Highly sensitive and selective lateral flow aptasensor for anti-coagulant dabigatran etexilate determination in blood.

Dabigatran etexilate (DBG) is a new anticoagulant drug (commercially sold under the names Pradaxa® and Pradax™) that replaces Warfarin, the landmark agent for anticoagulation therapy. Inadequate administration of DBG or in the cases of massive bleeding that occurs after renal impairment, DBG therapy can carry a substantial life-threatening risks. One of the major limitations of DBG treatment is the lack of a simple and quick tool for measuring its level in blood in the case of massive bleedings or emergency operations. In this work, we have incorporated a previously isolated aptamer for DBG to develop a simple competitive lateral flow aptasensor (LFA) for the determination of DBG in buffer and blood samples. A full-length 60-mer aptamer as well as a truncated 38-mer aptamer were conjugated to gold nanoparticles (AuNPs) via thiol-Au coupling chemistry. After appropriate AuNP surface passivation steps, the aptamer's core region was hybridized with 8-mer biotinylated sequences. The conjugated particles could be capture on the test line by the interaction of the biotin molecules with a previously deposited streptavidin. Incubation of the conjugated particles with DBG causes the aptamer to undergo a conformational change that releases the 8-mer biotinylated sequences and result in the disappearance of the test line. Lysozyme protein was used to construct the control line that non-specifically interacts with the conjugated particles whether or not the target compound is present. The developed LFA achieves 20 nM detection level in buffer and blood samples, operates within the nanomolar range, and shows excellent selectivity against potential interfering molecules. The developed sensor could help assessing the levels of DBG in medical conditions that require rapid interventions.

Antibiotic Adsorption by Metal-Organic Framework (UiO-66): A Comprehensive Kinetic, Thermodynamic, and Mechanistic Study.

Bacterial antibiotic resistance has been deemed one of the largest modern threats to human health. One of the root causes of antibiotic resistance is the inability of traditional wastewater management techniques, such as filtration and disinfection, to completely eliminate residual antibiotics from domestic and industrial effluents. In this study, we examine the ability of UiO-66; a metal-organic framework (MOF); in removing the antibiotic Doxycycline from aqueous environments. This study's findings suggest that UiO-66 was able to remove nearly 90% of the initial Doxycycline concentration. To correlate the isothermal data, Langmuir and Freundlich models were used. It was determined that the Langmuir model was best suited. Pseudo-first and -second order models were examined for kinetic data, where the pseudo-second order model was best suited-consistent with the maximum theoretical adsorption capacity found by the Langumir model. Thermodynamic analysis was also examined by studying UiO-66 adsorption under different temperatures. Mechanisms of adsorption were also analyzed through measuring adsorption at varying pH levels, thermogravimetric analysis (TGA), Infrared spectroscopy (IR) and Brunauer-Emmet-Teller (BET). This study also explores the possibility of recycling MOFs through exposure to gamma radiation, heat, and heating under low pressure, in order for UiO-66 to be used in multiple, consecutive cycles of Doxycycline removal.

Decomposition of DNA staining agent ethidium bromide by gamma irradiation: Conditions, kinetics, by-products, biological activity, and removal from wastewater.

Ethidium Bromide (Eth-Br) is an intercalating agent commonly used in medical and biological laboratories as a DNA staining dye. Despite its popular use, aqueous solutions containing Eth-Br showed high toxicity, mutagenic capacity, and deactivate DNA transcription. In this study, the removal of Eth-Br from aqueous solutions by gamma irradiation has been fully investigated. Gamma irradiation was capable of achieving a near complete removal of Eth-Br in neutral and non-buffered aqueous solutions at an absorbed dose of 15 kGy. Various experimental conditions were studied and showed that the removal efficiency is not diminished. The addition of hydrogen peroxide (2 %) to the irradiated solutions reduced the D50 and D90 by 50 %. Modeling Eth-Br decomposition showed that the reaction followed pseudo first-order kinetics and reaches at least 90 % removal under all experimental conditions. TOC and HPLC measurements confirmed that Eth-Br is fully mineralized when the absorbed dose reaches 15 kGy. The biological activity of Eth-Br after irradiation treatment was investigated with synthetic DNA and natural DNA. The biological activity of Eth-Br was deactivated at an absorbed dose as low as 5 kGy. Toxicity measurement with E-coli bacteria also confirmed that the absorbed dose of 5 kGy was sufficient to remove Eth-Br toxicity.

Removal of Antibiotics from Water by Polymer of Intrinsic Microporosity: Isotherms, Kinetics, Thermodynamics, and Adsorption Mechanism.

Traces of antibiotics within domestic and industrial effluents have toxic impact on human health as well as surrounding flora and fauna. Potential increase in antibiotic resistance of microorganisms is likely to rise due to the incomplete removal of antibiotics by traditional wastewater processing, methods such as membrane filtration and biological treatment. In this study, we investigated a novel class of material termed Polymer of Intrinsic Microporosity (PIM) that is based on amorphous microporous organic materials for the application of antibiotic removal form aqueous environments. The adsorption of four commonly used antibiotics (doxycycline, ciprofloxacin, penicillin G, and amoxicillin) was evaluated and found that at least 80% of the initial concentrations was eliminated under the optimized conditions. Langmuir and Freundlich models were then employed to correlate the equilibria data; the Freundlich model fit well the data in all cases. For kinetic data, pseudo-first and second order models were examined. Pseudo-second order model fit well the kinetic data and allowed the calculation of the adsorption rate constants. Thermodynamic parameters were obtained by conducting the adsorption studies at varied reaction temperatures. Surface potential, adsorption at various solution pHs, thermogravimetric analysis (TGA), Infrared spectroscopy (IR), and surface area experiments were conducted to draw possible adsorption mechanisms. The removal of antibiotics from water by PIM-1 is likely to be governed by both surface and pore-filling adsorption and could be facilitated by electrostatic interactions between the aromatic rings and charged functional groups as well as hydrogen bond formation between the adsorbent and adsorbate. Our work shows that the application of such novel microporous material could contribute to the removal of such challenging and persistent contaminants from wastewater with further optimizations of large-scale adsorption processes.

Lateral flow aptasensor for progesterone: Competitive target recognition and displacement of short complementary sequences.

There is a pressing need for simple and accurate analytical tools to assess the level of EDCs in environmental samples. In this work, a simple and highly sensitive competitive lateral flow assay (LFA) was developed for progesterone (P4). Gold nanoparticles (AuNPs) were functionalized with a previously isolated 60-mer aptamer for P4 and further hybridized with 8-mer complementary sequence modified with biotin. In the absence of P4, AuNP-duplexed aptamer conjugates are capture by a test line made with streptavidin. Conformational change within aptamer sequence upon target recognition causes the release of the biotinylated complementary sequence and disappearance of the colored test line. By optimizing the hybridization location of the 8-mer biotinylated sequences, the sensitivity of sensor was improved by 20-folds to achieve 5 nM detection level of P4 in buffer and spiked tap water samples. The simply fabricated sensor demonstrated a dynamic range in the lower nanomolar range and excellent selectivity against potential interfering molecules including the closely similar 17ß-estradiol (E2). The sensor can be used as a fast screening tool to assess the level of P4 in water. Implementing the developed assay avoids applying laborious extraction procedures and lengthily analysis by conventional chromatography based instruments.

Removal of antibiotics from water and waste milk by ozonation: kinetics, byproducts, and antimicrobial activity.

The use of antibiotics in the dairy farming for curing and growth promotion results in the production of massive quantities of non-recyclable wastewater by the conventional purification techniques. Additionally, waste milk is produced during the drug withholding periods, which is not suitable for human or animal consumption and cause huge economic loss as well as present serious environmental waste. This study was designed to investigate the decomposition of various antibiotic compounds in un-buffered aqueous solutions and milk samples by ozonation process. Commonly administered broad-spectrum antibiotics such as amoxicillin, doxycycline, ciprofloxacin, and sulphadiazine were selected as model examples in the current investigation. Gradual exposure of these antibiotics to increasing ozone gas concentration induced increasing removal percentages of the antibiotics in spiked water and milk samples. The removal reached 95% across all the tested treated antibiotics with ozone dose as low as 75 mg L-1. It was noted that the removal of antibiotics in milk samples is more efficient with faster rate constants. This was attributed to the self-buffering characteristic of milk that maintains the neutral pH, keeping the amine groups un-protonated and more reactive towards the electrophilic attack by the molecular ozone. 1H NMR as well as HPLC experiments support the near complete removal of antibiotics and indicated the break down to simpler and more soluble fragments of acidic nature. Bacterial growth experiments, conducted with E. coli, and milk ageing experiments provided clear evidences that the resulting decomposition byproducts lack both toxicity effect and antimicrobial activity. This study provides a viable route to remove hazardous materials, which contribute to a growing issue of antibiotic resistance of pathogenic bacteria.

Bidentate forms of ß-triketimines: syntheses, characterization and outstanding performance of enamine-diimine cobalt complexes in isoprene polymerization.

New cationic enamine-ß-diimine cobalt complex [LCoBr·THF][BArF] () and its neutral analogue [LCoBr2] () where L = [(2,4,6-Me3-C6H2)NHCMe[double bond, length as m-dash]C{CMe[double bond, length as m-dash](N-2,4,6-Me3(C6H2))}2] and BArF(-) = [{3,5-(CF3)2C6H3}4B](-), were synthesised and then characterized by single-crystal X-ray diffraction, MALDI-MS, IR and elemental analysis. These complexes, the first examples reported where putatively tridentate ß-triketimines prefer a bidentate coordination mode, were examined as catalysts for the polymerization of isoprene, activated by diethylaluminium chloride (DEAC) or ethylaluminium sesquichloride (EASC). The weakly coordinating BArF anion in strongly improved activity in comparison to . Both and produced polyisoprene of ca. 80% cis-1,4 and 20% 3,4 enchainment, with trace levels of trans-1,4 and no 1, 2 polymer. A kinetic study for both and demonstrated that the polymerization was first-order in monomer and that approximately 46% and 50% of cobalt formed active centres for and respectively. EASC was the most active of a range of organoaluminium compounds screened for both and . The resulting activities of up to 6 × 10(5) mol isoprene per mol Co per h are the highest yet recorded for catalysts selective for cis-1,4 enchained polyisoprene.

Synthesis and characterization of ß-triketimine cobalt complexes and their behaviour in the polymerization of 1,3-butadiene.

Three ß-triketimine ligands, (L(1): [CH{CMeN(2,4,6-Me3-C6H2)}2C(CMe3N(2-MeO-C6H4)], L(2): [CH{CMeN(2,4-Me2-C6H3)}2C(CMe3N(2-MeO-C6H4)] and L(3): [CH{CMeN(2-Me-C6H4)}2C(CMe3N(2-MeO-C6H4)]), were synthesized and then characterized by (1)H and (13)C{(1)H} NMR spectroscopy, elemental analysis and electrospray (ES) MS. ß-triketimine cobalt(ii) complexes were then prepared by the interaction of cobalt(ii) bromide with L(1-3) in the presence of NaBArF (BArF = [{3,5-(CF3)2-C6H3}4B](-) ). Five-coordinate dimeric bromide-bridged species [(LCoµ-Br)2][BArF]2 were obtained. The geometry of the complexes was found by single-crystal X-ray diffraction to be slightly distorted square-pyramidal. The polymerization of 1,3-butadiene catalysed by these complexes upon activation with methylaluminoxane (MAO) in chlorobenzene yielded high cis-1,4-polybutadiene (>97% cis). The effect of steric and electronic properties of the ligands on the performance of the catalytic system was investigated: it was found that ligands with fewer methyl substituents gave more active catalytic systems. It was also found that increasing MAO: Co ratio resulted in higher activity. Stereoselectivity of all catalysts slightly decreased at higher temperature, whereas activities were maximised at 20 °C, where very high values of activity were recorded.