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Nature-inspired small molecules such as catecholamines and polyphenols have gained a great deal of attention because of the exceptional surface-coating property that is applicable to many diverse substrates. Many researchers have conducted studies to expand molecular pools with surface-coating properties, but previous reports have still been limited to phenolic molecules as surface-coating agents. In this study, we describe for the first time the material-independent coating properties of nonphenolic molecules, namely, sulfonated pyrenes with ZrIV ions. Owing to the binding capability with several oxygen-containing ligands, ZrIV can be used for the molecular assembly of sulfonated pyrenes. We also report on the mixing of multiple sulfonated pyrenes and ZrIV results in cross-linked complexes that can coat diverse solid substrates. The resulting coating can serve as a platform for grafting functional polysaccharides.

Bacterial toxin–antitoxin (TA) systems correlate strongly with physiological processes in bacteria, such as growth arrest, survival and apoptosis. Here, the first crystal structure of a type II TA complex structure of Klebsiella pneumoniae at 2.3 Å resolution is presented. The K. pneumoniae MazEF complex consists of two MazEs and four MazFs in a heterohexameric assembly. It was estimated that MazEF forms a dodecamer with two heterohexameric MazEF complexes in solution, and a truncated complex exists in heterohexameric form. The MazE antitoxin interacts with the MazF toxin via two binding modes, namely, hydrophobic and hydrophilic interactions. Compared with structural homologs, K. pneumoniae MazF shows distinct features in loops β1–β2, β3–β4 and β4–β5. It can be inferred that these three loops have the potential to represent the unique characteristics of MazF, especially various substrate recognition sites. In addition, K. pneumoniae MazF shows ribonuclease activity and the catalytic core of MazF lies in an RNA-binding pocket. Mutation experiments and cell-growth assays confirm Arg28 and Thr51 as critical residues for MazF ribonuclease activity. The findings shown here may contribute to the understanding of the bacterial MazEF TA system and the exploration of antimicrobial candidates to treat drug-resistant K. pneumoniae.

Polyphenols containing catechol (1,2-dihydroxyphenyl)/pyrogallol (1,2,3-trihydroxyphenyl) groups have been employed as precursors to prepare substrate-independent (i.e., universal) coatings. However, quercetin, an interesting flavonol due to its unique biological properties, was previously found to be an inefficient compound for substrate coatings after screening polyphenolic compounds. We report that quercetin-based thin films could be formed on various substrates, including titanium dioxide, silicon wafers, gold, nylon, and glass, when diethylenetriamine (DETA) was used as an additive. DETA acted as a cross-linker to facilitate conjugate addition and imine formation with the catechol in quercetin. The film thickness was controllable by changing the quercetin concentration. Static water contact angles for all examined substrates converged to 25° regardless of the vastly different static water contact angles of the bare substrates, showing the universal coating capability of quercetin and DETA. Importantly, the films formed with quercetin and DETA were chemically modifiable; thus, specific functions on the surface could be introduced. α-Bromoisobutyryl bromide was immobilized on the films via esterification, and then a zwitterionic sulfobetaine polymer was subsequently grafted. Compared to the controls, the polymer-grafted surface effectively suppressed the adsorption of fibrinogen and platelets, demonstrating its non-biofouling effect. Considering its universal coating and postfunctionalization capabilities, this quercetin-based film provides a route for the preparation of functional organic coatings.

We report a facile approach for the fabrication of a marine antifouling coating using the red algae-derived polysaccharide, carrageenan (CAR). Because CAR is hydrophilic and negatively charged, we hypothesized that it would form strong hydration layers upon adsorption onto solid surfaces, thereby exhibiting marine antifouling properties. Although various types of CAR can be used for marine antifouling, a universally applicable coating method has not yet been developed; thus, a systematic study on the marine antifouling property of CAR coating is lacking. Here, we fabricated a versatile CAR coating via Zr

Klebsiella pneumoniae is one of the most critical opportunistic pathogens. TA systems are promising drug targets because they are related to the survival of bacterial pathogens. However, structural information on TA systems in K. pneumoniae remains lacking; therefore, it is necessary to explore this information for the development of antibacterial agents. Here, we present the first crystal structure of the VapBC complex from K. pneumoniae at a resolution of 2.00 A. We determined the toxin inhibitory mechanism of the VapB antitoxin through an Mg2+ switch, in which Mg2+ is displaced by R79 of VapB. This inhibitory mechanism of the active site is a novel finding and the first to be identified in a bacterial TA system. Furthermore, inhibitors, including peptides and small molecules, that activate the VapC toxin were discovered and investigated. These inhibitors can act as antimicrobial agents by disrupting the VapBC complex and activating VapC. Our comprehensive investigation of the K. pneumoniae VapBC system will help elucidate an unsolved conundrum in VapBC systems and develop potential antimicrobial agents.

Toxin-antitoxin (TA) systems have been considered essential factors for bacterial survival. During our drug development program aimed against tuberculosis (TB), we discovered certain peptides that mimic the binding of the VapBC30 complex, leading to the arrest of bacterial cell growth and eventually cell death. Herein, we optimized these candidate peptides based on a hydrocarbon stapling strategy and performed biological in vitro evaluations. The V30-SP-8 peptide successfully penetrated Mycobacterium smegmatis cell membranes and exerted bactericidal activity at a minimum inhibitory concentration that inhibited 50% of the isolates (MIC50) < 6.25 μM. With the aid of structural and biochemical information for the VapBC30 TA system from M. tuberculosis, we suggest potential antimicrobial agents that could provide a platform to establish a novel antibacterial strategy. Reflecting the limited number of therapeutic agents targeting TA systems, we believe that this study not only provides chemical tools for exploring the biological events relevant to TA systems but also opens a new gateway toward TB drug discovery.

Toxin–antitoxin (TA) systems regulate key cellular functions in bacteria. Here, we report a unique structure of the Streptococcus pneumoniae HigBA system and a novel antimicrobial agent that activates HigB toxin, which results in mRNA degradation as an antibacterial strategy. In this study, protein structure‐based peptides were designed and successfully penetrated the S. pneumoniae cell membrane and exerted bactericidal activity. This result represents the time during which inhibitors triggered S. pneumoniae cell death via the TA system. This discovery is a remarkable milestone in the treatment of antibiotic‐resistant S. pneumoniae, and the mechanism of bactericidal activity is completely different from those of current antibiotics. Furthermore, we found that the HigBA complex shows a crossed‐scissor interface with two intermolecular β‐sheets at both the N and C termini of the HigA antitoxin. Our biochemical and structural studies provided valuable information regarding the transcriptional regulation mechanisms associated with the structural variability of HigAs. Our in vivo study also revealed the potential catalytic residues of HigB and their functional relationships. An inhibition study with peptides additionally proved that peptide binding may allosterically inhibit HigB activity. Overall, our results provide insights into the molecular basis of HigBA TA systems in S. pneumoniae, which can be applied for the development of new antibacterial strategies. Databases Structural data are available in the PDB database under the accession number 6AF4., HigBA complex shows a crossed‐scissor interface with two intermolecular β‐sheets at both the N and C termini of the HigA antitoxin. The crossed‐scissor constitutes a new type of interface between HigB and HigA. We report a unique structure of the Streptococcus pneumoniae HigBA system and a novel antimicrobial agent that activates HigB toxin, which results in mRNA degradation as an antibacterial strategy.

We report a facile one-step thermal treatment method for the synthesis of biocompatible, fluorescent nitrogen-phosphorus-doped carbon nanodots (NPCDs) as multifunctional agents for the food matrix decontamination, cancer targeting, and cellular bio-imaging. NPCDs exhibit high toxicity towards L. monocytogenes, as illustrated by fluorescent live-dead cell counting, disruption of membrane permeability/potential, changes in the levels of cellular ions, genetic materials, and proteins, as well as intracellular production of reactive oxygen species. The tryptophan and protein peaks released in NPCDs treated cells contributed to indole ring breathing and correlated with induced cell death. NPCDs significantly inhibited bacterial biofilm formation on a solid substrate. NPCDs-coated low-density polyethylene (LDPE) film crosslinked with 1% aminopropyltriethoxy silane (APTES) via silane-hydroxyl linking as a food-grade wrap significantly reduced bacterial counts in a raw chicken food model. Furthermore, NPCDs induced apoptosis in HeLa cervical cancer cells, as confirmed by the distorted cell morphology, fluorescence microscopic analysis, presence of fragmented nuclei and the qPCR results of mRNA expression levels of apoptotic markers. Moreover, NPCDs were also applicable in utilized for the cellular bio-imaging of KM12-C colon cancer cells under confocal microscopy owing to their excellent luminescence properties. Overall, NPCDs represent a promising platform to reduce the environmental health risks associated with hazardous pathogens, anticancer targeting, and their application in cellular bio-imaging as multifunctional targets/nanocarriers.

Enhancement of blood compatibility with the implant surface is critical for biomedical devices. Coating solid surfaces with an anticoagulant is a potentially promising strategy to improve blood compatibility with the implant surface. This study aimed to develop an approach to enhance blood compatibility with titanium/titanium dioxide (Ti/TiO2) surfaces using a green seaweed-derived polysaccharide ulvan. The approach comprises surface coating with tannic acid (TA) and grafting of ulvan onto the surface. Zirconium(IV)-based coordination linkage between ulvan and TA facilitated robust deposition of ulvan multilayers onto Ti/TiO2 surfaces. Adhesion assays revealed that more than 95% of fibrinogen adsorption and platelet adhesion was suppressed through an ulvan multilayer coating. The present results show that ulvan multilayers are robust against chemical and physical treatments and resistant to the adsorption of adherent proteins and human platelets.

Rationale: The present study reports the multifunctional anticancer activity against B16F10 melanoma cancer cells and the bioimaging ability of fluorescent nitrogen-phosphorous-doped carbon dots (NPCDs). Methods: The NPCDs were synthesized using a single-step, thermal treatment and were characterized by TEM, XPS, fluorescence and UV-Vis spectroscopy, and FTIR analysis. The anticancer efficacy of NPCDs was confirmed by using cell viability assay, morphological evaluation, fluorescent live-dead cell assay, mitochondrial potential assay, ROS production, RT-PCR, western-blot analysis, siRNA transfection, and cellular bioimaging ability. Results: The NPCDs inhibited the proliferation of B16F10 melanoma cancer cells after 24 h of treatment and induced apoptosis, as confirmed by the presence of fragmented nuclei, reduced mitochondrial membrane potential, and elevated levels of reactive oxygen species. The NPCDs treatment further elevated the levels of pro-apoptotic factors and down-regulated the level of Bcl2 (B-cell lymphoma 2) that weakened the mitochondrial membrane, and activated proteases such as caspases. Treatment with NPCDs also resulted in dose-dependent cell cycle arrest, as indicated by reduced cyclin-dependent kinase (CDK)-2, -4, and -6 protein levels and an enhanced level of p21. More importantly, the NPCDs induced the activation of autophagy by upregulating the protein expression levels of LC3-II and ATG-5 (autophagy-related-5) and by downregulating p62 level, validated by knockdown of ATG-5. Additionally, owing to their excellent luminescence property, these NPCDs were also applicable in cellular bioimaging, as evidenced by the microscopic fluorescence imaging of B16F10 melanoma cells. Conclusion: Based on these findings, we conclude that our newly synthesized NPCDs induced cell cycle arrest, autophagy, and apoptosis in B16F10 melanoma cells and presented good cellular bioimaging capability.

Cesium lead bromide perovskite quantum dots (PQDs) have recently attracted much attention because of their remarkable optoelectronic properties, such as high photoluminescence quantum efficiency, n...

A graphene aerogel (GA) with a three-dimensional (3D) structure, ultra-lightweight nature, and high hydrophobicity was simply fabricated by the one-step pyrolysis of glucose and ammonium chloride. The as-synthesized GA exhibited a 3D interconnected microporous architecture with a high surface area of ∼2860 m

Catechols are prone to oxidative polymerization as well as complex formation with metal ions. These two features of catechols have played an important role in the construction of functional films on various surfaces. For example, marine antifouling films and antibacterial films were successfully prepared by oxidative polymerization and metal complexation of catechol-containing molecules, respectively. However, the effect of simultaneous metal complexation and oxidative polymerization on functional film formation has not yet been fully investigated. Herein, as a derivative of 3-(3,4-dihydroxyphenyl)-l-alanine (DOPA), we synthesized an ethylene glycol-derivatized DOPA (OEG-DOPA) and formed OEG-DOPA thin films based on (1) oxidative polymerization and (2) the complexation between catechol groups of OEG-DOPA and iron(III) (FeIII) ions. Either or both approaches were used for the film formation. OEG-DOPA film formation was characterized by ellipsometry, contact angle goniometry, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. Among the conditions used, the formation of a uniform film was only achieved with the dual cross-linking system of FeIII complexation and oxidation-induced covalent bond formation. Compared to the uncoated substrate and other OEG-DOPA films prepared under different conditions, the uniform OEG-DOPA film strongly inhibited bacterial adhesion, showing excellent antibacterial capability. We think that our surface-coating strategy can be applied to medical devices, tools, and implants where bacterial adhesion and biofilm formation should be prevented. This work can also serve as a basis for the construction of functional thin films for other catechol-functionalized materials.

Transcriptional regulator proteins are closely involved in essential survival strategies in bacteria. AcrR is a one-component allosteric repressor of the genes associated with lipid transport and antibiotic resistance. When fatty acid ligands bind to the C-terminal ligand-binding cavity of AcrR, a conformational change in the N-terminal operator-binding region of AcrR is triggered, which releases the repressed DNA and initiates transcription. This paper focuses on the structural transition mechanism of AcrR of Mycobacterium tuberculosis upon DNA and ligand binding. AcrR loses its structural integrity upon ligand-mediated structural alteration and bends toward the promoter DNA in a more compact form, initiating a rotational motion. Our functional characterization of AcrR and description of the ligand- and DNA-recognition mechanism may facilitate the discovery of new therapies for tuberculosis.

Dopamine surface chemistry has been of great interest because of its universal coating property and ability to transform nonadhesive molecules into adhesive molecules. Catechol oxidation and intramolecular cyclization underlie the unique property of dopamine (DA) surface chemistry and provide clues for developing new surface modification reagents such as norepinephrine, 5-pyrogallol-2-aminoethane, and perfluorinated DA derivatives. Based on these inspiring properties, a fast and universal surface chemistry technique using 4-(3-aminopropyl)-benzene-1,2-diol (3-catecholpropanamine, CPA) is reported herein. A single carbon insertion in the aliphatic chain of DA gives rise to the significantly accelerated intermolecular assembly and surface coating of CPA. The effect of CPA conjugation on an anticoagulant polysaccharide coating is also investigated. The use of CPA instead of DA to make polysaccharide coating materials improves the coating rate, while maintaining excellent antiplatelet performance on the coated surface.

We investigated the catalytic efficiency of alginate hydrogels used as a catalyst support. An alginate solution containing palladium and magnetic nanoparticles was dropped continuously through a tapered glass capillary using a syringe pump, and the generated alginate droplets were collected in an aqueous solution containing divalent cations. The prepared PdNPs/MNPs-embedded alginate particles were used as a catalyst, catalyst support, and magnetic stirrer for the reduction of 4-nitrophenol. The catalytic reactions were found to depend on the magnetic stirring of the alginate hydrogels. Furthermore, we examined the recyclability while changing the alginate concentration, divalent cation species, and incubation protocols.

In this work, a Prussian blue (PB)/graphene oxide (GO)/chitosan (CS) organic-inorganic composite was successfully synthesized and utilized as an adsorbent for the selective removal of cesium (Cs+) ions. Taking the advantage of synergistic effect GO, CS and PB nanoparticles, the PB/GO/CS composite exhibited maximum adsorption capacity of 48.35 mg g−1 for Cs+ ions. In the presence of competitive monovalent cations (K+ and Na+), PB/GO/CS showed excellent selectivity (86%) for Cs+ ions and had a 6-fold higher distribution coefficient (Kd) than GO/CS. This enhanced adsorption capacity with high selectivity of PB/GO/CS for Cs+ ions may have been attributed to (i) the presence of carboxylic, hydroxyl and amino functional groups on GO/CS matrix which strongly bind Cs+ ions through electrostatic attraction and chelation, and (ii) the trapping of Cs+ ions by the voids of the FCC-structured PB lattice whose size is equivalent to the hydration radius of Cs+ ions. Due to its low-cost, facile preparation, high adsorption capacity, and superior Cs+ ions selectivity, PB/GO/CS is a promising material for the selective removal of the Cs+ ions from the environment and for protecting ecosystems from the radiation hazards.

In this work, a unique one-pot green synthesis technique that utilizes high energy gamma-irradiation technology was successfully designed to fabricate a stable, highly-porous Prussian blue (PB)/polyvinylpyrrolidone (PVP)/reduced graphene oxide (rGO) aerogel (PB@PVP/rGO) with a 3D-network structure, low density, and high mechanical strength. In this synthesis process, PB nanoparticles were generated in situ and then homogenously distributed and entrapped within the PVP/rGO aerogel. The synthesized aerogel exhibited (i) a three-dimensional microporous architecture consisting of an interconnected network structure with an ultra-low density of 0.0273 g cm−3; (ii) remarkable swelling ability in the presence of water at low pH levels; and (iii) strong mechanical stability, leading to excellent deformability without cracks or the loss of structural integrity, due to the double-network structure of the PB@PVP/rGO aerogel and the crosslinking between the stiff GO sheets and the flexible PVP chains. The hydrophilic PB@PVP/rGO aerogel demonstrated the rapid adsorption of Cs+ ions and MB dye due to capillary action; based on the Langmuir model it demonstrated a maximum adsorption capacity of 143.88 and 44.73 mg g−1 for Cs+ and MB, respectively. The PB@PVP/rGO aerogel also exhibited outstanding oil absorption capacity, which we attribute to its highly interconnected porous structure and the presence of oleophilic rGO. The excellent adsorption properties coupling with the unique structural features of this PB@PVP/rGO aerogel make it a promising adsorbent for oil spills and for the removal of environmental pollutants such as Cs+ and MB in water.

N-doped graphene supported quaternary electrocatalyst (PtRuFeCo/NG) was synthesized and evaluated for potential oxygen reduction (ORR) and methanol oxidation reaction (MOR) in fuel cells. The catalyst exhibited excellent MOR (strong CO tolerance, lower onset potential), ORR (four electron transfer) activities and delivered maximum power densities of 778 and 122 mW cm−2 with direct methanol and proton exchange membrane fuel cells, respectively. The N-doping and synergistic effects of alloying low-cost Fe and Co with Pt and Ru makes PtRuFeCo/NG as excellent bifunctional catalyst that greatly reduces the processing cost of fuel cell which is the major problem facing the fuel cell industry.

The structure-function relationships of toxin-antitoxin (TA) systems from Mycobacterium tuberculosis have prompted the development of novel and effective antimicrobial agents that selectively target this organism. The artificial activation of toxins by peptide inhibitors can lead to the growth arrest and eventual death of bacterial cells. Optimizing candidate peptides by hydrocarbon α-helix stapling based on structural information from the VapBC TA system and in vitro systematic validation led to V26-SP-8, a VapC26 activator of M. tuberculosis. This compound exhibited highly enhanced activity and cell permeability owing to the stabilizing helical propensity of the peptide. These characteristics will increase its efficacy against multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis. Similar approaches utilizing structural and biochemical information for new antibiotic targets opens a new era for developing TB therapies.

Advances in microscale 3D cell culture systems have helped to elucidate cellular physiology, understand mechanisms of stem cell differentiation, produce pathophysiological models, and reveal important cell-cell and cell-matrix interactions. An important consideration for such studies is the choice of material for encapsulating cells and associated extracellular matrix (ECM). This Review focuses on the use of alginate hydrogels, which are versatile owing to their simple gelation process following an ionic cross-linking mechanism in situ, with no need for procedures that can be potentially toxic to cells, such as heating, the use of solvents, and UV exposure. This Review aims to give some perspectives, particularly to researchers who typically work more with poly(dimethylsiloxane) (PDMS), on the use of alginate as an alternative material to construct microphysiological cell culture systems. More specifically, this Review describes how physicochemical characteristics of alginate hydrogels can be tuned with regards to their biocompatibility, porosity, mechanical strength, ligand presentation, and biodegradability. A number of cell culture applications are also described, and these are subcategorized according to whether the alginate material is used to homogeneously embed cells, to micropattern multiple cellular microenvironments, or to provide an outer shell that creates a space in the core for cells and other ECM components. The Review ends with perspectives on future challenges and opportunities for 3D cell culture applications.

Toxin&ndash, antitoxin (TA) systems are prevalent in bacteria and are known to regulate cellular growth in response to stress. As various functions related to TA systems have been revealed, the importance of TA systems are rapidly emerging. Here, we present the crystal structure of putative mRNA interferase BC0266 and report it as a type II toxin MazF. The MazF toxin is a ribonuclease activated upon and during stressful conditions, in which it cleaves mRNA in a sequence-specific, ribosome-independent manner. Its prolonged activity causes toxic consequences to the bacteria which, in turn, may lead to bacterial death. In this study, we conducted structural and functional investigations of Bacillus cereus MazF and present the first toxin structure in the TA system of B. cereus. Specifically, B. cereus MazF adopts a PemK-like fold and also has an RNA substrate-recognizing loop, which is clearly observed in the high-resolution structure. Key residues of B. cereus MazF involved in the catalytic activity are also proposed, and in vitro assay together with mutational studies affirm the ribonucleic activity and the active sites essential for its cellular toxicity.

Surface modification using alginic acid and its salt, alginate (Alg), has attracted much attention owing to its potential applications in various fields, including tissue engineering, drug delivery, antiplatelet surface preparation, and energy-storage technologies. In these applications, efficient immobilization of Alg on the solid surface is required because the delamination of the surface-bound Alg eventually leads to a significant decrease in its function. Therefore, much effort has been made to introduce Alg onto solid surfaces in a stable manner. Despite recent advances, existing methods for immobilizing Alg on surfaces have some limitations: (i) derivatization of Alg is typically also required and (ii) these methods only function under specific reaction conditions. Herein, we report a Zr(IV)-mediated strategy to immobilize Alg on solid surfaces. We demonstrate efficient Alg grafting onto carboxyl-, catechol-, polydopamine-, and tannic acid-functionalized surfaces via Zr(IV)-mediated cross-linking reactions. This strategy yields Alg multilayers that suppress fibroblast and platelet adhesion onto the solid surfaces. Furthermore, we show that the Alg multilayers can be selectively constructed on specific sites of solid surfaces. Given its ease of use and the wide selection of available carboxyl polymers, the current strategy is expected to be a useful tool for preparing functional polymer films for various applications.

Mussel-inspired surface chemistry, in which catechol derivatives play an important role, has garnered extensive research interest owing to material-independent surface coating capability and easy implementation to a wide range of applications. Generally, sequential reactions comprising catechol oxidation, intramolecular reaction of oxidized catechols with nucleophiles, and intermolecular assembly result in polymers that can adhere to many diverse surfaces. Although amines and thiols have similar reactivity toward oxidized catechols, most studies have been conducted with catechol and amine groups as essentials. Surface coating with catechol-thiol has not been investigated. In this study, we show that 4-(2-mercapto-ethyl)-benzene-1,2-diol (catechol-thiol) can serve as a surface coating agent in the presence of a strong oxidant. A wide range of materials are coated with catechol-thiol, and an additional grafting of the functional molecules onto the surface is also performed through well-established thiol chemistry, Michael addition, and thiol-ene reaction.

Consumption of sunset yellow (SY) above a certain concentration through food products may leads to adverse health issues. Therefore, it is imperative to develop technologies for rapid and selective detection of SY. Herein, a flower-like reduced graphene oxide (rGO)-graphitic carbon nitride (g-CN)/ZnO-Au nanoparticle (NPs) has been prepared and utilized for the specific detection of SY. The fabricated rGO-g-CN/ZnO-AuNPs composite was characterized and investigated by XRD, FTIR, SEM, TEM, XPS, EIS, and voltammetry techniques. Characterization techniques elucidated the deposition of ZnO-AuNPs on to the rGO-g-CN and successful fabrication of rGO-g-CN/ZnO-AuNPs composite. rGO-g-CN/ZnO-AuNPs composite possesses excellent catalytic activity for the oxidation of SY. Developed rGO-g-CN/ZnO-AuNPs sensor exhibits LOD of 1.34 nM for SY concentrations ranging from 5 to 85 nM. Noteworthily, the sensor has been successfully employed for the detection and recovery of SY in real-time samples. Fabricated composite opens up new avenues to develop electrochemical sensor for food safety.

We synthesized a zwitterionic dopamine derivative ( ZW-DOPA) containing both catechol and amine groups, and we demonstrated an excellent marine antifouling surface by controlling the oxidation of ZW-DOPA. The oxidation was mediated by the deprotonation of catechol or the addition of an oxidant (ammonium persulfate (AP) or sodium periodate (NaIO4)). The oxidation and subsequent molecular transformation of ZW-DOPA was investigated over time by UV-vis spectroscopy. Among the different oxidation conditions tested, NaIO4-induced ZW-DOPA coating was the most efficient and successfully formed on various substrates, such as titanium dioxide, stainless steel, and nylon. Compared with uncoated substrates, ZW-DOPA-coated substrates showed high resistance to marine diatom adhesion. Considering the ease of use and substrate independence of the ZW-DOPA coating, this method shows promise as a basis for inhibiting marine fouling on a variety of substrates used in the marine industry and aquatic environments.

Several industries using gamma sterilization techniques for food safety, and long shelf-life purposes. Nuclear energy production has increased the amount of spent nuclear fuel produced, which poses risks of severe diseases in human. Cesium is one of the most hazardous material can cause human exposure to air, water, and food. The efficient removal of cesium ions (Cs+) has been emphasized using biological control strategies. In this study, we isolated a new Cs+-tolerant (100, 500, and 750 ppm) and gamma radiation resistant (1, 3, and 5 kGy) soil bacterium (CR1) from the soil around a nuclear power plant in Korea, which was identified as Exiguobacterium acetylicum CR1 by 16S rRNA sequencing. E. acetylicum CR1 was found to be resistant to high doses of gamma radiation without any loss in Cs+ tolerance or survival. Furthermore, E. acetylicum CR1 was found to act as a microbiological control agent with respect to the removal of cesium from contaminated water. Interestingly, after gamma radiation exposure, E. acetylicum CR1 developed significantly (p

Background/aim Few studies have examined the effect of 2'-hydroxycinnamaldehyde (HCA) on head and neck squamous cell carcinoma (HNSCC) cell invasion. This study examined the role of BMP7 on the anti-migration and anti-invasion activity of HCA using HNSCC cells. Materials and methods Matrigel invasion and wound healing assays were conducted to investigate cell migration or invasion. BMP7 overexpression vector or siRNA mixture was used for transient regulation of gene expression. Results HCA attenuated HNSCC cell migration and spheroids Matrigel invasion without cytotoxicity. mRNA and protein expression of BMP7 increased with HCA treatment. Exogenous BMP7 overexpression without HCA treatment attenuated Matrigel invasion of cells. Furthermore, suppression of BMP7 by siRNA alleviated the inhibitory effect of HCA on the invasion of Matrigel by the cell, indicating that BMP7 is responsible for the anti-migration effect of HCA in HNSCC cells. Conclusion HCA treatment led to a remarkable up-regulation of BMP7, which resulted in the attenuation of HNSCC cell invasion.

In this work, multifunctional Fe-aminoclay (FeAC)/carboxymethyl cellulose (CMC)/ polyhedral oligomeric silsesquioxane (POSS) composite (FeAC/CMC/POSS) with layered structure was successfully synthesized and utilized as adsorbent for the removal of cesium ions (Cs+) and cationic dyes methylene blue (MB) and chrysoidine G (CG) from aqueous solutions. The FeAC/CMC/POSS exhibit excellent adsorption capacities for Cs+ ions, MB and CG of 152, 438, and 791 mg g–1, respectively. The adsorption capacities for Cs+ ions, MB and CG are substantially greater than those of many previously reported adsorbents due to (i) the layered morphology of the composite and abundance of amino (−NH2) groups on clay surface and (ii) existence of carboxylate (−COO–) and hydroxyl (−OH–) groups on the CMC backbone, which contribute to the adsorption of large number of Cs+ ions and dye molecules through electrostatic attraction and ion-exchange process. More importantly, the incorporation of POSS increases the interlayer spacing of Fe-a...

A customized droplet-based microfluidic reactor was fabricated for the synthesis of silver nanoparticles (Ag NPs) using silver nitrate (AgNO3) and branched polyethyleneimine (BPEI) as a precursor and a reducing agent, respectively. The effects of static mixing, temperature, and the volumetric flow rates of AgNO3 and BPEI on the particle size were investigated. The use of a static mixer and the optimization of the reaction temperature enhanced the monodispersity of the Ag NPs. In addition, the size of the Ag NPs was manipulated by changing the flow rate ratio of AgNO3 to BPEI at 60 °C for 60 min.

Here, we designed and synthesized a recoverable multifunctional adsorbent using a microfluidic reaction system and evaluated the removal performance of the smart adsorbent toward radioactive cesium as a model sample. Prussian blue-laden magnetic micro-adsorbents (PB-MNPs-MAs) with uniform morphology and monodispersity were generated via two-step sequential procedures using a glass capillary microfluidic system, followed by chemical co-precipitation with a high production rate. The cesium removal efficacy of the PB-MNPs-MAs was analyzed based on Langmuir and Freundlich isotherms by controlling adsorption parameters such as adsorbent size, initial cesium concentration, and contact time. The adsorption isotherm of the PB-MNPs-MAs was better fitted to the Langmuir model with a maximum cesium adsorption capacity of 58.73 mg g−1, which was 40% higher than that of macro-adsorbents in a dynamic magnetic field. This result can be attributed to their large specific area, which increased the kinetic rate of cesium adsorption and achieved saturation within 20 min. Additionally, the PB-MNPs-MAs were recovered from wastewater within 5 s under a static magnetic field, indicating their great potential for magnetic actuation. We believe that our PB-MNPs-MAs can encapsulate nano-functional adsorbents and prevent actuation, making them promising for environmental remediation and especially for removal of radionuclides.

We describe a facile, economic, and environment friendly green method for simultaneous detection of palladium ions (Pd2+) and recovery Pd nanoparticles (Pd NPs) from wastewater through a non-toxic gamma-irradiation based reduction reaction. Basic orange 2 (BO), an azo dye, is used as a sensing probe in Pd2+ detection and acts as a stabilizing agent in the recovery of monodispersed small Pd NPs. The presence of Pd2+ in waste water was easily observed by naked eye through the color change from yellow to red upon adding the Basic orange 2. More importantly, Pd forms a square-planar structured complex with Pd2+ which aids the development of smaller and monodispersed Pd NPs during radiolytic reduction. The size control mechanism during the recovery of Pd NPs was ascertained by varying the intensity of gamma-ray (from 10 to 50 kGy) and initial concentrations of Pd2+ (from 20 to 100 ppm). We are able to control the size of Pd NPs from 5 to 400 nm by irradiating gamma-ray doses from 1 and 50 kGy, as evident from UV-vis absorption spectra (UV-vis) and transmission electron microscopy (TEM) images. About 15 nm colloidal Pd NPs were formed at 10 kGy gamma-irradiation, and various sizes of aggregates, which may be attributed to Ostwald ripening crystal growth, were observed in the irradiation condition of 20 to 50 kGy. Further, the size of the recovered Pd NPs increases as the Pd2+ concentration increased, due to the increase in the ion association rate. Our proposed green method is a promising strategy that can easily detect Pd2+ from waste water and recover Pd NPs in desired size and morphology.

In this work, we prepared two-dimensional (2D) stack-structured aminopropylIsobutyl polyhedral oligomeric silsesquioxane (POSS-NH2) intercalated titanium carbide (Ti3C2Tx) MXene material (Ti3C2Tx/POSS-NH2) using a post-intercalation strategy as a potential adsorbent for the removal of cesium (Cs+) and strontium (Sr2+) ions from aqueous solutions. Ti3C2Tx/POSS-NH2 exhibited unprecedented adsorption capacities of 148 and 172 mg g−1 for Cs+ and Sr2+ ions, respectively. Batch adsorption experimental data well fitted the Freundlich isotherm model, which revealed multilayer adsorption of Cs+ and Sr2+ ions onto heterogeneous –OH, –F, –O, and –NH2 adsorption sites of Ti3C2Tx/POSS-NH2 with different energies. Ti3C2Tx/POSS-NH2 exhibited rapid Cs+/Sr2+ ions adsorption kinetics and attained equilibrium within 30 min. Also, Ti3C2Tx/POSS-NH2 exhibited recyclable capability over three cycles and remarkable selectivities of 89% and 93% for Cs+ and Sr2+ ions, respectively, in the presence of co-existing mono- and divalent cations. We suggest the high adsorption capacity of Ti3C2Tx/POSS-NH2 might be due to the synergistic effects of (i) increased inter-lamellar distance between Ti3C2Tx galleries due to POSS-NH2 intercalation, enabling diffusion and encapsulation of large numbers of Cs+/Sr2+ ions, (ii) strong complexation of amine (–NH2) groups of POSS-NH2 with Cs+/Sr2+ ions, and (iii) the presence of large numbers of heterogeneous surface functional groups (e.g., –OH, –F, and –O), which resulted in the adsorptions of Cs+/Sr2+ ions through electrostatic, ion exchange, and surface complexation mechanisms. Given the extraordinary adsorption capacities observed, intercalation appears to be a promising strategy for the effective removal of radioactive Cs+ and Sr2+ ions from aqueous media.

In this study, we have synthesized N-doped graphene (NG) supported ternary PtRuFe nanocatalyst with size ranging from 2 to 3 nm using microwave-assisted polyol method and evaluated its electrochemical activity towards methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) in direct methanol fuel cell (DMFC) and proton exchange membrane fuel cell (PEMFC), respectively. The as-prepared bifunctional PtRuFe/NG catalyst exhibited excellent electrocatalytic activity towards both MOR and ORR. During MOR, the PtRuFe/NG catalyst showed the stronger CO tolerance, lower onset potential, and higher methanol oxidation current than that of its un-doped counterpart (PtRuFe/rGO). In ORR, the catalyst exhibited higher oxygen reduction current with four electron transfer. The maximum power density delivered by PEMFC and DMFC using PtRuFe/NG were 870 and 112 mW cm−2, respectively, which are 25% higher than that of its un-doped counterpart. Also PtRuFe/NG showed 2- to 3-fold improvement in MOR, ORR, PEMFC and DMFC performances as compared with previously reported values of mono-, bi-, and tri-metallic catalysts supported on NG and other carbon substrates. The enhanced electrochemical activity may be attributed to the synergetic effect of nitrogen-doping along with the bi-functional and ligand effects of alloying low-cost Fe with Pt and Ru. The bifunctional ternary PtRuFe nanocatalysts supported on N-doped graphene has excellent potential to catalyze both MOR and ORR with remarkable reduction in the processing cost of fuel cells which is the primary problem facing the commercialization of fuel cells.

The authors describe an electrochemical sensor for nitrite that is based on the use of a screen printed carbon electrode modified with palladium nanoparticles and an amino-functionalized metal-organic framework. The morphology and properties of the resulting material were examined by X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetry, FTIR spectroscopy and transmission electron microscopy. Nitrite was chosen as a model analyte to evaluate the electron transfer performance of the modified SPCE. Its preparation conditions were optimized. The response to nitrite was studied via cyclic voltammetry, linear sweep voltammetry, and square wave voltammetry. Under the optimal conditions, the oxidation current (typically measured at −0.86 V vs Ag/AgCl) increases linearly in the 5 to 150 nM nitrite concentration range, and the detection limit is 1.3 nM. The sensor was applied to the detection of nitrite in (spiked) sausage and pickle samples. It is highly selective to nitrite in the presence of high concentrations of other electro-active compounds, stable, and well reproducible. In our perception, the sensor presented here reveals the large potential of MOF-based hybrid materials for use as an electrode material.

The effect of oxytocin (OXT) on cancer invasion is controversial. Few studies have examined the effect of early growth response-1 (EGR1) on the invasion of head and neck squamous cell carcinoma (HNSCC). Here, we evaluated how EGR1 affects HNSCC cell migration through the molecular mechanism of OXT in exerting anti-invasion activity. Matrigel invasion and wound-healing assays were used to measure the in-vitro cell migration. The molecular mechanism of OXT was assessed by knockdown or overexpression of EGR1 in HNSCC cells. Three-dimensional (3-D) spheroids formation, followed by the image analysis for quantification was performed. OXT at 500 nmol/l increased mRNA and protein expression of E-cadherin without cytotoxicity. OXT upregulated mRNA and protein expression of EGR1 in 6 h. p53, phosphatase and tensin, and p21 expression was increased in an EGR1-dependent manner with OXT treatment. In addition, OXT significantly downregulated 3-D spheroids' formation according to spheroids' number and size. Our data showed that OXT downregulated HNSCC cell migration by EGR1 upregulation. OXT inhibited spheroids' formation of HNSCC cells under 3-D culture conditions.

Cesium (Cs), a radioactive contaminant of the ecosystem, causes a major risk to human health and environments. Till now, the cesium sensor fabrication methods have been reported with the usage of expensive chemicals that are complex and time-consuming. In this work, we have fabricated a paper-based colorimetric device impregnated with a chrysoidine G (CG) as chemo-indicator which is simple, rapid, low-cost, and portable using a naked-eye quantitative technique for the detection and monitoring of inactive cesium in environmental analysis. This chemo-indicator is designed to exhibit a powerful detection capability featuring high selectivity and sensitivity to inactive Cs, by means of color discrimination from light yellow to red orange. Interestingly, a portable smart phone camera, which determined the relative red/green/blue (RGB) values within 3 s, provided us with further information on environmental pollution. Using our new colorimetric reusable sensor (CRS) platform, the CRS shows excellent detection linearity (R2 = 0.99) of inactive Cs from the contaminated water. Our results will pave the way for portable and versatile sensors and, in turn, for the detection and monitoring of toxic inactive cesium in contaminated water samples.

In this study, highly biocompatible three-dimensional hierarchically porous activated carbon from the low-cost silver grass (Miscanthus sacchariflorus) has been fabricated through a facile carbonization approach and tested it as bioanode in microbial fuel cell (MFC) using Escherichia coli as biocatalyst. This silver grass-derived activated carbon (SGAC) exhibited an unprecedented specific surface area of 3027 m2 g−1 with the coexistence of several micro-, meso-, and macropores. The synergistic effect from pore structure (macropores — hosting E. coli to form biofilm and facilitates internal mass transfer; mesopores — favors fast electron transfer; and micropores — promotes nutrient transport to the biofilm) with very high surface area facilitates excellent extracellular electron transfer (EET) between the anode and biofilm which resulted in higher power output of 963 mW cm−2. Based on superior biocompatibility, low cost, environment-friendliness, and facile fabrication, the proposed SGAC bioanode could have a great potential for high-performance and cost-effective sustainable MFCs.

A facile approach to enhancing the blood compatibility of solid surfaces based on ZrIV -heparin complexation is reported. Solid surfaces are pretreated with tannic acid (TA)/ZrIV complexes. Heparin is then deposited on the surface through a spin-coating process and fixed by a ZrIV -mediated crosslinking reaction. Using this approach, TA/ZrIV /heparin complex multilayers that are highly resistant to human platelet adhesion are formed on various substrates including metal, metal oxides, ceramics, and synthetic polymers. This approach presents a sustainable way for the immobilization of heparin onto surfaces because it does not require any derivatization of heparin molecule as well as time-consuming processes.

The original version of this article unfortunately missed Prof. A.T. Ezhil Vilian’s project number in Acknowledgements. The missing project number is 2017R1D1A1B03034977.

In current work, Prussian blue (PB)- and hydroxyapatite (HAp)-embedded micro-adsorbents (PB-HAp-MAs) were rationally fabricated through an easy and flexible custom-made micronozzle system as a novel bifunctional adsorbent. The adsorption performance of the as–prepared samples was conducted based on the removal of cesium (Cs+) and strontium (Sr2+) ions. Adsorption behaviors of the PB-HAp-MAs were also evaluated as function extrusion dimensions and adsorbate concentration. The adsorption isotherm was well fitted by the Langmuir model with adsorption capacities of 24.688 mg g−1 and 29.254 mg g−1 for Cs+ and Sr2+, respectively. Specially, the enhanced adsorption activity can be synergistically attributed to the porous nature of the developed alginate backbone with a high surface area of encapsulated functional nanoparticles, thus leading to rapid saturation within 1 min. In addition, the as-synthesized PB-HAp-MAs were successfully separated from the aqueous solution within 10 s by applying a magnetic field. We expect that our findings will provide valuable guidelines towards developing highly efficient adsorbents for environmental remediation.

In the present study, spinel cobalt ferrite hierarchical flower-like microspheres (CoFe2O4-MS) are fabricated using a hydrothermal method and utilized as a biocompatible anode in microbial fuel cells (MFCs) for power generation. A maximum power density of 1964 mW m−2 is achieved with CoFe2O4-MS in a mediator-less MFC using Escherichia coli as a biocatalyst and glucose as a fuel. The unprecedented power generation by CoFe2O4-MS can be attributed to (i) the morphology of the flower-like CoFe2O4-MS, with a rough surface and large surface area suitable for biofilm formation, (ii) the rapid immobilization of negatively charged E. coli cells on the positively charged CoFe2O4-MS, facilitating stronger bacterial adhesion between the bacterial cells and CoFe2O4-MS, which leads to lower contact resistance and advantageous interfacial properties with rapid electron transfer, and, more importantly, (iii) enhanced interfacial charge transfer due to the presence of multi-valent cations and multiple valence states in the highly electrocapacitive CoFe2O4-MS. Thus, the enrichment of electroactive E. coli on CoFe2O4-MS produces a large number of electron-shuttling endogenous redox mediators, which promotes efficient extracellular electron transfer between E. coli and the electrocapacitive CoFe2O4-MS during the oxidation of the substrate, thus generating higher power output.

A cytocompatible method of surface-initiated, activator regenerated by electron transfer, atom transfer radical polymerization (SI-ARGET ATRP) is developed for engineering cell surfaces with synthetic polymers. Dopamine-based ATRP initiators are used for both introducing the ATRP initiator onto chemically complex cell surfaces uniformly (by the material-independent coating property of polydopamine) and protecting the cells from radical attack during polymerization (by the radical-scavenging property of polydopamine). Synthetic polymers are grafted onto the surface of individual yeast cells without significant loss of cell viability, and the uniform and dense grafting is confirmed by various characterization methods including agglutination assay and cell-division studies. This work will provide a strategic approach to the generation of living cell-polymer hybrid structures and open the door to their application in multitude of areas, such as sensor technology, catalysis, theranostics, and cell therapy.