Tb-coordination polymer-anchored nanocellulose composite film for selective and sensitive detection of ciprofloxacin.

In recent years, along with the extensive application of ciprofloxacin (CIP), it has gradually become one of key environmental issues to be solved urgently. A novel fluorescent responsive nanocellulose composite film was successfully prepared by combining TEMPO-oxidized cellulose nanofibers (TOCNF) and terbium coordination polymer (Tb-AMP), in aqueous medium at room temperature via in-situ synthesis to detect CIP. CIP could supply energy for terbium ion through antenna effect to achieve the green fluorescence of Tb-AMP@TOCNF under 365 nm UV lamp. The transparency of the Tb-AMP@TOCNF was 88% when the deposition ratio of Tb-AMP on TOCNF was 7.2% and the environmental stability was good, which was conducive to fluorescent detection. As CIP concentration increased, the fluorescence intensity of Tb-AMP@TOCNF increased, and fluorescence intensity had a good linear relationship with CIP concentration in the range of 1-8 µM (y = 4.57 + 3.17x, R2 = 0.999, LOD = 0.0392 µM). It was a new way to realize future quantitative colorimetric analysis of pollutants.

Methyl Orange-Doped Polypyrrole Promoting Growth of ZIF-8 on Cellulose Fiber with Tunable Tribopolarity for Triboelectric Nanogenerator.

Cellulose fiber (CelF) is a biodegradable and renewable material with excellent performance but negligible triboelectric polarizability. Methods to enhance and rationally tune the triboelectric properties of CelF are needed to further its application for energy harvesting. In this work, methyl-orange-doped polypyrrole (MO-PPy) was in situ coated on CelF as a mediating layer to promote the growth of metal-organic framework ZIF-8 and to construct a cellulose-based triboelectric nanogenerator (TENG). The results showed that a small amount of MO-PPy generated in situ significantly promoted the growth of ZIF-8 on CelF, and the ZIF-8 deposition ratio was able to increase from 7.8% (ZIF-8/CelF) to 31.8% (ZIF-8/MO-PPy@CelF). ZIF-8/MO-PPy@CelF remained electrically conductive and became triboelectrically positive, and the triboelectricity's positivity was improved with the increase in the ZIF-8 deposition ratio. The cellulose-based TENG constructed with ZIF-8/MO-PPy@CelF (31.8% ZIF-8 deposition ratio) and polytetrafluoroethylene (PTFE) could generate a transfer charge of 47.4 nC, open-circuit voltage of 129 V and short-circuit current of 6.8 µA-about 4 times higher than those of ZIF-8/CelF (7.8% ZIF-8 deposition ratio)-and had excellent cycling stability (open-circuit voltage remained almost constant after 10,000 cycles). MO-PPy not only greatly facilitated the growth of ZIF-8 on CelF, but also acted as an electrode active phase for TENG. The novel TENG based on ZIF-8/MO-PPy@CelF composite has cheerful prospects in many applications, such as self-powered supercapacitors, sensors and monitors, smart pianos, ping-pong tables, floor mats, etc.

Integrated Conductive Hybrid Electrode Materials Based on PPy@ZIF-67-Derived Oxyhydroxide@CFs Composites for Energy Storage.

Due to excellent flexibility and hydrophilicity, cellulose fibers (CFs) have become one of the most potential substrate materials in flexible and wearable electronics. In previous work, we prepared cobalt oxyhydroxide with crystal defects modified polypyrrole (PPy)@CFs composites with good electrochemical performance. In this work, we redesigned the crystalline and nanoscale cobalt oxyhydroxide with zeolitic imidazolate frameworks-67 (ZIF-67) as precursor. The results showed that the PPy@ZIF-67 derived cobalt oxyhydroxide@CFs (PZCC) hybrid electrode materials possess far better capacitance of 696.65 F·g-1 than those of PPy@CFs (308.75 F·g-1) and previous PPy@cobalt oxyhydroxide@CFs (571.3 F·g-1) at a current density of 0.2 A·g-1. The PZCC delivers an excellent cyclic stability (capacitance retention of 92.56%). Moreover, the PZCC-supercapacitors (SCs) can provide an energy density of 45.51 mWh cm-3 at a power density of 174.67 mWh·cm-3, suggesting the potential application in energy storage area.

Phytic Acid Doped Polypyrrole as a Mediating Layer Promoting Growth of Prussian Blue on Cotton Fibers for Solar-Driven Interfacial Water Evaporation.

Phytic acid doped polypyrrole (PPy) as a mediating layer was in-situ coated on cotton fibers (CFs) to promote the growth of Prussian blue (PB) and construct the PB/PPy@CFs composite. The results showed that the proper amounts of PA doped PPy in-situ generated significantly promoted the growth of PB on CFs, the PB deposition ratio increased from 12.29% (PB@CFs) to 32.4% (PB/PPy@CFs), and the growth of PB on PPy@CFs could be completed in 4 h. Scanning electron microscopy (SEM) showed that the PB particles with perfect nano cubic structure were formed in the composite. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) showed that both PB and PPy were successfully deposited on CFs. The PB/PPy@CFs composite had excellent light absorption, hydrophilicity, wettability, and photothermal property, and the surface could be heated up to 81.5 °C under one sun illumination. The PB/PPy@CFs composite as a photothermal conversion material was used for solar-driven interfacial water evaporation, the water evaporation rate was 1.36 kg·m-2·h-1 at the optical concentration of 1 kW·m2, and the corresponding photothermal conversion efficiency increased from 81.69% (PB@CFs) to 90.96% (PB/PPy@CFs).

Construction of flexible electrodes based on ternary polypyrrole@cobalt oxyhydroxide/cellulose fiber composite for supercapacitor.

With the development of flexible electronic devices, flexible energy storage systems have been research hotpot. Conductive polymers is potential pseudocapacitor materials in energy storage field. Meanwhile, cellulose fiber with natural, degradable, renewable and flexible properties is one of tremendous promising alternatives to the flexible substrates. Hence, a polypyrrole@cobalt oxyhydroxide/cellulose fiber composite electrode is prepared via "liquid phase reduction" strategy in open system at room temperature. The composite electrode exhibits excellent electrochemical properties, which has a high specific capacitance and capacitance retention. The highest specific capacitance of 571.3 F g-1 at 0.2 A g-1 is obtained. Besides, the specific capacitance of the composite electrode has no significant loss, showing high cycle stability (93.02% after 1000 cycles). The excellent electrochemical properties can be ascribed to the introduction of cobalt oxyhydroxide, which restrains the volumetric change of polypyrrole in the electrochemical redox process, and promotes the rapid migration of electrons.

[Mutagenesis of cysteine residues in dptC from Salmonella enteric serovar Cerro 87 and its effects on DNA phosphorothioate modification].

OBJECTIVE: DNA phosphorothioate modification (DNA sulfur modification, a non-bridging oxygen swapped with a sulfur) exists in diverse bacteria. Salmonella enterica serovar Cerro 87 is one of the bacteria that harbor the DNA sulfur modification. The modification is carried out by the products of a four-membered gene cluster, dptBCDE. Transformation of Escherichia coli DH10B with the dptBCDE gene cluster endows the strain with DNA sulfur modification capability. Deletion of dptC abolished the modification. Here, we studied the function of dptC in DNA sulfur modification. METHODS: Six cysteine residues in dptC were mutated individually within the dptBCDE gene cluster. Mutants were then tested for DNA sulfur modification. RESULTS: Among the 6 cysteine mutations (C39, C146, C262, C273, C280, and C283), 5 abolished DNA modification except for C39, suggesting that C146, C262, C273, C280, and C283 are essential for DNA sulfur modification. Sequence alignment shows that these five cysteine residues are conserved among different strains. CONCLUSION: Mutation at anyone of C146, C262, C273, C280 and C283 of dptC abolished DNA modification. Our results shed light on further study of DNA sulfur modification biochemical pathway.

A process of applying polypyrrole-engineered pulp fibers prepared using hydrogen peroxide as oxidant to detoxification of Cr(VI)-contaminated water.

In this study, different from previous reports, an alternative process for detoxification of Cr(VI)-contaminated water with polypyrrole-engineered pulp fibers prepared using low cost hydrogen peroxide as oxidant was proposed. The process conditions in preparation of the engineered fibers as well as the water treatment conditions were optimized, and the behavior of Cr desorption from the engineered fibers was evaluated. The results showed that the proposed process was highly efficient in Cr(VI)-detoxification via the integration of adsorption with reduction. Compared with the previously reported polyaniline-engineered fibers prepared with hydrogen peroxide as oxidant, the engineered fibers studied in this work was much more effective.

A novel target of IscS in Escherichia coli: participating in DNA phosphorothioation.

Many bacterial species modify their DNA with the addition of sulfur to phosphate groups, a modification known as DNA phosphorothioation. DndA is known to act as a cysteine desulfurase, catalyzing a key biochemical step in phosphorothioation. However, bioinformatic analysis revealed that 19 out of the 31 known dnd gene clusters, contain only four genes (dndB-E), lacking a key cysteine desulfurase corresponding gene. There are multiple cysteine desulfurase genes in Escherichia coli, but which one of them participates into DNA phosphorothioation is unknown. Here, by employing heterologous expression of the Salmonella enterica dnd gene cluster named dptBCDE in three E. coli mutants, each of which lacked a different cysteine desulfurase gene, we show that IscS is the only cysteine desulfurase that collaborates with dptB-E, resulting in DNA phosphorothioation. Using a bacterial two-hybrid system, protein interactions between IscS and DptC, and IscS and DptE were identified. Our findings revealed IscS as a key participant in DNA phosphorothioation and lay the basis for in-depth analysis of the DNA phosphorothioation biochemical pathway.