Paper-based colorimetric sensor using Photoshop and a smartphone app for the quantitative detection of carbofuran.

We developed a smartphone-assisted microchemistry analyzer for the quantitative detection of carbofuran using a paper-based colorimetric sensor, Photoshop software, and a smartphone app. The changes in color of the carbofuran enzymatic reaction in the paper-based sensor were captured and analyzed using a smartphone-controlled analyzer with an LED light source and a smartphone camera. The high accuracy of this method was demonstrated for the determination of carbofuran with a linear response in the range 0.05-1.0 ppm and limits of detection (LOD) of 0.02 and 0.018 ppm using Photoshop and smartphone app colorimetric analysis, respectively. These two methods not only show the high sensitivity and highly quantitative relationships between the concentrations of commercial carbofuran and characteristic color values of the blue channel in smartphone images but were also applied to infusions of tea. Moreover, the smartphone app is able to GPS tag the location of the test and transmit the results to a website that displays quantitative results from carbofuran samples on a map.

Past-expiration-date liquid disinfectants to deactivate biological and chemical toxins on building material surfaces.

In this study, we evaluated the deactivating efficacy of strong basicity-based (T4-102) and hydrogen peroxide-based (DF-200) disinfectants that were past their expiration date when used to deactivate biological and chemical toxins on building material surfaces. The decontamination efficacies of DF-200 and T4-102 disinfectants against dimethyl methylphosphonate (DMMP) and 2-chloroethyl ethylsulfide (2-CEES) were studied using GC-MS analysis. The bactericidal efficacies of disinfectants against Gram-negative E. coli and P. aeruginosa, and Gram-positive B. subtilis and S. aureus, were assessed in terms of the zone of inhibition, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The results indicated that the deactivation efficacy varied significantly according to the disinfectant amount, contact time, and building material. Higher efficacy of up to 99-100% was observed for biological toxins, despite passing their expiration dates. Approximately 70-78% of deactivation efficacies were observed for disinfectants against DMMP on the tile coupon at 100 µL and 24 h contact time. Moreover, the deactivation efficacy of DF-200 was better than that of T4-102. The data presented here demonstrate that the responders may use past-expiration-date disinfectants for efficacious disinfectaion in large-scale contamination incidents.

Colloidal silver-based lateral flow immunoassay for detection of profenofos pesticide residue in vegetables.

A colloidal silver nanoparticle (AgNP)-based lateral flow immunoassay (LFIA) was evaluated in terms of the rapid detection of profenofos (PEO) pesticide residue in vegetables. Colloidal AgNPs, of a diameter of approximately 20 nm, were surface-modified with trisodium citrate dehydrate (TSC) in order to improve their stability and dispersion. An anti-profenofos polyclonal antibody (pAb) was successfully immobilized on the surface of the AgNPs by ionic interaction and characterized using UV-vis, SEM, TEM, FTIR and XPS analyses. Surface modification of Ag-pAb conjugates of varying pH, pAb content and cross-reactivity was employed to design and prepare labels for use in an LFIA to examine whether these factors affect the performance of the assay. The visible detection limit and optical detection limit of the PEO test strip were 0.20 and 0.01 ppm, respectively, in PEO standard solution. This assay showed no cross-reaction with omethoate, methamidophos or pyraclofos. Finally, the PEO test strip was effectively applied for the detection of PEO in liquid vegetables A and B, with optical detection limits of 0.09 and 0.075 ppm, respectively.

Collaboration between Trinuclear Aluminum Complexes Bearing Bipyrazoles in the Ring-Opening Polymerization of ε-Caprolactone.

Trinuclear aluminum complexes bearing bipyrazoles were synthesized, and their catalytic activity for ε-caprolactone (CL) polymerization was investigated. DBu2Al3Me5 exhibited higher catalytic activity than did the dinuclear aluminum complex LBu2Al2Me4 (16 times as high for CL polymerization; [CL]:[DBu2Al3Me5]:[BnOH] = 100:0.5:5, [DBu2Al3Me5] = 10 mM, conversion 93% after 18 min at room temperature). Density functional theory calculations revealed a polymerization mechanism in which CL first approached the central Al atom and then moved to an external Al. The coordinated CL ring was opened because the repulsion of two tert-butyl groups on the ligands pushed an alkoxide initiator on an external Al to initiate CL. In these trinuclear Al catalysts, the central Al plays a role in monomer capture and then collaborates with the external Al to activate CL, accelerating polymerization.

Ultralong π-Conjugated Bis(terpyridine)metal Polymer Wires Covalently Bound to a Carbon Electrode: Fast Redox Conduction and Redox Diode Characteristics.

We developed an efficient and convenient electrochemical method to synthesize π-conjugated redox metal-complex linear polymer wires composed of azobenzene-bridged bis(terpyridine)metal (2-M, M = Fe, Ru) units covalently immobilized on glassy carbon (GC). Polymerization proceeds by electrochemical oxidation of bis(4'-(4-anilino)-2,2':6',2″-terpyridine)metal (1-M) in a water-acetonitrile-HClO4 solution, affording ultralong wires up to 7400 mers (corresponding to ca. 15 µm). Both 2-Fe and 2-Ru undergo reversible redox reactions, and their redox behaviors indicate remarkably fast redox conduction. Anisotropic hetero-metal-complex polymer wires with Fe and Ru centers are constructed via stepwise electropolymerization. The cyclic voltammograms of two hetero-metal-complex polymer wires, GC/[2-Fe]-[2-Ru] (3) and GC/[2-Ru]-[2-Fe] (4), show irreversible redox reactions with opposite electron transfer characteristics, indicating redox diodelike behavior. In short, the present electrochemical method is useful to synthesize polymer wire arrays and to integrate functional molecules on carbon.

Silver nanoparticle-base lateral flow immunoassay for rapid detection of Staphylococcal enterotoxin B in milk and honey.

A silver nanoparticle (AgNP)-based sandwich-type lateral flow immunoassay (LFIA) was evaluated for rapid detection of Staphylococcal enterotoxin B (SEB) in milk and honey. The role of trisodium citrate dihydrate (TSC) in the formation of Ag/TSC nanoparticles was established using UV-Vis spectroscopy. The association of silver with TSC in Ag/TSC nanoparticles was studied by the decrease in the intensity of anodic peak potential at 0.47 V and shift to 0.30 V in cyclic voltammetry (CV). The morphological, compositional and interaction studies of the AgNPs conjugated with the anti-SEB polyclonal antibody (Ag-sAb) was established using transmission electron microscopy (TEM) and X-ray photo electron spectroscopy (XPS) measurements. The visible detection limit and optical detection limit of the SEB test strip were 0.5 and 0.125 ppm, respectively, in SEB standard solution. This assay showed no cross-reaction with Staphylococcal enterotoxin A, Staphylococcal enterotoxin C or Salmonella typhi. Finally, the SEB test strip was effectively applied for the detection of SEB in spiked liquid milk and viscous honey, with optical detection limits of 0.25 and 0.5 ppm, respectively.

Use of pyrazoles as ligands greatly enhances the catalytic activity of titanium iso-propoxide for the ring-opening polymerization of l-lactide: a cooperation effect.

Using TiOiPr4 with a pyrazole ligand for one-pot LA polymerization improved catalytic activity compared with using TiOiPr4 only. At 60 °C, TiOiPr4 with furPz exhibited a higher catalytic activity (approximately 3-fold) than TiOiPr4. At room temperature, TiOiPr4 with BuPz exhibited a higher catalytic activity (approximately 17-fold) than TiOiPr4. High molecular mass PLA (M nGPC = 51 100, and D = 1.10) could be produced by using TiOiPr4 with furPz in melt polymerization ([TiOiPr4] : [furPz] = 1000 : 1 : 1 at 100 °C, 240 min). The crystal structure of MePz2Ti2OiPr7 revealed the cooperative activation between two Ti atoms during LA polymerization.

Preparation of polyoxometalate-doped aminosilane-modified silicate hybrid as a new barrier of chem-bio toxicant.

Nanohybrid membranes based on the Keggin-type polyoxometalate (POM) H5PV2Mo10O40 and aminosilane-modified silicate (Ormosil and Ormosil(NR4+Cl-)) hybrids were synthesized as a new barrier to protect against simulants of chemical and biological toxicant. The 31P NMR and XPS results indicated that POM was bound to the Ormosil and Ormosil(NR4+Cl-) hybrids after impregnation. The antibacterial effects of the hybrids and hybrid-impregnated fabrics against Gram-negative and Gram-positive bacteria were investigated with zone of inhibition, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and plate-counting method. The MIC/MBC values of Ormosil(NR4+Cl-)/POM and Ormosil/POM against bacteria were 0.267/2.67 and 2.67/26.7, respectively, and the percentage reduction of bacteria was approximately 100% after 20 laundry cycles of their fabrics. The reaction products and mechanisms of the adsorptive degradation of 2-chloroethylethylsulfide (CEES) by hybrids were investigated with 13C NMR. The results of this study showed that POM-doped Ormosil systems are capable of destroying bacteria and CEES.

Antibacterial Activity of Surface-Modified Fabric with Ag/AgCl-Doped Quaternary Ammonium-Modified Silicate Hybrid.

An organic-inorganic hybrid antibacterial material based on Ag/AgCl and quaternary ammoniummodified silicate (Ormosil (NR+4 Cl-)) was prepared by sol-gel processes and an in situ reduction method, in which silver nitrate, tetraethoxysilane (TEOS), N-trimethoxysilylpropyl-N,N,Ntrimethylammonium chloride (TMAPS) and N-[3-(trimethoxysilyl)propyl]diethylenetriamine (ATS) acted as precursor, linker and colloidal suspension stabilizer, respectively. The physical properties of the Ormosil (NR+4 Cl-) and Ormosil (NR+4 Cl-)/Ag hybrids were examined using XPS and TGA spectroscopy, the results of which indicated that Ag/AgCl was immobilized in channels by dipolar interactions with the Ormosil (NR+4 Cl-) matrix. Ormosil (NR+4 Cl-) and Ormosil (NR+4 Cl-)/Ag sol solutions were used to functionalize non-woven fabrics by simply immersing the textiles into the dispersions in order to obtain antimicrobial fabrics. The antibacterial effects of the Ormosil/Ag- and Ormosil (NR+4 Cl-)/Ag-modified fabrics against Gram-negative P. aeruginosa and E. coli, and Grampositive S. aureus and B. subtilis, were assessed using the zone of inhibition and the plate-counting method. The antibacterial efficacy was maintained even after 20 laundry cycles. The results indicated that the Ormosil/Ag and Ormosil (NR+4 Cl-)/Ag hybrids are useful as non-leaching agents imparting durable antimicrobial properties to fabrics.

Synthesis and Characterization of N,N,O-Tridentate Aminophenolate Zinc Complexes and Their Catalysis in the Ring-Opening Polymerization of Lactides.

A series of aminophenolate ligands with various pendant groups and associated ethyl Zn complexes were synthesized and studied as catalysts for the ring-opening polymerization (ROP) of lactides (LAs). The thiophenylmethyl group (L 4 ZnEt) increased the catalytic activity more than the benzyl group (L 1 ZnEt) did, and 2-fluorobenzyl (L 3 ZnEt) and 2-methoxybenzyl (L 2 ZnEt) groups had the opposite effect. In addition, the LA polymerization mechanism proved by Nuclear Magnetic Resonance and Density Function Theory was that LA was attracted by H···O bond of an α-hydrogen of the LA molecule and the phenoxyl oxygen of the catalyst. After the dissociation of amino group from the Zn atom, the benzyl alcohol initiated LA without replacing the ethyl group of Zn complex. It is the first case where the ethyl group is regarded as a ligand and cannot be replaced by benzyl alcohol, and this information is very important for the mechanism study of ROP.

Preparation and antibacterial effects of Ag/AgCl-doped quaternary ammonium-modified silicate hybrid antibacterial material.

Organic-inorganic hybrid antibacterial materials based on Ag/AgCl and quaternary ammonium-modified silicate (Ormosil(NR4+Cl-)) were prepared by sol-gel processes and an in situ reduction method. The physical properties of Ormosil(NR4+Cl-) and the Ormosil(NR4+Cl-)/Ag hybrids were examined using FTIR, UV-Vis, SEM, XRD and NMR spectroscopy. The results indicated that Ag/AgCl was incorporated into the Ormosil(NR4+Cl-) matrix after impregnation. Morphological analysis by SEM showed uniformly-distributed Ag and AgCl particles in the Ormosil(NR4+Cl-) matrix, of spherical nature and a size around 5-20 and <200 nm. The antibacterial effects of Ormosil(NR4+Cl-) and the Ormosil(NR4+Cl-)/Ag hybrids against Gram-negative P. aeruginosa and E. coli, and Gram-positive S. aureus and B. subtilis, were assessed in terms of the zone of inhibition, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and plate-counting method, and an excellent antibacterial performance was discovered. Moreover, the antibacterial performance of the Ormosil(NR4+Cl-)/Ag hybrid was better than that of Ormosil(NR4+Cl-) and the Ormosil/Ag hybrids.

Evaluation and efficacy of metal oxides in terms of antibacterial activity and toxic chemical degradation.

Inorganic metal oxides Ag2O, CuO and ZnO were examined using SEM, XRD, TGA and ICP spectroscopy to analyze their structures and physical properties in terms of resistance to germs and toxic chemicals. Zone of inhibition testing and the plate-counting method were used in this study to examine the antibacterial activities of the metal oxides against Gram-negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa), and Gram-positive Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis). Furthermore, 2­chloro­ethyl ethyl sulfide (2­CEES) was used to study the degradation efficacy of the metal oxides by the NMR method. The objective of the study was to develop and evaluate metal oxides that are able to protect against chemical and biological warfare agents. Excellent antibacterial and catalytic toxic chemical degradation properties were obtained.

Magnetic Nanoparticle-Based Lateral Flow Immunochromatographic Strip as a Reporter for Rapid Detection of Melamine.

Magnetite nanoparticles (MNPs) Fe3O4 and r-Fe2O3 were surface-modified with poly(ethylene glycol) (PEG) in order to improve their specificity and bioactivity. PEG and the anti-MEL monoclonal antibody (mAb) were successfully immobilized on the surface of MNPs and characterized using FTIR, UV-Vis and TEM analyses. Surface modification of MNPs-PEG-mAb conjugates of a variety of sizes and magnetite types was employed to design and prepare labels for use in a lateral flow immunoassay (LFIA) to test whether the size of the conjugate can affect the performance of the assay. The results showed that the detection limit was mainly determined by the size of the MNPs-PEG-mAb conjugate. Under optimized conditions, a detection limit of 0.4 ppm for melamine was achieved using Fe2O3-PEG-mAb, which was almost 5-fold lower than that of the Fe3O4-PEG-mAb conjugate (2.2 ppm).

Preparation and characterization of expanded graphite/metal oxides for antimicrobial application.

Composite materials based on expanded graphite (EG) and metal oxide (MO) particles was prepared by an explosive combustion and blending method. The objective of the study was to develop EG impregnated with metal oxide particulates (Ag2O, CuO and ZnO) and evaluate the level of protection the materials conferred against biological agents. The physical properties of the EG/MO composites were examined using SEM, EDX and XRD spectroscopy, and the results indicated that the MO particles were incorporated into the EG matrix after impregnation. The antimicrobial activities of the EG/MO composites against Gram-positive bacteria, Gram-negative bacteria and Bacillus anthracis were investigated using zone of inhibition, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and plate-counting methods. EG/Ag2O exhibited a stronger antibacterial activity than EG/CuO and EG/ZnO, with a MIC of 0.3mg/mL and a MBC of 0.5mg/mL. To the best of our knowledge, few studies have demonstrated that EG/MO composites can inhibit the growth of Bacillus anthracis-adhered cells, thus preventing the process of biofilm formation. Nanoscale metal oxides display enhanced reactive properties toward bacteria due to their high surface area, large number of highly reactive edges, corner defect sites and high surface to volume ratio.

Bis(aminothiolato)nickel nanosheet as a redox switch for conductivity and an electrocatalyst for the hydrogen evolution reaction.

A π-conjugated coordination nanosheet comprising bis(aminothiolato)nickel (NiAT) moieties was synthesized by the reaction of Ni(acac)2 with 1,3,5-triaminobenzene-2,4,6-trithiol at liquid-liquid and gas-liquid interfaces. The sheet thickness could be controlled down to a single layer (0.6 nm). Selected area electron diffraction and grazing incidence X-ray diffraction analyses indicated the formation of a flat crystalline sheet with a kagome lattice stacked in a staggered alignment. NiAT was reversibly interconverted to a bis(iminothiolato)nickel (NiIT) nanosheet by the chemical 2H+-2e- reaction, which was accompanied by a drastic change in electrical conductivity from 3 × 10-6 to 1 × 10-1 S cm-1. This change in conductivity was explained by the difference in band structures between NiAT and NiIT. NiAT acted as an efficient electrocatalyst for the hydrogen evolution reaction, showing strong acid durability and an onset overpotential of -0.15 V.

Heteroleptic bis(dipyrrinato)copper(II) and nickel(II) complexes.

Heteroleptic bis(dipyrrinato)copper(II) and nickel(II) complexes are synthesized. Their structures are determined by X-ray diffraction analysis, and their properties are investigated by using cyclic voltammetry, chronocoulometry, and UV/vis absorption spectroscopy.

π-Conjugated bis(terpyridine)metal complex molecular wires.

Bottom-up approaches have gained significant attention recently for the creation of nano-sized, ordered functional structures and materials. Stepwise coordination techniques, in which ligand molecules and metal sources are reacted alternatively, offer several advantages. Coordination bonds are stable, reversible, and self-assembling, and the resultant metal complex motifs may contain functionalities unique to their own characteristics. This review focuses on metal complex wire systems, specifically the bottom-up fabrication of linear and branched bis(terpyridine)metal complex wires on electrode surfaces. This system possesses distinct and characteristic electronic functionalities, intra-wire redox conduction and excellent long-range electron transport ability. This series of comprehensive studies exploited the customizability of bis(terpyridine)metal complex wires, including examining the influence of building blocks. In addition, simple yet effective electron transfer models were established for redox conduction and long-range electron transport. A fabrication technique for an ultra-long bis(terpyridine)metal complex wire is also described, along with its properties and functionalities.

A bis(terpyridine)iron network polymer on carbon for a potential energy storage material.

A bis(terpyridine)iron network polymer was fabricated by electropolymerisation on a glassy carbon electrode. The modified electrode allowed high-speed charging and discharging with a minor capacity decay (only 5% after 3000 cycles at 1 V s(-1)).

Instantaneous room-temperature and highly enantioselective ArTi(O-i-Pr)3 additions to aldehydes.

Direct asymmetric additions of ArTi(O-i-Pr)(3) to aldehydes catalyzed by a titanium catalyst of (R)-H(8)-BINOL are reported. The reactions proceed instantaneously at room temperature, affording alcohols in ≥90% ee. Importantly, the ArTi(O-i-Pr)(3) reagent differentiates the ligand effectiveness in an order of H(8)-BINOL > BINOL > TADDOL > diol 3 > disulfonamide 2.

Highly enantioselective arylation of aldehydes and ketones using AlArEt(2)(THF) as aryl sources.

A series of AlArEt(2)(THF) (Ar = Ph (1a), 4-MeC(6)H(4) (1b), 4-MeOC(6)H(4) (1c), 4-Me(3)SiC(6)H(4) (1d), 2-naphthyl (1e)) were synthesized from reactions of AlEt(2)Br(THF) with ArMgBr. In CDCl(3) solution, the (1)H NMR spectra showed that AlArEt(2)(THF) compounds exist as a mixture of four species of formulas of AlAr(x)Et(3-x) (THF) (x = 0, 1, 2, or 3). AlArEt(2)(THF) compounds were found to be superior and atom-economic reagents for asymmetric aryl additions to organic carbonyls. Aryl additions of AlArEt(2)(THF) to aldehydes catalyzed by the titanium(IV) complex of (R)-H(8)-BINOL were efficient with a short reaction time of 1 h, affording aryl addition products as exclusive or main products in high yields and excellent enantioselectivities of up to 98% ee. Although ethyl additions to aldehydes occurred in minor extent, this study demonstrates that increasing the amount of AlArEt(2)(THF) from 1.2 to 1.4 or to 1.6 equiv significantly improved the aryl addition products of up to >99%. On the other hand, asymmetric arylations of AlArEt(2)(THF) to ketones employing a titanium(IV) catalyst of (S)-BINOL produced optically active tertiary alcohols exclusively in excellent enantioselectivities of up to 94% ee.