PARD3 dysfunction in conjunction with dynamic HIPPO signaling drives cortical enlargement with massive heterotopia.

Proper organization and orderly mitosis of radial glial progenitors (RGPs) drive the formation of a laminated mammalian cortex in the correct size. However, the molecular underpinnings of the intricate process remain largely unclear. Here we show that RGP behavior and cortical development are controlled by temporally distinct actions of partitioning-defective 3 (PARD3) in concert with dynamic HIPPO signaling. RGPs lacking PARD3 exhibit developmental stage-dependent abnormal switches in division mode, resulting in an initial overproduction of RGPs located largely outside the ventricular zone at the expense of deep-layer neurons. Ectopically localized RGPs subsequently undergo accelerated and excessive neurogenesis, leading to the formation of an enlarged cortex with massive heterotopia and increased seizure susceptibility. Simultaneous removal of HIPPO pathway effectors Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) suppresses cortical enlargement and heterotopia formation. These results define a dynamic regulatory program of mammalian cortical development and highlight a progenitor origin of megalencephaly with ribbon heterotopia and epilepsy.

Biomarkers of Autologous Whole Blood Injection Efficacy in Patients with Chronic Spontaneous Urticaria with Autoreactivity: A Preliminary Study.

INTRODUCTION: Chronic spontaneous urticaria (CSU) with autoreactivity is often resistant to antihistamines. Autologous whole blood injection (AWBI) has shown potential efficacy in the treatment of this disease, but it is controversial. It is necessary to screen patients who are suitable for this therapy in advance. This study aimed to identify biomarkers that predict the efficacy of AWBI treatment in CSU patients with autoreactivity. METHODS: A total of 30 patients with autologous serum skin test-positive CSU treated with AWBI were included in this study; urticaria activity score (UAS7) was recorded and the treatment response was judged based on it. Levels of total serum IgE, anti-high-affinity IgE receptor (FcεRI) IgG, and basophils CD63 and FcεRI expressions, and D-dimer of all patients were determined and analyzed. RESULTS: Baseline levels of total IgE, D-dimer, basophil FcεRI and CD63 expressions showed good correlations with UAS7 variations. D-dimer, basophil FcεRI and CD63 expressions changed significantly before and after AWBI treatment in AWBI responders, and the basophil FcεRI and CD63 expressions consistently and dynamically decreased in AWBI responders during the treatment. Baseline levels of total IgE, D-dimer, basophil FcεRI and CD63 expressions showed certain predictive values for AWBI response. CONCLUSIONS: Baseline levels of total IgE, D-dimer, basophil FcεRI and CD63 expressions could be biomarkers of predicting AWBI efficacy in patients with CSU with autoreactivity.

Molecular docking and molecular dynamics simulation of wheat gluten-derived antioxidant peptides acting through the Keap1-Nrf2 pathway.

BACKGROUND: In our previous study, we successfully identified five peptides from wheat gluten: Ala-Pro-Ser-Tyr (APSY), Leu-Tyr (LY), Pro-Tyr (PY), Arg-Gly-Gly-Tyr (RGGY) and Tyr-Gln (YQ). Molecular docking and molecular dynamics simulation methods were employed to investigate the interaction between these antioxidant peptides and the Kelch-like ECH-associated protein 1 (Keap1 protein), revealing the molecular mechanism of their non-competitive binding. In addition, the total antioxidant capacity of the five peptides was determined using the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) method. RESULTS: The affinities of APSY, LY, PY, RGGY and YQ were -8.9, -8.3, -8.5, -9.1 and - 7.9 kcal mol-1, respectively. The five peptides effectively bound to Keap1 protein through hydrogen, π-σ, π-alkyl and alkyl interactions. Significant roles were observed for the P1 pocket residue ARG-415 and the P3 pocket residue ALA-556 in the interactions of the Keap1-peptide complexes. Molecular dynamics simulations further elucidated the dynamic process of peptide binding to the Keap1 protein. All five peptides formed stable complexes with Keap1 protein, with van der Waals forces playing crucial roles in these complex systems, indicative of the peptides' strong binding ability to Keap1 protein. The van der Waals forces were -178.74, -123.11, -134.36, -132.59, and -121.44 kJ mol-1 for the Keap1-APSY, Keap1-LY, Keap1-PY, Keap1-RGGY and Keap1-YQ complexes, respectively. These peptides exhibited excellent antioxidant effects. Among them, the YQ peptide exhibited the highest total antioxidant capacity, with an activity value of 1.18 ± 0.06 mmol Trolox equivalent (TE) L-1 at a concentration of 0.10 mg mL-1. The RGGY, PY, LY and APSY peptides followed in descending order, with activity values of 0.91 ± 0.05, 0.72 ± 0.06, 0.62 ± 0.04 and 0.60 ± 0.05 mmol TE L-1, respectively. CONCLUSION: These results unveiled the molecular mechanism by which the five antioxidant peptides act on active pockets through the Keap1-Nrf2 signaling pathway, providing a theoretical basis for the development of antioxidants. © 2024 Society of Chemical Industry.

Structural identification and combination mechanism of iron (II)-chelating Atlantic salmon (Salmo salar L.) skin active peptides.

In order to utilize salmon skin for high value, and investigate the structural identification and combination mechanism of iron (II)-chelating peptides systemically, Atlantic salmon (Salmo salar L.) skin, a by-product of Atlantic salmon processing, was treated by two-step enzymatic hydrolysis to obtain salmon skin active peptides (SSAP). Then they reacted with iron (II) to obtain iron (II)-chelating salmon skin active peptides (SSAP-Fe) with a high iron (II) chelating ability of 98.84%. The results of Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD) spectroscopy, 8-anilino-1-naphthalenesulfonic acid ammonium salt hydrate (ANS) combined fluorescence measurement, isothermal titration calorimetry (ITC) and full wavelength ultraviolet (UV) scanning showed that the structural characteristics of SSAP changed before and after chelating iron (II). Reverse phase high performance liquid chromatography (RP-HPLC) and mass spectrometry were used to identify and quantify the peptides in SSAP-Fe. Four peptide sequences (STEGGG, GIIKYGDDFMH, PGQPGIGYDGPAGPPGPPGPPGAP and QNQRESWTTCRSQSSLPDG) were identified. The content of PGQPGIGYDGPAGPPGPPGPPGAP was the highest, at 25.17 µg/mg. The pharmacokinetic and pharmacodynamic properties of these four peptides were also investigated, and the results indicated that they have satisfactory predicted ADMET properties. Molecular docking technology was used to analyze the binding sites between iron (II) and SSAP, and it was found that PGQPGIGYDGPAGPPGPPGPPGAP had the lowest predicted binding energy with iron (II) and the most stable predicted binding energy with iron (II). This results showed that the stability of SSAP-Fe were closely related to the number of covalent bonds and the types of amino acids. This study revealed the structure and combination mechanism of SSAP-Fe, and indicated that SSAP-Fe prepared by chelation may be used as a Fe supplement that can be applied in functional foods or ingredients.

Higher House Dust Mite-Specific IgE Levels among Chronic Spontaneous Urticaria Patients May Implicate Higher Basophil Reactivity.

INTRODUCTION: Allergen-specific IgE (sIgE) sensitization exists in a considerable fraction of chronic spontaneous urticaria (CSU) patients. Basophils have been implicated in the pathogenesis of CSU. This paper aimed to explore the relationship between allergic sensitization and basophil reactivity in CSU and the possible underlying mechanism. METHODS: Basophil-enriched leukocytes were isolated from the peripheral blood of 76 CSU patients and 9 healthy controls. Basophil CD63 and FcεRIα (the alpha subunit of the high-affinity IgE receptor) expression in the blood samples with various house dust mite (HDM)-sIgE levels were determined by flow cytometry. Basophil reactivity and SHIP-1 (a molecule related to the IgE/FcεRI signaling pathway) expression were analyzed after stimulation with an HDM allergen or other stimuli. RESULTS: HDM-sIgEstrong positive (≥3.5 kU/L) CSU patients had a significantly higher mean percentage of basophil CD63 and higher baseline levels of FcεRIα expressed by basophils than HDM-sIgEnormal (<0.35 kU/L) CSU patients and healthy controls; the same went for total serum IgE. After stimulation with Dermatophagoides pteronyssinus peptidase 1 (Derp1) alone or together with Derp1-sIgE, the stimulation index of CD63 and levels of FcεRIα expressed by basophils in HDM-sIgEstrong positive CSU patients were significantly higher than those in HDM-sIgEnormal CSU patients and healthy controls. Significantly more SHIP-1 mRNA expression in HDM-sIgEstrong positive CSU patients was induced after the combined stimulation in comparison to other subjects. CONCLUSION: CSU patients with higher HDM-sIgE levels (≥3.5 kU/L) may have higher CD63 and FcεRIα expression on peripheral blood basophils. Peripheral blood basophils in these CSU patients are more responsive to HDM allergen stimulation. Higher HDM-sIgE levels among CSU patients may implicate higher basophil reactivity.

Featured immune characteristics of COVID-19 and systemic lupus erythematosus revealed by multidimensional integrated analyses.

BACKGROUND: Coronavirus disease 2019 (COVID-19) shares similar immune characteristics with autoimmune diseases like systemic lupus erythematosus (SLE). However, such associations have not yet been investigated at the single-cell level. METHODS: We integrated and analyzed RNA sequencing results from different patients and normal controls from the GEO database and identified subsets of immune cells that might involve in the pathogenesis of SLE and COVID- 19. We also disentangled the characteristic alterations in cell and molecular subset proportions as well as gene expression patterns in SLE patients compared with COVID-19 patients. RESULTS: Key immune characteristic genes (such as CXCL10 and RACK1) and multiple immune-related pathways (such as the coronavirus disease-COVID-19, T-cell receptor signaling, and MIF-related signaling pathways) were identified. We also highlighted the differences in peripheral blood mononuclear cells (PBMCs) between SLE and COVID-19 patients. Moreover, we provided an opportunity to comprehensively probe underlying B-cell‒cell communication with multiple ligand-receptor pairs (MIF-CD74+CXCR4, MIF-CD74+CD44) and the differentiation trajectory of B-cell clusters that is deemed to promote cell state transitions in COVID-19 and SLE. CONCLUSIONS: Our results demonstrate the immune response differences and immune characteristic similarities, such as the cytokine storm, between COVID-19 and SLE, which might pivotally function in the pathogenesis of the two diseases and provide potential intervention targets for both diseases.

Effect of Cathodal Transcranial Direct Current Stimulation for Lower Limb Subacute Stroke Rehabilitation.

Methods: A pilot double-blind and randomized clinical trial. Ninety-one subjects with subacute stroke were treated with cathodal/sham stimulation tDCS based on CGR (physiotherapy 40 min/d and occupational therapy 20 min/d) once daily for 20 consecutive working days. Computer-based stratified randomization (1 : 1) was employed by considering age and sex, with concealed assignments in opaque envelopes to ensure no allocation errors after disclosure at the study's end. Patients were evaluated at T0 before treatment, T1 immediately after the posttreatment assessment, and T2 assessment one month after the end of the treatment. The primary outcome index was assessed: lower limb Fugl-Meyer motor score (FMA-LE); secondary endpoints were other gait assessment and relevant stroke scale assessment. Results: Patients in the trial group performed significantly better than the control group in all primary outcome indicators assessed posttreatment T1 and at follow-up T2: FMA-LE outcome indicators between the two groups in T1 (P = 0.032; effect size 1.00, 95% CI: 0.00 to 2.00) and FMA-LE outcome indicators between the two groups in T2 (P = 0.010; effect size 2.00, 95% CI: 1.00 to 3.00). Conclusion: In the current pilot study, ctDCS plus CGR was an effective treatment modality to improve lower limb motor function with subacute stroke. The effectiveness of cathodal tDCS in poststroke lower limb motor dysfunction is inconclusive. Therefore, a large randomized controlled trial is needed to verify its effectiveness.

Effect of phosphorus fertilizer on phytoextraction using Ricinus communis L. in Cu and Cd co-contaminated soil.

Mining activities have led to Cu and Cd contaminated of surrounding agricultural soil. To decrease the Cu and Cd accumulation in crops, the Ricinus communis L. (castor) has been used for phytoremediation. A pot experiment was served to investigate the effect of phosphate fertilizer (Ca(H2PO4)2) on the growth and Cu/Cd uptake of castor in contaminated soil. The results showed that the application of P fertilizer improved the leaf cell morphology, decreased the malonaldehyde (MDA) content of castor leaves, and increased the plant biomass (28.2-34.2%). Besides, phosphate fertilizer still facilitated accumulation Cu and Cd by castor. The addition of phosphate fertilizer increased the contents of Cu in the root of castor, improved the bioconcentration factor (BCF) of Cu, and observably enhanced the accumulation of Cu (up to 201 µg/plant) in castor. Applying phosphorus increased the percentage of residual Cd, diminished the percentage of acid extractable Cd in soil, and the accumulation of Cd in castor was not significantly increased. These results suggest that phosphorus alleviated the stress of heavy metals on castor leaves and enhanced the accumulation of Cu and Cd in castor by promoting the growth of castor.

Applying phosphate fertilizer effectively alleviated the stress of heavy metals on castor and significantly increased the biomass of castor.The reason of applying phosphorus enhanced the castor uptake Cu and Cd was that phosphorus promoted the growth of castor.Applying phosphorus markedly increased the percentage of residual Cd but diminished the percentage of acid extractable Cd in soil.

SERS enhancement induced by the Se vacancy defects in ultra-thin hybrid phase SnSex nanosheets.

Improving the photo-induced charge transfer (PICT) efficiency by adjusting the energy levels difference between adsorbed probe molecules and substrate materials is a key factor for boosting the surface enhanced Raman scattering (SERS) based on the chemical mechanism (CM). Herein, a new route to improve the SERS activity of two-dimensional (2D) selenium and tin compounds (SnSex, 1 ≤ x ≤ 2) by the hybrid phase materials is researched. The physical properties and the energy band structure of SnSex were analyzed. The enhanced SERS activity of 2D SnSex can be attribute to the coupling of the PICT resonance caused by the defect energy levels induced by Se vacancy and the molecular resonance Raman scattering (RRS). This established a relationship between the physical properties and SERS activity of 2D layered materials. The resonance probe molecule, rhodamine (R6G), which is used to detect the SERS performance of SnSex nanosheets. The enhancement factor (EF) of R6G on the optimized SnSe1.35 nanosheets can be as high as 2.6 × 106, with a detection limit of 10-10 M. The SERS result of the environmental pollution, thiram, shows that the SnSex nanosheets have a practical application in trace SERS detection, without the participation of metal particles. These results demonstrate that, through hybrid phase materials, the SERS sensitivity of 2D layered nanomaterials can be improved. It provides a kind of foreground non-metal SERS substrate in monitoring or detecting and provide a deep insight into the chemical SERS mechanism based on 2D layered materials.

SERS Sensing Using Graphene-Covered Silver Nanoparticles and Metamaterials for the Detection of Thiram in Soil.

Multilayer hyperbolic metamaterial (HMM)-based SERS substrates have received special consideration because they accommodate various propagation modes such as surface plasmonic polaritons (SPP). However, the SPP modes are difficult to generate in HMM due to their weak electric field enhancement. In this article, we designed novel SERS substrates consisting of graphene-covered AgNPs and HMM. The graphene-covered AgNPs work as an external coupling structure for hyperbolic metamaterials due to this structure exhibiting significant plasmonic effects as well as unique optical features. The localized surface plasmonic resonance (LSPR) of the graphene-covered AgNPs excited the SPP and thus formed a strong hot spot zone in the nanogap area of the graphene. The Raman experiment was performed using rhodamine 6G (R6G) and crystal violet (CV), which showed high stability and a maximum enhancement factor of 2.12 × 108. The COMSOL simulation further clarified that enhanced SERS performance was due to the presence of monolayer graphene and provided an atomically flat surface for organic molecules in a more controllable manner. Interestingly, the proposed SERS structure carries out quantitative detection of thiram in soil and can satisfy the basic environmental need for pesticide residue in the soil.

Role of Dorsomedial Hypothalamus GABAergic Neurons in Sleep-Wake States in Response to Changes in Ambient Temperature in Mice.

Good sleep quality is essential for maintaining the body's attention during wakefulness, which is easily affected by external factors such as an ambient temperature. However, the mechanism by which an ambient temperature influences sleep-wake behaviors remains unclear. The dorsomedial hypothalamus (DMH) has been reported to be involved in thermoregulation. It also receives projection from the preoptic area, which is an important region for sleep and energy homeostasis and the suprachiasmatic nucleus-a main control area of the clock rhythm. Therefore, we hypothesized that the DMH plays an important role in the regulation of sleep related to ambient temperatures. In this study, we found that cold exposure (24/20/16/12 °C) increased wakefulness and decreased non-rapid eye movement (NREM) sleep, while warm exposure (32/36/40/44 °C) increased NREM sleep and decreased wakefulness compared to 28 °C conditions in wild-type mice. Then, using non-specific and specific apoptosis, we found that lesions of whole DMH neurons and DMH γ-aminobutyric acid (GABA)-ergic neurons induced by caspase-3 virus aggravated the fluctuation of core body temperature after warm exposure and attenuated the change in sleep-wake behaviors during cold and warm exposure. However, chemogenetic activation or inhibition of DMH GABAergic neurons did not affect the sleep-wake cycle. Collectively, our findings reveal an essential role of DMH GABAergic neurons in the regulation of sleep-wake behaviors elicited by a change in ambient temperature.

Physicochemical characterization and identification of major linear epitopes of sarcoplasmic calcium-binding protein (SCP) allergen from Pacific oyster (Crassostrea gigas).

BACKGROUND: Food allergy is a serious public nutritional health problem that has attracted extensive worldwide attention. Shellfish allergy is a long-lasting disorder that has a lifelong impact on health. Sarcoplasmic calcium-binding protein (SCP) plays a vital role in cell and muscle functions and has been identified as an allergen in oyster. RESULTS: In this study, recombinant SCP (rSCP) with a molecular mass of 21 kDa was produced and identified based on SCP amino acid sequencing of Pacific oyster (Crassostrea gigas), and was used as a follow-up experimental material. Its physicochemical characterization showed that purified rSCP is highly stable to heat and acid-alkali and trypsin digestion but less resistant to pepsin digestion. We established an animal sensitization model and rSCP displayed stronger Immunoglobulin E (IgE)-binding activity with rat serum in the rSCP + cholera toxin (CT) group compared with the CT group and a control group. Five epitope peptides were identified as linear immunodominant epitopes by indirect competitive enzyme-linked immunosorbent assay (icELISA) for the first time. We also found that conformational epitopes may play a major role in the immunoreactivity of SCP. CONCLUSION: These results are significant for understanding hypersensitization of humans to oyster and offer available preventive measures and treatment programs in further research. © 2021 Society of Chemical Industry.

Physicochemical characterization and linear epitopes identification of arginine kinase allergen from Crassostrea gigas.

BACKGROUND: Molluscan shellfish, including oysters, often cause allergic reactions in sensitive people throughout the world. It has been demonstrated that arginine kinase (AK) is one of the major allergens of oyster. The present study aimed to evaluate the immunoreactivity and structure of oyster AK as affected by heat treatment, pH change, and in vitro digestion. What is more, the immunoglobulin E-binding epitopes of this allergen were also predicted and validated. RESULTS: Thermal and pH assays revealed that AK was unstable at temperature >40 °C or pH ≤5.0 by sodium dodecyl sulfate polyacrylamide gel electrophoresis and circular dichroism, and the digestibility assays suggested that AK was more easily digested by pepsin than by trypsin and chymotrypsin. The potential epitopes were predicted through immunoinformatics tools, and seven linear epitopes were identified by indirect competition enzyme-linked immunosorbent assay with pooled sera and individual serum from oyster-allergic patients. The critical amino acids in each epitope were also confirmed using mutant peptides. These linear epitopes and critical amino acids were apt to distribute on the outer surface of homology-based AK model. Moreover, the three denaturants (sodium dodecyl sulfate, ß-mercaptoethanol, and urea) can destroy the spatial structure of AK and increase or reduce its allergenicity by denaturation treatments. CONCLUSION: Processing conditions lay the foundation for the variation of allergenicity. Seven linear epitopes and their critical amino acids were identified by indirect competitive enzyme-linked immunosorbent assay. These findings will be helpful in allergy diagnosis and development of hypoallergenic products in the near future. © 2021 Society of Chemical Industry.

Isolation and characterization of oligopeptides with vascular disease suppression effects derived from wheat gluten.

Wheat gluten was hydrolyzed with both alkaline protease and neutral protease to produce high-protein and low-wheat-weight oligopeptides (WOP), which was subjected to a multistage purification. Then, high performance liquid chromatography was applied to separate WOP. In order to identify WOP sequences, six major fractions were gathered for mass spectrometry. A total of 15 peptides were synthesized for further in vitro analyses of their antithrombotic activity, vasorelaxation activity, and cholesterol reducing activity. Two antithrombotic peptides (ILPR and ILR), three vasorelaxant peptides (VN, FPQ, and FR), and four cholesterol-lowering peptides (QRQ, ILPR, FPQ, and ILR) were identified. These active peptides in WOP were also quantified. These peptides are novel candidate peptides with vascular disease suppressing effects. The results indicate WOP as good protein sources for multifunctional peptides.

Identification and characterization of a novel L-type lectin (MjLTL2) from kuruma shrimp (Marsupenaeus japonicus).

L-type lectins (LTLs) belong to the lectin family and are characterized by a conserved structural motif in their carbohydrate recognition domain. LTLs are homologous to leguminous lectins. In this study, we identified and functionally characterized an LTL from kuruma shrimp Marsupenaeus japonicus. We designated this LTL as MjLTL2. MjLTL2 contains a signal peptide, a Lectin_leg domain, a coiled coil, and transmembrane domain. MjLTL2 is distributed in hemocytes, heart, hepatopancreas, gill, stomach, and intestine; higher expression levels are seen in hemocytes and the hepatopancreas than in other tissues. MjLTL2 was upregulated following challenge of shrimp with Vibrio anguillarum and white spot syndrome virus (WSSV). MjLTL2 can agglutinate several bacteria without Ca2+. In addition, MjLTL2 could bind to several Gram-positive and -negative bacteria by binding to their lipopolysaccharide and peptidoglycan. However, MjLTL2 could not enhance the clearance of V. anguillarum in vivo. In the presence of WSSV infection, MjLTL2 knockdown by RNA interference resulted in a 7-day lower cumulative mortality of M. japonicus. Moreover, less VP19, VP24, VP26, and VP28 mRNAs were extracted from the hemocytes of MjLTL2 knockdown shrimp than from the control. These results suggest that MjLTL2 is involved in immune responses in shrimp.

Chemical Surface Modification of Polymeric Biomaterials for Biomedical Applications.

This review focuses on the attachment of polymer brushes to polymeric biomaterial substrates by chemical surface modification methods for biomedical applications. In the first part of this paper, a general introduction to the synthesis of polymer brushes is given. Thereafter, a comprehensive overview of recent work on the chemical surface modification of polymeric biomaterials, with a focus on "grafting-to," "grafting-from," and "grafting-through" strategies, is provided. Finally, some representative cutting-edge biomedical applications of modified polymeric biomaterials, mainly including antifouling materials and biocompatible materials, are highlighted. On the basis of this literature study, a perspective on future trends in this field is provided.

Effect of acid and in vitro digestion on conformation and IgE-binding capacity of major oyster allergen Cra g 1 (tropomyosin).

INTRODUCTION AND OBJECTIVES: The production and consumption of oysters is increasing annually because it can provide essential nutrients and benefit for human health, leading to frequent occurrence of severe allergic reactions observed in sensitized individuals. The aim of the present study was to investigate the effects of acid and protease treatment on the conformation and IgE-binding capacity of recombinant Crassostrea gigas tropomyosin (Cra g 1). RESULTS: Under acidic conditions, Cra g 1 did not undergo degradation, however, the changes obvious in the intensity of CD signal and ANS-binding fluorescence were observed, which was associated with a decrease in antibody reactivity. In simulated gastrointestinal fluid (SGF) and simulated intestinal fluid (SIF) digestion system, acid-treated Cra g 1 was relatively resistant to digestion, but the degradative patterns were very different. Moreover, owing to alterations of secondary structure and hydrophobic surface of the protein during digestive processing, antigenicity of acid-induced Cra g 1 reduced in SGF while it increased significantly in SIF. CONCLUSION: To our knowledge, this is the first study reporting that antigenicity of acid-treated oyster tropomyosin increased after SIF digestion. These results revealed that treatment with acid and pepsin, rather than trypsin, was an effective way of reducing IgE-binding capacity of tropomyosin from oyster.

Design, Synthesis, and Application of a Difunctional Y-Shaped Surface-Tethered Photoinitiator.

Mixed homopolymer brushes have unique interfacial properties that can be exploited for both fundamental studies and applications in technology. Herein, the synthesis of a new catechol-based biomimetic Y-shaped binary photoinitiator (Y-photoinitiator) and its applications for surface modification with polymer brushes through both "grafting to" and "grafting from" strategies are reported. The "leg" of the Y consists of a catechol group as surface anchoring moiety. The arms are photoinitiator moieties that can be "addressed" independent of each other by radiation of different wavelengths. Using ultraviolet and visible light successively, each arm of the Y-photoinitiator was activated, thereby allowing the synthesis of Y-shaped block copolymer brushes with dissimilar polymer chains. The suitability of the Y-photoinitiator for surface modification was first investigated using N-vinylpyrrolidone and styrene as the model monomers for successive UV-photoiniferter-mediated polymerization and visible-light-induced polymerization, respectively. Switching of the wetting properties of the Y-shaped block copolymer brush poly( N-vinylpyrrolidone)- block-poly(styrene) (PVP- b-PS)-grafted surfaces by contact with different solvents was also investigated. To further exploit this novel Y-photoinitiator for the preparation of functional interfaces, Y-shaped block copolymer brushes poly(1-(2-methacryloyloxyhexyl)-3-methylimidazolium bromide)- block-poly( N-vinylpyrrolidone- co-glycidyl methacrylate) (PIL(Br)- b-P(NVP- co-GMA)) were also prepared and subsequently functionalized with the cell-adhesive arginine-glycine-aspartic acid (RGD) peptides by reaction with the glycidyl groups (PILPNG-RGD). The PILPNG-RGD grafted surfaces showed excellent cell-adhesive, bacteriostatic, and bactericidal properties. Thus, it can be concluded that further exploitation of this novel Y-photoinitiator for graft polymerization should allow the preparation of a wide range of functional interfaces with tailored properties.

Efficient Heterodifunctional Unimolecular Ring-Closure Method for Cyclic Polymers by Combining RAFT and SuFEx Click Reactions.

A novel ring-closure strategy for cyclic polymers by combining reversible addition-fragmentation chain transfer polymerization (RAFT) and the sulfur(VI)-fluoride exchange (SuFEx) click reaction is presented. Herein, a new heterodifunctional trithiocarbonate RAFT agent, 2-((tert-butyldimethylsilyl)oxy)ethyl (4-(fluorosulfonyl)benzyl) carbonotrithioate (TBDMS-FSBCT), containing both tert-butyldimethylsilyl ether and sulfonyl fluoride moieties, is developed. The polymerization behavior of TBDMS-FSBCT is first demonstrated by a standard RAFT polymerization procedure for two types of vinyl monomers, N-isopropylacrylamide (NIPAAm) (conjugated vinyl monomer) and N-vinylpyrrolidone (NVP) (unconjugated vinyl monomer). The tert-butyldimethylsilyl ether and sulfonyl fluoride groups at the α and ω positions of the obtained linear polymer precursors (L-PNIPAAm and L-PVP) are verified by 1 H, 13 C, and 19 F NMR spectra. Subsequent intramolecular SuFEx click cyclization of the α,ω-heterofunctionalized linear precursors in air at room temperature conveniently yields the corresponding cyclic polymers (C-PNIPAAm and C-PVP). Overall, this is the first report on the preparation of cyclic polymers based on the SuFEx reaction under ambient conditions. It is envisioned that the approach may open an avenue for the formation of cyclic polymers.

Enhancement of Bactericidal Activity via Cyclic Poly(cationic liquid) Brushes.

In addition to extensive studies of conventional linear poly(ionic liquids) (PILs), exploration of the effects of PIL topology, especially cyclic architecture, on bactericidal properties will expand the design possibilities for the development of excellent antibacterial surfaces. Herein, the preparation of antibacterial surfaces based on cyclic PIL brushes is reported for the first time and how the cyclic PIL architecture affects bactericidal activity is investigated. It is shown that the cyclic architecture imparted PIL brushes with enhanced bactericidal activity, achieving only 1.7% of bacterial viable percentage against gram-negative Escherichia coli using Live/Dead staining methods, compared to 6.6% for the corresponding linear PIL brushes. The enhanced bactericidal activity is also validated by the direct observation of scanning electron microscopy and a colony counting assay. Further mechanism studies reveal that the substantially different morphologies of cyclic aggregates and altered surface charge density induced by the cyclic PIL architecture can account for the enhanced bactericidal activity.