In Situ Formation of o-Phenylenediamine Cascade Polymers Mediated by Metal-Organic Framework Nanozymes for Fluorescent and Photothermal Dual-Mode Assay of Acetylcholinesterase Activity.

A fluorescent and photothermal dual-mode assay method was established for the detection of acetylcholinesterase (AChE) activity based on in situ formation of o-phenylenediamine (oPD) cascade polymers. First, copper metal-organic frameworks of benzenetricarboxylic acid (Cu-BTC) were screened out as nanozymes with excellent oxidase-like activity and confinement catalysis effect. Then, an ingenious oPD cascade polymerization strategy was proposed. That is, oPD was oxidized by Cu-BTC to oPD oligomers with strong yellow fluorescence, and oPD oligomers were further catalyzed to generate J-aggregation, which promotes the formation of oPD polymer nanoparticles with a high photothermal effect. By utilizing thiocholine (enzymolysis product of acetylthiocholine) to inhibit the Cu-BTC catalytic effect, AChE activity was detected through the fluorescence-photothermal dual-signal change of oPD oligomers and polymer nanoparticles. Both assay modes have low detection limitation (0.03 U L-1 for fluorescence and 0.05 U L-1 for photothermal) and can accurately detect the AChE activity of human serum (recovery 85.0-111.3%). The detection results of real serum samples by fluorescent and photothermal dual modes are consistent with each other (relative error ≤ 5.2%). It is worth emphasizing that this is the first time to report the high photothermal effect of oPD polymers and the fluorescence-photothermal dual-mode assay of enzyme activity.

Severe Periodontitis Is Associated with Early-Onset Poststroke Depression Status.

BACKGROUND: Poststroke depression (PSD) is one of the most common complications after ischemic stroke, and periodontitis is associated with depression. However, whether severe periodontitis is associated with early-onset PSD status remains unknown. In this study, we aimed to investigate whether there is an association between severe periodontitis and PSD status in acute ischemic stroke patients. MATERIAL AND METHODS: We recruited 202 acute ischemic stroke patients within 7 days after stroke onset. Pocket depth and clinical attachment loss were assessed by oral examination to define the severe periodontitis. On the basis of diagnosis of PSD status according to DSM-5 criteria and a 24-item Hamilton Depression Rating Scale score greater than or equal to 8 within 2 weeks after stroke onset, we stratified patients into PSD status or non-PSD status groups and identified the independent predictors for the development of PSD status in multivariate logistic analysis. RESULTS: 77 (38.1%) patients were diagnosed as early-onset PSD status. PSD status group showed more severe periodontitis, lower income, lower Barthel Index (BI) score and Montreal Cognitive Assessment score, higher National Institutes of Health Stroke Scale score and modified Rankin scale (mRS) score compared with non-PSD status group. Multivariate logistic regression showed that severe periodontitis (odds ratio 2.401) and NIHSS score (>4, odds ratio 2.130) were independent predictors for early-onset PSD status. CONCLUSIONS: Severe periodontitis is found to be an important independent predictor of early-onset PSD status in patients with acute ischemic stroke, in addition to the well-known prognostic factors such as nonminor stroke assessed by NIHSS greater than 4.

[Triton X-100 Enhanced the Detection of Hodge Test and Carba NP Test for Carbapenemase-producing Acinetobacter baumannii Complex].

OBJECTIVE: To find out highly effective phenotypic methods to detect carbapenemase-producing Acinetobacter baumannii (A. baumannii complex) so as to support the epidemiological investigation and clinical application. METHODS: We included 113 A. baumannii complex and compared the detection performance of modified Hodge test, Carba NP test, Triton Hodge test, and the simplified Carba NP-direct test with Tritont X-100. RESULTS: We tested 83 carbapenemase-producing A. baumannii complex and 30 non-carbapenemase producers. The sensitivity and specificity of Hodge test were significantly higher than those of Carba NP test (71.1% versus 35.0%, 100% versus 86.7%, P<0.05, respectively). The sensitivity of Triton Hodge test and Carba NP-direct test was respectively significantly higher than Hodge test and Carba NP test (98.8% versus 71.1%, 85.5% versus 35.0%, P<0.001, respectively ). However, the specificities were comparable (P>0.05). The positive additive effects of the two methods with Triton X-100 were more obvious than those of the methods without Triton X-100 (P<0.001). CONCLUSION: Triton X-100 could increase the sensitivity and positive additive effect on phenotypic detection of A. baumannii complex. Triton Hodge test and Carba NP-direct test were more applicable for clinical routine procedure.

Facilely Prepared Thirsty Granules Arouse Tough Wet Adhesion on Overmoist Wounds for Hemostasis and Tissue Repair.

Bioadhesives have been widely used in hemostasis and tissue repair, but the overmoist and wet nature of wound surface (due to the presence of blood and/or wound exudate) has led to poor wet adhesion of bioadhesives, which interrupts the continuous care of wounds. Here, a thirsty polyphenolic silk granule (Tan@SF-pwd-hydro), which absorbs blood and exudate to self-convert to robust bioadhesives (Tan@SF-gel-hydro) in situ, was facilely developed in this study for enhanced wet adhesion toward hemostasis and tissue repair. Tan@SF-pwd-hydro could shield wounds' wetness and immediately convert itself to Tan@SF-gel-hydro to seal wounds for hemorrhage control and wound healing. The maximum adhesiveness of Tan@SF-gel-hydro over wet pigskin was as high as 59.8 ± 2.1 kPa. Tan@SF-pwd-hydro is a promising transformative dressing for hemostasis and tissue repair since its hemostatic time was approximately half of that of the commercial hemostatic product, CeloxTM, and its healing period was much shorter than that of the commercial bioadhesive product, TegadermTM. This pioneering study utilized adverse wetness over wounds to arouse robust adhesiveness by converting thirsty granules to bioadhesives in situ, creatively turning adversity into opportunities. The facile fabrication approach also offers new perspectives for manufacturing sustainability of biomaterials.

Alteration of bacterial communities and co-occurrence networks as a legacy effect upon exposure to polyethylene residues under field environment.

The use of plastic film mulch threatens the sustainability of the terrestrial environment because of the persistence of plastic residue. Identification of the potential long-term impacts of polyethylene (PE) residue on the soil microbiome has been overlooked in most studies. A long-term field experiment was conducted to expand this understanding by performing a co-occurrence network analysis of bacterial communities among different compartment niches (i.e. plastisphere, rhizosphere, and bulk soil) and three PE residue concentrations to determine the differential operational taxonomic units (OTUs) and keystone taxa. The specific set of bacterial microbes in the plastisphere was different from that of bulk soil and rhizosphere (R2 = 0.372, P < 0.001, PERMANOVA). Totally, 215 and 257 differential OTUs were identified in response to the different compartment niches and PE residue concentrations, respectively. Among these, several hubs or keystone taxa responsible for the exposure to PE residues were further identified, most of which have potential biodegradation functions. Exposure to PE residues led to a reduced network complexity and microbiome stability in the soil ecosystem. This study provides a comprehensive evidence on the alteration of bacterial communities and co-occurrence networks in the terrestrial environment as a legacy effect when exposed to PE residues, and has potential implications for predicting the ecological functions of the soil ecosystem.

Organocatalytic enantioselective hydroxymethylation of oxindoles with paraformaldehyde as C1 unit.

A bifunctional thiourea-tertiary amine-catalyzed asymmetric hydroxymethylation of 3-substituted oxindoles using paraformaldehyde as the C1 unit was developed. A wide scope of oxindoles, bearing C3 sterically congested quaternary carbon centers, were smoothly obtained in good to excellent yields (up to 99%) and high enantioselectivities (up to 91% ee) under mild reaction conditions. A more significant feature of this approach employs cheap and readily available paraformaldehyde as a hydroxymethylation C1 unit, which is activated by chiral bifunctional thiourea organocatalysts.

Enzyme-mediated nitric oxide production in vasoactive erythrocyte membrane-enclosed coacervate protocells.

The design and construction of synthetic therapeutic protocells capable of establishing cognate chemical communication channels with living cells is an important challenge for synthetic biology and bio-engineering. Here we develop a step towards protocell-mediated nitric-oxide-induced vasodilation by constructing a new synthetic cell model based on bio-derived coacervate vesicles with high haemocompatibility and increased blood circulation times. The hybrid protocells are prepared by the spontaneous self-assembly of haemoglobin-containing erythrocyte membrane fragments on the surface of preformed polysaccharide-polynucleotide coacervate micro-droplets containing glucose oxidase. We use the sequestered enzymes to program a spatially coupled glucose oxidase/haemoglobin reaction cascade, which in the presence of glucose and hydroxyurea generates a protocell-mediated flux of nitric oxide that we exploit for in vitro and in vivo blood vessel vasodilation. Taken together, our results provide new opportunities for the development of endogenously organized cell-like entities (biocompatible micro-bots) geared specifically towards active interfacing with individual living cells and cell communities.

Bio-based UV protective films prepared with polylactic acid (PLA) and Phoebe zhennan extractives.

In this study, diethyl ether extractives were isolated from Phoebe zhennan wood and then added into PLA matrix for the preparation of UV protective films (UV-PF). The results revealed that the diethyl ether extractives had good compatibility with PLA. The prepared UV-PF with the addition of 24 wt% extractives showed complete absorption of UV-C (200-280 nm) and UV-B (280-315 nm) and more than 90% absorption of UV-A (315-400 nm), indicating the addition of extractives into PLA contributed to the super UV resistant ability of the PLA based films. The UV-PF still exhibited excellent UV absorbability after strong UV light irradiation. The differential Scanning Calorimetry (DSC) analysis of the films showed that the UV-PF had relatively low thermal degradation temperature compared to the neat PLA films (PF), while the UV-PF showed stronger tensile strength with comparison to that of the PF. The results on the chemical composition analysis of the diethyl ether extractives revealed that the UV absorbability of the UV-PF may own to the benzene structure, CO bonds, CC bonds in the constituents of the extractives, which all have strong absorption in the near UV-region (200-400 nm).

Computational and experimental insight into the molecular mechanism of carboxamide inhibitors of succinate-ubquinone oxidoreductase.

Succinate-ubiquinone oxidoreductase (SQR, EC 1.3.5.1), also known as mitochondrial respiratory complex II or succinate dehydrogenase (SDH), catalyzes the oxidation of succinate to fumarate as part of the tricarboxylic acid cycle. SQR has been identified as a novel target of a large family of agricultural fungicides. However, the detailed mechanism of action between the fungicides and SQR is still unclear, and the bioactive conformation of fungicides in the SQR binding pocket has not been identified. In this study, the kinetics of porcine SQR inhibition by ten commercial carboxamide fungicides were measured, and noncompetitive inhibition was observed with respect to succinate, DCIP, and cytochrome c, while competitive inhibition was observed with respect to ubiquinone. With the aim to uncover the binding conformation of these fungicides, molecular docking, molecular dynamics simulation, and molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) calculations were then performed. The excellent correlation (r(2) =0.94) between the calculated (ΔGcal ) and experimental (ΔGexp ) binding free energies indicates that the obtained docking conformation could be the bioactive conformation. The acid moiety of carboxamide fungicides inserts into the ubiquinone binding site (Q-site) of SQR, forming van der Waals (vdW) interactions with C_R46, C_S42, B_I218, and B_P169, while the amine moiety extends to the mouth of the Q-site, forming vdW interactions with C_W35, C_I43, and C_I30. The carbonyl oxygen atom of the carboxamide forms hydrogen bonds with B_W173 and D_Y91. These findings provide valuable information for the design of more potent and specific inhibitors of SQR.