased in vitro CnEO release from SLN at an acidic pH (endolysosomal compartment) was observed. SLN/CnEO proved to be safe against blood components and non-toxic for normal WI-38 cells at therapeutic concentrations. SLN/CnEO substantially enhanced A549 cell death and cell migration inhibition compared with free CnEO.

Convenient and Controllable Synthesis of Poly(2-oxazoline)-Conjugated Doxorubicin for Regulating Anti-Tumor Selectivity.

Polyethylene glycol (PEG)-doxorubicin (DOX) conjugation is an important strategy to improve toxicity and enhance clinically therapeutic efficacy. However, with the frequent use of PEG-modified drugs, the accumulation of anti-PEG antibodies has become a tough issue, which limits the application of PEG-drug conjugation. As an alternative solution, poly(2-oxazoline) (POX)-DOX conjugation has shown great potential in the anti-tumor field, but the reported conjugation process of POX with DOX has drawbacks such as complex synthetic steps and purification. Herein, we propose a convenient and controllable strategy for the synthesis of POX-DOX conjugation with different chain lengths and narrow dispersity by N-boc-2-bromoacetohydrazide-initiated 2-ethyl-oxazoline polymerization and the subsequent deprotection of the N-Boc group and direct reaction with DOX. The DOX-PEtOx conjugates were firstly purified, and the successful conjugations were confirmed through various characterization methods. The synthetic DOX-PEtOxn conjugates reduce the toxicity of DOX and increase the selectivity to tumor cells, reflecting the promising application of this POX-DOX conjugation strategy in drug modification and development.

Genome-wide analysis reveals distinct global populations of pink bollworm (Pectinophora gossypiella)

The pink bollworm (Pectinophora gossypiella) is one of the world’s most destructive pests of cotton. This invasive lepidopteran occurs in nearly all cotton-growing countries. Its presence in the Ord Valley of North West Australia poses a potential threat to the expanding cotton industry there. To assess this threat and better understand population structure of pink bollworm, we analysed genomic data from individuals collected in the field from North West Australia, India, and Pakistan, as well as from four laboratory colonies that originated in the United States. We identified single nucleotide polymorphisms (SNPs) using a reduced-representation, genotyping-by-sequencing technique (DArTseq). The final filtered dataset included 6355 SNPs and 88 individual genomes that clustered into five groups: Australia, India-Pakistan, and three groups from the United States. We also analysed sequences from Genbank for mitochondrial DNA (mtDNA) locus cytochrome c oxidase I (COI) for pink bollworm from six countries. We found low genetic diversity within populations and high differentiation between populations from different continents. The high genetic differentiation between Australia and the other populations and colonies sampled in this study reduces concerns about gene flow to North West Australia, particularly from populations in India and Pakistan that have evolved resistance to transgenic insecticidal cotton. We attribute the observed population structure to pink bollworm’s narrow host plant range and limited dispersal between continents.

Natural extract-polymer monodisperse submicron particles from Plateau-Rayleigh microjets

Particles of interest in food, pharmaceutical, and nutraceutical sectors are often formulated with a polymer and one or more natural or synthetic active compound. The two components frequently have distinct hydrophilicity. Submicrometric particles with narrow size dispersion can be made by the droplet-to-particle route by electrospray. In the steady cone-jet mode a liquid Taylor cone (TC) continuously emits a Plateau-Rayleigh microjet which breaks up spontaneously and periodically into tiny droplets, which later dry up to form solid particles. To achieve a stable process of this kind, we argue that it is necessary to: (i) operate near the minimum solution flow rate compatible with TC stability, (ii) prevent the drying of the TC by surrounding it with a gentle gas stream saturated in solvent vapor, and (iii) monitor the electric current and image the TC. We demonstrate this process in the preparation of curcumin (CUR) loaded polyvinylpyrrolidone (PVP) submicrometric particles as a function of solution composition and ambient relative humidity. In the atomization step (jet and droplet formation), the initial droplet size and charge are determined by the liquid properties and flow rate. The particles’ shapes were spherical (with or without internal voids), corrugated due to shell buckling (with compact interiors), and filamented due to Coulombic instabilities, depending on the interplay of different factors at the droplet drying step. These included the droplet size and charge, solvent evaporation, solute diffusion, water uptake from the ambient, mechanical forces, and solution thermodynamics. The electric current and droplet size are suitably predicted by scaling laws developed for simple Newtonian fluids. Hence, our particle sizes lie always between the predicted droplet and compact-sphere sizes, at a distance which depends on the particle morphology. CUR-loaded PVP quasi-monodisperse submicron particles could be an interesting model for drug delivery and biomedical applications.

Phenanthroline Derivatives as Efficient Organic Photocatalysts for Visible‐Light‐Mediated PET‐RAFT Polymerization

Comprehensive SummaryPhenanthroline is an excellent and stable π‐electron acceptor with a large conjugated chromophore. Phenanthroline derivatives are widely used in adsorption, photodegradation, solar cells, biology, and so on. At present, there are still limited organic molecules utilized to efficiently photocatalyze reversible‐deactivation radical polymerization (RDRP). Therefore, the design of organic photocatalysts (OPCs) for RDRP remains a challenge. Herein, according to the strategy of combining the donor groups and weak acceptor groups, donor‐acceptor (D‐A) type OPCs based on phenanthroline were utilized for the first time in photoinduced electron transfer‐reversible addition‐fragmentation chain transfer (PET‐RAFT) polymerization. 1,10‐Phenanthroline‐5‐amine (Aphen) with a donor group‐amino was screened out for efficacious photo‐controlled radical polymerization under blue light for various monomers with conjugated and unconjugated structures with high monomer conversion and well‐defined narrow dispersity polymers (Đ < 1.20). Controllable homo‐polymers and block copolymers were successfully realized by chain extension reaction and block copolymerization of structurally diverse monomers.

Electron transport by intramolecular cascaded π-conjugation channels of D-A two-dimensional conjugated microporous polymer mediate photo-induced RCMP

The photo-induced reversible complexation-mediated radical polymerization (photo-induced RCMP) has the feature of energy-saving and environmentally friendly, which is compatible with the sustainable development advocated by the world. To promote the development of photo-induced RCMP, three two-dimensional conjugated microporous polymers (CMPs) based on different construction units were developed by aldehyde-ammonia condensation and used as catalysts, producing polymethacrylates with precise molecular weight and narrow molecular weight dispersion. Chain extension, monomer compatibility and spatiotemporal control experiments revealed the high chain end fidelity of obtain polymethacrylates and the universality of photo-RCMP process by using synthetic CMPs catalysts. The density functional theory (DFT) calculation reveals that all the highest unoccupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of three CMPs are in junction segment and connecting segment respectively, which exhibits strong electron distribution asymmetry. Moreover, the DFT and experimental results verified that the (donor-acceptor) D-A structure with push-pull electron ability and π-conjugated electron channel promote intermolecular charge transfer, which reduce the Gibbs free energy of photo-induced RCMP to increase the electron transport ability and the polymerization rate. This work indicates that by the construction of D-A structure and π-conjugated electron channel can effectively enhance the catalytic properties of CMPs-based photocatalysts, which provides a methodology to design heterogeneous photocatalysts for photo-induced RCMP.

Living Suzuki-Miyaura Catalyst-Transfer Polymerization for Precision Synthesis of Length-Controlled Armchair Graphene Nanoribbons and Their Block Copolymers.

The bottom-up synthesis of graphene nanoribbons (GNRs) offers a promising approach for designing atomically precise GNRs with tuneable photophysical properties, but controlling their length remains a challenge. Herein, we report an efficient synthetic protocol for producing length-controlled armchair GNRs (AGNRs) through living Suzuki-Miyaura catalyst-transfer polymerization (SCTP) using RuPhos-Pd catalyst and mild graphitization methods. Initially, SCTP of a dialkynylphenylene monomer was optimized by modifying boronates and halide moieties on the monomers, affording poly(2,5-dialkynyl-p-phenylene) (PDAPP) with controlled molecular weight (Mn up to 29.8k) and narrow dispersity (Đ = 1.14-1.39) in excellent yield (>85%). Subsequently, we successfully obtained N = 5 AGNRs by employing a mild alkyne benzannulation reaction on the PDAPP precursor and confirmed their length retention by size-exclusion chromatography. In addition, photophysical characterization revealed that a molar absorptivity was directly proportional to the length of the AGNR, while its highest occupied molecular orbital (HOMO) energy level remained constant within the given AGNR length. Furthermore, we prepared, for the very first time, N = 5 AGNR block copolymers with widely used donor or acceptor-conjugated polymers by taking advantage of the living SCTP. Finally, we achieved the lateral extension of AGNRs from N = 5 to 11 by oxidative cyclodehydrogenation in solution and confirmed their chemical structure and low band gap by various spectroscopic analyses.

Temperature-Responsive Lactic Acid-Based Nanoparticles by RAFT-Mediated Polymerization-Induced Self-Assembly in Water.

This work demonstrates for the first-time biobased, temperature-responsive diblock copolymer nanoparticles synthesized by reversible addition-fragmentation chain-transfer (RAFT) aqueous emulsion polymerization-induced self-assembly (PISA). Here, monomers derived from green solvents of the lactic acid portfolio, N,N-dimethyl lactamide acrylate (DMLA) and ethyl lactate acrylate (ELA), were used. First, DMLA was polymerized by RAFT aqueous solution polymerization to produce a hydrophilic PDMLA macromolecular chain transfer agent (macro-CTA), which was chain extended with ELA in water to form amphiphilic PDMLA-b-PELA diblock copolymer nanoparticles by RAFT aqueous emulsion polymerization. PDMLAx homopolymers were synthesized targeting degrees of polymerization, DPx from 25 to 400, with relatively narrow molecular weight dispersities (Đ < 1.30). The PDMLA64-b-PELAy diblock copolymers (DPy = 10-400) achieved dispersities, Đ, between 1.18 and 1.54 with two distinct glass transition temperatures (Tg) identified by differential scanning calorimetry (DSC). Tg(1) (7.4 to 15.7 °C) representative of PELA and Tg(2) (69.1 to 79.7 °C) of PDMLA. Dynamic light scattering (DLS) studies gave particle z-average diameters between 11 and 74 nm (PDI = 0.04 to 0.20). Atomic force microscopy (AFM) showed evidence of spherical particles when dispersions were dried at ∼5 °C and film formation when dried at room temperature. Many of these polymers exhibited a reversible lower critical solution temperature (LCST) in water with a concomitant increase in z-average diameter for the PDMLA-b-PELA diblock copolymer nanoparticles.

High-Glass-Transition Polyesters Produced with Phthalic Anhydride and Epoxides by Ring-Opening Copolymerization (ROCOP).

Polyesters with a high glass transition temperature above 130 °C were obtained from limonene oxide (LO) or vinylcyclohexene oxide (VCHO) and phthalic anhydride (PA) in the presence of commercial salen-type complexes with different metals-Cr, Al, and Mn-as catalysts in combination with 4-(dimethylamino) pyridine (DMAP), bis-(triphenylphosphorydine) ammonium chloride (PPNCl), and bis-(triphenylphosphoranylidene)ammonium azide (PPNN3) as cocatalysts via alternating ring-opening copolymerization (ROCOP). The effects of the time of precontact between the catalyst and cocatalyst and the polymerization time on the productivity, molar mass (Mw), and glass transition temperature (Tg) were evaluated. The polyesters were characterized by a molar mass (Mw) of up to 14.0 kg/mol, a narrow dispersity Tg of up to 136 °C, and low (<3 mol%) polyether units. For poly(LO-alt-PA) copolymers, biodegradation tests were performed according to ISO 14851 using the respirometric biochemical oxygen demand method. Moreover, the vinyl double bond present in the poly(LO-alt-PA) copolymer chain was functionalized using three different thiols, methyl-3-mercaptopropionate, isooctyl-3-mercaptopropionate, and butyl-3-mercaptopropionate, via a click chemistry reaction. The thermal properties of poly(LO-alt-PA), poly(VCHO-alt-PA) and thiol-modified poly(LO-alt-PA) copolymers were extensively studied by DSC and TGA. Some preliminary compression molding tests were also conducted.

N,N-Bis(2,4-Dibenzhydryl-6-cycloalkylphenyl)butane-2,3-diimine-Nickel Complexes as Tunable and Effective Catalysts for High-Molecular-Weight PE Elastomers.

Four examples of N,N-bis(aryl)butane-2,3-diimine-nickel(II) bromide complexes, [ArN=C(Me)-C(Me)=NAr]NiBr2 (where Ar = 2-(C5H9)-4,6-(CHPh2)2C6H2 (Ni1), Ar = 2-(C6H11)-4,6-(CHPh2)2C6H2 (Ni2), 2-(C8H15)-4,6-(CHPh2)2C6H2 (Ni3) and 2-(C12H23)-4,6-(CHPh2)2C6H2 (Ni4)), disparate in the ring size of the ortho-cycloalkyl substituents, were prepared using a straightforward one-pot synthetic method. The molecular structures of Ni2 and Ni4 highlight the variation in the steric hindrance of the ortho-cyclohexyl and -cyclododecyl rings exerted on the nickel center, respectively. By employing EtAlCl2, Et2AlCl or MAO as activators, Ni1-Ni4 displayed moderate to high activity as catalysts for ethylene polymerization, with levels falling in the order Ni2 (cyclohexyl) > Ni1 (cyclopentyl) > Ni4 (cyclododecyl) > Ni3 (cyclooctyl). Notably, cyclohexyl-containing Ni2/MAO reached a peak level of 13.2 × 106 g(PE) of (mol of Ni)-1 h-1 at 40 °C, yielding high-molecular-weight (ca. 1 million g mol-1) and highly branched polyethylene elastomers with generally narrow dispersity. The analysis of polyethylenes with 13C NMR spectroscopy revealed branching density between 73 and 104 per 1000 carbon atoms, with the run temperature and the nature of the aluminum activator being influential; selectivity for short-chain methyl branches (81.8% (EtAlCl2); 81.1% (Et2AlCl); 82.9% (MAO)) was a notable feature. The mechanical properties of these polyethylene samples measured at either 30 °C or 60 °C were also evaluated and confirmed that crystallinity (Xc) and molecular weight (Mw) were the main factors affecting tensile strength and strain at break (εb = 353-861%). In addition, the stress-strain recovery tests indicated that these polyethylenes possessed good elastic recovery (47.4-71.2%), properties that align with thermoplastic elastomers (TPEs).

Influence of air swirl orientation on the spray characteristics of a micro-channel-based rotary (MCR) atomizer

In this work, we investigate the atomization and spray characteristics of a novel rotary atomizer with micro-channel grooves, using optical diagnostics. Micro-jets emanate from the grooves provided in the rotating injector. The spiraling liquid jets interact with the surrounding high-speed swirling air flow, resulting in the creation of a well-dispersed fine spray. Attention is focused on the effects of air swirler orientation with respect to that of injector rotation. Accordingly, the co- and counter-swirl cases are investigated. The primary jet breakup process is visualized using back-lit illumination technique, which also provides the measurement of jet breakup length. The jet break-up modes are identified for different air swirl strength and orientation and injector rotational speed. The size, number density and velocity components of the spray droplets are measured using PDPA technique at different axial and radial locations. Air velocity is also measured (in the absence of liquid injection) using the LDV technique. In addition, Laser Sheet Imaging (LSI) is employed to investigate the overall spray structure. Results show that the droplet size significantly reduces when air swirl strength or injector rotational speed is increased. Though not much difference is observed in the characteristic droplet size between the co- and counter-swirl cases, the droplet size distribution is narrower and droplet dispersion is improved for the latter. The current findings demonstrate the potential of the rotary injector to dynamically control the spray characteristics as per requirement.

Synergistic photocatalytic performance of Fe@Fe2O3 core-shell nanostructures supported on g-C3N4 nanosheets for RhB and phenol decolorization: Fabrication, characterization, and mechanistic insights

In this study, Fe@Fe2O3 core-shell nanoparticles were synthesized and adsorbed onto g-C3N4 nanosheets through a chemical adsorption process. The resulting Fe@Fe2O3/g-C3N4 nanocomposites exhibited a unique morphology and were characterized by a narrow dispersion of Fe@Fe2O3 nanostructures uniformly distributed on the g-C3N4 nanosheets. The impact of varying reaction parameters, such as reaction time and reducing agent concentration, on the reactivity and properties of iron was investigated. The enhanced photoactivity of Fe@Fe2O3/g-C3N4 nanocomposites for RhB and phenol was explored, and it was found that the heterojunction formed between Fe2O3 and g-C3N4 facilitated efficient charge partition, thereby reducing electron-hole recombination, and promoting the separation of photogenerated charges. Mechanistic insights into the degradation process of the pollutant RhB were gained using Fe@Fe2O3/g-C3N4 nanocomposites, and it was found that the holes (h+) and superoxide radicals (O2−) were the main active species involved in the degradation of RhB. The study highlights the potential of Fe@Fe2O3/g-C3N4 nanocomposites to eliminate contaminants.

Atom Transfer Radical Polymerization of 2-Isopropenyl-2-Oxazoline in Solution and from the Surface of Carbonyl Iron Particles toward Fabrication of a Cytocompatible Magneto-Responsive Hybrid Filler

Atom transfer radical polymerization (ATRP) of 2-isopropenyl-2-oxazoline was optimized both in solution and initiated from carbonyl iron (CI) particle surface (SI-ATRP) in order to obtain polymers with well-defined molar mass and narrow dispersity. The polymerization procedure was thoroughly investigated by size exclusion chromatography and 1H NMR and optimized from the point of view type of initiator, ligand, copper catalyst, and solvent. Finally, the poly(2-isopropenyl-2-oxazoline) (PIPOx) with controlled molar masses up to 20,000 g/mol and dispersity in the range of 1.2–1.5 were successfully prepared, while high conversions could be reached. Polymerization conditions using halogen exchange leading to well-defined PIPOx were also developed and used for SI-ATRP. SI-ATRP was finally applied for synthesis of magnetic CI-PIPOx core–shell particles with two various molar masses of the grafted PIPOx. Finally, as a proof of applicability of such hybrid particles, the particles were dispersed in the phosphate buffer saline and glycerol to obtain the magnetorheological fluid with blood-like characteristics. Magnetorheological and cytotoxicity investigations proved that non-cytotoxic CI-PIPOx core–shell particles provided the system with sufficient yield stress values to act as an embolization agent.

Comparative Study of Polymer-Grafted BaTiO3 Nanoparticles Synthesized Using Normal ATRP as Well as ATRP and ARGET-ATRP with Sacrificial Initiator with a Focus on Controlling the Polymer Graft Density and Molecular Weight.

Structurally well-defined polymer-grafted nanoparticle hybrids are highly sought after for a variety of applications, such as antifouling, mechanical reinforcement, separations, and sensing. Herein, we report the synthesis of poly(methyl methacrylate) grafted- and poly(styrene) grafted-BaTiO3 nanoparticles using activator regeneration via electron transfer (ARGET ATRP) with a sacrificial initiator, atom transfer radical polymerization (normal ATRP), and ATRP with sacrificial initiator, to understand the role of the polymerization procedure in influencing the structure of nanoparticle hybrids. Irrespective of the polymerization procedure adopted for the synthesis of nanoparticle hybrids, we noticed PS grafted on the nanoparticles showed moderation in molecular weight and graft density (ranging from 30,400 to 83,900 g/mol and 0.122 to 0.067 chain/nm2) compared to PMMA-grafted nanoparticles (ranging from 44,620 to 230,000 g/mol and 0.071 to 0.015 chain/nm2). Reducing the polymerization time during ATRP has a significant impact on the molecular weight of polymer brushes grafted on the nanoparticles. PMMA-grafted nanoparticles synthesized using ATRP had lower graft density and considerably higher molecular weight compared to PS-grafted nanoparticles. However, the addition of a sacrificial initiator during ATRP resulted in moderation of the molecular weight and graft density of PMMA-grafted nanoparticles. The use of a sacrificial initiator along with ARGET offered the best control in achieving lower molecular weight and narrow dispersity for both PS (37,870 g/mol and PDI of 1.259) and PMMA (44,620 g/mol and PDI of 1.263) nanoparticle hybrid systems.

The synthesis of gmelinite microspheres and their post-synthetic modification for improved defluoridation

ABSTRACT A method for synthesizing microspheres of the zeolite gmelinite (GME) with mean diameter 8 µm, and narrow dispersion, has been developed and establishes the key role of aging the gel prior to heating to produce a narrow size distribution. Fluoride adsorption from acidic media has been evaluated for GME microspheres following post-synthetic modifications by calcium ion exchange, iron(III) surface modification, and dealumination. In each instance, the post-synthetic modification leads to appreciable equilibrium fluoride loadings, with the highest loadings observed for dealuminated GME microspheres, capable of 97.4% fluoride removal from acidified 22 ppm fluoride solutions at equilibrium. Accordingly, dealuminated GME microspheres show promise as a potential adsorbent for reducing the aqueous fluoride content in dangerously high natural sources (up to 30 ppm) to safe drinking levels (≤1.5 ppm) in one treatment.

Preparation and Self-Assembly of pH-Responsive Hyperbranched Polymer Peptide Hybrid Materials.

In recent years, the coupling of structurally and functionally controllable polymers with biologically active peptide materials to obtain polymer-peptide hybrids with excellent properties and biocompatibility has led to important research progress in the field of polymers. In this study, a pH-responsive hyperbranched polymer hPDPA was prepared by combining atom transfer radical polymerization (ATRP) with self-condensation vinyl polymerization (SCVP) using a three-component reaction of Passerini to obtain a monomeric initiator ABMA containing functional groups. The pH-responsive polymer peptide hybrids hPDPA/PArg/HA were obtained by using the molecular recognition of polyarginine (β-CD-PArg) peptide modified with β-cyclodextrin (β-CD) on the hyperbranched polymer, followed by the electrostatic adsorption of hyaluronic acid (HA). The two hybrid materials, h1PDPA/PArg12/HA and h2PDPA/PArg8/HA could self-assemble to form vesicles with narrow dispersion and nanoscale dimensions in phosphate-buffered (PB) at pH = 7.4. The assemblies exhibited low toxicity as drug carriers of β-lapachone (β-lapa), and the synergistic therapy based on ROS and NO generated by β-lapa had significant inhibitory effects on cancer cells.

Controlled Synthesis, Chiral Assembly, and Circularly Polarized Luminescence of Poly(Phenyl Isocyanide)-Block-Polyfluorene Copolymers.

In this work, π-conjugated block copolymers consisting of poly(phenyl isocyanide) (PPI) and polyfluorene (PF) segments are facilely prepared by one-pot sequential polymerization of phenyl isocyanide (monomer 1) and 7-bromo-9,9-dioctylfluorene-2-boronic acid pinacol ester (monomer 2). The Pd(II)-terminated PPI is first prepared via polymerizing monomer 1catalyzed with phenyl alkyne-Pd(II) complex and then utilized to initiate the controlled Suzuki cross-coupling polymerization of monomer 2, yielding various PPI-b-PF copolymers possessing controlled molar mass and narrow dispersity. Owing to the helical conformation of PPI segment and π-conjugated structure of PF segment, PPI-b-PF copolymers present distinctive optical property and fascinating chiral self-assembly behavior. During the self-assembly process, chirality transfer from helical PPI block to the supramolecular aggregates of helical nanofibers occurs to afford optically active helical nanofibers with high optical activity. Furthermore, the self-assembled helical nanofibers exhibit excellent circularly polarized luminescence performance.

Interrupting the blood-testis barrier with a flutamide-loaded nanostructured lipid carrier: A novel nonsurgical contraceptive approach for male animals

Flutamide is an antagonist of testosterone, an essential hormone in male reproduction. However, the use of flutamide as a contraceptive agent for nonsurgical castration in veterinary practice remains challenging due to its poor bioavailability. Here, the flutamide-loaded nanostructure lipid carrier (FLT-NLC) was synthesized, and its biological effects were demonstrated by an in vitro blood-testis barrier model. The flutamide was incorporated into the nanostructure lipid carrier by a homogenization method resulting in a high encapsulation efficiency (99.7 ± 0.04%). The FLT-NLC was negatively charged (−27.90 ± 0.10 mV), with a nano size (182.13 ± 0.47 nm) and narrow dispersity index (0.17 ± 0.01). An in vitro release study demonstrated a slower release profile of FLT-NLC when compared with flutamide solution (FLT). The FLT-NLC at doses up to 50 μM showed no significant cytotoxic effects against mouse Sertoli cells (TM4) or mouse fibroblast cells (NIH/3T3) (p > 0.05). An in vitro blood-testis barrier with FLT-NLC demonstrated remarkable lower transepithelial electrical resistance when compared with those lacking FLT-NLC (p < 0.01). Moreover, FLT-NLC significantly decreased the mRNA expression of blood-testis barrier proteins, CLDN11 and OCLN. In conclusion, we successfully synthesized FLT-NLC and confirmed its potential antifertility effects on in vitro blood-testis barrier, thus indicating its possible application as nonsurgical contraception for male animals.