The appealing mechanisms by which nanocomposites knit biomolecules not only lend credence in designing novel nanosensors but considerably advance medical applications. 1 Recent headline news about Escherichia coli (E. coli) contamination in produce and Bacillus anthracis attacks pinpoint the urgent need for an effective method for microbial decontamination and rapid detection without time-consuming cell culturing. It is known that many bacteria use mammalian cell surface carbohydrates as anchors for attachments, which subsequently results in infection. 2 The unique combination of magnetic nanocomposites and diverse carbohydrate bioactivities prompts us to embark on a biosensing research program. Herein, we report a magnetic glyco-nanoparticle (MGNP)-based system to not only detect E. coli within 5 min, but also remove up to 88% of the target bacteria from the medium. Furthermore, the identities of three different E. coli strains were easily determined on the basis of the response patterns to two MGNPs highlighting their potential in biosensing.It is advantageous to use magnetic nanoparticles (NPs) for detection. The high surface/volume ratio offers more contact surface area for attaching carbohydrates and for capturing pathogens. 3 The sizes of NPs are typically about 2 orders of magnitude smaller than a bacterium, which allows the attachment of multiple NPs onto a bacterial cell rendering easy magnet-mediated separation. 3,4 Moreover, the small NPs have faster kinetics in solution as compared to their micrometer-sized counterparts, which can result in fast detection.Our journey commenced with functionalization of silica-coated magnetite NP (NP 1) with D-mannose (Man) through either a triazole linker (MGNP 2) formed by the [2+3] Huisgen reaction 5 or an amide linkage (MGNP 3) (Schemes 1 and S1). With our covalent approach, 6 all carbohydrates are uniformly oriented on the NP surface, which is crucial for high performances in cell-capturing studies. 7 All MGNPs were characterized by X-ray diffraction, transmission electron microscopy (TEM), thermogravimetric analyses, and IR spectroscopy ( Figures S1-4).To ensure that carbohydrates on MGNP retain their binding abilities, the interaction between various MGNPs with a mannose binding lectin, concanavalin A (Con A), 8 was first investigated. Carbohydrate-lectin interaction 9 is central in devising our biosensor. After mixing NPs with fluorescein-labeled Con A, a magnetic field was applied to the mixture through a handheld magnet inducing aggregation of magnetic NPs on the side of the vial. The residual fluorescence of supernatants was then recorded ( Figure S5). With MGNP 3, the emission intensity of the supernatant decreased 87% indicating that most Con A was removed by 3. Triazole linked MGNP 2 was less efficient accounting for a 60% emission decrease probably because of the low efficiency of the Huisgen reaction with immobilized alkynes. 5 NP 1 without carbohydrates (control) did not remove any Con A, proving that the separation of Con A is due to its interaction...

Existing stormwater systems require significant investments to meet challenges imposed by climate change, rapid urbanization, and evolving regulations. There is an unprecedented opportunity to improve urban water quality by equipping stormwater systems with low-cost sensors and controllers. This will transform their operation from static to adaptive, permitting them to be instantly "redesigned" to respond to individual storms and evolving land uses.

In this study, multiple roles of biofilm EPS were assessed with respect to the resistance of biofilm and detached biofilm clusters to chlorine disinfection. Strains from an opportunistic pathogen, Pseudomonas aeruginosa (wild type, EPS- and EPS+) with altered extracellular polymeric substances (EPS) secretion capabilities were tested. The impact of biofilm EPS quantity on disinfection was evaluated by monitoring biofilm viability, biofilm structure, removal of dissolved organic matter (DOM), and viability of detached biofilm simultaneously during chlorine disinfection. The obtained results suggested that the presence of EPS increased biofilm and detached biofilm resistance to chlorine in both presence and absence of DOM. The quantity of EPS had an effect on biofilm structure and the structural characteristics were closely related to both overall biofilm viability and the spatial distribution of viable cells within the biofilm. Additionally, the increased amount of EPS influenced selective removal of DOM with polar functional groups. However the DOM removal did not have a significant impact on the viability of biofilm cells during chlorine disinfection. Meanwhile, the viability of detached biofilm clusters, particularly the EPS overproducing strain, was significantly increased in the presence of DOM. The combined results suggested that biofilm EPS played multiple roles toward influencing the resistance of both biofilm and detached biofilm to disinfectant.

Benzotriazole derivatives are widely used corrosion inhibitors and their fate during wastewater treatment processes is unknown. The purpose of this research was to study the toxic effects and fate of the two commercially significant benzotriazole isomers used in aircraft deicing fluids (4-, and 5-, methylbenzotriazole [MeBT]) during anaerobic digestion. Experiments were executed in microcosms using mesophilic anaerobic biomass co-digesting wastewater sludge and propylene glycol. Sorption of MeBT to digesting solids could be approximated with a Freundlich model, and no anaerobic breakdown of either MeBT isomer was detected. Digesters fed more than 300 mg/L MeBT responded with a significant decrease in methanogenic microbial activity and volatile solids production and a concomitant increase in accumulation of volatile fatty acids. Direct microscopic measurements using fluorescent phylogenetic probes applied to digesting biomass revealed that members of both Archaea and Bacteria domains were sensitive to MeBT. Granular activated carbon (GAC) (volatile solids: GAC ϭ 10%) reduced the apparent toxic effects of MeBT; GAC addition nearly restored the baseline activity of digesters fed MeBT (500 to 1000 mg/L). Water Environ. Res., 73, 72 (2001).

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