Self-assembly Of Polymers Research Articles

Self-Assembled Chiral Polymers Exhibiting Amplified Circularly Polarized Electroluminescence.

Circularly polarized electroluminescence (CPEL) is highly promising in realm of 3D display and optical data storage. However, designing a groundbreaking chiral material with high comprehensive CPEL performance remains a formidable challenge. In this work, a pair of chiral polymers with self-assembled behavior is designed by integrating a chiral BN-moiety into polyfluorene backbone, named R-PBN and S-PBN, respectively. The chiral polymers show narrowband emission centered at 490 nm with full-width half maximum (FWHM) of 29 nm and high photoluminescence quantum yield (PLQY) of 79 %. After thermal annealing treatment, the chiral polymers undergo self-assembly, exhibiting amplified circularly polarized luminescence (CPL) with asymmetry factor (|glum|) of up to 0.11. Moreover, the solution-processed nondoped CP-OLEDs based on the chiral polymers as emitting layers exhibit maximum external quantum efficiency (EQEmax) of 9.8 %, intense CPEL activities with |gEL| of up to 0.07, and small FWHM of 36 nm, simultaneously. This represents the first case of self-assembled chiral polymers that combines high EQE, large gEL value and narrowband emission.

Synthesis and self-assembly of high grafting density core-shell bottlebrush polymer with amphiphilic side chain

Self-assembly of bottlebrush polymers are widely studied in photonic bandgap materials, biomedical materials and nanomaterial with different structures. In this work, high grafting density bottlebrush polymer with amphiphilic QPDMA[FeCl4]-b-PS side chains grafting on every carbon atom of the backbone are prepared via grafting from approach. The para-isocyanobenzoate monomer modified with chain transfer agent (CTA) is designed and synthesized to prepared polymer backbones with CTA grafting on each atoms. The core-shell bottlebrush block copolymer is prepared by sequential reversible addition-fragmentation chain transfer polymerization of dimethylaminoethyl methacrylate and styrene. The inner core follows quaternization and ion exchange to form water soluble QPDMA[FeCl4] magnetic block. The resulting core-shell bottlebrush magnetic polymer (PCN-g-[QPDMA[FeCl4]-b-PS]) self-assembles into nanowires with magnetic QPDMA[FeCl4] as core and PS as corona in the shell selected solvent dichloromethane, the length of nanowires increases with self-assembly time. While it self-assembles into nanoparticle clusters in core selected aqueous solution. And, the thermal and magnetic properties are affected by the self-assembly morphology. Especially, the as prepared PCN-g-[QPDMA[FeCl4]-b-PS] and the nanoparticles cluster self-assembly are paramagnetic, but the nanowire self-assembly is superparamagnetic.

Self-assembled network polymer electrolyte membranes for application in fuel cells at 250 °C

Self-assembled network polymer electrolyte membranes for application in fuel cells at 250 °C

Heat-activated growth of metastable and length-defined DNA fibers expands traditional polymer assembly

Biopolymers such as nucleic acids and proteins exhibit dynamic backbone folding, wherein site-specific intramolecular interactions determine overall structure. Proteins then hierarchically assemble into supramolecular polymers such as microtubules, that are robust yet dynamic, constantly growing or shortening to adjust to cellular needs. The combination of dynamic, energy-driven folding and growth with structural stiffness and length control is difficult to achieve in synthetic polymer self-assembly. Here we show that highly charged, monodisperse DNA-oligomers assemble via seeded growth into length-controlled supramolecular fibers during heating; when the temperature is lowered, these metastable fibers slowly disassemble. Furthermore, the specific molecular structures of oligomers that promote fiber formation contradict the typical theory of block copolymer self-assembly. Efficient curling and packing of the oligomers – or ‘curlamers’ – determine morphology, rather than hydrophobic to hydrophilic ratio. Addition of a small molecule stabilises the DNA fibers, enabling temporal control of polymer lifetime and underscoring their potential use in nucleic-acid delivery, stimuli-responsive biomaterials, and soft robotics.

Assembly Structure Formation in Bulk and Ultrathin Films of Poly(substituted methylene) Having an Azobenzene Side Chain.

The density of the side chain introduced to a polymer main chain greatly influences the properties and functions of the polymer. This work first reports on the packing structure and properties at an interface of a poly(substituted methylene) where an azobenzene side chain is introduced at every carbon atom in the main chain (C1PAz). The structure and properties are compared with those of a conventional vinyl polymer [poly(methacrylate)] possessing an identical side-chain structure (C2PAz). The packing structure in the bulk state analyzed by X-ray measurements revealed that C1PAz adopts a highly ordered rectangular unit cell structure, whereas C2PAz shows a less ordered lamellar one. Langmuir film balance experiments indicated that both polymers with the trans-azobenzene give essentially the identical 2D side-chain occupying area on water, which agrees well with the smectic B (hexatic packing) model based on the X-ray data. Upon transfer onto a solid substrate, only C1PAz shows a conformational transformation to a spread bilayer-type layer, most probably due to conformational frustration stemming from the crowding of the side chains. This study proposes new insights into the effects of side-chain density on the self-assembly and photoreaction of azobenzene-containing polymers, which are expected to expand the possibilities of polymer design for various applications.

Cell membrane-inspired regulation of reactant diffusion for active agent microencapsulation via interface engineering

Microencapsulation of hydrophilic amines in nonaqueous emulsions provides opportunities for a variety of applications, such as CO2 absorbents, and adhesives, but also presents challenges due to the intense reactant diffusion and disruptive interfacial reaction kinetics. Drawing inspiration from cellular systems, where cell membranes effectively regulate mass transfer for essential activities, we propose an interface engineering approach to manage interfacial reactant diffusion. This strategy obviates the modification of emulsion phases with additives in literature, which lowered effective core content. To achieve this, a solvent-induced polymer self-assembling method is adopted. The self-assembled polymer effectively formed a stabilizing viscoelastic film, which kinetically traps the microdroplets, serves as a viscous barrier lowering intense amine diffusion and interfacial polymerization kinetics, and provides protection for the microdroplets against the destructive forces from reaction turbulence and emulsion collision. This approach possesses high tolerance against microencapsulation conditions and is technically friendly, laying the groundwork for scalable microencapsulation of amines to meet industrial demands. We successfully synthesized Tetraethylenepentamine (TEPA)-loaded microcapsules with adjustable shell tightness, hierarchical shell structures, high shell strength and high core content. The method's versatility is further evidenced with different species containing reactive hydrogens. The demonstrated potential of TEPA-loaded microcapsules in effective CO2 capture and instant adhesives provides a fresh perspective on the microencapsulation of distinct polar payloads through interface engineering and its wide-ranging applications.

Reactive oxygen species-responsive supramolecular deucravacitinib self-assembly polymer micelles alleviate psoriatic skin inflammation by reducing mitochondrial oxidative stress.

The new topical formula is urgent needed to meet clinical needs for majority mild patients with psoriasis. Deucravacitinib exerts outstanding anti-psoriatic capacity as an oral TYK2 inhibitor; however, single therapy is insufficient to target the complicated psoriatic skin, including excessive reactive oxygen species (ROS) and persistent inflammation. To address this need, engineered smart nano-therapeutics hold potential for the topical delivery of deucravacitinib. hydrophobic Deucravacitinib was loaded into polyethylene glycol block-polypropylene sulphide (PEG-b-PPS) for transdermal delivery in the treatment of psoriasis. The oxidative stress model of HaCaT psoriasis was established by TNF-α and IL-17A in vitro. JC-1 assay, DCFH-DA staining and mtDNA copy number were utilized to assess mitochondrial function. 0.75% Carbopol®934 was incorporated into SPMs to produce hydrogels and Rhb was labeled to monitor penetration by Immunofluorescence. In vivo, we established IMQ-induced psoriatic model to evaluate therapeutic effect of Car@Deu@PEPS. Deu@PEPS exerted anti-psoriatic effects by restoring mitochondrial DNA copy number and mitochondrial membrane potential in HaCaT. In vivo, Car@Deu@PEPS supramolecular micelle hydrogels had longer retention time in the dermis in the IMQ-induced ROS microenvironment. Topical application of Car@Deu@PEPS significantly restored the normal epidermal architecture of psoriatic skin with abrogation of splenomegaly in the IMQ-induced psoriatic dermatitis model. Car@Deu@PEPS inhibited STAT3 signaling cascade with a corresponding decrease in the levels of the differentiation and proliferative markers Keratin 17 and Cyclin D1, respectively. Meanwhile, Car@Deu@PEPS alleviated IMQ-induced ROS generation and subsequent NLRP3 inflammasome-mediated pyroptosis. Deu@PEPS exerts prominent anti-inflammatory and anti-oxidative effects, which may offers a more patient-acceptable therapy with fewer adverse effects compared with oral deucravacitinib.

Asymmetric Aldol Reactions Catalyzed by Polymeric Self-Assembly with Side-Chain Dipeptide Pendants.

To explore the role of proline amide moieties in polymer-supported organocatalysts, side-chain l-proline-l-alanine (Pro-Ala) dipeptide-containing block copolymers were synthesized, and their catalytic potential for the aldol reaction was explored. The dipeptide monomer (Boc-Pro-Ala-HEMA) was polymerized to prepare block copolymers in the presence of hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) and hydrophobic poly(methyl methacrylate) (PMMA) macro-chain transfer agents. Boc group expulsion from the block copolymers produced double hydrophilic PPEGMA-b-P(Pro-Ala-HEMA) (1b) and amphiphilic PMMA-b-P(Pro-Ala-HEMA) (1c) polymers. The solution behaviors of the polymers were studied by various physical techniques, which showed the formation of self-assembled aggregates of 1c in water and N,N-dimethylformamide (DMF)/water solvent mixtures. These polymers are used as organocatalysts during the aldol reaction of cyclohexanone and 4-nitrobenzaldehyde in different solvent polarities, catalyst loadings, temperatures, and reaction times. This work emphasizes superior catalytic activity of 1c at lower catalyst loadings (5%) while maintaining high conversion (95%) and enantioselectivity (94%) across multiple recycling cycles in DMF/water at a 3:1 ratio (v/v).

Metabolic dysfunction-associated steatohepatitis treated by poly(ethylene glycol)-block-poly(cysteine) block copolymer-based self-assembling antioxidant nanoparticles

Non-alcoholic steatohepatitis (NASH), now known as metabolic dysfunction-associated steatohepatitis (MASH), involves oxidative stress caused by the overproduction of reactive oxygen species (ROS). Small-molecule antioxidants have not been approved for antioxidant chemotherapy because of severe adverse effects that collapse redox homeostasis, even in healthy tissues. To overcome these disadvantages, we have been developing poly(ethylene glycol)-block-poly(cysteine) (PEG-block-PCys)-based self-assembling polymer nanoparticles (NanoCyses), releasing Cys after in vivo degradation by endogenous enzymes, to obtain antioxidant effects without adverse effects. However, a comprehensive investigation of the effects of polymer design on therapeutic outcomes has not yet been conducted to develop our NanoCys system for antioxidant chemotherapy. In this study, we synthesized different poly(L-cysteine) (PCys) chains whose sulfanyl groups were protected by tert-butyl thiol (StBu) and butyryl (Bu) groups to change the reactivity of the side chains, affording NanoCys(SS) and NanoCys(Bu), respectively. To elucidate the importance of the polymer design, these NanoCyses were orally administered to MASH model mice as a model of oxidative stress-related diseases. Consequently, the acyl-protective NanoCys(Bu) significantly suppressed hepatic lipid accumulation and oxidative stress compared to NanoCys(SS). Furthermore, we substantiated that shorter PCys were much better than longer PCys for therapeutic outcomes and the effects related to the liberation properties of Cys from these nanoparticles. Owing to its antioxidant functions, NanoCyses also significantly attenuated hepatic inflammation and fibrosis in the MASH mouse model.

Polymer Conjugate as the New Promising Drug Delivery System for Combination Therapy against Cancer.

This review highlights the advantages of combination therapy using polymer conjugates as drug delivery systems for cancer treatment. In this review, the specific structures and materials of polymer conjugates, as well as the different types of combination chemotherapy strategies, are discussed. Specific targeting strategies, such as monoclonal antibody therapy and small molecule ligands, are also explored. Additionally, self-assembled polymer micelles and overcoming multidrug resistance are described as potential strategies for combination therapy. The assessment of combinational therapeutic efficacy and the challenges associated with polymer conjugates are also addressed. The future outlook aims to overcome these challenges and improve the effectiveness of drug delivery systems for combination therapy. The conclusion emphasizes the potential of polymer conjugates in combination therapy while acknowledging the need for further research and development in this field.

Design of Bio-Optical Transceiver for In Vivo Biomedical Sensor Applications.

This paper presents an enhanced version of our previously developed bio-optical transceiver, presenting a significant advancement in nanosensor technology. Using self-assembled polymers, this nanodevice is capable of electron detection while maintaining biocompatibility, an essential feature for in vivo medical biosensors. This enhancement finds significance in the field of infectious disease control, particularly in the early detection of respiratory viruses, including high-threat pathogens such as SARS-CoV-2. The proposed system harnesses bioluminescence by converting electric signaling to visible blue light, effectively opening the path of linking nano-sized mechanisms to larger-scale systems, thereby pushing the boundaries of in vivo biomedical sensing. The performance evaluation of our technology is analytical and is based on the use of Markov chains, through which we assess the bit error probability. The calculated improvements indicate that this technology qualifies as a forerunner in terms of supporting the communication needs of smaller, safer, and more efficient manufactured sensor technologies for in vivo medical applications.

Co-delivery of fucoxanthin and Twist siRNA using hydroxyethyl starch-cholesterol self-assembled polymer nanoparticles for triple-negative breast cancer synergistic therapy

IntroductionTriple-negative breast cancer (TNBC) represents the most aggressive subtype of breast cancer with an extremely dismal prognosis and few treatment options. As a desmoplastic tumor, TNBC tumor cells are girdled by stroma composed of cancer-associated fibroblasts (CAFs) and their secreted stromal components. The rapidly proliferating tumor cells, together with the tumor stroma, exert additional solid tissue pressure on tumor vasculature and surrounding tissues, severely obstructing therapeutic agent from deep intratumoral penetration, and resulting in tumor metastasis and treatment resistance. ObjectivesFucoxanthin (FX), a xanthophyll carotenoid abundant in marine algae, has attracted widespread attention as a promising alternative candidate for tumor prevention and treatment. Twist is a pivotal regulator of epithelial to mesenchymal transition, and its depletion has proven to sensitize antitumor drugs, inhibit metastasis, reduce CAFs activation and the following interstitial deposition, and increase tumor perfusion. The nanodrug delivery system co-encapsulating FX and nucleic acid drug Twist siRNA (siTwist) was expected to form a potent anti-TNBC therapeutic cyclical feedback loop. Methods and resultsHerein, our studies constituted a novel self-assembled polymer nanomedicine (siTwist/FX@HES-CH) based on the amino-modified hydroxyethyl starch (HES-NH2) grafted with hydrophobic segment cholesterol (CH). The MTT assay, flow cytometry apoptosis analysis, transwell assay, western blot, and 3D multicellular tumor spheroids growth inhibition assay all showed that siTwist/FX@HES-CH could kill tumor cells and inhibit their metastasis in a synergistic manner. The in vivo anti-TNBC efficacy was demonstrated that siTwist/FX@HES-CH remodeled tumor microenvironment, facilitated interstitial barrier crossing, killed tumor cells synergistically, drastically reduced TNBC orthotopic tumor burden and inhibited lung metastasis. ConclusionSystematic studies revealed that this dual-functional nanomedicine that targets both tumor cells and tumor microenvironment significantly alleviates TNBC orthotopic tumor burden and inhibits lung metastasis, establishing a new paradigm for TNBC therapy.

Redox-sensitive self-assembling polymer micelles based on oleanolic modified hydroxyethyl starch: Synthesis, characterisation, and oleanolic release

Our study aimed at developing polymer micelles that possess redox sensitivity and excellent controlled release properties. 3,3′-dithiodipropionic acid (DTDPA, Abbreviation in synthetic polymers: SS) was introduced as ROS (Reactive oxygen species)response bond and connecting arm to couple hydroxyethyl starch (HES) with oleanolic acid (OA), resulting in the synthesis of four distinct grafting ratios of HES-SS-OA. FTIR (Fourier Transform infrared spectroscopy) and 1H NMR (1H Nuclear magnetic resonance spectra) were used to verify the triumphant combination of HES-SS-OA. Polymer micelles were found to encapsulate OA in an amorphous form, as indicated by the results of XRD (X-ray diffraction) and DSC (Differential scanning calorimetry). When the OA grafting rate on HES increased from 7.72 % to 11.75 %, the particle size decreased from 297.79 nm to 201.39 nm as the polymer micelles became compact due to enhanced hydrophobicity. In addition, the zeta potential changed from −16.42 mv to −25.78 mv, the PDI (polydispersity index) decreased from 0.3649 to 0.2435, and the critical micelle concentration (CMC) decreased from 0.0955 mg/mL to 0.0123 mg/mL. Results of erythrocyte hemolysis, cytotoxicity and cellular uptake illustrated that HES-SS-OA had excellent biocompatibility and minimal cytotoxicity for AML-12 cells. Disulfide bond breakage of HES-SS-OA in the presence of H2O2 and GSH confirmed the redox sensitivity of the HES-SS-OA micelles and their excellent controlled release properties for OA. These findings suggest that HES-SS-OA can be potentially used in the future as a healthcare drug and medicine for the prevention or adjuvant treatment of inflammation.

Abstract 477: Tumor treating fields (TTFields) targeted self assembling nanoparticles for pancreatic cancer treatment: In vitro and in vivo assessment

Abstract Tumor Treating Fields (TTFields) is a novel, non-invasive and safe treatment modality, which is prescribed to be used in conjunction with classical anticancer chemotherapeutic drugs. TTFields when used alone are safe, but their use in combination with classical chemotherapy continues to offer drug related adverse reactions which ultimately impacts the patient compliance. To address this challenge, we earlier reported meticulously optimized self-assembling cationic-anionic polymer nanoparticles (S-CAP NPs) with average particle size of about 200 nM, encapsulation efficiency of 55-65 % and sustained drug release over 60 h. We also reported that, TTFields were capable of destabilizing the S-CAP NPs leading to targeted drug release. The results were also corroborated with in vitro cytotoxicity and colony formation studies in presence of TTFields using multiple pancreatic cancer cell lines. After establishing the proof-of-concept, the objective was to assess the in vitro cellular uptake of S-CAP NPs. For this, fluorescent dye loaded S-CAP NPs were developed and subjected to cellular uptake analysis. The in vitro cellular uptake studies confirmed the enhanced uptake of S-Cap NPs by passive diffusion in the pancreatic cancer cell lines compared to normal pancreatic epithelial cell line. The studies corroborated preferential cellular uptake of S-Cap NPs by the pancreatic tumor. Among all the formulations, the chitosan- bovine serum albumin S-CAP NPs was most optimum and was used for in vivo safety studies. For this, in vivo acute and repeated dose 28-day toxicity of the optimum placebo S-CAP NPs was conducted in Sprague Dawley rats (Western University of Health Sciences Protocol #R20IACUC031) and OECD guidelines. The in vivo studies showed a LD50 value above 2000 mg/kg and NOAEL value of 1000 mg/kg. These high doses safety of S-CAP NPs confirmed the potential of this approach for future preclinical efficacy studies followed by clinical translation. Lastly, the in vitro stability studies were conducted as per the ICH guidelines for a period of 36 months and the formulations were concluded to be stable. The tumor targeting potential, in vivo safety and stability of S-CAP NPs, establish their translational potential for TTFields triggered targeted drug release in cancer treatment. This approach will not only reduce the adverse effect associated with combination of TTFields and chemotherapy but can also be explored as a platform technology for management of other cancers. This study is supported by AACR-Novocure tumor treating fields research fellowship. Citation Format: Preshita Prafulla Desai, Sunil Prabhu. Tumor treating fields (TTFields) targeted self assembling nanoparticles for pancreatic cancer treatment: In vitro and in vivo assessment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 477.

Mitochondrial-Targeted Metal-Phenolic Nanoparticles to Attenuate Intervertebral Disc Degeneration: Alleviating Oxidative Stress and Mitochondrial Dysfunction.

As intervertebral disc degeneration (IVDD) proceeds, the dysfunctional mitochondria disrupt the viability of nucleus pulposus cells, initiating the degradation of the extracellular matrix. To date, there is a lack of effective therapies targeting the mitochondria of nucleus pulposus cells. Here, we synthesized polygallic acid-manganese (PGA-Mn) nanoparticles via self-assembly polymerization of gallic acid in an aqueous medium and introduced a mitochondrial targeting peptide (TP04) onto the nanoparticles using a Schiff base linkage, resulting in PGA-Mn-TP04 nanoparticles. With a size smaller than 50 nm, PGA-Mn-TP04 possesses pH-buffering capacity, avoiding lysosomal confinement and selectively accumulating within mitochondria through electrostatic interactions. The rapid electron exchange between manganese ions and gallic acid enhances the redox capability of PGA-Mn-TP04, effectively reducing mitochondrial damage caused by mitochondrial reactive oxygen species. Moreover, PGA-Mn-TP04 restores mitochondrial function by facilitating the fusion of mitochondria and minimizing their fission, thereby sustaining the vitality of nucleus pulposus cells. In the rat IVDD model, PGA-Mn-TP04 maintained intervertebral disc height and nucleus pulposus tissue hydration. It offers a nonoperative treatment approach for IVDD and other skeletal muscle diseases resulting from mitochondrial dysfunction, presenting an alternative to traditional surgical interventions.

Multifunctional polypeptide-based polymersome for chemophotothermal therapy of melanoma in vitro and in vivo

To date, combination therapy using chemo-photothermal therapy (Ch-PTT) has attracted tremendous interest due to its efficient ablation of cancerous cells. Furthermore, there are several advantages to using peptide-based nanocarriers for theranostic nanoplatforms, such as excellent biocompatibility and biodegradability, significant encapsulation efficacy for lipophilic drugs with negligible drug leakage, excellent stability, and excellent enzymatic degradation. In the current study, a multifunctional theranostic system based on polymersome (vesicular nanocarrier of self-assembled amphiphilic polymer) was developed for targeted Ch-PTT and x-ray CT imaging of melanoma cancer. For this purpose, using ring opening polymerization (ROP) of γ-benzyl l-glutamate-N-carboxyanhydride (LG-NCA) lipophilic polypeptide PLG (poly(γ-benzyl-l-glutamate) was synthesized and covalently linked to bifunctional COOH-PEG-NH2. Next, polypeptide-based polymersome nanocarier based on amphiphilc PEG-PLG was fabricated and co-encapsulated with hydrophilic gold nanorod (AuNR) and lipophilic curcumin (CUR) in aqueous core and lipophilic bilayer of polymersome (P-AuNR-CUR), respectively. Then, Sgc8-c aptamer were decorated on the polymersome surface (Apt-P-AuNR-CUR) for targeted delivery, and the size of P-AuNR-CUR and Apt-P-AuNR-CUR were determined using DLS device (174.3 ± 5.95 and 206 ± 52, respectively). NIR (near-infrared)-laser-triggered drug delivery release performance of multifunctional polymersome was demonstrated in both citrate and phosphate buffer saline. According to both in vitro and in vivo studies, NIR-responsive polymersomes possess remarkable therapeutic efficacy for Chemo-PTT in comparison to individual cancer therapy. Furthermore, the diagnostic capability of the designed nanoplatform was confirmed using in vivo CT scan imaging 6 h post-intravenous injection.

Access to Advanced Functional Materials through Postmodification of Biomimetic Assemblies via Click Chemistry.

The design, synthesis, and fabrication of functional nanomaterials with specific properties remain a long-standing goal for many scientific fields. The self-assembly of sequence-defined biomimetic synthetic polymers presents a fundamental strategy to explore the chemical space beyond biological systems to create advanced nanomaterials. Moreover, subsequent chemical modification of existing nanostructures is a unique approach for accessing increasingly complex nanostructures and introducing functionalities. Of these modifications, covalent conjugation chemistries, such as the click reactions, have been the cornerstone for chemists and materials scientists. Herein, we highlight some recent advances that have successfully employed click chemistries for the postmodification of assembled one-dimensional (1D) and two-dimensional (2D) nanostructures to achieve applications in molecular recognition, mineralization, and optoelectronics. Specifically, biomimetic nanomaterials assembled from sequence-defined macromolecules such as peptides and peptoids are described.

Cylinders-in-Undulating-Lamellae Morphology from ABC Bottlebrush Block Terpolymers.

Block polymer self-assembly affords a versatile bottom-up strategy to develop materials with the desired properties dictated by specific symmetries and dimensions. Owing to distinct properties compared with linear counterparts, bottlebrush block polymers with side chains densely grafted on a backbone have attracted extensive attention. However, the morphologies found in bottlebrush block polymers so far are limited, and only lamellar and cylindrical ordered phases have been reported in diblock bottlebrushes. The absence of complex morphologies, such as networks, might originate from the intrinsically stiff backbone architecture. We experimentally investigated the morphologies of nonfrustrated ABC bottlebrush block terpolymers, based on two chemistries, poly(ethylene-alt-propylene)-b-polystyrene-b-poly(dl-lactic acid) (PEP-PS-PLA) and PEP-b-PS-b-poly(ethylene oxide) (PEP-PS-PEO), synthesized by ring-opening metathesis polymerization of norbornene-terminated macromonomers. Structural characterization based on small-angle X-ray scattering and transmission electron microscopy measurements revealed an unprecedented cylinders-in-undulating-lamellae (CUL) morphology with p2 symmetry for both systems. Additionally, automated liquid chromatography was employed to fractionate the PEP-PS-PLA bottlebrush polymer, leading to fractions with a spectrum of morphologies, including the CUL. These findings underscore the significance of macromolecular dispersity in nominally narrow dispersity bottlebrush polymers while demonstrating the power of this fractionation technique.

Ni3+-Rich Ni/NiOx@C Nanocapsules Below 4nm Constructed by Low-Temperature Graphitization of Self-Assembled Few-Layer Coordination Polymers toward Efficient Alkaline Hydrogen Evolution Electrocatalysis.

Low-cost and eco-friendly Ni/NiO heterojunctions have been theoretically proven to be the ideal candidate for stepwise electrocatalysis of alkaline hydrogen evolution reaction, attributed to the preferred OHad adsorption by incompletely filled d orbitals of NiO phase and favorable Had adsorption energy of Ni phase. Nevertheless, most Ni/NiO compounds reported so far fail to exhibit excellent catalytic activity, possibly due to the lack of efficient electron transport, limited interfacial active sites, and unregulated Nin+ ratios. To address the above bottlenecks, herein, the ultrasmall Ni/NiOx@C nanocapsules (<5nm) are directly constructed by graphitization of four-layer Ni-based coordination polymers at record low temperatures of 400 °C. Ascribed to the accelerated electron and mass transfer by the carbon nano-onions coated around Ni/NiOx heterojunctions, the extreme rise in interfaces and Ni3+ defects with t6 2ge1 g electronic configuration owed to the ultrasmall size, the Ni/NiOx@C nanocapsules exhibit the highest catalytic activity and the lowest overpotential of η10 = 80mV among various Ni/NiO materials (measured on the glassy carbon electrode). This work not only constructs an industrialized high-efficiency electrocatalyst toward alkaline HER, but also provides a novel strategy for the constant-scale preparation of multicomponent transition metals-based nanocrystals below 4nm.

Mechanism of Action and Design of Potent Antibacterial Block Copolymer Nanoparticles.

Self-assembled polymer nanoparticles are promising antibacterials, with nonspherical morphologies of particular interest as recent work has demonstrated enhanced antibacterial activity relative to their spherical counterparts. However, the reasons for this enhancement are currently unclear. We have performed a multifaceted analysis of the antibacterial mechanism of action of 1D nanofibers relative to nanospheres by the use of flow cytometry, high-resolution microscopy, and evaluations of the antibacterial activity of pristine and tetracycline-loaded nanoparticles. Low-length dispersity, fluorescent diblock copolymer nanofibers with a crystalline poly(fluorenetrimethylenecarbonate) (PFTMC) core (length = 104 and 472 nm, height = 7 nm, width = 10-13 nm) and a partially protonated poly(dimethylaminoethyl methacrylate) (PDMAEMA) corona (length = 12 nm) were prepared via seeded growth living crystallization-driven self-assembly. Their behavior was compared to that of analogous nanospheres containing an amorphous PFTMC core (diameter of 12 nm). While all nanoparticles were uptaken into Escherichia coli W3110, crystalline-core nanofibers were observed to cause significant bacterial damage. Drug loading studies indicated that while all nanoparticle antibacterial activity was enhanced in combination with tetracycline, the enhancement was especially prominent when small nanoparticles (ca. 15-25 nm) were employed. Therefore, the identified differences in the mechanism of action and the demonstrated consequences for nanoparticle size and morphology control may be exploited for the future design of potent antibacterial agents for overcoming antibacterial resistance. This study also reinforces the requirement of morphological control over polymer nanoparticles for biomedical applications, as differences in activity are observed depending on their size, shape, and core-crystallinity.