Amyloid ß-Peptide Segment Conjugated Side-Chain Proline-Based Polymers as Potent Inhibitors in Lysozyme Amyloidosis.

Developing effective amyloidosis inhibitors poses a significant challenge due to the dynamic nature of the protein structures, the complex interplay of interfaces in protein-protein interactions, and the irreversible nature of amyloid assembly. The interactions of amyloidogenic polypeptides with other peptides play a pivotal role in modulating amyloidosis and fibril formation. This study presents a novel approach for designing and synthesizing amyloid interaction surfaces using segments derived from the amyloid-promoting sequence of amyloid ß-peptide [VF(Aß(18-19)/FF(Aß(19-20)/LVF(Aß(17-19)/LVFF(Aß(17-20)], where VF, FF, LVF and LVFF stands for valine phenylalanine dipeptide, phenylalanine phenylalanine dipeptide, leucine valine phenylalanine tripeptide and leucine valine phenylalanine phenylalanine tetrapeptide, respectively. These segments are conjugated with side-chain proline-based methacrylate polymers serving as potent lysozyme amyloidosis inhibitors and demonstrating reduced cytotoxicity of amyloid aggregations. Di-, tri-, and tetra-peptide conjugated chain transfer agents (CTAs) were synthesized and used for the reversible addition-fragmentation chain transfer polymerization of tert-butoxycarbonyl (Boc)-proline methacryloyloxyethyl ester (Boc-Pro-HEMA). Deprotection of Boc-groups from the side-chain proline pendants resulted in water-soluble polymers with defined peptide chain ends as peptide-polymer bioconjugates. Among them, the LVFF-conjugated polymer acted as a potent inhibitor with significantly suppressed lysozyme amyloidosis, a finding supported by comprehensive spectroscopic, microscopic, and computational analyses. These results unveil the synergistic effect between the segment-derived amyloid ß-peptide and side-chain proline-based polymers, offering new prospects for targeting lysozyme amyloidosis.

Inverse Vulcanization of Activated Norbornenyl Esters - A Versatile Platform for Functional Sulfur Polymers.

Elemental sulfur has shown to be a promising alternative feedstock for development of novel polymeric materials with high sulfur content. However, the utilization of inverse vulcanized polymers is restricted by the limitation of functional comonomers suitable for an inverse vulcanization. Control over properties and structure of inverse vulcanized polymers still poses a challenge to current research due to the dynamic nature of sulfur-sulfur bonds and high temperature of inverse vulcanization reactions. In here, we report for the first time the inverse vulcanization of norbornenyl pentafluorophenyl ester (NB-PFPE), allowing for post-modification of inverse vulcanized polymers via amidation of reactive PFP esters to yield high sulfur content polymers under mild conditions. Amidation of the precursor material with three functional primary amines (α-amino-ω-methoxy polyethylene glycol, aminopropyl trimethoxy silane, allylamine) was investigated. The resulting materials were applicable as sulfur containing poly(ethylene glycol) nanoparticles in aqueous environment. Cross-linked mercury adsorbents, sulfur surface coatings, and high-sulfur content networks with predictable thermal properties were achievable using aminopropyl trimethoxy silane and allylamine for post-polymerization modification, respectively. With the broad range of different amines available and applicable for post-polymerization modification, the versatility of poly(sulfur-random-NB-PFPE) as a platform precursor polymer for novel specialized sulfur containing materials was showcased.

From Squaric Acid Amides (SQAs) to Quinoxaline-Based SQAs─Evolution of a Redox-Active Cathode Material for Organic Polymer Batteries.

The search for new redox-active organic materials (ROMs) is essential for the development of sustainable energy-storage solutions. In this study, we present a new class of cyclobuta[b]quinoxaline-1,2-diones or squaric acid quinoxalines (SQXs) as highly promising candidates for ROMs featuring exceptional stability and high redox potentials. While simple 1,2- and 1,3-squaric acid amides (SQAs), initially reported by Hünig and coworkers decades ago, turned out to exhibit low stability in their radical cation oxidation states, we demonstrate that embedding the nitrogen atoms into a quinoxaline heterocycle leads to robust two-electron SQX redox systems. A series of SQX compounds, as well as their corresponding radical cations, were prepared and fully characterized, including EPR spectroscopy, UV-vis spectroscopy, and X-ray diffraction. Based on the promising electrochemical properties and high stability of the new ROM, we developed SQX-functionalized polymers and investigated their physical and electrochemical properties for energy-storage applications. These polymers showed remarkable thermal stability well above 200 °C with reversible redox properties and potentials of about 3.6 V vs Li+/Li. By testing the galvanostatic cycling performance in half-cells with lithium-metal counter electrodes, a styrene-based polymer with SQX redox side groups showed stable cycling for single-electron oxidation for more than 100 cycles. These findings render this new class of redox-active polymers as highly promising materials for future energy-storage applications.

Aggregation Behavior of Cyclodextrin-Based [3]Rotaxanes.

The aggregation of a cyclodextrin (CD)-based [3]rotaxane has been observed and analyzed in detail for the first time in this work. Although the hexagonal packing aggregation of CD-based polyrotaxane is a well known phenomenon, corresponding studies in terms of rotaxanes without any polymer structure have not been conducted so far, probably owing to the difficulty of the molecular design. We synthesized a series of [3]rotaxane species by using a urea-end-capping method and evaluated their aggregation behavior by XRD and SEM measurements. [3]Rotaxane species containing native CD rings showed clear signals assigned to the hexagonal packing by XRD measurement as did polyrotaxane; this proved their aggregation capability. Because the corresponding per-acetylated derivatives did not show this aggregation behavior, the driving force of this aggregation was suggested to be hydrogen bond formation among CD units. The effect of axle end structures and partial acetylation of CDs were also studied.

Polymeric Janus nanorods via anodic aluminum oxide templating.

We report a novel method for the fabrication of polymeric Janus nanorods via sequential polymerization from anodic aluminum oxide (AAO) templates. Dual compositions can be incorporated into individual nanorods and endow versatile potential applications. This fabrication strategy paves the way for constructing multifunctional nanostructures and brings together different materials in a single entity.

Photoresponsive Spiropyran and DEGMA-Based Copolymers with Photo-Switchable Glass Transition Temperatures.

Herein, novel photoresponsive spiropyran (SP)-based P(DEGMA-co-SpMA) copolymers with variable percentages of SP fractions are synthesized. The SP group present in these polymers exhibited the abilities of reversible photoisomerism. Their photoresponsive, structural, and thermal properties have been investigated and compared using various characterization techniques. These light-responsive copolymers are found to exhibit photoswitchable glass transition temperature (Tg ), high thermal stability (Td > 250°C), instant photochromism as well as fluorescence upon exposure to UV light. It is demonstrated that the Tg of these synthesized polymers increased when irradiated with UV light (λ = 365 nm), as a consequence of the photoisomerization of incorporated SP groups into their merocyanine form. This increase in Tg is attributed to an increase in polarity and a decrease in the overall entropy of the polymeric system when it switches from the ring-closed SP form (less-ordered state) to the ring-opened merocyanine form (more-ordered state). Therefore, such polymers with a unique feature of phototunable glass transition temperatures provide the possibility to be integrated into functional materials for various photoresponsive applications.

Decarboxylation of Poly[N-(acryloyloxy)phthalimide] as a Versatile Tool for Postpolymerization Modification.

Herein the decarboxylation of poly[N-(acryloyloxy)phthalimide] (PAP) for the synthesis of functionalized polymers is reported. PAP homopolymer and block copolymers are used as precursor polymers for the straightforward functionalization via decarboxylation and subsequent Michael-type addition or nitroxide radical coupling (NRC).

Cage-Shaped Polymers Synthesis: A Comprehensive State-of-the-Art.

Researchers have dedicated their efforts for the creation of a wide choice of complex and precise macromolecular architectures over the past 100 years. Among them, cyclic polymers benefit from their absence of terminal chains and from their singular topology to minimize their hydrodynamic volume in solution, increase their chemical stability, limit their number of possible conformations as well as a reduce their propensity to crystallize or to form entanglements in comparison to their acyclic counterparts. While monocyclic structures have already been widely investigated and reviewed, reports on more complex polycyclic structures are rare. In this regard, cage-shaped polymers-consisting of at least three polymer chains covalently interconnected through strictly two junction points-have received little attention over the past two decades. Although their synthesis is a worthy challenge, only a few synthetic methodologies of polymer cages were successfully developed so far. Thus, this review intends to highlight the key concepts of the conception of cage-shaped polymers in addition to propose an actual and exhaustive state-of-art concept of their synthesis to rationally promote the next-generation synthesis strategies.

Inverse Vulcanization of Norbornenylsilanes: Soluble Polymers with Controllable Molecular Properties via Siloxane Bonds.

The inverse vulcanization produces high sulfur content polymers from alkenes and elemental sulfur. Control over properties such as the molar mass or the solubility of polymers is not well established, and existing strategies lack predictability or require large variations of the composition. Systematic design principles are sought to allow for a targeted design of materials. Herein, we report on the inverse vulcanization of norbornenylsilanes (NBS), with a different number of hydrolysable groups at the silicon atom. Inverse vulcanization of mixtures of NBS followed by polycondensation yielded soluble high sulfur content copolymers (50 wt % S) with controllable weight average molar mass (MW ), polydispersity (D), glass transition temperature (TG ), or zero-shear viscosity (η0 ). Polycondensation was conducted in the melt with HCl as a catalyst, abolishing the need for a solvent. Purification by precipitation afforded polymers with a greatly reduced amount of low molar mass species.

Synthesis and Post-Polymerization Modification of Poly(N-(4-Vinylphenyl)Sulfonamide)s.

Herein, a straightforward synthesis of a novel class of polymers, that is, poly(N-(4-vinylphenyl)sulfonamide)s, and their monomers is reported. A set of monomers with varying electron densities, fine-tuned by different substituents on the aromatic sulfonamide moiety, is polymerized by free radical polymerization featuring low molar masses (2300  ≤ Mn  ≤ 3200 g mol-1 ) and low dispersities (1.15 ≤ D ≤ 1.47). Further, the post-polymerization modification of the obtained polymers via aza-Michael addition with electron-deficient alkenes is demonstrated using organic superbases as catalysts, paving the way toward the facile synthesis of novel polymeric protected ß-amino acid derivatives.

Acyclic Diene Metathesis (ADMET) Polymerization of 2,2,6,6-Tetramethylpiperidine-1-sulfanyl (TEMPS) Dimers.

The preparation of polymers containing sulfur-nitrogen bond derivatives, particularly 2,2,6,6-tetramethylpiperidine-1-sulfanyl (TEMPS) dimers (i.e., BiTEMPS), has been limited to free-radical or conventional step-growth polymerization as result of the inherent thermal lability of the BiTEMPS unit. Accordingly, a novel poly(diaminodisulfide) possessing the BiTEMPS functional group is synthesized via acyclic diene metathesis (ADMET) polymerization at 65-75 °C within 3 h with precise control over the primary polymer structure. Polymer is isolated with an Mn of 20 400 g mol-1 and Ð of 1.9. Importantly, detailed nuclear magnetic resonance (NMR), size exclusion chromatography, attenuated total reflectance Fourier transform infrared (ATR-IR) in addition to elemental analysis studies of the BiTEMPS polymer confirm the successful polymerization, and show that the BiTEMPS unit remains intact during the polymerization process. Furthermore, the previously unexplored UV-responsiveness of the BiTEMPS decorated polymer backbone is investigated for the very first time.

Elemental Sulfur Mediated Novel Multicomponent Redox Polycondensation for the Synthesis of Alternating Copolymers Based on 2,4-Thiophene/Arene Repeating Units.

A sulfur-based self-condensation method is investigated as an efficient tool for the synthesis of polythiophene derivatives. The reaction proceeds through multicomponent redox polycondensation between readily available diketone compounds and elemental sulfur in the presence of a Brønsted acid/base pair. Six different diketone derivatives have been screened and the polymerization is generalized by the synthesis of so-far-unprecedented alternating copolymers based on 2,4-thiophene/arene repeating units. By exploiting microwave heating the synthetic procedure is optimized, particularly for alternating copolymers containing aryl and thiophene units, such that a copolymer can be synthesized in only 24 h compared to the conventional process taking 6 d, yielding polymers within the same apparent weight average molar mass (Mw ). All obtained copolymers are analyzed in detail using size exclusion chromatography (SEC), nuclear magnetic resonance (NMR), attenuated total reflectance infrared spectroscopy (ATR-IR), thermal gravimetric analysis and differential scanning calorimetry (DSC).

Synthesis and Post-Polymerization Modification of Defined Functional Poly(vinyl ether)s.

Living cationic polymerization is known for a good control over chain growth yielding polymers with well-defined molar mass distributions and low dispersities. However, the practical challenges involved in the synthesis of poly(vinyl ether)s limited suitable post-polymerization modifications (PPM) via chemoselective click reactions. Herein the successful controlled cationic polymerization of vinyl ethers bearing pendant CC double and C≡C triple bonds using a single-component initiation under ambient conditions is reported. Furthermore, the PPM via thiol-ene/-yne and copper(I)-catalyzed alkyne-azide cycloaddition reaction of the obtained polymers is successfully realized laying the foundation for the synthesis of unprecedented functional poly(vinyl ether)s.

Aggregation-Induced Emissive Carbon Dots Gels for Octopus-Inspired Shape/Color Synergistically Adjustable Actuators.

Some living organisms such as the octopus have fantastic abilities to simultaneously swim away and alter body color/morphology for disguise and self-protection, especially when there is a threat perception. However, it is still quite challenging to construct artificial soft actuators with octopus-like synergistic shape/color change and directional locomotion behaviors, but such systems could enhance the functions of soft robotics dramatically. Herein, we proposed to utilize unique hydrophobic carbon dots (CDs) with rotatable surficial groups to construct the aggregation-induced emission (AIE) active glycol CDs polymer gel, which could be further employed to be interfacially bonded to an elastomer to produce anisotropic bilayer soft actuator. When putting the actuator on a water surface, glycol spontaneously diffused out from the gel layer to allow water intake, resulting in a color change from a blue dispersion fluorescence to red AIE and a shape deformation, as well as a large surface tension gradient that can promote its autonomous locomotion. Based on these findings, artificial soft swimming robots with octopus-like synergistic shape/color change and directional swimming motion were demonstrated. This study provides an elegant strategy to develop advanced multi-functional bio-inspired intelligent soft robotics.

Conductive hydrogel composites with autonomous self-healing properties.

Conventional conductive hydrogels usually lack self-healing properties, but might be favorable for smart electronic applications. Therefore, we present the fabrication of conductive self-healing hydrogels that merge the merits of electrical conductivity and self-healing properties. The conductive self-healing hydrogel composite was prepared by using single-walled carbon nanotubes (SWCNTs), poly(vinyl alcohol) (PVA), and a poly(N,N-dimethyl acrylamide) copolymer derivative modified with pyrene and borate functional moieties. While the tethered pyrene groups of the copolymer facilitated an even dispersion of the conductive components, i.e., SWCNTs, in aqueous solution viaπ-π stacking, the hydrogel system was formed via covalent dynamic cross-linking through tetrahedral borate ion interaction with the -OH group of PVA. The hydrogel composites exhibited bulk conductivity (1.27 S m-1 with 8 mg mL-1 SWCNTs) with a fast and autonomous self-healing ability that restored 95% of the original conductivity within 10 s under ambient conditions. Accordingly, due to their outstanding properties, we postulate that these composites may have potential in biomedical applications, such as tissue engineering, wound healing or electronic skins.

Making the Best of Polymers with Sulfur-Nitrogen Bonds: From Sources to Innovative Materials.

Polymers with sulfur-nitrogen bonds have been underestimated for a long time, although the intrinsic characteristics of these polymers offer a myriad of superior properties (e.g., degradation, flame retardancy, film-forming ability, good solubility in polar solvents, and high refractivity with small chromatic dispersions, among other things) compared to their carbon analogues. The remarkable characteristics of these polymers result from the unique chemical properties of the sulfur-nitrogen bond (e.g., its polar character and the multiple valence states of sulfur), and thus open excellent perspectives for the development of innovative (bio)materials. Accordingly, this review describes the most common chemical approaches toward the efficient synthesis of these ubiquitous polymers possessing diverse sulfur-nitrogen bonds, and furthermore highlights their applications in multiple fields, ranging from biomedicine to energy storage, with the aim of providing an informative perspective on challenges facing the synthesis of sulfur-nitrogen polymers with desirable properties.

Inverse Vulcanization of Styrylethyltrimethoxysilane-Coated Surfaces, Particles, and Crosslinked Materials.

Sulfur as a side product of natural gas and oil refining is an underused resource. Converting landfilled sulfur waste into materials merges the ecological imperative of resource efficiency with economic considerations. A strategy to convert sulfur into polymeric materials is the inverse vulcanization reaction of sulfur with alkenes. However, the materials formed are of limited applicability, because they need to be cured at high temperatures (>130 °C) for many hours. Herein, we report the reaction of elemental sulfur with styrylethyltrimethoxysilane. Marrying the inverse vulcanization and silane chemistry yielded high sulfur content polysilanes, which could be cured via room temperature polycondensation to obtain coated surfaces, particles, and crosslinked materials. The polycondensation was triggered by hydrolysis of poly(sulfur-r-styrylethyltrimethoxysilane) (poly(Sn -r-StyTMS) under mild conditions (HCl, pH 4). For the first time, an inverse vulcanization polymer could be conveniently coated and mildly cured via post-polycondensation. Silica microparticles coated with the high sulfur content polymer could improve their Hg2+ ion remediation capability.

Glucose-Responsive Polymeric Micelles via Boronic Acid-Diol Complexation for Insulin Delivery at Neutral pH.

In the present study, glucose-responsive polymeric complex micelles based on the complexation of phenylboronic-acid-based (PBA-based) block copolymer and diol-functionalized polymers are reported. The phenylboronic-acid- and diol-based block copolymers were successfully synthesized in only two reaction steps using reversible addition-fragmentation chain-transfer (RAFT) polymerization and postpolymerization modification of the obtained poly[( N-acryloylmorpholine- block-( N-acryloylmorpholine- co-pentafluorophenyl acrylate)], poly[(AMP- b-(AMP- co-PFPA)], reactive block copolymer. The self-assembly of the complex micelles was investigated under neutral conditions using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The interaction of the PBA block copolymer and diol-containing polymer via boronate ester bond was investigated by 1H NMR and UV-vis spectroscopy. The complex micelles enhanced the glucose responsiveness under physiological conditions compared to simple PBA micelles. Furthermore, the successful glucose-triggered release of FITC-insulin from the polymeric micelles was investigated.

Sulfur Chemistry in Polymer and Materials Science.

Sulfur and its functional groups are major players in an area of exciting research taking place in modern polymer and materials science, both in academia and industry. In fact, manifold sulfur-based reactions that are both exceptionally versatile as well as tremendously useful have been implemented, and further utilized for the design and preparation of polymeric materials that lead to a plethora of applications ranging from medicine to optics and nanotechnology to separation science. Hence, within this review, an overview of strategies and developments used over the last 5 years to reinforce the importance of the sulfur functional group in modern polymer and materials science is presented. In particular, many important references in the primary literature of sulfur chemistry are referred to, including thiol-ene, thiol-yne, thiol-Michael addition, disulfide cross-linking, and thiol-disulfide exchange, among others, by explaining and illustrating the important principles. Last but not least, the grand aim to underpin the importance of sulfur in modern polymer and materials science is achieved by presenting selected examples in diverse fields and postulating the respective potential for real-world applications.

pH and Thermo Dual-Responsive Fluorescent Hydrogel Actuator.

As one of the most important smart materials, fluorescent hydrogel actuators can produce both color and shape changes under external stimuli. In the present work, an effective approach to develop a novel fluorescent hydrogel actuator with pH and thermo dual responsiveness is proposed. Through incorporating pH-responsive perylene tetracarboxylic acid (PTCA), which is a typical fluorescent moiety with aggregation-caused quenching (ACQ) effect, into an anisotropic poly(N-isopropylacrylamide)-polyacrylamide (PNIPAm-PAAm) structure, the obtained hydrogel exhibits stable thermoresponsive shape deformation and switchable fluorescence performance upon a pH trigger. Therefore, fluorescence-quenching-based and actuation-based information can be revealed when exposed to UV light and immersed into warm water, respectively. Moreover, the thermoresponsive actuating behavior can be applied to further hide the fluorescence-quenching-based images. The present work may provide new insights into the design and preparation of novel stimuli-responsive hydrogel actuators.