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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.

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.

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.

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.

Here we describe a tetrapod microneedle injector that produces multifunction encoded particles. The custom-built tetrapod-like needle injector consists of spatially oriented microneedles operated by micropump using programmed on and off sequences. For the purpose of this study to achieve various functions from one particle, each constituent contained in a multifunction encoded particle confirms the cesium adsorption of PB, the drug release behavior of DTPA, and rapid mixing of immiscible liquids due to magnetic actuation. We believe that the multi-functionalized particles may have synergistic multifunctional properties and push the boundaries of advanced biomaterials in biomedical engineering.

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.

Over the past two decades, the radiosynthesis of metallic nanoclusters (MNCs) using γ-irradiation (γ-radiosynthesis) has presented a wealth of opportunities for the application of nanomaterials in areas such as medicine, energy, catalysis, and sensors. Unlike conventional methods, this technique provides fully reduced and highly stable MNCs that are free from by-products or impurities. γ-Radiosynthesis has thus proven to be a clean and green approach for bulk fabrication of MNCs with tunable particle sizes and morphologies. More recently, the in-situ decoration of MNCs on support materials using γ-irradiation has attracted much attention due to the synergistic effect between MNCs and the underlying support. In this review, we discuss the current state of research into the mechanisms underlying the γ-radiosynthesis of supported and unsupported mono- and bi-metallic nanoclusters and summarize the use of MNCs in catalysis, sensing, biomedicine, and energy applications.

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.

This paper reports the development of a novel mechanical sensing elastomer that leverages the advantages of graphene, and multi-walled carbon nanotubes (MWCNTs) into Ecoflex and integrated using a unique liquid phase fusion process. The graphene-MWCNT elastomer is used to form a stretchable sensor for monitoring subtle changes of the plant growth over multiple days in a field condition.

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.

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.

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.

Sung-Chan Jang,1,2,* Sung-Min Kang,1,* Jun Young Lee,3,* Seo Yeong Oh,1 AT Ezhil Vilian,4 Ilsong Lee,1,2 Young-Kyu Han,4 Jeong Hoon Park,3 Wan-Seob Cho,5,* Changhyun Roh,2,6 YunSuk Huh1 1Department of Biological Engineering, Biohybrid Systems Research Center (BSRC), Inha University, Incheon, 2Biotechnology Research Division, 3Radiation Instrumentation Research Division, Advanced Radiation Technology Institute (ARTI), Korea Atomic Energy Research Institute (KAERI), Jeongeup, 4Department of Energy and Materials Engineering, Dongguk University, Seoul, 5Laboratory of Toxicology, Department of Medicinal Biotechnology, College of Health Sciences, Dong-A University, Busan, 6Radiation Biotechnology and Applied Radioisotope Science, University of Science and Technology (UST), Daejeon, Republic of Korea *These authors contributed equally to this work Introduction: Positron emission tomography (PET) tracers has the potential to revolutionize cancer imaging and diagnosis. PET tracers offer non-invasive quantitative imaging in biotechnology and biomedical applications, but it requires radioisotopes as radioactive imaging tracers or radiopharmaceuticals. Method: This paper reports the synthesis of 18F-nGO-PEG by covalently functionalizing PEG with nano-graphene oxide, and its excellent stability in physiological solutions. Using a green synthesis route, nGO is then functionalized with a biocompatible PEG polymer to acquire high stability in PBS and DMEM. Results and discussion: The radiochemical safety of 18F-nGO-PEG was measured by a reactive oxygen species and cell viability test. The biodistribution of 18F-nGO-PEG could be observed easily by PET, which suggested the significantly high sensitivity tumor uptake of 18F-nGO-PEG and in a tumor bearing CT-26 mouse compared to the control. 18F-nGO-PEG was applied successfully as an efficient radiotracer or drug agent in vivo using PET imaging. This article is expected to assist many researchers in the fabrication of 18F-labeled graphene-based bio-conjugates with high reproducibility for applications in the biomedicine field. Keywords: graphene oxide, nanocomposite, imaging, radiotracer

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.

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.

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.

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.

The control of marine biofouling has gained significant attention because the uncontrolled adhesion of marine organisms onto synthetic surfaces leads to serious problems. Here, we demonstrate a facile method to inhibit the adhesion of marine organisms using the sulfated polysaccharide, heparin. Heparin was conjugated with an adhesive molecule, catechol, and the resulting adhesive heparin was used as a surface coating for stainless steel, a material commonly used for marine vessels. Immersion of stainless steel surfaces in a solution of adhesive heparin resulted in a stable heparin coating. The marine antifouling property of the surface was confirmed using marine diatom adhesion assays, which revealed that the adhesive heparin coating reduced diatom adhesion by ~75%, as compared with untreated surfaces.

Chemosensors have attracted increasing attention for their usefulness on-site detection and monitoring. In this study, we elucidated a novel, facile, and highly selective Chemo-Paper-Sensor (CPS) for detection and monitoring of strontium (Sr(2+)) ions, which means a potent colorimetric sensor based on a Chrysoidine G (CG)-coated paper strip. The CPS for highly selective colorimetric detection of strontium ion was handily analyzed to determine the red-green-blue (RGB) value using portable devices such as desktop digital scanner and mobile phone camera, quantitatively. Interestingly, an orange to dark orange color transition was observed when the aqueous and solid paper colorimetric sensor was introduced to Sr(2+) ion, respectively. It was demonstrated that the value of the signal has a linear relationship with concentrations of the strontium in the 500 ppm to 100 ppb range with a detection limit of 200 ppb. We believe that a newly developed Chemo-Paper-Sensor will be useful in a wide range of sensing applications.

We present a simple synthetic approach for the preparation of monodisperse thermosensitive gelatin microspheres in a microfluidic system. Based on the mechanism of shear force-driven break-off, aqueous droplets of a gelatin solution were continuously produced in an immiscible continuous fluid. Under cooling conditions, the gelatin droplets solidified into hydrogel microspheres, which resulted from the aggregation or crystallization of collagen folds. The produced gelatin microspheres possess a high monodispersity and fast response to environmental temperature. In addition, the size of the prepared microspheres can be manipulated by altering the flow rate of the continuous phase or aqueous phase, and the physical strength of the gelatin microspheres can be controlled by simply changing the gelatin concentration. Furthermore, this approach enables the preparation of monodisperse microspheres with the ability to exhibit different thermosensitivities and encapsulate colloidal particles under mild conditions, which demonstrate sequential release of the desired encapsulants according to the responsive temperature.

The exceptional mechanical properties of the byssus—the fibrous holdfast of mussels that provides underwater adhesion—have potential applications in medicine and technology. The catechol–Fe3+–catechol interaction underlies the unique properties of mussel byssus and has emerged as a tool for developing functional hybrid materials such as pH-responsive, self-healing gels. Herein, the construction of functional alginate (Alg) film on a solid substrate inspired by mussel byssus is reported. The approach consists of spin-coating-assisted deposition of Alg catechols onto a solid substrate and their subsequent crosslinking via catechol–Fe3+–catechol interactions. This yields robust and multilayered Alg films that are resistant to protein adsorption and suppress bacterial adhesion. This method can be used to create antibacterial films for coating implanted medical devices.

Three-dimensional (3D) in vitro model systems such as spheroids and organoids provide an opportunity to extend our physiological understanding using recapitulated tissues that mimic physiological characteristics of in vivo microenvironments. Unlike two-dimensional (2D) systems, 3D in vitro systems can bridge the gap between inadequate 2D cultures and the in vivo environments, providing novel insights on complex physiological mechanisms at various scales of organization, ranging from the cellular, tissue-, to organ-levels. To satisfy the ever-increasing need for highly complex and sophisticated systems, many 3D in vitro models with advanced microengineering techniques have been developed to answer diverse physiological questions. This review summarizes recent advances in engineered microsystems for the development of 3D in vitro model systems. We highlight and discuss in detail the relationship between the underlying physics behind the microengineering techniques, and their ability to recapitulate distinct 3D cellular structures and functions of diverse types of tissues and organs. We also introduce a number of 3D in vitro models and their engineering principles. Finally, we summarize current limitations, and provide perspectives for future directions in guiding the development of 3D in vitro model systems using microengineering techniques.

MXenes have very recently emerged as an intriguing family of graphene-like two-dimensional (2D) layer-structured transition metal carbides and/or nitrides with a high specific surface area, a large interlayer spacing, hydrophilicity, and abundant highly active surface sites, and they have found a niche in environmental remediation, as materials capable of efficiently removing and sequestering heavy metals, dyes, and radioactive nuclides. With exceptional surface tunable chemical compatibility and compositional flexibility, MXenes are resistant to radiation-induced damage and show high chemical compatibility and excellent thermal stability. They are thought to have the potential to serve as ideal adsorbents for a plethora of radionuclides such as uranium (238U), thorium (232Th), cesium (137Cs), and strontium (90Sr) with respect to technology and the economy. In this article, we comprehensively review state-of-the-art research progress on and the promising potential of MXenes as an adsorbent for the removal of radioactive nuclides from the environment. First, we discuss the structure, synthesis, intercalation/delamination and properties of MXenes. Subsequently, we emphasize their radionuclide removal applications. Finally, we present an outlook on the current challenges in the use of MXene materials for the adsorptive remediation of radionuclides and outline future opportunities for these materials. This article presents a timely and systematic review of MXenes as efficient and cost-effective radionuclide adsorbents. Furthermore, it highlights the main challenges in their use for environmental remediation and provides possible research directions.

In this research, we successfully synthesized a reduced graphene oxide/tin oxide (rGO/SnO2) composite for the electrochemical detection of fungal contaminant, patulin (PAT) that does not require a biological or chemical receptor or specific antibodies. The resulting rGO/SnO2 composite exhibited promising electrochemical properties and demonstrated outstanding performance in the direct measurement of PAT levels in contaminated apple juice samples. The differential pulse voltammetric response of the rGO/SnO2 composite electrode exhibited a linear relationship with PAT concentration in the 50–600 nM range and had a lower detection limit of 0.6635 nM. The sensor electrode exhibited high sensitivity, reliable reproducibility, and good selectivity. The designed electrochemical sensor was also tested against the time-consuming and conventional high-performance liquid chromatography (HPLC) approach for the detection of PAT in spiked apple juice samples. We found that the electrochemical sensor had ability to rapidly detect PAT in apple juice samples without the need of extraction or clean-up steps and achieved a higher recovery rate (74.33 ± 0.70 to 99.26 ± 0.70%) within a short-time analysis than did by the HPLC (61.97 ± 1.78 to 84.31 ± 1.96%), thus illustrating its feasibility for use in agricultural and food safety industries.

Inorganic perovskite nanocrystals (NCs) of cesium lead mixed halides (CsPb(X/Y)3, X = Br, Y = Cl and I) are promising optical materials for developing the high-performance photonic devices. Traditionally, anion-exchange reaction in perovskite halide NCs provides a simple substitutional way to tune the composition and emitting color with good luminescence properties in the human eye detectable visible spectral regions. However, prior synthetic procedures of perovskite NCs have employed conventional flask-based reactions which limit the fine control of perovskite NCs because of extremely fast anion-exchange kinetics. To overcome such problems, we demonstrate a droplet-based microfluidic system with simple, fast, and high-throughput parametric screening for the synthesis of perovskite NCs. By using the customized microfluidic operational system consisting of serially integrated two microfluidic reactors and heating block, we have successfully synthesized CsPbX3 perovskite NCs. In addition, we can finely control the anion-exchange reaction which can generate the formation of CsPb(X/Y)3 perovskite NCs with a wide range of visible spectrum (410–630 nm). Ultimately, we have established their potential applications in the development of solid-state lighting-based flexible display systems.

Development of advanced cell culture methods has gained increasing attention because it allows for efficient genetic engineering and precise regulation of animal reproduction on a cellular basis. Numerous studies have attempted to develop an advanced cell culture method. Previous studies have altered cell culture media and pretreated culture plates with functional molecules. Among them, a mussel-inspired polymer coating has been extensively utilized owing to its wide applicability. For instance, adhesion of human embryonic stem cells and neuronal cells on solid surfaces has been improved. Despite the excellent capability of the mussel-inspired polymer coating, most studies have primarily focused on mammalian cells. However, the efficacy of these coatings on the adhesion of other cell lines is yet unclear. This study aimed to assess the potential of the mussel-inspired polymer coating in the regulation of the adhesion of fish ovarian germline stem cells on solid surfaces. Solid surfaces were coated by polydopamine and poly-L-lysine, and the effect of the coatings on cellular behaviors was investigated.

The primary objective of this review article is to summarize the development and structural diversity of 2D/3D molybdenum disulfide (MoS2) based modified electrodes for electrochemical sensors and biosensor applications. Hydrothermal, mechanical, and ultrasonic techniques and solution-based exfoliation have been used to synthesize graphene-like 2D MoS2 layers. The unique physicochemical properties of MoS2 and its nanocomposites, including high mechanical strength, high carrier transport, large surface area, excellent electrical conductivity, and rapid electron transport rate, render them useful as efficient transducers in various electrochemical applications. The present review summarizes 2D/3D MoS2-based nanomaterials as an electrochemical platform for the detection and analysis of various biomolecules (e.g., neurotransmitters, NADH, glucose, antibiotics, DNA, proteins, and bacteria) and hazardous chemicals (e.g., heavy metal ions, organic compounds, and pesticides). The substantial improvements that have been achieved in the performance of enzyme-based amperometry, chemiluminescence, and nucleic acid sensors incorporating MoS2-based chemically modified electrodes are also addressed. We also summarize key sensor parameters such as limits of detection (LODs), sensitivity, selectivity, response time, and durability, as well as real applications of the sensing systems in the environmental, pharmaceutical, chemical, industrial, and food analysis fields. Finally, the remaining challenges in designing MoS2 nanostructures suitable for electroanalytical applications are outlined. Graphical abstract • MoS2 based materials exhibit high conductivity and improved electrochemical performance with great potential as a sensing electrode. • The role of MoS2 nanocomposite films and their detection strategies were reviewed. • Biomarkers detection for disease identification and respective clinical treatments were discussed. • Future Challenges, as well as possible research development for "MoS2 nanocomposites", are suggested.

In this work, we elucidate polymer-layered hollow Prussian blue-coated magnetic nanocomposites as an adsorbent to remove radioactive cesium from environmentally contaminated water. To do this, Fe3O4 nanoparticles prepared using a coprecipitation method were thickly covered with a layer of cationic polymer to attach hollow Prussian blue through a self-assembly process. The as-synthesized adsorbent was confirmed through various analytical techniques. The adsorbent showed a high surface area (166.16 m2/g) with an excellent cesium adsorbent capacity and removal efficiency of 32.8 mg/g and 99.69%, respectively. Moreover, the superparamagnetism allows effective recovery of the adsorbent using an external magnetic field after the adsorption process. Therefore, the magnetic adsorbent with a high adsorption efficiency and convenient recovery is expected to be effectively used for rapid remediation of radioactive contamination.

The control of biofouling, which is the unwanted adsorption of biomolecules and organisms on solid surfaces, is a prerequisite for wider applicability of the functional materials that are currently being used in biomedical industries. One of the frequently used methods for controlling biofouling is the use of surface coatings with antifouling materials. Herein, fucoidan, which is a marine-derived polysaccharide, is reported as a new type of antifouling material that is safe and broadly applicable. Fucoidan is conjugated with catechols, which are known to act as adhesives for grafting functional molecules onto solid substrates. Fucoidan catechol (FD-C) is subsequently utilized for robust fucoidan coatings of solid substrates, and the FD-C-coated surfaces show excellent antifouling capability for fouling organisms, including platelets and bacteria. The FD-C coating is also confirmed to be nonirritating upon skin contact, demonstrating its potential use in public places for inhibiting contagions.

In the present study, we successfully synthesized a porous three-dimensional Prussian blue-cellulose aerogel (PB-CA) composite and used it as a decorporation agent for the selective removal of ingested cesium ions (Cs+) from the gastrointestinal (GI) tract. The safety of the PB-CA composite was evaluated through an in vitro cytotoxicity study using macrophage-like THP-1 cells and Caco-2 intestinal epithelial cells. The results revealed that the PB-CA composite was not cytotoxic. An adsorption study to examine the efficiency of the decorporation agent was conducted using a simulated intestinal fluid (SIF). The adsorption isotherm was fitted to the Langmuir model with a maximum Cs+ adsorption capacity of 13.70 mg/g in SIF that followed pseudo-second-order kinetics. The PB-CA composite showed excellent stability in SIF with a maximum Cs+ removal efficiency of 99.43%. The promising safety toxicology profile, remarkable Cs+ adsorption efficacy, and excellent stability of the composite demonstrated its great potential for use as an orally administered drug for the decorporation of Cs+ from the GI tract.

We report an effective and versatile approach to control marine fouling on artificial surfaces based on specific chemical interactions found in marine mussels. The approach consists of mussel-inspired polydopamine coating, spin-coating-assisted deposition of poly(ethylene glycol) (PEG) catechols, and their cross-linking via catechol–Fe3+–catechol interactions. Using this approach, multilayered PEG films that were highly resistant to marine diatom adhesion were successfully constructed on various substrates, such as stainless steel, nylon, titanium oxide, and silicon oxide. We believe that our results will provide a basis for the construction of a marine antifouling agent that can be applied by a large variety of industries owing to its applicability to different types of substrates and stability under marine environments.

The surface coating of solid substrates using dextrans has gained a great deal of attention, because dextran-coated surfaces show excellent anti-fouling property as well as biocompatibility behavior. Much effort has been made to develop efficient methods for grafting dextrans on solid surfaces. This led to the development of catechol-conjugated dextrans (Dex-C) which can adhere to a number of solid surfaces, inspired by the underwater adhesion behavior of marine mussels. The present study is a systematic investigation of the characteristics of surface coatings developed with Dex-C. Various Dex-C with different catechol contents were synthesized and used as a surface coating material. The effect of catechol content on surface coating and antiplatelet performance was investigated.

Curry stains on clothes and dishes in daily life inspired us to investigate the potential use of turmeric powder, the major ingredient in curry, as a universal coating material. After condition optimization, the coating solution was made by boiling and filtering a turmeric slurry, and the coating was formed at pH 3, leading to the formation of ultrathin, transparent films. Various inorganic and polymeric substrates were successfully coated with turmeric-based materials, including gold, TiO2, SiO2, glass, stainless steel, indium tin oxide, nylon, polyethylene, polycarbonate, polypropylene, acryl, and poly(ethylene terephthalate). The turmeric-based coating was also applied to poly(tetrafluoroethylene) (PTFE, Teflon) and cyclic olefin copolymer (COC), and after double dip-coating, the water contact angle was changed from 118.2° to 49.1° for PTFE and from 91.2° to 44.7° for COC. The water contact angles for the other substrates converged to 35° after coating, confirming the substrate-independent universal co...

Herein we demonstrate a systematic investigation of chemically functionalizable, non-biofouling agarose films over large-area glass surfaces. Agarose films, prepared with various concentrations of aqueous agarose, were activated by using periodate oxidation to generate aldehyde groups at the termini of the agarose chains. The non-biofouling efficacy and binding capabilities of the activated films were evaluated by using protein and cellular patterning, performed by using a microarrayer, microcontact printing, and micromolding in capillaries. Characterization by using a fluorescence slide scanner and a scanning-probe microscope revealed that the pore sizes of the agarose films played an important role in achieving desirable film performance; the 0.2 wt % agarose film exhibited the optimum efficacy in this work.

Cell nanoencapsulation, generating cell-in-shell structures ("artificial spores"), provides a chemical toolbox for controlling the cellular behaviors and functional characteristics of individual cells. Among the shell materials studied so far, naturally occurring polyphenolic compounds, including polydopamine and tannic acid, have intensively been employed in cell-surface engineering, because their material-independent coating property eliminates an extra priming step for inducing subsequent shell formation. Albeit successful in generating cell-in-shell structures, the coating of polyphenolic compounds generally requires alkaline conditions and/or high salt conditions, which are not compatible with certain cell types. In this work, we demonstrate that the nanocoating of individual cells with a plant-derived phenolic compound, pyrogallol (1,2,3-trihydroxybenzene), occurs at mildly alkaline pH of 7.8 in an isotonic buffer. Three different cell types (anucleate, microbial, and mammalian cells) are coated with pyrogallol without noticeable decrease in cell viability. The protocol developed in this work could be applied to other polyphenolic compounds, and, considering the many polyphenols identified as a coating material, provides an advanced chemical tool in cell-surface engineering.

Directed self-assembly can produce ordered or organized superstructures from pre-existing building blocks through pre-programmed interactions. Encoding desired information into building blocks with specific directionality and strength, however, poses a significant challenge for the development of self-assembled superstructures. Here, we demonstrate that controlling the shape and patchiness of particles trapped at the air–water interface can represent a powerful approach for forming ordered macroscopic complex structures through capillary interactions. We designed hexagram particles using a micromolding method that allowed for precise control over the shape and, more importantly, the chemical patchiness of the particles. The assembly behaviors of these hexagram particles at the air–water interface were strongly affected by chemical patchiness. In particular, two-dimensional millimeter-scale ordered structures could be formed by varying the patchiness of the hexagram particles, and we attribute this effect to the delicate balance between the attractive and repulsive interactions among the patchy hexagram particles. Our results provide important clues for encoding information into patchy particles to achieve macroscopic assemblies via a simple molding technique and potentially pave a new pathway for the programmable assembly of particles at the air–water interface.