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Bacteroides xylanisolvens Y-11 and Bifidobacterium longum y37 isolated from human gut were found to inhibit each other's growth after co-culturing in previous studies. To further reveal the potential mechanism of mutual inhibition between them, ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to investigate the metabolic changes of the strains after monoculture and co-culture, and the key differential metabolites were subject to the validation. The results showed that the types and amounts of metabolites were significantly changed during co-culture, with hydrocarbons and their derivatives, organic acids and esters being the main differential metabolites, which posed a greater influence on the metabolism of B. xylanisolvens Y-11 than on B. longumy y37. Further studies suggest that cycloserine and succinic acid may be the main metabolites that inhibit the growth of both strains, and the decrease of pH may be the main reason for succinic acid to inhibit the growth of the two strains. Moreover, B. longum y37 played a dominant role in the co-culture and its metabolites influenced the growth of B. xylanisolvens Y-11 to a greater extent. This study provides a new perspective for further understanding of the interaction between intestinal microbes and the influence of intestinal microecology on the occurrence and development of diseases.

A novel electrochemiluminescence (ECL) amplification strategy was established aiming to overcome the inherent shortcomings of the current oxygen (O

In this study, the probiotic potential and treatment effects of Lactiplantibacillus plantarum N-1 in hypercholesterolemic rats were investigated, and the possible regulatory mechanisms of lipid metabolism via short-chain fatty acids (SCFAs) and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase were elucidated. The strain N-1 displayed probiotic properties of antioxidant capacity, adhesion to Caco-2 cells, susceptibility to antibiotics in vitro. The results in animal study showed that the total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels in serum and TC in liver declined significantly in both N-1 and simvastatin (Sta) treatment groups compared to the control (P 0.05), and the extent of these decreases were similar between them. The expression of the HMG-CoA gene in the N-1 group was downregulated significantly by 31.18% compared to the control (P 0.01), and the contents of butyrate and valerate in N-1 groups were significantly higher than those in both model and Sta group (P 0.05). Thus, promoting the production of the intestinal SCFAs and inhibiting the expression of HMG-CoA reductase by L. plantarum N-1 may contribute to the improved lipid metabolism and thus lowering cholesterol level in rats. Our investigation indicated that L. plantarum N-1 has the potential to be developed into a functional food supplement for hypercholesterolemia treatment.

Due to the complexity of the synthetic process of cobalt phosphides (CoP), ongoing efforts concentrate on simplifying the preparation process of CoP. In this work, amino tris(methylene phosphonic acid) (ATMP, L1) and melamine (MA, L2) are assembled into two-dimensional (2D) organic nanostructures by hydrogen bonding and ionic interactions

Reasonable control of the redox states within the catalytic units together with the interconnection degrees of the substrate is of great significance in the modulation of a well-performing transducer. Herein, a novel carbon black (CB)-modified copper metal–organic framework nanomaterial (CB@Cu-MOF) prepared at room temperature was utilized as a precursor to synthesize mixed-valent copper–oxide composite catalysts (NC/CuxO-T). By tuning the carbonization process of the precursor at different temperatures (T = 100 °C, 200 °C, 300 °C and 400 °C), the different ratio configurations of the redox-alternated CuxO portions were successfully controlled with the simultaneous effective tailoring of the defect abundance in the N-doped carbon substrate. As a result, an optimized NC/CuxO-300 electrochemical H2O2 sensor was able to present a low detection limit (0.26 μM) and decent linear ranges (0.02–1.79 mM and 2.29–9.29 mM). Our strategy using easily available initial materials with mild preparation conditions is expected to promote the practical application of the star materials in laboratories.

Aim: The mechanisms behind antibiotic resistance by bacteria are important to create alternative molecules. Objective: This study focuses on the impact of environmental pollutants on bacterial resistance to antibiotics. Materials & methods: The effect of various environmental pollutants on noninherited bacterial resistance to antibiotics was examined. Results: The tolerance to the polymyxin-B antibiotic was shown to be conferred to Escherichia coli, by pretreatment with subinhibitory concentrations of environmental toxicants. The cell survival to a sublethal dosage of antibiotics was tested. Exposure to low concentrations of toxic compounds (500 ppb copper, 2% [v/v] ethanol or 0.5 μg/ml trimethoprim) stimulated the bacterial heat shock systems and led to increased tolerance to polymyxin B. Conclusion: Environmental pollutants induce a temporary bacterial noninheritable resistance to antibiotic.

Eliminating colloidal toxicity and enabling its intrinsic fluorescence in aggressive environmental conditions are the key challenges for commercializing hydrophobic cadmium based quantum dots (QD). Polyarylene ether nitriles (PEN) are an example of super-engineering thermoplastics that possess a unique combination of thermal stability, intrinsic fluorescence, biocompatibility and distinct emulsion self-assembly feature. Herein, the co-self-assembly of amphiphilic PEN with hydrophobic CdSe@ZnS QD, confined in the three dimensional (3D) oil-in-water emulsion droplets, has been explored to fabricate fluorescent microparticles (FMP). It was found that these FMP demonstrated good biocompatibility (cell viability above 90%), while exhibiting a fluorescence emission in aqueous solution that was retained (intensity retention ratio above 80%) within the whole pH range of 1–14, as well as, after being subjected to autoclaving at 120 °C for 1 h. Interestingly, it was discovered that introduction of calcium ions in the emulsion self-assembly contributed to in-situ generation of phase changing nanoplates inside the FMP, which led to the photo-thermal modulated solid state fluorescence from drop-casted FMP film. Thanks to their versatile fluorescence, these FMP colloids were exploited as fluorescent probes for macrophages imaging, while micro-patterns with reversible changing of emission color were induced via thermal treatment and direct laser lithography.

Rational design and facile synthesis of highly active electrocatalysts with low cost for oxygen reduction reaction (ORR) are always of great challenge. Specifically, development of a new type of energy-saving materials with convenient method is regarded as the current bottleneck. Herein, an innovative strategy based on amino trimethylene phosphonic acid (ATMP) as chelating agent for cobalt-metaphosphate coordination polymer is reported to one-pot synthesis of a novel precursor in methanol for ORR electrocatalyst. Carbonization of the precursor at 900 °C at N2 atmosphere results in the feasible formation of cobalt metaphosphate based composite (Co(PO3)2/NC). A further step in the thermal cleavage at 650 °C at air for 4 h, Co(PO3)2/NC can be finally transformed into inorganic Co(PO3)2. Advanced spectroscopic techniques and density function theory (DFT) calculations are applied to confirm the main catalytically active center and the physical properties of Co(PO3)2/NC. This obtained Co(PO3)2/NC nanocomposite exhibits superior electrocatalysis to Co(PO3)2 with an enhanced onset potential (0.906 V vs. RHE) and diffusion limiting current (5.062 mA cm−2), which are roughly close to those of commercial 20% Pt/C (0.916 V, 5.200 mA cm−2).

Metal-enhanced fluorescence (MEF) has become an increasingly important technology in recent years, with thorough research addressing the fundamentals of MEF. In many studies, spectral distortion is observed in the enhanced spectra as compared to free-space fluorescence emission profiles. Despite this observation, very little experimentation has hitherto been undertaken to investigate the mechanistic underpinnings of spectral distortion in MEF. Herein we investigate MEF spectral distortion using Rose Bengal and Fluorescein on silver nanoparticle substrates, subsequently isolating the coupled fluorescence spectrum for a deeper understanding of the spectral modifications. Clear experimental evidence for bathochromic distortion is reported. Remarkably, we also report hypsochromic distortion in one of the first experimental observations of plasmonic coupling to high-energy excited states. Additionally, the coupled fluorescence spectra from other published literature has also been both extracted and examined, and the subsequent spectral distortion reported here. The previously asserted theory of radiative decay rate modification for spectral distortion is discussed in the context of both plasmonic properties as well as fluorophore photophysical characteristics including lifetime and quantum yield. The dual enhancement mechanism of MEF is also explored in the context of spectral distortion. The results and discussion reported herein subsequently provide one of the first comprehensive examinations of spectral distortion in MEF to date.

An imbalance in gut microbiota, termed dysbiosis, has been shown to affect host health. Several factors, including dietary changes, have been reported to cause dysbiosis with its associated pathologies that include inflammatory bowel disease, cancer, obesity, depression, and autism. We recently demonstrated the inhibitory effects of artificial sweeteners on bacterial quorum sensing (QS) and proposed that QS inhibition may be one mechanism behind such dysbiosis. QS is a complex network of cell–cell communication that is mediated by small diffusible molecules known as autoinducers (AIs). Using AIs, bacteria interact with one another and coordinate their gene expression based on their population density for the benefit of the whole community or one group over another. Bacteria that cannot synthesize their own AIs secretly “listen” to the signals produced by other bacteria, a phenomenon known as “eavesdropping”. AIs impact gut microbiota equilibrium by mediating intra- and interspecies interactions as well as interkingdom communication. In this review, we discuss the role of QS in normobiosis (the normal balance of bacteria in the gut) and how interference in QS causes gut microbial imbalance. First, we present a review of QS discovery and then highlight the various QS signaling molecules used by bacteria in the gut. We also explore strategies that promote gut bacterial activity via QS activation and provide prospects for the future.

In view of the shortcomings of the current coreactant electrochemiluminescence (ECL) and inspired by natural oxygen (O

Reasonable control of the redox states within the catalytic units together with the interconnection degrees of the substrate is of great significance in the modulation of a well-performing transducer. Herein, a novel carbon black (CB)-modified copper metal-organic framework nanomaterial (CB@Cu-MOF) prepared at room temperature was utilized as a precursor to synthesize mixed-valent copper-oxide composite catalysts (NC/Cu

Metal-organic frameworks (MOFs) act as versatile coordinators for the subsequent synthesis of high-performance catalysts by providing dispersed metal-ion distribution, initial coordination condition, dopant atom ratios, and so on. In this work, a crystalline MOF

Tuning the coordination environment between metal centers and organic ligands is a promising way to design of the precursors of electrocatalysts for water splitting or other renewable energy options. In this work, a novel coordinated polymer was prepared feasibly in polyvinyl pyrrolidone (PVP) aqueous solution using aminotrimethylene phosphonic acid (ATMP, L1) and 2-methylimidazole (MeMI, L2) as ligands with the ratio of 2:5, Co2+ and Zn2+ as metal centers. Based on the concept of acid-base neutralization reaction, the proton-transfer induced “deprotonation and protonation” for L1 and L2, respectively. Thus, the coordination was dominated by the deprotonated L1. Owing to also partial of protonated L2 adsorbed as “counter ions”, carbonization of the obtained precursor at 800 °C under N2 atmosphere endows the pyrolysis product with nitrogen-doped carbon supported metal pyrophosphate (M2P2O7@NC). Thus, the resulting M2P2O7@NC exhibits the enhanced and durable ORR and HER performance. For ORR in 0.1 M KOH, an enhanced onset potential (0.925 V vs. RHE), half wave potential (0.793 V vs. RHE) and diffusion limiting current (6.132 mA cm−2) can be obtained comparable to those of Pt/C. For HER in 0.5 M H2SO4, it only needs an over potential of 180 mV to realize a current density of 10 mA cm−2.

The rational design and synthesis of an efficient bielectrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) by tuning the chemical composition, structure and the catalytic sites of the hybrid materials is always of a great challenge. In this work, an innovative strategy based on the highly active N,N′-carbonyldiimidazole (CDI) is described to one-pot synthesis of a novel precursor for bifunctional O2-electrocatalyst. The coordination of Co2+ with the in situ generated ligands imidazole and carbonate results in ultrafine cobalt carbonate (CoCO3)-involved cobalt-based zeolitic imidazole framework (CoCO3/Co-ZIF). Owing to the presence of ultrafine CoCO3, carbonization of CoCO3/Co-ZIF at 800 °C under N2 atmosphere endows the pyrolysis product with a special skeleton of carbon nanotube (CNT)-tipped end CoOx, multivalent CoOx wrapped in graphitic carbon layers. Thus, the resulting CoOx/Co-N-C exhibits the enhanced and durable ORR/OER performance in alkaline media, due to the fast electron and mass transfers. For ORR, a large limiting current density of 4.59 mA cm−2 can be obtained by CoOx/Co-N-C, which is comparable to that of Pt/C. For OER, it only needs an over potential of 1.65 V to achieve a current density of 10 mA cm−2, merely 30 mV behind IrO2 (1.62 V).

Porphyrin based nanomaterials have attracted widespread attention due to their similarity of the key dyes of natural photosynthesis. To develop new chromophores for photoelectrochemical (PEC) devices, in this work, we synthesized 3 different aggregated nanostructures of meso-tetra(4-carboxyphenyl)porphine (TCPP) via self-assembly technique. The micro-environments of porphyrin self-assembly were modulated by using sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB) as “soft template” respectively, aqueous solution without surfactant as control. Due to the different driving forces of self-assembly, the as-prepared TCPP nanostructures exhibited remarkably different morphologies, electrochemical and PEC properties. Among them, the self-assembled TCPP using SDS (SA-TCPP/SDS) possessed enhanced PEC performance. In presence of dopamine, a significant photocurrent response can be feasibly obtained in aqueous media at −0.4 V (vs. Ag/AgCl). Moreover, the self-assembly process was also investigated using in situ UV–visible spectroscopy and the corresponding structure formation mechanisms were proposed.

Enzyme mimetics have attracted wide interest due to their inherent enzyme-like activity and unique physicochemical properties, as well as promising applications in disease diagnosis, treatment and monitoring. Inspired by the attributes of nonheme iron enzymes, synthetic models were designed to mimic their capability and investigate the catalytic mechanisms. Herein, metal-organic gels (Fe-MOGs) with horseradish peroxidase (HRP) like Fe-N

Background Accumulating data suggest blood biomarkers could inform stroke etiology. Objective The purpose of this study was to investigate the performance of multiple blood biomarkers in elucidating stroke etiology with a focus on new-onset atrial fibrillation (AF) and cardioembolism. Methods Between January and December 2017, information on clinical and laboratory parameters and stroke characteristics was prospectively collected from ischemic stroke patients recruited from the National University Hospital, Singapore. Multiple blood biomarkers (N-terminal pro–brain natriuretic peptide [NT-proBNP], d -dimer, S100β, neuron-specific enolase, vitamin D, cortisol, interleukin-6, insulin, uric acid, and albumin) were measured in plasma. These variables were compared with stroke etiology and the risk of new-onset AF and cardioembolism using multivariable regression methods. Results Of the 515 ischemic stroke patients (mean age 61 years; 71% men), 44 (8.5%) were diagnosed with new-onset AF, and 75 (14.5%) had cardioembolism. The combination of 2 laboratory parameters (total cholesterol ≤169 mg/dL; triglycerides ≤44.5 mg/dL) and 3 biomarkers (NT-proBNP ≥294 pg/mL; S100β ≥64 pg/mL; cortisol ≥471 nmol/l) identified patients with new-onset AF (negative predictive value [NPV] 90%; positive predictive value [PPV] 73%; area under curve [AUC] 85%). The combination of 2 laboratory parameters (total cholesterol ≤169 mg/dL; triglycerides ≤44.5 mg/dL) and 2 biomarkers (NT-proBNP ≥507 pg/mL; S100β ≥65 pg/mL) identified those with cardioembolism (NPV 86%; PPV 78%; AUC 87%). Adding clinical predictors did not improve the performance of these models. Conclusion Blood biomarkers could identify patients with increased likelihood of cardioembolism and direct the search for occult AF.

In traditional coreactant electrochemiluminescence (ECL), the efficiency of the coreactant catalyzed into an active intermediate is one of the dominant factors restricting the luminous intensity. In this work, Co-2-MI-ZnTCPP is designed as a composite material integrating coreaction accelerator (Co-N) and luminophore. Through the catalytic effect of Co-N structures on hydrogen peroxide, the in situ generation and accumulation of active intermediates are achieved, which will react with porphyrin anion radical, thereby bringing out self-enhanced ECL. By adjusting the scanning potential range, the ECL mechanism is thoroughly studied and the contribution of each potential window to the luminescence is obtained. This work provides inspiration for the design of integrated ECL emitters with a coreaction accelerator and luminophore, providing a new way for the construction of a self-enhanced ECL emitter.

Guiding legislation and associated bureaucracy for the ethical review of clinical trials observational studies and food related research play an important role in the competitiveness of a nation in the face of tough global competition to attract sponsors and investigators. This is of particular relevance in the case of multicentre trials and multidisciplinary research. Accordingly, in this report we tried to gather in-depth knowledge of the current role and practices of ethics committees nationwide in both clinical and research settings. This mini-review aims to describe the formulation and organization of ethical committees in Italy in order to provide a focus for deliberations on ethical issues in medical and scientific research in line with human rights, as set out in the European Union charter. Furthermore, we evaluated the impact of an institution’s ethical committee intervention on reducing the time required to obtain an opinion from Research Ethics Committees by guiding investigators in addressing ethical issues in their proposed studies. (www.actabiomedica.it)

Stroke is a widespread condition that causes 7 million deaths globally. Survivors suffer from a range of disabilities that affect their everyday life. It is a complex condition and there is a need to monitor the different signals that are associated with it. Stroke patients need to be rapidly diagnosed in the emergency department in order to allow the admission of the time-limited treatment of tissue plasminogen activator (tPA). Stroke diagnostics show the use of sophisticated technologies; however, they still contain limitations. The hidden information and technological advancements behind the utilization of biomarkers for stroke triaging are significant. Stroke biomarkers can revolutionize the way stroke patients are diagnosed, monitored, and how they recover. Different biomarkers indicate different cascades and exhibit unique expression patterns which are connected to certain pathologies in the human body. Over the past decades, B-type natriuretic peptide (BNP) and its derivative N-terminal fragment (NT-proBNP) have been increasingly investigated and highlighted as significant cardiovascular biomarkers. This work reviews the recent studies that have reported on the usefulness of BNP and NT-proBNP for stroke triaging. Their classification association is also presented, with increased mortality in stroke, correlation with cardioembolic stroke, and an indication of a second stroke recurrence. Moreover, recent scientific efforts conducted for the technological advancement of a bedside point-of-care (POC) device for BNP and NT-proBNP measurements are discussed. The conclusions presented in this review may hopefully assist in the major efforts that are currently being conducted in order to improve the care of stroke patients.

In this study, 2D-MoS2 quantum dots (MQDs) were combined with the zirconium based porphyrinic metal-organic framework (MOF-545-Zn) through simple ultrasonic method for the purpose of the enhanced electrochemiluminescence (ECL). In addition, electrochemiluminescence (ECL), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed to investigate the synergistic effect on electron transfer of the composite. MQD loading with confined orientation on the surface of MOF-545-Zn was confirmed by morphology and spectroscopy. Moreover, from hybrids material, the higher ECL intensity was received. MOF-545-Zn@MQDs was functionalized by alpha lipoic acid (LA) and was further applied to develop a novel ECL immunosensors for carcinoembryonic antigen (CEA).

The electrocatalytic hydrogen evolution reaction (HER) is one of the core components of energy conversions. The chemical-physical properties and morphological structures of electrocatalysts are the main factors that determine the HER performance. Thus, the rational design of efficient electrocatalysts is essentially required. A new heteronanostructured system is proposed, which comprises MoS 2 nanoparticles (MoS 2 NPs) coupled to SnS 2 ultrathin nanosheets (SnS 2 NS) and operates as an efficient HER electrocatalyst. Advanced spectroscopic techniques are applied to confirm formation of heteronanostructure and occurred electron modulation of MoS 2 NPs/SnS 2 NS. Surprisingly, the MoS 2 NPs/SnS 2 NS electrocatalyst is highly efficient for HER with a low overpotential (∼0.249 V at the current density of 10 mA cm −2 ), small Tafel slope (∼42.1 mV decade −1 ) and excellent electrocatalytical stability.

The development of a rapid, affordable, and sensitive diagnostic kit for point-of-care is important in most healthcare settings. In this follow-up paper to our previous work on quantification of dengue NS1 protein via impedimetric measurement, our present technology aims to provide quantification by utilizing proprietary stabilized and improved electroactive immunonanoparticles that bind to the target biomarker and subsequently move along toward the biofunctionalized screen-printed gold electrodes (SPGE) to generate an amperometric signal. The SPGE functions simultaneously as a signal transducer and a solid-state support for a sandwich ELISA-like immunoassay. The successful immunocomplex formation is then recorded electrochemically using a potentiostat, whereby the signal was contributed by the presence of a more hydrophilic redox label than ferrocene, namely radical TEMPO (TEMPO ), on the formulated nanoparticles. In this paper, a bifunctional ligand, thiolated polyethylene glycol (PEG-thiol) polymer, was used to stabilize 20 nm gold colloidal nanoparticles (AuNPs) in the formulation. PEG was incorporated to not only prevent the salt-mediated AuNPs aggregations, but also provide an anchor for antibody and redox species conjugation. To-date, we have successfully miniaturized a 3D-printed prototype device able to sensitively detect and quantify dengue NS1 protein with only 0.6 μL human clinical serum samples diluted in a volume ratio of 1:100 (PBS diluent) in less than 30 min with a simple cyclic voltammetry analysis. The positive and negative samples were also tested with ELISA, a gold standard validation method, which means that the development of the prototype is a promising start as a point-of-care diagnostic technology.

One of the greatest challenges that define the performance of a fibre optic biosensor (FOBS) is the immobilization of the bio-receptor molecules onto the surface of fibre optic. In this study, a photoinducible silane diazirine was developed as an effective crosslinker in the construction of a chemiluminescent immunosensor targeting a model E. coli analyte. After optimization, it has shown superior adaptability over traditional chemiluminescent ELISA and a commonly used glutaraldehyde chemical immobilization method in detection limit (6.44 * 102 CFU/ml) and dynamic range (6.44 *105 to 6.44 *108 CFU/ml, r2 = 0.98; 6.44 *102 to 6.44 *105, r2 = 0.92). The newly developed immobilization method has enhanced the function of FOBS as an affordable and dispatchable tool in the early warning monitoring of the putative presence of E. coli cells. It can be used either in individual sample screening or in continuous monitoring of the environment to indicate the need for further investigation. The diazirine crosslinking method can also be adopted in the immobilization of other protein-based bioentities thus expanding its real-world utility. NRF (Natl Research Foundation, S’pore)

In the quest of greater sensitivity and specificity of diagnostic systems, one continually searches for alternative DNA hybridization methods, enabling greater versatility and where possible field-enabled detection of target analytes. We present, herein, a hybrid molecular self-assembled scaffolded DNA origami entity, intimately immobilized via capture probes linked to aminopropyltriethoxysilane, onto a glass optical fiber end-face transducer, thus producing a novel biosensor. Immobilized DNA nanorobots with a switchable flap can then be actuated by a specific target DNA present in a sample, by exposing a hemin/G-quadruplex DNAzyme, which then catalyzes the generation of chemiluminescence, once the specific fiber probes are immersed in a luminol-based solution. Integrating organic nanorobots to inorganic fiber optics creates a hybrid system that we demonstrate as a proof-of-principle can be utilized in specific DNA sequence detection. This system has potential applications in a wide range of fields, including point-of-care diagnostics or cellular in vivo biosensing when using ultrathin fiber optic probes for research purposes.

Despite having been tagged as safe and beneficial, recent evidence remains inconclusive regarding the status of artificial sweeteners and their putative effects on gut microbiota. Gut microorganisms are essential for the normal metabolic functions of their host. These microorganisms communicate within their community and regulate group behaviors via a molecular system termed quorum sensing (QS). In the present study, we aimed to study the effects of artificial sweeteners on this bacterial communication system. Using biosensor assays, biophysical protein characterization methods, microscale thermophoresis, swarming motility assays, growth assays, as well as molecular docking, we show that aspartame, sucralose, and saccharin have significant inhibitory actions on the Gram-negative bacteria N-acyl homoserine lactone-based (AHL) communication system. Our studies indicate that these three artificial sweeteners are not bactericidal. Protein-ligand docking and interaction profiling, using LasR as a representative participating receptor for AHL, suggest that the artificial sweeteners bind to the ligand-binding pocket of the protein, possibly interfering with the proper housing of the native ligand and thus impeding protein folding. Our findings suggest that these artificial sweeteners may affect the balance of the gut microbial community via QS-inhibition. We, therefore, infer an effect of these artificial sweeteners on numerous molecular events that are at the core of intestinal microbial function, and by extension on the host metabolism.

Lanthanide coordinating polymeric microparticles are considered as versatile building blocks for construction of various advanced functional materials and devices, but the research involving the modulation of their fine morphology, luminescence properties and processability is still limited. Herein, we have synthesized an amphiphilic aromatic multi-block copolymer (abbreviated as amPENS) showing intrinsic blue fluorescence emission, which was further employed as a coordination ligand to sensitize the intrinsic fluorescence emission of Tb3+ and Eu3+. Specifically, the three dimensional (3D) emulsion confinement self-assembly of amPENS with lanthanide ions was explored to fabricate sub-micron sized Ln-PENS microparticles, whose fluorescence emission and surface morphology can be readily tuned via the concentration of amPENS and lanthanide ions, as well as stirring speed during emulsion self-assembly. More importantly, we further proved that the Ln-PENS doped polyvinyl alcohol (PVA) solution can be processed into multi-band emissive fluorescent nanofibers coatings via electrospinning. Basically, the current work reveals a new strategy to design lanthanide coordination polymeric superparticles with tunable morphology and fluorescence, which would open the way for fabrication of advanced lanthanide based materials for various applications such as sensing, anti-counterfeiting, information recording and optoelectric devices.

International audience; Enzyme mimetics have attracted wide interest due to their inherent enzyme-like activity and unique physicochemical properties, as well as promising applications in disease diagnosis, treatment and monitoring. Inspired by the attributes of nonheme iron enzymes, synthetic models were designed to mimic their capability and investigate the catalytic mechanisms. Herein, metal-organic gels (Fe-MOGs) with horseradish peroxidase (HRP) like Fe-NX structure were successfully synthesized though the coordination between iron and 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) and exhibited excellent peroxidase-like activity. Its structure-activity relationship and the in-situ electrochemiluminescence (ECL) detection of H2O2 secreted by Hela cells were further investigated. The highly dispersed Fe-NX active sites inside Fe-MOGs were able to catalyze the decomposition of H2O2 into large amounts of reactive oxygen species (ROS) via a Fenton-like reaction under a low overpotential. Due to the accumulation of ROS free radicals, the luminol ECL emission was significantly amplified. A proof-ofconcept biosensor was constructed with a detection limit as low as 2.2 nM and a wide linear range from 0.01 to 40 μM. As a novel metal organic gels based enzyme mimetic, Fe-MOGs show great promises in early cancer detection and pathological process monitoring.

Carbon nanotubes (CNTs) have emerged recently as superior adsorbent materials for the removal of recalcitrant pollutants. The potential of combining the sorption capability of CNTs with bacterial degradation for pollutant removal, however, necessitates further investigation of the mechanisms of CNTs’ toxicity towards bacterial cells. In this study, we used a panel of stress-responsive recombinant Escherichia coli bioluminescence bacterial strains to explore the possible mechanisms of toxicity of multiwalled carbon nanotubes (MWCNTs). The effects of MWCNTs on markers of oxidative stress, protein, DNA, and membrane damage enabled the exposition of some of the mechanisms of their antimicrobial properties. Using both a bioluminescence bioreporter panel and live/dead staining, we observed that membrane damage played a role in the toxicity of MWCNTs. A subsequent viability study using three strains of bacteria—two gram-negative (Escherichia coli, Pseudomonas aeruginosa) and one gram-positive (Bacillus subtilis)—showed significant MWCNT toxicity in hypotonic water and phosphate-buffered saline solution, compared with the MWCNT toxicity towards the same bacteria incubated in isotonic-rich media. Using a field-emission scanning electron microscope, we demonstrated that membrane damage is caused largely by MWCNTs trapping bacteria and piercing the cell walls. As a result of our observations, we propose integrating MWCNTs and bacteria degradation for pollutant removal in nutrient-rich media to minimize the toxicity effect of CNTs. NRF (Natl Research Foundation, S’pore) Accepted version

An easy, rapid and sensitive method for the detection of meat species is important to identify adulteration or fraudulent substitution in raw meats with undeclared species. We report herein the development of an optical fibre genosensor able to detect low level of pork (Sus Scrofa) meat in mixtures of minced meat obtained by an optimized and faster DNA extraction protocol. Our approach uses highly specific and sensitive DNA capture and secondary probes designed out of the mitochondrion genome of Sus Scrofa. Once DNA capture probes were immobilized on optical fibres, we demonstrate their putative application as genosensors in detecting Sus Scrofa DNA in purified samples obtained first using a commercial DNA extraction kit and thereafter using our improved extraction method. Furthermore, analysis of beef (Bos taurus) minced meat samples also show that the assay can determine 1% (w/w) of Sus Scrofa DNA. The sensitivity obtained by the optical fibre and the short time required for the results (about 2.5 h) indicate the usefulness of the system. We envision that this genosensor may serve as a diagnostic tool for food sample screening using a technology that is accurate, simple to perform and has the potential to be used in portable format.

An original versatile methodology for molecular grafting on different surfaces via the photoinduced formation of a covalent bond based on a diazirine group is reported. The synthesis and electrochemical behavior of a new diazirine derivative which acts as a molecular linking bridge bearing both a photoactivatable covalent binding group (diazirine) and a non-covalent binding group (pyrene) is described. The resulting pyrene-diazirine was electropolymerized onto a platinum electrode and under UV irradiation was successfully used to graft ferrocenemethanol and glucose oxidase (model small molecule and protein, respectively), conferring specific properties on the resulting materials. Furthermore, the immobilization of the diazirine derivative onto multi-walled carbon nanotubes (MWCNT) by π-stacking interaction or by electropolymerization onto both bare and MWCNT-coated platinum electrodes enabled photografting of glucose oxidase. Keywords: Diazirine, Pyrene, Photografting, Electropolymerization, Glucose oxidase, Carbon nanotubes

Stroke is the second top leading cause of death globally. It is caused by an abrupt interruption of blood flow to the brain. In that course, brain natriuretic peptide (BNP) and its derivative N-terminal pro b-type natriuretic peptide (NT-proBNP), neurohormones produced mainly by the heart ventricles in response to excessive stretching of cardiomyocytes (heart muscle cells), are proven to be good biomarkers for heart failure diagnosis. Moreover, there is growing clinical interest of the use of NT-proBNP for stroke diagnosis and prognosis because it is significantly associated with cardioembolic stroke and secondary stroke reoccurrence, with sensitivity >90% and specificity >80%. However, in diagnostic settings, there is still a need to address the encountered analytical problems, particularly assay specificity and set up. In this study, a novel approach for NT-proBNP detection is demonstrated using an electrochemical immunoassay method. A label-free impedimetry immunosensor for stroke biomarker was developed using modified disposable screen-printed gold electrodes (SPGE) hosting specific anti-NT-proBNP capture antibody. The performance of our immunosensor was studied in the presence of NT-proBNP in both buffered and mock (porcine) plasma samples. A linear relation between the relative total resistance (ΔRtot) responses and the NT-proBNP concentrations in buffer was observed in a range from 0.1 to 5 ng mL-1 with a correlation coefficient (R2) of 0.94656. Overall, the biosensor has demonstrated the capability to quantitate NT-proBNP and differentiate such concentrations in a low concentration range, especially among 0, 0.1, 0.5, 1, and 3 ng mL-1 in plasma samples within 25 min. This range is valuable not only for classifying cardioembolic stroke (higher or equal to 0.5 ng mL-1), but also predicting the risk of secondary stroke reoccurrence (higher than 0.255 ng mL-1). Our biosensor has the potential to be used as an easy-to-use point-of-care test that is both accurate and affordable.

The residual catalyst (K2CO3) presented in the super engineering polyarylene ethers exerts side effects onto their processability and electrical properties. However, the sensitive and reliable analytical tools, that are able to detect residual K2CO3 content in these high performance thermoplastics, are rarely reported. Herein, we firstly synthesized an aromatic amphiphilic block copolymer bearing pendent carboxyl and sulfonate groups (named as D5S5). Next, a lanthanide ions mediated solvent-exchange self-assembly was explored to fabricate fluorescent metallopolymeric nanospheres composed of D5S5 and Tb3+ with strong green emission (named as Tb-D5S5). Then, the rhodamine B (RB) dyes were combined with the Tb-D5S5 to obtain the fluorescent probe of Tb-D5S5/RB, which exhibited a ratiometric fluorescence response to K2CO3. Specifically, the I545/I585 (intensity ratio of two emission bands at 545 nm and 585 nm) of probe linearly increased with the increasing K+ concentration of K2CO3 in the range from 0.05 to 7.41 mM. Furthermore, the sensing mechanism of this probe towards K2CO3 was revealed. Finally, the Tb-D5S5/RB probe was employed to determine the residual K2CO3 in a super engineering polyarylene ether produced by an industrial plant, which showed 85.98 %–89.31 % recoveries of the benchmark results obtained from the inductively coupled plasma optical emission spectrometer (ICP-OES).

Cigarette smoking is considered to be a risk factor for several chronic diseases and even premature death. However, despite the importance of this detrimental habit, little seems known in terms of the overall toxicity potential of its ingredients in humans. In this study, a panel of genetically modified bioluminescent bioreporter bacteria was used to evaluate its usefulness in estimating the cigarette smoke's complex molecular mixture on a bacterial toxicity-bioreporter panel, both filtered or unfiltered. This work enabled to confirm the usefulness of cigarette filters, with better protection found in higher priced brands despite both having genotoxic and cytotoxic attributes. Quorum sensing interference was also shown, which may explain why cigarette smokers are at greater risk for pulmonary infections. Moreover, the findings of this study support the fact that the filter is a dominating contributor to reducing the harm caused by cigarette smoke. Increased efforts should be conducted to reduce the harmful effects of cigarette smoke, via increasingly effective filters. To conclude, the panel of bioreporter bacteria was found to be useful in the evaluation of the general effect of the toxic mixture found in cigarette smoke and therefore has the potential to be used in cigarette research, helping researchers pinpoint the reduction of toxicity when working with filter improvement.

Quorum sensing (QS), a sophisticated system of bacterial communication that depends on population density, is employed by many pathogenic bacteria to regulate virulence. In view of the current reality of antibiotic resistance, it is expected that interfering with QS can address bacterial pathogenicity without stimulating the incidence of resistance. Thus, harnessing QS inhibitors has been considered a promising approach to overriding bacterial infections and combating antibiotic resistance that has become a major threat to public healthcare around the globe. Pseudomonas aeruginosa is one of the most frequent multidrug-resistant bacteria that utilize QS to control virulence. Many natural compounds, including furanones, have demonstrated strong inhibitory effects on several pathogens via blocking or attenuating QS. While the natural furanones show no activity against P. aeruginosa, furanone C-30, a brominated derivative of natural furanone compounds, has been reported to be a potent inhibitor of the QS system of the notorious opportunistic pathogen. In the present study, we assess the molecular targets and mode of action of furanone C-30 on P. aeruginosa QS system. Our results suggest that furanone C-30 binds to LasR at the ligand-binding site but fails to establish interactions with the residues crucial for the protein’s productive conformational changes and folding, thus rendering the protein dysfunctional. We also show that furanone C-30 inhibits RhlR, independent of LasR, suggesting a complex mechanism for the agent beyond what is known to date.

The world acceptance of medical cannabis slowly widens. Cannabinoids are known as the main therapeutic active compounds in the cannabis plant, yet their bioactive physiological effects are still unknown. In this study, the mode of action of nine selected cannabinoids was examined using a bioluminescent bacterial panel, as well as the extracts of six different cannabis varieties and cannabinoids standards artificial mixtures. The bacterial panel was composed of genetically modified E. coli bacteria that is commonly found in the gut microbiome, to which a lux operon was added to various stress promoters. The panel was exposed to the cannabinoids in order to identify bacterial defense mechanism, via the aforementioned specific stress types response. This enables the understanding of the toxicity mode of action of cannabinoids. From all the tested cannabinoids, only delta-9-tetrahydrocannabinol (THC) and delta-9-tetrahydrocannabinolic acid A (THCA) produced a genotoxic effect, while the other tested cannabinoids, demonstrated cytotoxic or oxidative damages. Unlike pure cannabinoids, cannabis plant extracts exhibited mostly genotoxicity, with minor cytotoxicity or oxidative stress responses. Moreover, cannabinoids standards artificial mixtures produced a different response patterns compared to their individual effects, which may be due to additional synergistic or antagonistic reactions between the mixed chemicals on the bacterial panel. The results showed that despite the lack of cannabigerol (CBG), cannabidivarin (CBDV), cannabinol (CBN), and cannabichromene (CBC) in the artificial solution mimicking the CN6 cannabis variety, a similar response pattern to the cannabinoids standards mixture was obtained. This work contributes to the understanding of such correlations and may provide a realistic view of cannabinoid effects on the human microbiome.

Aptamer-ligand binding has been utilized for biological applications due to its specific binding and synthetic nature. However, the applications will be limited if the binding or the ligand is unstable. Malachite green aptamer (MGA) and its labile ligand malachite green (MG) were found to have increasing apparent dissociation constants (Kd) as determined through the first order rate loss of emission intensity of the MGA-MG fluorescent complex. The fluorescent intensity loss was hypothesized to be from the hydrolysis of MG into malachite green carbinol base (MGOH). Random screening organic additives were found to reduce or retain the fluorescence emission and the calculated apparent Kd of MGA-MG binding. The protective effect became more apparent as the percentage of organic additives increased up to 10% v/v. The mechanism behind the organic additive protective effects was primarily from a ~5X increase in first order rate kinetics of MGOH→MG (kMGOH→MG), which significantly changed the equilibrium constant (Keq), favoring the generation of MG, versus MGOH without organic additives. A simple way has been developed to stabilize the apparent Kd of MGA-MG binding over 24 h, which may be beneficial in stabilizing other triphenylmethane or carbocation ligand-aptamer interactions that are susceptible to SN1 hydrolysis. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

In this study, composite calcium-alginate/carbon nanotubes/TiO2 beads were prepared and tested for their potential in the removal of bisphenol A (BPA) from aqueous solutions. The removal traits were inspected using a fixed-bed sorption column. By varying parameters such as bed height (15–20 cm), flow rate (2.0–6.0 mL.min−1) and inlet BPA concentration (10–30 mg.L−1) we assessed the removal capacity of these composites. The highest sorption capacity of 5.46 mg.g−1 was achieved at 10 mg.L−1 BPA concentration, 2.0 mL.min−1 flow rate and 20 cm bed height at saturation. Adams-Bohart, Yoon-Nelson and Dose-Response isotherm models were applied to evaluate the performance of the column at different inlet concentrations. The experimental data satisfactorily fit the Dose-Response model with high correlation (r2 > 0.97) across the breakthrough curve. Regeneration of the used adsorbent beads were performed by immersion in the desorption solvent followed by light irradiation. It was postulated that inclusion of TiO2 facilitates the desorbed pollutant degradation from the used adsorbent beads.

Mercury ion (Hg(2+)) is an extremely toxic ion, which will accumulate in human bodies and cause severe nervous system damage. Therefore, the sensitive and efficient monitoring of Hg(2+) in human bodies is of great importance. Upconversion nanoparticle (UCNPs) based nano probes exhibit no autofluorescence, deep penetration depth and chemical stability in biological samples, as well as a large anti-stokes shift. In this study, we have developed thiazole-derivative-functionalized UCNPs, and employed an upconversion emission intensity ratio of 540 nm to 803 nm (I540/I803) as a ratiometric signal to detect Hg(2+) in living cells showing excellent photo stability and high selectivity. Our nano probe was characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). The low cytotoxicity of our probe was confirmed by an MTT assay and the UCL test in HeLa cells was carried out by confocal microscopy. Our results demonstrated that organic-dye-functionalized UCNPs should be a good strategy for detecting toxic metal ions when studying cellular biosystems.

Governments are creating regulations for consumers to reduce their sugar intake, prompting companies to increase the ratio of artificial sweeteners in their products. However, there is evidence of some deleterious effects ascribed to the aforementioned synthetic agents and therefore consumers and food manufacturers have turned their attention to natural dietary sweeteners, such as stevia, to meet their sweetening needs. Stevia is generally considered safe, however, emerging scientific evidence has implicated the agent in gut microbial imbalance. In general, regulation of microbial behavior is known to depend highly on signaling molecules via quorum sensing (QS) pathways. This is also true for the gut microbial community. We, therefore, evaluated the possible role of these stevia-based natural sweeteners on this bacterial communication pathway. The use of a commercial stevia herbal supplement resulted in an inhibitory effect on bacterial communication, with no observable bactericidal effect. Purified stevia extracts, including stevioside, rebaudioside A (Reb A), and steviol revealed a molecular interaction, and possible interruption of Gram-negative bacterial communication, via either the LasR or RhlR receptor. Our in-silico analyses suggest a competitive-type inhibitory role for steviol, while Reb A and stevioside are likely to inhibit LasR-mediated QS in a non-competitive manner. These results suggest the need for further safety studies on the agents.

Metal-enhanced fluorescence (MEF) is a promising technology with impact in diagnostics, electronics, and sensing. Despite investigation into MEF fundamentals, some properties remain unresearched, notably spectral distortion. To date, publications have described its underpinnings, yet comprehensive analysis is needed, as presented recently for silver films. Herein we expand this description using zinc substrates (ZnNPs). Significant red-edge and blue-edge distortions are reported using Rose Bengal. Radiative decay rate modification is identified as key in amplifying fast/slow electronic transitions by the enhanced emission mechanism. Furthermore, we identify distortion in published studies, bolstering our thinking that spectral distortion is an intrinsic property of MEF.

Paper-based diagnostics are rapid, robust, affordable and user-friendly, thus have potential for point-of-care. Modulation of sample flow in these technologies have the advantage of increased exposure between immunoreagents, which ensures higher sensitivity and specificity. In this study, common membrane types were compared and modified to modulate sample flow. Five different membranes were compared: glassfiber, polyester, nitrocellulose, polyvinylidene-difluoride and cellulose. Several parameters were tested for their effect on the sample flow: membranes absorption capacity, immobilization of buffer solution, different membrane types as separation layer and sample volume. The effect of separation membrane on the sample flow was tested using a ‘Stack-Pad’ sensor layout. Higher antibody levels could reach the three absorption pads, with the use of polyester separation membrane (340, 440 and 408 RLU), as compared to the glassfiber separation membrane (208, 198 and 107 RLU), thus potentially increasing the sensor sensitivity. Lastly, the effect of the membrane type and its modifications on the detection sensitivity was also compared. The finalized modified setup (862 RLU) demonstrated a higher detection sensitivity vs. the initial setup (290 RLU). To conclude, the selection of membrane types and their modifications can modulate sample flow and increase the sensitivity of detection in paper diagnostics.

Paper-based colorimetric biosensors combine the use of paper with colorimetric signal detection. However, they usually demonstrate lower sensitivities because a signal amplification procedure has not been used. Stopping the reaction of colorimetric signal generation is often used in lab-based assays in order to amplify and stabilize the colorimetric signal for detection. In this study, the generation of a stopped colorimetric signal was examined for accurate and enhanced signal detection in paper-based biosensors. The colorimetric reaction in biosensors is usually based on the interaction between the enzyme horseradish peroxidase (HRP) and a selected chromogenic substrate. The two most commonly used HRP substrates, 3, 3&rsquo, 5, 5&rsquo, tetramethylbenzidine (TMB) and 2&rsquo, azinobis (3-ethylbenzothiazoline-6-sulfonic-acid) (ABTS), were compared in terms of their ability to generate a stopped colorimetric signal on membrane. The stopped colorimetric signal was visible for TMB but not for ABTS. Moreover, the generation of stopped colorimetric signal was dependent on the presence of polyvinylidene-difluoride (PVDF) membrane as the separation layer. With PVDF the colorimetric signal (color intensity) was higher (TMB: 126 &plusmn, 6 and ABTS: 121 &plusmn, 9) in comparison to without PVDF (TMB: 110 &plusmn, 2 and ABTS: 102 &plusmn, 4). The TMB stopped colorimetric signal demonstrated a more stable signal detection with lower standard deviation values. To conclude, a stopped colorimetric signal can be generated in paper-based biosensors for enhanced and accurate signal detection.

Artificial sweeteners have become increasingly controversial due to their questionable influence on consumers&rsquo, health. They are introduced in most foods and many consume this added ingredient without their knowledge. Currently, there is still no consensus regarding the health consequences of artificial sweeteners intake as they have not been fully investigated. Consumption of artificial sweeteners has been linked with adverse effects such as cancer, weight gain, metabolic disorders, type-2 diabetes and alteration of gut microbiota activity. Moreover, artificial sweeteners have been identified as emerging environmental pollutants, and can be found in receiving waters, i.e., surface waters, groundwater aquifers and drinking waters. In this study, the relative toxicity of six FDA-approved artificial sweeteners (aspartame, sucralose, saccharine, neotame, advantame and acesulfame potassium-k (ace-k)) and that of ten sport supplements containing these artificial sweeteners, were tested using genetically modified bioluminescent bacteria from E. coli. The bioluminescent bacteria, which luminesce when they detect toxicants, act as a sensing model representative of the complex microbial system. Both induced luminescent signals and bacterial growth were measured. Toxic effects were found when the bacteria were exposed to certain concentrations of the artificial sweeteners. In the bioluminescence activity assay, two toxicity response patterns were observed, namely, the induction and inhibition of the bioluminescent signal. An inhibition response pattern may be observed in the response of sucralose in all the tested strains: TV1061 (MLIC = 1 mg/mL), DPD2544 (MLIC = 50 mg/mL) and DPD2794 (MLIC = 100 mg/mL). It is also observed in neotame in the DPD2544 (MLIC = 2 mg/mL) strain. On the other hand, the induction response pattern may be observed in its response in saccharin in TV1061 (MLIndC = 5 mg/mL) and DPD2794 (MLIndC = 5 mg/mL) strains, aspartame in DPD2794 (MLIndC = 4 mg/mL) strain, and ace-k in DPD2794 (MLIndC = 10 mg/mL) strain. The results of this study may help in understanding the relative toxicity of artificial sweeteners on E. coli, a sensing model representative of the gut bacteria. Furthermore, the tested bioluminescent bacterial panel can potentially be used for detecting artificial sweeteners in the environment, using a specific mode-of-action pattern.