Oligo Ethylene Research Articles

A Nanocomposite Dynamic Covalent Cross-Linked Hydrogel Loaded with Fusidic Acid for Treating Antibiotic-Resistant Infected Wounds.

Methicillin-resistant Staphylococcus aureus (MRSA) is associated with high levels of morbidity and is considered a difficult-to-treat infection, often requiring nonstandard treatment regimens and antibiotics. Since over 40% of the emerging antibiotic compounds have insufficient solubility that limits their bioavailability and thus efficacy through oral or intravenous administration, it is crucial that alternative drug delivery products be developed for wound care applications. Existing effective treatments for soft tissue MRSA infections, such as fusidic acid (FA), which is typically administered orally, could also benefit from alternative routes of administration to improve local efficacy and bioavailability while reducing the required therapeutic dose. Herein, we report an antimicrobial poly(oligoethylene glycol methacrylate) (POEGMA)-based composite hydrogel loaded with fusidic acid-encapsulating self-assembled polylactic acid-b-poly(oligo(ethylene glycol) methyl ether methacrylate) (PLA-POEGMA) nanoparticles for the treatment of MRSA-infected skin wounds. The inclusion of the self-assembled nanoparticles (380 nm diameter when loaded with fusidic acid) does not alter the favorable mechanical properties and stability of the hydrogel in the context of its use as a wound dressing, while fusidic acid (FA) can be released from the hydrogel over ∼10 h via a diffusion-controlled mechanism. The antimicrobial studies demonstrate a clear zone of inhibition in vitro and a 1-2 order of magnitude inhibition of bacterial growth in vivo in an MRSA-infected full-thickness excisional murine wound model even at very low antibiotic doses. Our approach thus can both circumvent challenges in the local delivery of hydrophobic antimicrobial compounds and directly deliver antimicrobials into the wound to effectively combat methicillin-resistant infections using a fraction of the drug dose required using other clinically relevant strategies.

Phase Behavior and Conformational Asymmetry near the Comb-to-Bottlebrush Transition in Linear-Brush Block Copolymers.

This study explores how conformational asymmetry influences the bulk phase behavior of linear-brush block copolymers. We synthesized 60 diblock copolymers composed of poly(trifluoroethyl methacrylate) as the linear block and poly[oligo(ethylene glycol) methyl ether methacrylate] as the brush block, varying the molecular weight, composition, and side-chain length to introduce different degrees of conformational asymmetry. Using small-angle X-ray scattering, we determined the morphology and phase diagrams for three different side-chain length systems, mainly observing lamellar and cylindrical phases. Increasing the side-chain length of the brush block from three to nine ethylene oxide units introduces sufficient asymmetry between the blocks to alter the phase behavior, shifting the lamellar-to-cylindrical transitions toward lower brush block compositions and transitioning the brush block from the dense comb-like regime to the bottlebrush regime. Coarse-grained simulations support our experimental observations and provide a mapping between the composition and conformational asymmetry. A comparison of our findings to strong stretching theory across multiple phase boundary predictions confirms the transition between the dense comb-like regime and the bottlebrush regime.

Generalist versus Specialist Self-Replicators.

Darwinian evolution, including the selection of the fittest species under given environmental conditions, is a major milestone in the development of synthetic living systems. In this regard, generalist or specialist behavior (the ability to replicate in a broader or narrower, more specific food environment) are of importance. Here we demonstrate generalist and specialist behavior in dynamic combinatorial libraries composed of a peptide-based and an oligo(ethylene glycol) based building block. Three different sets of macrocyclic replicators could be distinguished based on their supramolecular organization: two prepared from a single building block as well as one prepared from an equimolar mixture of them. Peptide-containing hexamer replicators were found to be generalists, i. e. they could replicate in a broad range of food niches, whereas the octamer peptide-based replicator and hexameric ethyleneoxide-based replicator were proven to be specialists, i. e. they only replicate in very specific food niches that correspond to their composition. However, sequence specificity cannot be demonstrated for either of the generalist replicators. The generalist versus specialist nature of these replicators was linked to their supramolecular organization. Assembly modes that accommodate structurally different building blocks lead to generalist replicators, while assembly modes that are more restrictive yield specialist replicators.

Alcohol‐Soluble n‐Type Polythiophenes as Cathode Interlayer in Organic Photodetectors for Hole Blocking

AbstractFor organic photodetectors (OPDs), cathode interlayer (CIL) with low‐lying highest occupied molecular orbital (EHOMO) energy level is required to reduce dark current density (Jd). In this study, toward application as CIL in OPDs, an alcohol‐processable n‐type conjugated polymer (n‐PT8) based on imide/cyano‐substituted polythiophene backbone and branched oligo(ethylene glycol) side chain is developed. Owing to the electron‐accepting imide/cyano groups on the backbone, n‐PT8 exhibits deep‐lying EHOMO of −5.80 eV and a high conductivity of 5.12 × 10−6 S cm−1. OPD with n‐PT8 as CIL exhibits dark current density one order of magnitude lower than that with the state‐of‐the‐art CIL material because of the large energy barrier for reverse hole injection. Moreover, the device performance is insensitive to the n‐PT8 layer thickness, which is very desirable for the mass production of OPDs. The near‐infrared (NIR) OPDs based on n‐PT8 exhibit an ultra‐low dark current density of 1.76 × 10−9 A cm−2 and a specific detectivity of 2.88 × 1012 cm Hz1/2 W−1 at −1 V. To the best knowledge, this is the first report on n‐type polythiophene derivatives as CIL in organic opto‐electronic devices.

Synthesis of Novel Nanocomposite Materials with Enhanced Antimicrobial Activity based on Poly(Ethylene Glycol Methacrylate)s with Ag, TiO2 or ZnO Nanoparticles

The aim of this investigation was to prepare novel hybrid materials with enhanced antimicrobial properties to be used in food preservation and packaging applications. Therefore, nanocomposite materials were synthesized based on two stimuli-responsive oligo(ethylene glycol methacrylate)s, namely PEGMA and PEGMEMA, the first bearing hydroxyl side groups with three different metal nanoparticles, i.e., Ag, TiO2 and ZnO. The in situ radical polymerization technique was employed to ensure good dispersion of the nanoparticles in the polymer matrix. FTIR spectra identified the successful preparation of the corresponding polymers and XRD scans revealed the presence of the nanoparticles in the polymer matrix. In the polymer bearing hydroxyl groups, the presence of Ag-NPs led to slightly lower thermal stability as measured by TGA, whereas both ZnO and TiO2 led to nanomaterials with better thermal stability. The antimicrobial activity of all materials was determined against the Gram-negative bacteria E. coli and the Gram-positive S. aureus, B. subtilis and B. cereus. PEGMEMA nanocomposites had much better antimicrobial activity compared to PEGMA. Ag NPs exhibited the best inhibition of microbial growth in both polymers with all four bacteria. Nanocomposites with TiO2 showed a very good inhibition percentage when used in PEGMEMA-based materials, while in PEGMA material, high antimicrobial activity was observed only against E. coli and B. subtilis, with moderate activity against B. cereus and almost absent activity against S. aureus. The presence of ZnO showed antimicrobial activity only in the case of PEGMEMA-based materials. Differences observed in the antibacterial activity of the polymers with the different nanoparticles could be attributed to the different structure of the polymers and possibly the more efficient release of the NPs.

Cross-Linked Hyaluronan Derivatives in the Delivery of Phycocyanin.

An easy and viable crosslinking technology, based on the "click-chemistry" reaction copper(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (click-crosslinking), was applied to graft copolymers of medium molecular weight (i.e., 270 kDa) hyaluronic acid (HA) grafted with ferulic acid (FA) residues bearing clickable propargyl groups, as well as caffeic acid derivatives bearing azido-terminated oligo(ethylene glycol) side chains. The obtained crosslinked materials were characterized from the point of view of their structure and aggregation liability to form hydrogels in a water environment. The most promising materials showed interesting loading capability regarding the antioxidant agent phycocyanin (PC). Two novel materials complexes (namely HA(270)-FA-TEGEC-CL-20/PC and HA(270)-FA-HEGEC-CL-20/PC) were obtained with a drug-to-material ratio of 1:2 (w/w). Zeta potential measurements of the new complexes (-1.23 mV for HA(270)-FA-TEGEC-CL-20/PC and -1.73 mV for HA(270)-FA-HEGEC-CL-20/PC) showed alterations compared to the zeta potential values of the materials on their own, suggesting the achievement of drug-material interactions. According to the in vitro dissolution studies carried out in different conditions, novel drug delivery systems (DDSs) were obtained with a variety of characteristics depending on the desired route of administration and, consequently, on the pH of the surrounding environment, thanks to the complexation of phycocyanin with these two new crosslinked materials. Both complexes showed excellent potential for providing a controlled/prolonged release of the active pharmaceutical ingredient (API). They also increased the amount of drug that reach the target location, enabling pH-dependent release. Importantly, as demonstrated by the DPPH free radical scavenging assay, the complexation process, involving freezing and freeze-drying, showed no adverse effects on the antioxidant activity of phycocyanin. This activity was preserved in the two novel materials and followed a concentration-dependent pattern similar to pure PC.

The chemoenzymatic synthesis of glycan-terminated oligo(Leu)x

Introduction: Glycopeptides contain carbohydrate moieties (glycans) covalently attached to the side chain and/or terminal peptide units. Since glycans are present on cell surfaces, these constructs can potentially address a wide array of therapeutic functions. To overcome the deficiencies associated with current synthetic routes to glycopeptides, such as costly processes and toxic reagents, this work aimed to develop versatile environmentally friendly protease-catalyzed peptide synthesis routes to peptides decorated with a glycan at their N-terminus.Methods: “Grafters” were first synthesized that consist of a glycan conjugated directly, or through a spacer, to the amine group of L-Phe-ethyl ester (Phe-OEt). The role of Phe-OEt is to increase the conjugate’s recognition by the protease (papain) catalytic active site. A series of grafters were synthesized with variation of the glycan structure, linkage-chemistry, and presence of an oligo (ethylene glycol) “spacer” of varied length between the glycan and Phe-OEt moiety. High grafter efficiency will result by the successful acceptance of the grafter at the enzymes S1/S2 subsites, formation of an acyl enzyme complex and subsequent conversion to glycan-terminated oligo(Leu)x (x ≥ 1), as opposed to construction of non-glycan N-terminated oligo(Leu)x.Results and discussion: While glycan-Phe-OEt grafters without a spacer between the glycan and Phe-OEt resulted in low grafter efficiency (8.3% ± 2.0%), insertion of a short oligo (ethylene glycol) spacer between the glycan and Phe-OEt moieties (glycan-PEGn-Phe-OEt, n ≥ 3) increased the grafter efficiency by 3-fold–24.5% ± 1.8%. In addition, computational modeling was performed using Rosetta software provided insights on a molecular level of how grafter efficiency is influenced by the PEG spacer length.

Photoresponsive Ru Metalloprodrug Assemblies: Red‐Light‐Controlled Self‐Delivery Systems for Enhanced Anticancer Phototherapy

AbstractSmall‐molecule ruthenium (Ru) complexes exhibit limitations in terms of nonspecific delivery, rapid metabolism, and low tumor accumulation. Their delivery can be improved through physical encapsulation into nanocarriers via hydrophobic forces, metallophilic interactions, or π–π stacking interactions. However, delivering Ru complexes for efficient therapy is substantially hindered by potential leakage of drugs, low drug‐loading capacity, or batch‐to‐batch variations. Moreover, current metalloprodrug‐based self‐delivery systems necessitate supramolecular interactions, which are unsuitable for Ru complexes because of their octahedral structures. Herein, two self‐assembled molecular Ru drugs, Ru‐3XOEG and Ru‐PEG, are reported. Ru‐3XOEG involves a three‐arm dendritic oligo(ethylene glycol) (OEG), while Ru‐PEG involves a linear poly(ethylene glycol) (PEG) chain. Furthermore, these drugs contain an anticancer Ru moiety and a planar pyrene moiety to render hydrophobic forces and π–π stacking supramolecular interactions. Ru‐3XOEG self‐assembles into large compound micelles. Ru‐PEG self‐assembles into vesicles. These Ru‐containing self‐delivered systems exhibit well‐defined structures, high Ru loading contents, and long circulation in blood without external nanocarriers. Red light irradiation induces the release of Ru‐H2O anticancer agents and the generation of 1O2 to inhibit tumor growth. The presented design of self‐assembled molecular Ru complexes opens avenues for the concept of self‐delivered metalloprodrugs.

Oligo(ethylene glycol) methyl ether methacrylate based hydrogel with intrinsic antibacterial activity against Pseudomonas aeruginosa as a model of a major wound infecting human pathogen

Wound dressings represent the first important defense line against potentially life-threatening infections. Successful materials should unify efficiency, simplicity of production with the ease of application. Cationic polymers based on quaternary ammonium salt moieties along the polymer chain promise high efficacy against growth of relevant pathogens including drug-resistant strains. We present a novel and easy-to-handle wound dressing material based on the well-defined copolymers of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA), using quaternization with 1,6-dibromohexane for hydrogel formation. The material obtained from this robust approach was perfectly biocompatible with human dermal fibroblasts and revealed an auspicious degree of intrinsic antibacterial activity against P. aeruginosa as a model pathogen for hospital-acquired infections. Formation of bacterial biofilms was prevented in early- and late-stages and even planktonic cells were killed upon gel contact. The rheological properties of the hydrogel materials were comprehensively characterized in both dry and swollen states. Excellent biological performance and appropriate viscoelastic properties qualify the hydrogels from our production approach as truly promising novel wound dressing materials with long-lasting and contact-active bactericidal activities. We believe that this charmingly simple procedure and the mechanical properties of the hydrogel may open new avenues towards cost-effective next-generation first-line wound-care materials.

Functionalized [2.2]Paracyclophanedienes as Monomers for Poly(p-phenylenevinylene)s.

Poly(p-phenylenevinylene)s (PPVs) featuring complex side-chains, to date, have only been synthesized by nonliving polymerization methods which have no control over PPV molecular weights, dispersities, or end groups. [2.2]Paracyclophane-1,9-diene (pCpd) has gained attention as a monomer for its ability to be ring-opened to PPV in a living fashion. pCpd, an organic cyclic scaffold with planar chirality, has seen minimal structural diversity due to the harsh reaction conditions required to afford the highly strained compound. Herein, we introduce a general method to overcome this by targeting the synthesis of a monohydroxy-pCpd via mono-demethylation of a dialkoxy-pCpd. The monohydroxy-pCpd can then be functionalized easily, which we demonstrate using three distinct side-chains with four moieties commonly incorporated in conjugated polymers: an alkyl bromide, an oligo(ethylene glycol) chain, an enantiomerically pure side-chain, and a Boc-protected amine. These monofunctionalized-pCpds were investigated as monomers in the ring-opening metathesis polymerization (ROMP) to afford functionalized PPVs in a living manner. The functional-group-containing PPVs are synthesized with full control over their end groups, repeat units, and dispersities. The feasibility of post-polymerization modifications to incorporate any desired moiety to PPV fabricated by this method was demonstrated using an azide-alkyne click reaction. All synthesized PPVs were soluble in organic solvents and display the same fluorescent emission, indicating their conjugated backbones are unaltered.

Oligo (ethylene glycol)-grafted poly(terphenyl indole piperidinium) with high water diffusivity for anion exchange membrane fuel cells

The water diffusivity of polymeric anion exchange membranes (AEMs) plays a critical role in determining the AEM fuel cells (AEMFCs) performance because it generates an imbalance in the amount of water at the anode and cathode. However, the correlation between water diffusivity and the chemical structure of AEMs remains unclear. This study focuses on a series of oligo(ethylene glycol) (OEG) functionalized poly(arylene indole piperidinium) AEMs, in which OEG grafts are directly attached onto the polymer backbones. The polar and flexible OEG side chains afford a microphase-separated morphology, close polymer-chain packing, and extra sites for water–ion transport, resulting in high ion-exchange-capacity (IEC)-normalized conductivity, improved water diffusivity, and dimensional stability. Moreover, these side chains provide excellent ex-situ stability in a 1 M NaOH solution (80 °C) for 1080 h, surpassing the stability of its alkyl side chain counterpart (PITP-C10Q85) by a significant margin. The resultant PITP-OEG-85 with the highest water diffusivity exhibits a highest peak power density of 1.23 W cm−2 at 80 °C despite its low IEC value and conductivity. In-situ durability tests of this membrane at 0.2 A cm−2 for 24 h revealed the degradation of piperidinium under harsh conditions (70 % anode relative humidity at 60 °C). This work opens a new avenue for designing highly conductive and alkali-stable AEM materials with high water diffusivity to realize high-performance AEMFCs.

Synthesis of Oligo(Ethylene Glycol)- Functionalized Pyrroles and their Electrochemical Deposition

Synthesis of Oligo(Ethylene Glycol)- Functionalized Pyrroles and their Electrochemical Deposition

The effect of comb length on the in vitro and in vivo properties of self-assembled poly(oligoethylene glycol methacrylate)-based block copolymer nanoparticles.

Comb copolymer analogues of poly(lactic acid)-polyethylene glycol block copolymers (PLA-b-PEG) offer potential to overcome the inherent chemistry and stability limitations of their linear block copolymer counterparts. Herein, we examine the differences between P(L)LA10K-b-PEG10K and linear-comb copolymer analogues thereof in which the linear PEG block is replaced by poly(oligo(ethylene glycol) methacrylate) (POEGMA) blocks with different side chain (comb) lengths but the same overall molecular weight. P(L)LA10K-b-POEGMA47510K and P(L)LA10K-b-POEGMA200010K block copolymers were synthesized via activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) and fabricated into self-assembled nanoparticles using flash nanoprecipitation via confined impinging jet mixing. Linear-comb copolymer analogues based on PLA-b-POEGMA yielded smaller but still well-controlled nanoparticle sizes (88 ± 2 nm and 114 ± 1 nm respectively compared to 159 ± 2 nm for P(L)LA10K-b-PEG10K nanoparticles) that exhibited improved colloidal stability relative to linear copolymer-based nanoparticles over a 15 day incubation period while maintaining comparably high cytocompatibility, although the comb copolymer analogues had somewhat lower loading capacity for doxorubicin hydrochloride. Cell spheroid studies showed that the linear-comb copolymers promoted enhanced tumor transport and thus cell killing compared to conventional linear block copolymers. In vivo studies showed all NP types could passively accumulate within implanted CT26 tumors but with different accumulation profiles, with P(L)LA10K-b-POEGMA200010K NPs showing continuous accumulation throughout the full 24 h monitoring period whereas tumor accumulation of P(L)LA10K-b-POEGMA47510K NPs was significant only between 8 h and 24 h. Overall, the linear-comb copolymer analogues exhibited superior stability, biodistribution, spheroid penetration, and inherent tunability over linear NP counterparts.

Distinguishing anti-PEG antibodies by specificity for the PEG terminus using nanoarchitectonics-based antibiofouling cello-oligosaccharide platforms.

The conjugation of poly(ethylene glycol) (PEG) to therapeutic proteins or nanoparticles is a widely used pharmaceutical strategy to improve their therapeutic efficacy. However, conjugation can make PEG immunogenic and induce the production of anti-PEG antibodies, which decreases both the therapeutic efficacy after repeated dosing and clinical safety. To address these concerns, it is essential to analyze the binding characteristics of anti-PEG antibodies to PEG. However, distinguishing anti-PEG antibodies is still a difficult task. Herein, we demonstrate the use of antibiofouling cello-oligosaccharide assemblies tethering one-terminal methoxy oligo(ethylene glycol) (OEG) ligands for distinguishing anti-PEG antibodies in a simple manner. The OEG ligand-tethering two-dimensional crystalline cello-oligosaccharide assemblies were stably dispersed in a buffer solution and had antibiofouling properties against nonspecific protein adsorption. These characteristics allowed enzyme-linked immunosorbent assays (ELISAs) to be simply performed by cycles of centrifugation/redispersion of aqueous dispersions of the assemblies. The simple assays revealed that the specific OEG ligand-tethering assemblies could distinguish anti-PEG antibodies to detect a specific antibody that preferentially binds to the methoxy terminus of the PEG chain with 3 repeating ethylene glycol units. Furthermore, quantitative detection of the antibodies was successfully performed with high sensitivity even in the presence of serum. The detectable and quantifiable range of antibody concentrations covered those required clinically. Our findings open a new avenue for analyzing the binding characteristics of anti-PEG antibodies in biological samples.

An integrated "rigid-flexible" strategy by side chain engineering towards high ion-conduction cationic covalent organic framework electrolytes.

In recent years, solid-state lithium metal batteries (SSLMBs) have become a new development trend, and it has become a top priority to design solid-state electrolytes (SSEs) that can rapidly and stably transport lithium ions in a variety of climatic environments. In this work, an integrated "rigid-flexible" dual-functional strategy is proposed to develop a cationic covalent organic framework (EO-BIm-iCOF) with well-defined flexible oligo(ethylene oxide) (EO) chains as an SSE for SSLMBs. As expected, the synergistic effects of the rigid cationic framework and flexible EO chains not only promote the dissociation of LiTFSI salts, but also greatly improve the transport of lithium ions, which endows LITFSI@EO-BIm-iCOF SSEs with a high Li+ conductivity of 1.08 × 10-4 S cm-1 and ionic transference number of 0.69 at room temperature. Besides, the molecular dynamics (MD) simulations have also elucidated the diffusion and transport mechanism of lithium ions in LITFSI@EO-BIm-iCOF SSEs. Interestingly, the assembled SSLMBs wherein LiFePO4 is paired with LITFSI@EO-BIm-iCOF SSEs display decent electrochemical properties at higher and lower temperatures. This work provides a great development prospect for the application of cationic COFs in solid-state batteries.

Fair surface modification with mixed alkanethiols on gold nanoparticles through minimal unfair ligand exchange.

Surface modification with functional molecules is essential for introducing various surface properties. As gold nanoparticles (AuNPs) have extraordinary chemical, physical, and optical properties, control of their surface, mainly through modification with mixed alkanethiols via Au-S interactions, has attracted much attention. However, surface modification of AuNPs with mixed alkanethiols to provide a strictly regulated composition remains challenging. Further, there are very few methods that can easily establish the nature of ligands and their replacement with similar molecules at nanoparticle surfaces, limiting precise analyses. Herein, we demonstrate an unfair ligand exchange between oligo(ethylene glycol) (OEG)-attached alkanethiols as a source of unfair surface modification utilizing programable thermo-responsive properties of OEG-alkanethiols-modified AuNPs and fair surface modification with mixed OEG-alkanethiols by minimizing this effect. OEG-alkanethiols-modified AuNPs show an assembly/disassembly behavior in response to the solution temperature. Assembly temperature (T A) changes in the presence of other OEG-alkanethiols, confirming the ligand exchange between alkanethiols in an aqueous solution. Kinetic analyses indicate that the competitive exchange reaction of these two alkanethiols results in an unfair ligand exchange, which leads to gradual changes in surface composition. As this ligand exchange between alkanethiols takes a longer time compared to that from citric acid, which initially covered the AuNPs, exact surface modification of AuNPs with OEG-alkanethiols is performed by moderate reaction conditions (25 °C, several to 24 hours). This insight regarding "more prolonged reaction is not always better" could be widely applied for surface modifications with various thiol-ligands.

Effect of Architecture on the Thermo-induced Phase Transition of Methacrylate-based Symmetric Pentablock Terpolymers

A series of six symmetric pentablock terpolymers were synthesised using group transfer polymerisation (GTP). The chemical composition of these terpolymers comprises 45 wt% of oligo(ethylene glycol) methyl ether methacrylate (molar...

Supramolecular assembly of isomeric SN-38 prodrugs regulated by conjugation sites.

Supramolecular polymers (SPs) are an emerging class of drug transporters employed to improve drug therapy. Through the rational design of self-assembling monomers, one can optimize the properties of the resulting supramolecular nanostructures, such as size, shape, surface chemistry, release, and, therefore, biological fates. This study highlights the design of isomeric SN38 prodrugs through the conjugation of hydrophilic oligo(ethylene glycol) (OEG) with hydroxyls at positions 10 and 20 on hydrophobic SN-38. Self-assembling prodrug (SAPD) isomers 10-OEG-SN38 and 20-OEG-SN38 can self-assemble into giant nanotubes and filamentous assemblies, respectively, via aromatic associations that dominate self-assembly. Our study reveales the influence of modification sites on the assembly behavior and ability of the SN38 SAPDs, as well as drug release and subsequent in vitro and in vivo antitumor effects. The SAPD modified at position 20 exhibits stronger π-π interactions among SN38 units, leading to more compact packing and enhanced assembly capability, whereas OEG at position 10 poses steric hindrance for aromatic associations. Importantly, owing to its higher chemical and supramolecular stability, 20-OEG-SN38 outperforms 10-OEG-SN38 and irinotecan, a clinically used prodrug of SN38, in a CT26 tumor model, demonstrating enhanced tumor growth inhibition and prolonged animal survival. This study presents a new strategy of using interactions among drug molecules as dominating features to create supramolecular assemblies. It also brings some insights into creating effective supramolecular drug assemblies via the engineering of self-assembling building blocks, which could contribute to the optimization of design principles for supramolecular drug delivery systems.

A bioinspired bifunctional catalyst: an amphiphilic organometallic catalyst for ring-closing metathesis forming liquid droplets in aqueous media.

Inspired by phase-separated biopolymers with enzymatic activity, we developed an amphiphilic catalyst consisting of alternating hydrophilic oligo(ethylene glycol) and hydrophobic aromatic units bearing a Hoveyda-Grubbs catalyst center (MAHGII). MAHGII served as both a droplet-forming scaffold and a catalyst for ring-closing metathesis reactions, providing a new biomimetic system that promotes organic reactions in an aqueous environment.

A comparative study on surface-engineered nanoceria using a catechol copolymer design: colloidal stability vs. antioxidant activity.

Nanoceria (NC) are widely studied as potent nanozyme antioxidants, featuring unique multifunctional, self-regenerative, and high-throughput enzymatic functions. However, bare NC are reported to show poor colloidal stability in biological media. Despite this, the nexus between colloidal stability and antioxidant activity has rarely been assessed. Here, a library of three copolymeric stabilising agents was synthesised, each consisting of hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) brushes (P(OEGMA)) and a novel catechol anchoring block, and used for surface engineering of NC. The colloidal stability of the surface-engineered NC was assessed in phosphate buffered saline (PBS) by monitoring their precipitation via UV-Vis spectrophotometry, and their catalase (CAT)- and superoxide dismutase (SOD)-like activities were analysed using fluorospectrophotometry. The obtained results indicate that P(OEGMA) coating improves colloidal stability of NC over 48 h, highlighting the stable attachment of catechol functionalities to the surface of NC. In addition, X-ray photoelectron spectroscopy (XPS) indicates that the catechol functionalities lead to an increase in Ce3+/Ce4+ ratio and the concentration of oxygen vacancies, depending on the number of catechol units. Altogether, surface engineering of NC optimally results in an increase in CAT- and SOD-like activities by, respectively, 41% (=57.7% H2O2 elimination) and 78% (=78.0% O2˙- elimination) relative to bare NC, signifying a positive correlation between colloidal stability and antioxidant activity of the NC nanozymes.