Targeted Analysis of Microplastics Using Discrete Frequency Infrared Imaging

An analytical strategy to improve sample throughput with discrete frequency infrared image-based targeted analysis of microplastics using a laser direct infrared chemical imaging system was successfully developed and implemented. Leveraging a quantum cascade laser as a light source, the system could lock the frequency at predetermined wavelengths and use a discrete frequency infrared imaging technique to identify particles with absorption at desired wavelengths. In this way, targeted analysis can be achieved by selectively characterizing these particles. In the concept demonstration study, the targeted analysis was able to identify 87.7% of spiked polyethylene particles by scanning only 20% of the particles in the sample. The technique substantially improves sample throughput by at least a factor of 4 under conditions used. In the tests performed with real environmental samples, the targeted analysis workflow correctly identified eight types of common microplastics by only investigating around 60% of the particles and less than 30% of the sample area. Results obtained demonstrated that this scanning strategy is a game changer to enhance sample throughput in microplastic analysis. The technique has the potential of being applied to other infrared-based analytical platform

Synthesis of a Au/Silica/Polymer Trilayer Composite and the Corresponding Hollow Polymer Microsphere with a Movable Au Core

Gold/silica/poly(N,N‘-methylenebisacrylamide) (Au/SiO2/polyMBAAm) trilayer composite materials were prepared by distillation precipitation polymerization of N,N‘-methylenebisacrylamide (MBAAm) in the presence of Au/SiO2 particles as seeds, in which the seeds were prepared by a combination of gold-complexing and silane coupling agent with a further modified Stöber method. The polymerization of MBAAm was performed in neat acetonitrile with 2,2‘-azobisisobutyronitrile as an initiator to encapsulate the Au/SiO2 seeds driven by the hydrogen-bonding interaction between the hydroxyl group on the surface of the seeds and the amide unit of polyMBAAm without modification of the Au/SiO2 surface in the absence of any stabilizer or surfactant. Hollow polyMBAAm microspheres with movable Au cores were further developed by the selective removal of the middle silica layer with hydrofluoric acid. The resultant trilayer Au/SiO2/polyMBAAm composite and hollow polyMBAAm microspheres with movable Au cores were characterized by transmission electron microscopy. The diffusion of chemicals across the polyMBAAm shell was investigated by a catalytic reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride as a reductant

Preventing Dendrite Growth by a Soft Piezoelectric Material

We report a piezoelectric mechanism to stop dendrite growth, which enables inherently safe lithium metal battery. For demonstration, a polarized piezoelectric polyvinylidene fluoride (PVDF) film is used as a separator. When the film is deformed by any local protrusion because of surface instability of the deposited lithium, a local piezoelectric over-potential is generated to suppress lithium deposition on the protrusion. Our optical in situ cell shows that a polarized PVDF film ensures lithium metal depositing to form a flat surface, even when starting from an uneven surface. In contrast, a nonpolarized PVDF film cannot suppress dendrite growth under the same condition, with dendrite penetrating the separator within minutes. Coin cell results further confirm that the piezoelectric mechanism is effective in practical battery applications. Analysis suggests that the effectiveness of piezoelectric mechanism by over-potential is easily 104 stronger than the maximum physical limit of mechanical blocking from infinitely stiff blocking materials, suggesting a new direction of material innovation

Preventing Dendrite Growth by a Soft Piezoelectric Material

We report a piezoelectric mechanism to stop dendrite growth, which enables inherently safe lithium metal battery. For demonstration, a polarized piezoelectric polyvinylidene fluoride (PVDF) film is used as a separator. When the film is deformed by any local protrusion because of surface instability of the deposited lithium, a local piezoelectric over-potential is generated to suppress lithium deposition on the protrusion. Our optical in situ cell shows that a polarized PVDF film ensures lithium metal depositing to form a flat surface, even when starting from an uneven surface. In contrast, a nonpolarized PVDF film cannot suppress dendrite growth under the same condition, with dendrite penetrating the separator within minutes. Coin cell results further confirm that the piezoelectric mechanism is effective in practical battery applications. Analysis suggests that the effectiveness of piezoelectric mechanism by over-potential is easily 104 stronger than the maximum physical limit of mechanical blocking from infinitely stiff blocking materials, suggesting a new direction of material innovation

Preventing Dendrite Growth by a Soft Piezoelectric Material

We report a piezoelectric mechanism to stop dendrite growth, which enables inherently safe lithium metal battery. For demonstration, a polarized piezoelectric polyvinylidene fluoride (PVDF) film is used as a separator. When the film is deformed by any local protrusion because of surface instability of the deposited lithium, a local piezoelectric over-potential is generated to suppress lithium deposition on the protrusion. Our optical in situ cell shows that a polarized PVDF film ensures lithium metal depositing to form a flat surface, even when starting from an uneven surface. In contrast, a nonpolarized PVDF film cannot suppress dendrite growth under the same condition, with dendrite penetrating the separator within minutes. Coin cell results further confirm that the piezoelectric mechanism is effective in practical battery applications. Analysis suggests that the effectiveness of piezoelectric mechanism by over-potential is easily 104 stronger than the maximum physical limit of mechanical blocking from infinitely stiff blocking materials, suggesting a new direction of material innovation

<i>N</i>. <i>cinerea</i> reduces association of <i>N</i>. <i>meningitidis</i> with epithelial cells.

(A) Cells were infected with N. cinerea (Nc346T) for 4.5 h prior to infection with N. meningitidis (Nm8013). The number of cell associated bacteria of each species was determined 1.5 h later. Results are the mean ± SD of three independent experiments carried out in triplicate. NS, not significant; ***pB and C) Epithelial cells were infected with N. meningitidis (Nm 8013) alone or with N. cinerea (Nc 346T). The number of cell associated bacteria (CFU/mL) was determined at time points as indicated. Filled shapes show the number of CFU/well in single infections, while empty shapes show the number of CFU/well in co-infections. Each data point represents a single well from three independent experiments conducted in triplicate. NS, not significant; *, pD) Epithelial cells were infected with N. meningitidis (Nm 8013) alone or co-infected with N. cinerea (Nc 346T) at a ratio of 1:100 (Nm 8013 to Nc 346T) for 20 h. (E) Single and mixed cultures of N. meningitidis (8013) and N. cinerea (346T) were grown in the absence of cells for 6 hrs, and the number of bacteria was determined by selective plating. Results are the mean +SD of three independent experiments carried out in triplicate. NS, not significant. (F) Epithelial cells were infected with N. meningitidis (Nm 8013) alone or co-infected with E. coli (BL21 pET21b) at an MOI of 50 for each strain. Cell associated N. meningitidis and E. coli (CFU/well) was determined at 6 hpi. Filled circles show Nm8013 (red) and E. coli (blue) in single infections; filled squares show Nm8013 (red) and E. coli (blue) in co-infection. Results are the mean ± SD of 9 replicates from three independent experiments. NS, not significant; *pp(G) Epithelial cells were infected with N. meningitidis (Nm 8013) alone or co-infected with wild-type N. cinerea (Nc346T) or a mutant lacking ACP (NcΔacp). At 6 hpi, cell associated N. meningitidis was quantified and presented as CFU per well. Filled circles show Nm8013 bacterial numbers in single infections; empty circles or empty triangles show levels of Nm8013 in co-infection. Results are the mean ± SD of at least three independent experiments carried out in duplicate. NS, not significant; *, pp<0.001 (one-way ANOVA test for multiple comparison).</p

<i>N</i>. <i>cinerea</i> Tfp are required for microcolony formation and fusion.

(A) Epithelial cells were infected with N. cinerea wild-type (Wt) expressing sfCherry for 16 h. Images were captured at 10 min intervals; time points 2, 4 and 8 h are shown. (B) Microcolony size was quantified by measuring their surface area. Each line corresponds to a single microcolony tracked over time. Data shown are for eight microcolonies from one representative experiment of three independent experiments. (C) Epithelial cells infected with N. cinerea 346TΔpilE1/2 expressing GFP. Images were captured at 10 min intervals, and images from 2, 4 and 8 h post infection are shown. (D) Epithelial cells co-infected with wild-type N. cinerea (Wt, red in merge) and the pilE mutant (ΔpilE1/2, green in merge). Images are representative of three independent experiments performed in triplicate. In each case merged panels show both phase-contrast and fluorescence channels (GFP and Texas Red). Scale bars, 75 μm.</p

<i>N</i>. <i>cinerea</i> restricts <i>N</i>. <i>meningitidis</i> microcolony motility and expansion.

(A) Representative time-lapse images of epithelial cells infected with N. meningitidis pNCC101::sfCherry alone (red, Nm8013), or with N. cinerea 346T expressing GFP (green, Nc346T) or N. cinerea 346TΔpilE1/2 expressing GFP (green, NcΔpilE1/2). Time points 3, 4 and 6 hpi are shown. Scale bar, 50 μm. (B) The frequency of microcolonies containing Nc346T and Nm8013 assessed by time-lapse microscopy. Most microcolonies harbour both species. Data shows the mean + SD of at least 700 Nm8013 microcolonies from three independent experiments. NS, not significant; ***, pC) The size of N. meningitidis aggregates in single and mixed infections was quantified by measuring the area of meningococcal microcolonies. Each point shows the mean ± SD (dotted lines) of 36 microcolonies from three independent experiments. NS, not significant; *, pppD) Total distance travelled by N. meningitidis microcolonies in presence or absence of N. cinerea. Cumulative microcolony displacement was calculated based on the total distance covered per microcolony between 3 and 6 hpi. Data shown represent the mean + SD of 36 microcolonies tracked from three independent experiments. NS, not significant; ***, p<0.0005 (one-way ANOVA test for multiple comparisons).</p

Tfp are not required for colocalisation of <i>N</i>. <i>cinerea</i> with CD44 honeycomb-like structures.

(A) Epithelial cells were infected with wild-type N. cinerea 346T (Wt) or N. cinerea 346TΔpilE1/2 both expressing GFP (green in merge) at an MOI of 100. At 3 hpi, cells were stained for CD44 (red in merge). Scale bar, 10 μm. (B) Quantification of CD44 colocalisation with bacterial colonies. Results represent the mean ± SD of three independent experiments. NS, not significant using unpaired two-tailed Student’s t-test.</p

<i>N</i>. <i>cinerea</i> co-localises with components of cortical plaques on epithelial cells.

(A) Epithelial cells were infected for 3 h with N. cinerea expressing GFP and stained for CD44, ezrin or actin. Bacteria co-localised with each protein (white arrows); magnified areas in the panels on the right show the honeycomb-like arrangement of each protein. (B) Non-infected A549 cells were immunostained for CD44, ezrin or actin and analysed by microscopy. Magnified areas shown in the panels on the right do not show a honeycomb-like arrangement. Scale bars, 10 μm. (C) Frequency of co-localisation of each protein in honeycomb-like arrangement at the site of attachment was determined by scoring 50 microcolonies. Data shown represent the mean ± SD of three independent experiments; NS, not significant. (D) Epithelial cells were infected for 3 h with N. cinerea and double fluorescence labelling was performed. Actin (red) and CD44 (green) in the top panels; or ezrin (red) and CD44 (green) in the bottom panels. Scale bars correspond to 10 μm. (E) XZ sections of cells dual labelled for actin (red) and CD44 (green), or CD44 (green) and ezrin (red). Bacteria and nuclei were stained with DAPI (white). Arrows indicate cellular protrusions enriched with actin-CD44 or ezrin-CD44.</p