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The harm of a global rise in the biofilms formation caused by bacteria adhering to surfaces calls for the design and fabrication of a generation of bactericidal materials. Recently, much inspiration has been drawn from naturally occurring mechano-bactericidal surfaces with physical structures such as cicada wings in fabricating their synthetic analogues. Here, we fabricated a series of the highly controllable nanometer-scale characteristic polycarbonate (PC) surfaces using anodic aluminum oxide template-assisted hot embossing and wet etching. The influences of geometric parameters of PC nanostructured surfaces, including the height, diameter, and interspacing, which can be adjusted independently, on the bactericidal efficiency were systematically investigated. Our experimental results demonstrate that, for the surfaces able to kill bacteria, there is a critical height of nanostructures required, ∼200 nm; the smaller the cap diameter of nanopillars, the greater the pressure exerted on bacterial cell by nanopillars, namely, the cell is likely to be destroyed; bacteria are also sensitive to interpillar spacing. It is possible that an optimal range of interpillar spacing on nanostructured surface will result in its high bactericidal activity. In this work, the highest bactericidal rates (98.4% for Escherichia coli) were obtained from the nanostructured surfaces with above 200 nm of height, less than 60 nm of cap diameter, and 170 nm of interpillar spacing. [ABSTRACT FROM AUTHOR]

Biomimetic nanostructures with bactericidal performance have become the research focus in constructing sterilization surfaces, but the mechano-bactericidal mechanism is still not fully understood, especially for the hierarchical nanostructure arrays with different heights. Herein, the interaction between Escherichia coli cells and nanostructure arrays was simulated by finite element, and the initial rupture points, i.e., critical action sites, of bacterial cells and the effects of nanostructure geometries on the cell rupture speed were analyzed based on the mechano-response of Escherichia coli cells on flat (identical heights) and hierarchical nanostructure arrays. The critical action sites of bacterial cells on nanostructure arrays are all at the three-phase junction zone of cell-liquid-nanostructure, but they are slightly shifted by the height difference Δ H of nanostructures on hierarchical nanopillar (NP)/nanosheet (NS) arrays, where the NP is higher than the NS. When Δ H < 20 nm, the site nears the NS corners, and when Δ H ≥ 20 nm, the site is consistent with that of the NP/NP array, i.e., the site locates at the three-phase junction zone of cell-liquid-high NP. In addition, except for decreasing the NP diameter, the NS thickness/width, or properly increasing the nanostructure spacing, the cell rupture can be accelerated via increasing the Δ H of nanostructures. Δ H = 40 nm is distinguished as the boundary for the effect of nanostructure Δ H on the cell rupture speed. When Δ H < 40 nm, the cell rupture speed rapidly increases as the Δ H increases; when Δ H ≥ 40 nm, the cell rupture speed reaches the maximum value and remains stable. This study provides a new strategy on how to design high-efficiency bactericidal surfaces.

A novel signal-off biosensing platform based on the CdLa 2 S 4 /SnIn 4 S 8 /Sb 2 S 3 heterojunction as photoactive materials and NiCo 2 O 4 nanospheres as a photoquencher was developed to achieve the sensitive detection of CA19-9. First, the narrow band gap hydrangea-like CdLa 2 S 4 /SnIn 4 S 8 /Sb 2 S 3 not only provided excellent photocurrent response but also supplied a mass of active sites that facilitated the loading of capture antibody (Ab 1 ). Second, a double type II CdLa 2 S 4 /SnIn 4 S 8 /Sb 2 S 3 heterojunction promoted the fast separation and migration of photogenerated e - /h + and overcame the problem of short carrier lifetime caused by the recombination of photogenerated carriers. In addition, to improve the sensitivity of the constructed sensor to detect CA19-9, signal tags (p-type NiCo 2 O 4 ) with large steric hindrance were introduced to accomplish signal amplification by the effect of double signal quenching. On one hand, NiCo 2 O 4 , which was strongly responsive to visible light, utilized its own advantages to compete for AA with CdLa 2 S 4 /SnIn 4 S 8 /Sb 2 S 3 , resulting in a decrease in the hole scavenging rate of the substrate. On the other hand, the photoquencher NiCo 2 O 4 also prevented AA from contacting the matrix and further aggravated the photoelectrochemical (PEC) signal-damping effect. The PEC immunosensor was prepared with brilliant selectivity and splendid stability to detect CA19-9 (0.001-50 U/mL), and the detection limit was 0.0004 U/mL (S/N = 3).

One-step total hydrogenation of furfural (FAL) toward tetrahydrofurfuryl alcohol in continuous flow using cheap transition metals still remains a great challenge. We herein reported the total hydrogenation of FAL over Ni (∼5 nm) nanoparticles loaded on TiO 2 -SiO 2 composites with long-term stability. The TiO 2 -SiO 2 composites comprise amorphous TiO x which was grafted on the silica aerogel by acetyl acetone-aided controlled hydrolysis of tetrabutyl titanate. The catalysts were characterized by several techniques including Brunauer-Emmett-Teller, X-ray diffraction, transmission electron microscopy, H 2 -temperature-programmed reduction, and H 2 -temperature-programmed desorption. The hydrogenation performances were systematically explored in terms of TiO 2 content, Ni loading, liquid hour space velocity, and so forth. Ni nanoparticles in contact with amorphous TiO x showed strengthened interaction with the C=O bond of FAL as well as enhanced hydrogen dissociation and desorption ability, hence benefiting the overall hydrogenation process., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)

Research on perfluoroalkyl substances (PFASs) continues to grow. However, very little is known about these substances in amphibians. Here we report for the first time on the occurrence, tissue distribution, and bioaccumulation of two novel PFASs, chlorinated polyfluorinated ether sulfonic acid (6:2 Cl-PFESA) and hexafluoropropylene oxide trimer acid (HFPO-TA), in the black-spotted frog (Pelophylax nigromaculatus) from China. Frogs from cities with large-scale fluorochemical industries had significantly greater liver ∑PFAS levels (mean 54.28 ng/g in Changshu; 31.22 ng/g in Huantai) than those from cities without similar industry (9.91 ng/g in Zhoushan; 7.68 ng/g in Quzhou). Females had significantly lower liver PFAS levels than males, and older frogs tended to have lower PFAS levels than younger frogs. Skin, liver, and muscle contributed nearly 80% to the whole body burden of 6:2 Cl-PFESA in males, whereas the female ovary alone accounted for 58.4%. These results suggest substantial maternal transfer of 6:2 Cl-PFESA to eggs, raising concern regarding its developmental toxicity on frogs and other species. The bioaccumulation factor results (6:2 Cl-PFESA > PFOS; HFPO-TA > PFOA) suggest a stronger accumulative potential in the black-spotted frog for these alternative substances compared to their predecessors. Future studies on their toxicity and ecology risk are warranted.