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Chloroform is a toxic and persistent solvent that cannot be effectively removed from the environment by actual remediation methods. Chloroform removal using persulfate activated by iron nanoparticles has been tested but is limited by chloroform inertness and nanoparticle inactivation in the real environment. Here we hypothesized that tannic acid could improve the activation of persulfate with Fe/Ni nanoparticles. We studied the influence of tannic acid/Fe ratio, persulfate concentration, initial pH, temperature, inorganic anions and natural organic matters on chloroform removal. We found that tannic acid-Fe/Ni-persulfate system with 1.65 mol% of tannic acid-Fe and 3.2 mM of persulfate yielded about 87–97% chloroform removal in the 2.9–10.7 pH range. Electron paramagnetic resonance and radical quenching experiments revealed that SO4•− and •OH were primarily responsible for chloroform removal. High removal is probably due to Fe-tannic acid chelation that prevents the precipitation of iron hydroxide on Fe/Ni nanoparticles, thus preserving active sites.

Chloroform is an harmful chlorinated hydrocarbon which is hardly degraded using actual dechlorination methods. Alternatively, carboxymethyl cellulose/zero-valent iron appears promising to degrade chlorinated hydrocarbons in water, yet actually carboxymethyl cellulose cannot inhibit the oxidation and sedimentation of iron ions under alkaline condition. Here, polyethylene glycol, a green and low-cost non-ionic polymer, was used as a stabilizer to synthesize polyethylene glycol-stabilized Fe/Ni nanoparticles (PEG-Fe/Ni) for removing chloroform from water in a wide range of pH, from 3 to 11. PEG-Fe/Ni was prepared by a stepwise liquid-phase chemical reduction, then added into groundwater to remove chloroform. Results show that polyethylene glycol can both reduce the particle size from 106.9 to 79.6 nm and prevent the oxidation and sedimentation of iron ions under alkaline condition. The removal efficiency of chloroform increased from 86.3 to 100% at pH 6 in the presence of polyethylene glycol, and slightly decreased to 95.4% at pH 11. The calculated rate constant (k) indicates that chloroform removal follows pseudo-first-order kinetics. Furthermore, the PEG-Fe/Ni also removed chloroform from real groundwater at pH 8 with an efficiency of 90.1% in 4 h, which is higher than that for Fe/Ni nanoparticles, of 41.7%.

The construction of a nanozyme that mimics a natural enzyme is a promising strategy to obtain a highly stable catalyst. Laccases are members of copper-containing oxidases, as environmental catalysts, and show significant potential in biotechnology and environmental remediation. In this study, inspired by the active site and electron transfer of laccase, a new laccase mimic (defined as CA-Cu) was synthesized via the coordination of copper with a cysteine (Cys)–aspartic acid (Asp) dipeptide. The as-prepared CA-Cu nanozyme exhibits significant laccase-like activity and catalytic oxidation of a wide range of phenolic pollutants, such as 2,4-dichlorophenol, phenol, p-chlorophenol, 2,6-dimethoxyphenol, hydroquinone, o-nitrophenol and o-aminophenol hydroquinone. It has a similar Km (Michaelis constant), a higher vmax (maximum rate) and better recyclability than laccase at the same mass concentration. In addition, the CA-Cu nanozyme is robust in a broad temperature range (0–100 °C), at extreme pH and under long-term storage. Surprisingly, the catalytic performance of the CA-Cu nanozyme was enhanced under high-salt conditions or at high concentrations of heavy metal ions, which lead to severe loss in the catalytic activity of laccase. We believe that this nanozyme is a promising environmental catalyst for the treatment of phenolic pollutants under high-salt or heavy metal ion conditions.

Zinc oxide (ZnO) nanomaterials are functional photocatalysts that show excellent photocatalytic activity, among which diverse morphologies, such as nanospheres, nanorods, nanoleaves, nanodisks, or nanoflowers, often possess different photocatalytic activities. In this study, we employed a simple ultrasonic treatment to controllably synthesize three types of three-dimensional (3D) fluffy ZnO nanoflowers with different nanostructures. Specifically, one nanoflower with smooth edges was formed via direct hydrothermal reaction without ultrasonic treatment (denoted as ZnO-0), and the other two with different jagged margins were obtained by ultrasonic treatment at 250 W and 950 W, respectively, before the hydrothermal procedure (denoted as ZnO-250 and ZnO-950). The results showed that the size, specific surface area, crystallite dimension, intrinsic donor defects and the signals of reactive radicals of ZnO nanoflowers all decreased with increasing ultrasonic intensity. Furthermore, the photocatalytic performance of such ZnO nanoflowers with similar morphologies but different nanostructures was investigated using methyl orange (MO) as a model pollutant. As expected, ZnO-0 possessed the highest photocatalytic activity with a kinetic constant of 0.0478 min−1, while the value decreased to 0.0251 min−1 and 0.013 min−1 for ZnO-250 and ZnO-950 under simulated sunlight irradiation, respectively, suggesting that the photocatalytic efficiency of ZnO nanoflowers decreased due to the ultrasonic treatment. These findings provide structural insight into the photocatalytic activity of ZnO nanoflowers.

The treatment of multicontaminant wastewater has attracted extensive attention in recent years. Herein, we synthesized a porous and hydrophobic composite (Zr-MOF-SH/MF) via the in situ growth of mercapto-functionalized Zr-metal–organic frameworks (MOFs) (Zr-MOF-SH) on the surface of a melamine formaldehyde (MF) sponge. The successful growth of hydrophobic Zr-MOF-SH, as confirmed by SEM, XRD, and XPS analysis, made the MF sponge become hydrophobic with a water contact angle of 125°. The adsorption capacity of the Zr-MOF-SH/MF composite for dichloromethane can reach up to 113 g/g. Moreover, the composite can efficiently and selectively remove Hg2+ ions from water. Especially, PCN-224-MAA/MF had an adsorption capacity of 412.5 mg/g for Hg2+ ions. The removal efficiency of Hg2+ ions increased as the oil content in the oil–water mixture increased. In addition, PCN-224-MAA/MF can be recovered and reused five times with only a slight decrease in adsorption capacity. This study provides a promising strategy for the synthesis of a dual-functional composite that exhibits excellent performance in removing oil and heavy metal ions simultaneously from water.

Pollution of waters by chlorinated organic pollutants is difficult to clean using actual remediation methods because these pollutants are highly stable. For instance, chloroform (CHCl3) is poorly reactive with common oxidants such as iron-activated persulfate, ozone and Fenton’s reagents. Therefore, there is a need to develop new oxidants. Here, we designed a new dechlorination system, in which tannic acid and NaOH work synergistically to activate persulfate. We tested the effect of temperature and concentrations of persulfate, NaOH and tannic acid, on chloroform removal from water. Free radical-quenching experiments were performed to identify active species. Results show that chloroform removal increased from 42.5 to 97.6 wt.% after the addition of 300 mg/L tannic acid in 0.4 M NaOH. Superoxide radicals (O 2 ·− ) was primarily responsible for the degradation of chloroform in the persulfate/NaOH/tannic acid system, in which tannic acid reacts with persulfate to produce hydroperoxide. Hydroperoxide then reduces persulfate to generate sulfate radicals (SO4·−), and produces O 2 ·− . NaOH-activated persulfate produces hydroxyl radicals (HO·), which can oxidize chloroform. This dechlorination system showed excellent degradation efficiency for recalcitrant halogenated compounds, making it a very promising candidate for practical applications.

Expansin has nonhydrolytic disruptive activity and synergistically acts with cellulases to enhance the hydrolysis of cellulose. The adsorption-desorption of expansin on noncellulosic lignin can greatly affect the action of expansin on lignocellulose. In this study, three lignins with different sources (kraft lignin (KL), sodium lignin sulfonate (SLS), and enzymatic hydrolysis lignin (EHL)) were selected as the substrates. The real-time adsorption-desorption of Bacillus subtilis expansin (BsEXLX1) on lignins was monitored using quartz crystal microgravimetry with dissipation (QCM-D). The effects of temperature and Tween 80 on the adsorption-desorption behaviors were also investigated. The results show that BsEXLX1 exhibited high binding ability on lignin and achieved maximum adsorption of 283.2, 273.8, and 266.9 ng cm-2 at 25 °C on KL, SLS, and EHL, respectively. The maximum adsorption decreased to 148.2-192.8 ng cm-2 when the temperature increased from 25 to 45 °C. Moreover, Tween 80 competitively bound to lignin and significantly prevented expansin adsorption. After irreversible adsorption of Tween 80, the maximum adsorption of BsEXLX1 greatly decreased to 33.3, 37.2, and 10.3 ng cm-2 at 25 °C on KL, SLS, and EHL, respectively. Finally, a kinetic model was developed to analyze the adsorption-desorption process of BsEXLX1. BsEXLX1 has a higher adsorption rate constant (kA) and a lower desorption rate constant (kD) on KL than on SLS and EHL. The findings of this study provide useful insights into the adsorption-desorption of expansin on lignin.

A convenient and efficient approach for the surface modification of antifouling materials is highly desirable in numerous applications like affinity-based biosensors. Herein, we fabricated a hybrid antifouling coating on Au surfaces, with thiolated hyaluronic acid (HA) being chemically adsorbed to Au surfaces by the "graft to" approach, followed by a self-assembly of a smaller zwitterionic peptide named p-EK to obtain HA/p-EK-modified surfaces. The real-time sensorgrams of surface plasmon resonance biosensor manifested the successful modification of HA and p-EK on Au surfaces, indicating that there were some bare Au substrates on the HA-modified surfaces for peptide binding. The obtained HA/p-EK surfaces exhibited high hydrophilicity with a water contact angle of 9°. Quartz crystal microbalance and surface plasmon resonance experiments verified that further grafting the zwitterionic p-EK peptide on HA-modified surfaces could enhance the antifouling performance by one time. The improved protein resistance could be mainly contributed by the modification of the zwitterionic peptide that shields the exposed Au substrates from interacting with protein foulings. This strategy by grafting a smaller zwitterionic peptide might provide a novel way to achieve an enhanced protein-resistant performance of the macromolecular coating obtained by the "graft to" surface modification approach.

Biological pretreatment is a safe and environmentally friendly method for disrupting recalcitrant lignocellulose structures. Expansin and expansin-like proteins are used to open up the cellulose structure and display significant synergism when mixed with cellulases that catalyze the breakdown of (hemi)cellulose into sugars. However, the adsorption behavior of expansin in the presence of sugar products is yet unknown. In this work, we monitored the effects of various sugars on the real-time adsorption of Bacillus subtilis expansin (BsEXLX1) onto cellulose films using a quartz crystal microbalance with dissipation. Cellobiose and xylose at low concentrations enhanced BsEXLX1 adsorption, whereas they disrupted adsorption at higher concentrations. Arabinose and mannose continuously inhibited expansin adsorption with increasing concentration. No obvious influence of glucose and galactose on BsEXLX1 adsorption was found. Contact angle measurements and atomic force microscopy of cellulose upon BsEXLX1 adsorption in the presence of sugars showed that both hydrophilicity and roughness increased with BsEXLX1 treatment. These results give us the ability to modulate and control expansin adsorption and provide insights into effective expansin use during enzymatic hydrolysis of lignocellulose in biorefineries.

A superhydrophobic and superoleophilic porous composite was successfully prepared via a polydopamine-assisted surface coating of MIL-53(Fe) and 1-dodecanethiol (DDT) on a melamine formaldehyde (MF) sponge. The as-prepared sponge composite (MIL-DDT@MF) has a high water contact angle (WCA) of 151.8°, which is probably attributed to both the rough surface derived from in situ growth of MIL-53 nanocrystals and the low surface energy due to grafting of hydrophobic 1-dodecanethiol. The MIL-DDT@MF sponge can effectively absorb oil or organic solvent with an absorption capacity of up to 54.1 (for petroleum) to 120.2 (for chloroform) times its own weight. In addition, the MIL-DDT@MF sponge retained a high absorption capacity and maintained approximately 78% of its original value after 50 cycles of reuse. Moreover, the MIL-DDT@MF sponge can selectively absorb the oil/organic solvent from water and achieve continuous oil-water separation. The separation efficiency of n-hexane, dichloromethane, and crude oil from water or seawater can reach above 95%. The superhydrophobic and superoleophilic MIL-DDT@MF sponge has potential as a promising absorbent for treatment of oily wastewater.

The application of protein units and architectures as supports in the synthesis of metal and metal oxide nanoparticles (NPs) is a relatively new emerging issue. While avoiding toxic stabilizers and solvents, this new synthesis route mostly fulfils the long-desired prospect of designing and synthesizing size- and morphology-controlled nanocatalysts with long-term stability towards maintaining their catalytic activity during reactions and facilitating their separation and recycling. Biotemplates of protein units and architectures with different dimensions, such as protein cages, bacteriophages, protein fibers, protein membranes, and protein crystals, have been widely adopted for the controllable synthesis and immobilization of metal and metal oxide NPs, owing to their abundant functional surface groups for NP anchoring and well-defined structures for accommodating NPs. Various bioinorganic nanohybrids have been constructed and applied in electrocatalysis for fuel cells, photocatalysis for clean energy and pollutant remediation, hydrogenation and oxidation reactions, catalytic syntheses of organic chemicals, etc. This review is meant to present several pivotal aspects of nanocatalysts, their protein-assisted synthesis and their catalytic applications, providing a description of common protein biotemplates, synthesized NPs and applied catalytic reactions.

The symbiotic interaction between arbuscular mycorrhizal fungi (AMF) and land plants is essential for efficient nutrient acquisition and utilisation. Our understanding of key processes controlling the AMF colonisation in rice is still limited. Dongxiang wild rice (DY) exhibited a stronger colonisation with Rhizophagus irregularis than the rice cultivar Zhongzao 35 (ZZ35). Chromosome segment substitution lines were constructed and the OsCERK1 gene from DY was mapped. Transgenic plants in the japonica rice Zhonghua 11 (ZZ11) were constructed to compare root colonisation by AMF. Chromosome single-segment substitution lines containing OsCERK1DY showed higher phosphorus content and grain yield relative to ZZ35. Four amino acids substitutions were identified among the OsCERK1 haplotypes of DY, ZZ35 and ZH11 and two of these were in the second lysine-motif domain, which is essential for the differences of AMF colonisation level among rice varieties. Heterologous expression of OsCERK1DY in ZH11 significantly enhanced AMF colonisation and increased resistance against the pathogenic fungi Magnaporthe oryzae. Notably, the OsCERK1DY haplotype was absent from 4660 cultivated rice varieties. We conclude that OsCERK1 is a key gene affecting the symbiotic interaction with AMF and OsCERK1DY has the biotechnological potential to increase rice phosphorus acquisition and utilisation efficiency for sustainable agriculture.

Nanozymes, defined as nanomaterials with enzyme-like activity, have attracted extensive interest in both fundamental and applied research. Laccases are members of the multi-copper oxidases, which are utilized as green catalysts in the environmental catalysis and biochemical industry. In this paper, we report a facile strategy for the preparation of a new class of nanozyme (denoted as CH-Cu) with laccase-like activity inspired by the structure of the active site and the electron transfer pathway of laccase via the coordination of Cu+/Cu2+ with a cysteine (Cys)-histidine (His) dipeptide. The CH-Cu nanozymes exhibit excellent catalytic activity, recyclability and substrate universality and have a similar Km (Michaelis constant) and a higher vmax (maximum rate) than laccase at the same mass concentration. They are robust under a variety of conditions, such as extreme pH, high temperature, long-term storage and high salinity, which can cause severe loss in the catalytic activity of laccase. Higher efficacy of the CH-Cu nanozymes compared with laccase in the degradation of chlorophenols and bisphenols is also demonstrated in a batch reaction. Furthermore, a method for the quantitative detection of epinephrine by a smart phone is established based on the CH-Cu nanozymes. We believe that this nanozyme has promising applications in environmental catalysis and rapid detection and expect that combining key peptides as metal ligands with metal ions to mimic the structure of the catalytic center of a natural enzyme will be a general and important strategy for the design and synthesis of a new type of nanozyme that can be used in various applications.

Challenges associated with nonspecific adsorption of proteins on sensor surfaces have steered the development of novel antifouling materials and strategies. Inspired by human synovial fluid composition and structure, we designed synergistic antifouling coatings with mixtures of hyaluronic acid (HA) and a zwitterionic bottlebrush polymer (BB). Using a fast and convenient online surface modification method, the polymers were immobilized on the Au surface, significantly increasing its hydrophilicity. Using surface plasmon resonance (SPR), a 10:1 ratio of HA to BB was found optimal to provide the best antifouling performance. Bovine serum albumin (BSA) adsorption on HA-BB coated surfaces was 0.2 ng/cm2, which was 60 times lower than BB or HA alone and 25 times lower than the commonly accepted ultralow adsorption limit (

Effective binding between cellulases and cellulose is essential for enzymatic hydrolysis of lignocellulose. Expansin can loosen the cellulose structure and can enhance the efficiency of cellulase. However, possible synergy between cellulases and expansin is not clear. In this work, the real-time adsorption of exoglucanases (Cel7A) or endoglucanases (Cel7B) with Bacillus subtilis expansin (BsEXLX1) and the enzymatic hydrolysis of cellulose were followed using quartz crystal microbalance with dissipation (QCM-D). Initial adsorption rate, adsorption capacity, and pseudo-steady-state rate of cellulose hydrolysis by Cel7A/Cel7B increased in the presence of BsEXLX1. When injecting Cel7A or Cel7B together with BsEXLX1 at a mass ratio of 1:1, the hydrolysis rate was almost 5 times the rate for Cel7A or Cel7B alone at 25 °C. These results increase our understanding of the real-time synergism between cellulases and expansin on cellulose, as well as the impact of their synergy on the enzymatic hydrolysis of cellulose. ispartof: CARBOHYDRATE POLYMERS vol:253 ispartof: location:England status: published

To analyze multiple analytes in trace samples, low-dosage and high efficiency are crucial in many common cases. Herein, we developed a facile method using a single-channel surface plasmon resonance (SPR)-based biosensor for the simultaneous detection of gentamicin (GEN) and melamine (MEL) in milk and serum with only one sample injection. Based on a sandwich immunoassay, non-interfering antibodies against GEN from mouse (AbGEN) and against MEL from rabbit (AbMEL) were chosen to capture the analytes. Secondary antibodies against mouse (AbM) and rabbit (AbR) were used to bind with AbGEN and AbMEL to determine the concentrations of GEN and MEL on a single channel of an SPR sensor. All of the detection process could be done in 10 min with 50 μL of sample injection. According to the response shifts of AbM and AbR, two standard curves for GEN and MEL were obtained successively, with the limit of detection (LOD) values at 4.4 ng mL-1 and 1.3 ng mL-1, respectively. Moreover, the feasibility was determined by spiking milk and serum samples with GEN and MEL, with recoveries in the range of 81.6%-118.0%. Importantly, the analytes can be substituted by others for much more applications. This method is also expected to multiply the detection efficiency of multi-channel SPR biosensors with low-dosage samples in the future.

Mercapto functionalized Zr-MOFs have been developed via a one-pot synthesis for the selective adsorption of Hg2+ ions. Mercaptoacetic acid (MAA) or alpha lipoic acid (ALA) was used as the modulators and functionalized molecules to synthesize mercapto functionalized Zr-MOFs (Zr-MOFs-SH(O)). In comparison with the mercapto functionalized Zr-MOFs via the traditional postsynthetic modification (Zr-MOFs-SH(P)), Zr-MOFs-SH(O) had a much higher content of –SH groups, thus leading to a much higher adsorption capacity for Hg2+ ions. In particular, PCN-224-MAA(O) had an adsorption capacity for Hg2+ ions up to 843.6 mg g−1, which is much higher than that of PCN-224-MAA(P) (138.5 mg g−1). Additionally, PCN-224-MAA(O) can be used to reduce Hg2+ ion concentrations (5–20 μg L−1) in water to the limit acceptable (1 μg L−1) for drinking water. Moreover, PCN-224-MAA(O) also exhibited good selectivity, recyclability, and chemical stability.

2,5-Diformylfuran (2,5-DFF) is an important furan-based chemical with broad application potential. To address the difficulties in isolating/purifying the product and recycling the 2,2,6,6- tetramethylpiperidine-1-oxy (TEMPO)-based catalysts, we employed a solvent with a low boiling point in which TEMPO has a low solubility to investigate the effects of TEMPO and its analogs on catalyzing the oxidation of 5-hydroxymethylfurfural (5-HMF). The results indicated that in ethyl acetate with the substitution of one H of TEMPO at the C4 position with either an acetamido ( NH-Ac), methoxy ( OCH3), hydroxy ( OH) or isothiocyanato ( N C S) group, the resulting compound had a product selectivity similar to that of TEMPO (>86%), except for the 4-isothiocyanato-TEMPO-catalyzed reaction. However, after two Hs were substituted with an oxo group ( O), the catalytic efficiency significantly decreased (product yield 16%, selectivity 52%). Based on both the catalytic efficiency and catalyst solubility, a highly efficient method for preparing 2,5-DFF was established using ethyl acetate as the solvent, 4-acetamido-TEMPO as the catalyst and Fe(NO3)3 and NaCl as cocatalysts. At 40 °C with a substrate concentration of 0.125 mol/L, 5-HMF was completely converted in 2 h, and the yield of 2,5-DFF was 89%. Moreover, when the substrate concentration increased to 0.25 mol/L, the yield of 2,5-DFF was 87%. When 4-acetamido-TEMPO was recovered by centrifugation, the product yield remained as high as 86% after three cycles, demonstrating good recyclability.

In this study, we proposed a bioinspired approach for the deposition and zwitteration of hyaluronic acid (HA) with a reduced glutathione (GSH) to form a composite layer that functions as a low fouling coating. A polyanion of the HA–dopamine conjugate (HADA) possessing catechol groups was synthesized by carbodiimide chemistry between HA and dopamine. Then, the dopamine conjugated biofunctional polymers (HADA) were grafted onto Au substrates via the transformation of catechol into a quinone group under mild oxidative conditions followed by a reaction with GSH to avoid undesired adhesion and also to shield the exposed Au substrate. Analysis of XPS spectra and wettability indicated that HADA and GSH were successfully grafted onto Au substrates. Surface plasmon resonance analysis showed that both HADA and further GSH modified surfaces exhibited reduced nonspecific adsorption. The attachment of GSH to HADA modified surfaces (HADA-G) resulted in better antifouling performance, with a low or ultralow protein adsorption of 0–7.51 ng cm−2 when exposed to single protein solutions, and a reduction in nonspecific adsorption from cow's milk to 10% compared to that of bare gold. The enhanced antifouling performance of HADA-G modified surfaces was likely due to the zwitterionic structure in GSH, which can induce stronger surface hydration through electrostatic interactions as well as the hydrogen bonding induced by HADA. Our results provide a facile and universal approach to surface modification and demonstrate the benefits of using a composite layer for the design of low fouling surfaces.

Enzyme-responsive supramolecular hydrogels are a new class of smart materials and have enormous potential to be used in biology and medicine. In this study, α-chymotrypsin was proposed to promote the self-assembly of amino acid derivatives for the preparation of such supramolecular hydrogels. It is found that α-chymotrypsin significantly shortens the gelation time from 8 days (or no gelation occurred within 2 weeks) to 10 min–4 h depending on the structure of amino acid derivatives. The chemical compositions and microstructures of the hydrogels were further investigated by LC-MS, microscopy and spectroscopy techniques. The results show that the transparent hydrogels consist of long nanofibers with approximately 20 nm in diameter. These nanofibers are composed of Fmoc-amino acid and amino acid, which were formed from the hydrolysis of amino acid ester, with a molar ratio of 4.346 : 1 (Fmoc-F/F) and 0.548 : 1 (Fmoc-F/Y), respectively. Furthermore, the molecular simulation was performed to investigate the specific recognition of α-chymotrypsin to amino acid derivatives. The results indicate that the enzyme–substrate interactions are responsible for promoting the supramolecular self-assembly of these amino acid derivatives into fibrous hydrogels. In addition to being the first example of enzyme–substrate interaction-promoted supramolecular self-assembly, this novel concept opens up the possibility of making use of various enzymes and their substrates (or analogues) in the discovery of new supramolecular materials with enzyme responsiveness.

Amyloid fibrillation of proteins is likely a key factor leading to the development of amyloidosis-associated diseases. Inhibiting amyloid fibrillation has become a crucial therapeutic strategy. Water-soluble, fluorescent silicon nanoparticles (SiNPs) have great potential in biomedicine for various therapeutic and diagnostic purposes; however, it is unclear whether SiNPs have the ability to inhibit amyloid fibrillation. Herein, insulin was chosen as a protein model, and SiNPs of varying sizes were synthesized upon UV irradiation. The influence of size and concentration of the SiNPs on insulin fibrillation was investigated, and it has been observed that these variables were crucial in regulating insulin fibrillation. Using an average particle size of 6.6 nm and increasing the concentration of the SiNPs to 5.0 μg mL−1, the Thioflavin T (ThT) fluorescence intensity decreased significantly by 90%, with an increased lag time of 76.8 h, compared to that of the control. Insulin aggregates were short, thin fibrils or clusters when incubated with SiNPs, compared to the long, thick fibrils formed for insulin alone. Additionally, we found that the SiNPs prevent the conformational transition of insulin from its initial structure to β-sheets, and thus inhibit nucleation, which is necessary for the formation of large fibrils. The inhibitory activity is attributed to the interactions between the SiNPs and insulin during the nucleation period. Our results demonstrate that the SiNPs disrupt insulin amyloid fibrillation, and thus, may play a useful role in new therapeutic and diagnostic strategies for amyloid-related disorders.

Three-dimensional (3D) printing techniques bring the possibility of making electronic devices in any desired shape and dimensions. Here, we report on a printable black phosphorous nanosheet/polypyrrole composite ink for constructing a high-performance supercapacitor (SC) electrode. The printed BPNS/PPy electrode shows a good energy storage performance with a specific capacitance of up to 417 F g−1 and an excellent cycling stability.

The increasing demand for long lasting antifouling surfaces has steered the development of accessible, novel, biocompatible and environmentally-friendly materials. Inspired by lubricin (LUB), a component of mammalian synovial fluid with excellent antifouling properties, we designed three block polymers with bottle-brush structures and outstanding stability, efficacy, and ease of use. By a simple drop casting or online exposure, the polymers strongly adsorbed on silica surfaces in less than 10 min and were found to be stable in extremely high-salinity solutions and under an unprecedented wide range of pH. The polymers antifouling properties against proteins and bacteria were evaluated using different techniques, demonstrating ultralow fouling properties. With serum albumin and lysozyme adsorption < 0.2 ng/cm2, the polymers were found to be 50 and 25 times more effective than LUB and the known ultralow fouling coatings. The antifouling properties were also successfully tested under MPa compression pressures by direct force measurements using the surface forces apparatus (SFA). The findings of this study suggest that these polymers are amongst the most robust and efficient antifouling agents known today.

Nanoscale zero valent iron (nZVI) and bimetallic nZVI has been widely applied to remove various contaminants from water and soil, but their activities can be greatly reduced due to the precipitation of the generated Fe ions. Here we adopted tannic acid (TA) as stabilizer to synthesize high activity Fe-Pd nanoparticles (NPs) and scavenger of the generated Fe ions to keep the rapid dechlorination of two organochlorides. Inductively coupled plasma optical emission spectrometry and UV–vis spectroscopy measurements indicated the generated Fe ions were harvested by TA and formed bis- and tris-TA-iron complexes in the dechlorination solution. TA promoted 40-fold and 10-fold increase in dechlorination efficiency of p-chlorophenol and florfenicol attributing to the complexation of Fe ion by TA. This strategy may inspire novel ways to deal with the passivation of nZVI caused by the precipitation of Fe ions and benefits for the developing of longevity and high-efficient nZVI materials.

Effective regulation of cellulase adsorption is key to improving the efficiencies of the two major bottlenecks of lignocellulose hydrolysis and cellulase recovery. In this work, we investigated the effect of inhibitors, pH, and temperature on the adsorption of exo- and endoglucanases (Cel7A and Cel7B, respectively) on cellulose using quartz crystal microgravimetry with dissipation. The addition of glucose and cellobiose can both inhibit the hydrolysis activity of Cel7A, whereas only cellobiose can inhibit that of Cel7B. Notably, the adsorption was favored by acidic conditions (pH ≤ 4.8) and low temperature, whereas alkaline conditions (pH 9 and 10) facilitated enzyme desorption, which is useful to guide the process of cellulase recovery. The adsorption and hydrolysis activity of Cel7A and Cel7B were both higher at 45 °C than at 25 °C. These findings pave the way to effective regulation of cellulase adsorption and thus improve lignocellulose conversion and cellulase recovery. ispartof: LANGMUIR vol:34 issue:45 pages:13514-13522 ispartof: location:United States status: published

We report the spontaneous formation of lyotropic liquid crystals from the self-assembly of a series of minimalistic peptides. The highly charged peptides could self-assemble into rigid helical nanofilaments in water and spontaneously order into hexagonal liquid-crystalline phases with interfilament separations of ≤240 A. The formation of liquid crystals from the self-assembly of such simple peptides is dictated not only by the concentration and pH but also by the amino acid sequence of the peptides. Peptides containing the rigid Phe-Phe (FF) segment showed much higher propensities to form a liquid-crystalline phase with long-range order. Moreover, because of the intrinsic chirality of the peptides, the self-assembled birefringent liquid crystals could serve as sensing elements for the visual discrimination of chiral species and as templates for the biomimetic synthesis of mesoporous silica with ordered cavities. The results offer new opportunities for the design of peptide liquid crystals that are potenti...

5-Hydroxymethylfurfural is an important bio-based chemical that shows broad application potential. In the present study, the use of chitosan nanoparticles was proposed to adsorb and recycle chromium ions from aqueous solution with Cr(III) and Cr(VI) removal rates of up to 97.5% and 81.2%, respectively. A chromium-based ceramic powder catalyst was designed and synthesized, the structural properties of the catalyst were characterized, and the catalytic performances of the catalyst were evaluated. The results showed that after chromium was doped into the blank ceramic, the main lattice structure of the ceramic was preserved. Both the specific surface area and pore diameter decreased, and a portion of the Cr(VI) was transformed to Cr(III). The chromium-based ceramic powder and sulfuric acid co-catalyzed the one-pot synthesis of 5-hydroxymethylfurfural from glucose in the water/dimethyl sulfoxide system, with the product yield reaching 64.7%. After the catalyst was reused 5 times, the product yield was still close to 60%. Thus, the catalyst exhibited good recyclability. The results of this study provide a good example of the one-step synthesis of 5-hydroxymethylfurfural from glucose.

Black phosphorus quantum dots (BPQDs) as novel nanomaterials have many potential applications in biomedicine. However, the interaction of BPQDs with proteins and their biological effects and potential risks are still unclear. Here, mucin, which serves biologically as a physical barrier against foreign substances entering tissues, was chosen as a model substrate for studying the adsorption–desorption behavior of BPQDs using surface plasmon resonance sensing and a quartz crystal microbalance with dissipation monitoring. We found that the surface modification of BPQDs with poly(ethylene glycol)-amine (PEG-NH2) reduces the adsorption rate of the quantum dots but increases their adsorbed amount on the mucin surface. The pH value, ionic strength, and ionic valence also had significant effects on the adsorption behavior of BPQDs. Upon increasing the pH from 2 to 7, the amount of BPQD adsorption decreased from 14.1 to 3.2 ng/cm2. A high ionic strength and ionic valence (e.g., Mg2+, Al3+) also inhibit the surface ...

Polyvinylidene fluoride (PVDF) membranes are limited in the field of oil-in-water emulsion treatment because the intrinsic hydrophobicity of PVDF can cause serious membrane fouling. Here, a superhydrophilic PVDF membrane (PVDF@PDA-GSH) was fabricated using a facile, versatile, mussel-inspired method. The pristine PVDF membrane was coated with dopamine under mild alkaline conditions by a dip-coating method, followed by addition of glutathione (GSH) via a simple reaction. GSH was successfully coated onto the membrane surface and confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray spectrometry. Hierarchical surface structure and superhydrophilicity were examined by scanning electron microscopy and contact angle, respectively, giving the PVDF@PDA-GSH membrane excellent wettability and antifouling ability. The water flux of PVDF@PDA-GSH was several-fold higher than conventional filtration membranes, and the oil rejection ratio was nearly 99%. The PVDF@PDA-GSH membrane also showed favorable reusability because the flux recovery ratio (FRR) remained above 90% after five cycles. In general, these results indicated that this modification might provide a good method for the fabrication of superhydrophilic PVDF membranes with good prospects for water filtration applications.

An alkaline-modified natural sponge was applied as support of gold and silver nanocatalysts and a deformable reactor to hold the reaction solution, quickly adsorb several kinds of environmental pollutants (4-nitrophenol, hexavalent chromium, and methyl orange) and efficiently catalyse their conversion. As the reaction solution is sustained in the connecting micro-pores constructed by the stretched and knotted sponge fibers, the catalytic reaction is free from external mass transfer and suffers slight internal mass transfer limitation. This batch-wise reaction system employing an operation procedure of injection-extrusion achieved a nearly complete conversion of the reactants within 1 min or much less. This compressible support can also be packed in a continuous flow reaction system and can be repeated use for 37 times without any loss of catalytic activity. This study provides a generalizable and straightforward strategy for utilizing deformable soft supports that may inspire some unique industrial applications.

In recent years, nanocellulose-based materials have been increasingly applied as a lot of biosorbents for the treatment of water pollutants due to their large specific surface area, easy modification, environmental friendliness, and reproducibility. In this review, surface modification of nanocellulose-based adsorbents with various effective adsorption groups is described, as well as polymer grafting and hybrid composite fabrication. The adsorption mechanisms involved in the adsorption process of pollutants by adsorbents are further analysed and summarized. The regeneration methods of nanocellulose adsorbents with different adsorption mechanisms are also demonstrated. In addition, this paper also briefly describes the forms of nanocellulose-based adsorbents with large-scale application including membranes, gels, flocculants and magnetic composites.

Black phosphorus (BP) nanodots inevitably interact with electrolyte ions because of their extensive applications in many fields. In biomedical applications, BP-nanodots might encounter various salt ions in body fluids and have a propensity to aggregate, further resulting in an enhanced toxicity risk. In this study, the effects of electrolyte cations (Na+, K+, Ca2+, and Mg2+) on the aggregation kinetics of BP-nanodots were investigated by means of dynamic light scattering (DLS). The critical coagulation concentration values of BP-nanodots were determined to be 242.11 mM NaCl, 95.01 mM KCl, 1.92 mM CaCl2, and 5.88 mM MgCl2. Divalent cations accelerated aggregation of BP-nanodots because of the stronger surface charge screening and their bridging with oxidized phosphorus species (PxOy) available on BP-nanodot surfaces. Furthermore, the divalent cations may interact with PxOy to form insoluble complex coatings on the nanoparticle surface and shield the charge. After modification with PEG, BP-nanodots presented enhanced stability in the presence of 2.5 mM CaCl2. This work is of great significance for understanding the aggregation behaviors of ultrasmall nanoparticles such as BP-nanodots in electrolyte solutions and provides insight into their safety assessment associated with biomedical applications.

4-Nitrophenol (4-NP) is a priority pollutant in water and is both carcinogenic and genotoxic to humans and wildlife even at very low concentrations. Thus, we herein fabricated a novel molecularly imprinted core-shell nanohybrid as a ratiometric fluorescent sensor for the highly sensitive and selective detection of 4-NP. This sensor was functioned by the transfer of fluorescence resonance energy between photoluminescent carbon dots (CDs) and 4-NP. This sensor was synthesized by linking organosilane-functionalized CDs to silica-coated CdSe quantum dots (CdSe@SiO2) via Si–O bonds. The nanohybrids were further modified by anchoring a molecularly imprinted polymer (MIP) layer on the ratiometric fluorescent sensor through a facile sol–gel polymerization method. The morphology, chemical structure, and optical properties of the resulting molecularly imprinted dual-emission fluorescent probe were characterized by transmission electron microscopy and spectroscopic analysis. The probe was then applied in the detection of 4-NP and exhibited good linearity between 0.051 and 13.7 μg/mL, in addition to a low detection limit of 0.026 μg/mL. Furthermore, the simplicity, reliability, high selectivity, and high sensitivity of the developed sensor demonstrate that the combination of MIPs and ratiometric fluorescence allows the preparation of excellent fluorescent sensors for the detection of trace or ultra-trace analytes. Electronic supplementary material The online version of this article (10.1186/s11671-018-2440-6) contains supplementary material, which is available to authorized users.

Preventing the unwanted adsorption of proteins and cells at articular cartilage surfaces plays a critical role in maintaining healthy joints and avoiding degenerative diseases such as osteoarthritis. Immobilized at the surface of healthy articular cartilage is a thin, interfacial layer of macromolecules consisting mainly of hyaluronic acid (HA) and lubricin (LUB; a.k.a. PRG4) that is believed to form a co-adsorbed, composite film now known to exhibit synergistic tribological properties. Bioinspired by the composition of cartilage surfaces, composite layers of HA and LUB were grafted to Au surfaces and the antiadhesive properties were assessed using surface plasmon resonance and quartz crystal microbalance. A clear synergistic enhancement in antiadhesive properties was observed in the composite films relative to grafted HA and LUB layers alone. Atomic force microscopy (AFM) normal force measurements provide insight into the architecture of the HA/LUB composite layer and implicate a strong contribution of hydrophobic interactions in the binding of LUB end-domains directly to HA chains. These AFM force measurements indicate that the adhesion of LUB to HA is strong and indicate that the hydrophobic coupling of LUB to HA shields the hydrophobic domains in these molecules from interactions with other proteins or molecules.

The treatment of oil spill and the separation of oil-water mixture have been widely concerned in recent years. In this work, a one-pot synthesis strategy is developed to prepare fluorine functionalized zirconium-based metal organic framework (Zr-MOFs) (denoted as UiO-66-1F) by using 4-fluorobenzoic acid as modulator and modifier and p-phthalic acid (PTA) as ligand. 4-fluorobenzoic acid can participate in the formation of frameworks structure and cause structural defects, causing larger surface area and hierarchically porous structure. The hydrophobicity of UiO-66-1F increases with increasing of the ratio of 4-fluorobenzoic acid to zirconium chloride and when the ratio is 10, the synthesized UiO-66-1F(10) shows high hydrophobicity with a water contact angle (WCA) of 122° while the WCA of original UiO-66 is only 21°. UiO-66-1F(10) also has good chemical stability over a wide pH range (pH 1∼11) and good hydrothermal stability. In addition, a superhydrophobic sponge (UiO-66-1F(10)@PDA@sponge) with a WCA of 150° was prepared via in situ growth of UiO-66-1F(10) on a polydopamine modified sponge (PDA@sponge). The resulting composite shows high absorption capacities for various oils and organic solvents ranging from 50.5 g/g (n-hexane)– 107.8 g/g (dichloromethane) and good recyclability.

We investigated the effects of ultrasound treatment on cellulase adsorption and lignocellulose hydrolysis. The activity of cellulase remained constant upon low-power ultrasound treatment ( 280 W). Oscillating cellulase adsorption occurred upon ultrasound treatment with any intensity. The maxima for desorption and adsorption were 41.9 and 83.1%, respectively, during 1 h of 90 W ultrasound treatment at 50 °C. A comparison between the short-time with long-time ultrasound experiments indicated that ultrasound treatment tended to desorb cellulase from substrate. However, ultrasound treatment also led to further surface erosion of biomass, which increased cellulase accessibility. These joint actions of ultrasound treatment induced the oscillating adsorption of cellulase. The increase in cellulase accessibility caused by ultrasound treatment led to a significant enhancement in lignocellulose hydrolysis.

Recycling cellulases by substrate adsorption is a promising strategy for reducing the enzyme cost of cellulosic ethanol production. However, β-glucosidase has no carbohydrate-binding module (CBM). Thus, additional enzymes are required in each cycle to achieve a high ethanol yield. In this study, we report a new method of recycling cellulases without β-glucosidase supplementation using lignocellulosic substrate, an engineered strain expressing β-glucosidase and Tween 80. The cellulases and Tween 80 were added to an aqueous suspension of diluted sulfuric acid/ammonia-treated corncobs in a simultaneous saccharification and fermentation (SSF) process for ethanol production. Subsequently, the addition of fresh pretreated corncobs to the fermentation liquor and remaining solid residue provided substrates with absorbed cellulases for the next SSF cycle. This method provided excellent ethanol production in three successive SSF cycles without requiring the addition of new cellulases. For a 10% (w/v) solid loading, a cellulase dosage of 30 filter paper units (FPU)/g cellulose, 0.5% Tween 80, and 2 g/L of the engineered strain, approximately 90% of the initial ethanol concentration from the first SSF process was obtained in the next two SSF processes, with a total ethanol production of 306.27 g/kg corncobs and an enzyme productivity of 0.044 g/FPU. Tween 80 played an important role in enhancing cellulase recovery. This new enzyme recycling method is more efficient and practical than other reported methods. Biotechnol. Bioeng. 2017;114: 543-551. © 2016 Wiley Periodicals, Inc.

A catalytic membrane reactor, which contains a membrane matrix and a catalytic film of alloy nanoparticle-loaded β-lactoglobulin fibrils (NPs@β-LGF), was developed for the continuous-flow reduction of 4-nitrophenol (4-NP). The Cu–Ag and Cu–Ag–Au alloy NPs were synthesized using β-LGF as a scaffold and stabilizing agent. In this process, the Cu nanoclusters were formed in the initial stage and were able to promote the synthesis of Ag0, which acts as a reducing agent for the rapid formation of Au0. Furthermore, a catalytic membrane reactor was constructed by depositing the NPs@β-LGFs on a membrane matrix. The catalytic activity of the Cu–Ag–Au alloy NPs was higher than that of the Cu–Ag alloy NPs, using the reduction of 4-NP to 4-AP as a model reaction. The observed rate constant in the continuous-flow system is also higher than that in the batch system. In addition, these catalytic membrane reactors had good operating stability and antibacterial activity.

Functionalized silica nanoparticles with strong acidity and different hydrophobicity were successfully synthesized by an alkali co-condensation method. The structure of the hydrophobic solid acids were characterized, and the catalytic properties were investigated in fructose dehydration to 5-hydroxymethylfurfural (5-HMF). Experiment results indicated that catalyst hydrophobicity has a positive influence on both 5-HMF yield and selectivity. The highest yield of 5-HMF (87%) with full conversion of fructose was obtained when the most hydrophobic solid acid (SiNP-SO3H-C16) was used as the catalyst. The reason can be interpreted as the hydrophobic groups in the silica nanoparticles can effectively isolate SO3H groups with water molecules in the reaction system, and thus hinder the rehydration of 5-HMF, which is the main side-reaction in 5-HMF formation. Other important reaction parameters such as reaction medium, temperature, time and catalyst loading were also studied for fructose dehydration. Recycling and control experiments demonstrated the good reusability and stability of the functionalized silica nanoparticles. Furthermore, inulin was also used as a feedstock for 5-HMF production and gave a high 5-HMF yield of 65% in the catalysis of a moderate hydrophobic silica nanoparticle.

A universal strategy is developed to construct a superhydrophobic and superoleophilic metal-organic framework (MOF) by an amidation reaction between amino group and acid chloride of octadecanoyl chloride. The introduction of long alkyl chain reduced the surface free energy, yielding a superhydrophobic Zr-MOF (UiO-66-NH-C18) with a high water contact angle (WCA) of 151.7°. The adsorbed amount of water on the UiO-66-NH-C18 was only 5.59 mmol/g, which was just 28 % of that on the UiO-66-NH2. More importantly, the hydrophobic modification improved the stability of Zr-MOFs under strong alkaline conditions (e.g., pH = 13). Furthermore, the UiO-66-NH-C18 can selectively absorb organic solvent from water and achieve continuous oil-water separation. The oil-water separation efficiency could reach up to 99.9 %. In addition, the UiO-66-NH-C18@sponge was also prepared through dip-coating of UiO-66-NH-C18 on the melamine sponge in the presence of PDMS solution. The resulting composite shows high adsorption capacities for various oils and organic solvents ranging from 32.3–66.1 g/g. The superhydrophobic UiO-66-NH-C18@sponge has potential as a promising absorbent for treatment of oily wastewater.

Summary Amyloid are protein aggregates formed by cross β structures assemblies. Inhibiting amyloid aggregation or facilitating its disassembly are considered to be two major effective therapeutic strategies in diseases involving peptide or protein fibrillation such Alzheimer's disease or diabetes. Using thioflavin-T fluorescence, far-UV circular dichroism spectroscopy, and atomic force microscopy, we found nontoxic and biocompatible black phosphorus quantum dots (BPQDs) appear to have an exceptional capacity to inhibit insulin aggregation and to disassemble formed mature fibrils, even at an ultralow concentration (100 ng/mL). The inhibition of fibrillation persists at all stages of insulin aggregation and increases PC12 cells survival when exposed to amyloid fibrils. Molecular dynamics simulations suggest that BPQDs are able to stabilize the α-helix structure of insulin and obliterate the β-sheet structure to promote the fibril formation. These characteristics make BPQDs be promising candidate in preventing amyloidosis, disease treatment, as well as in the storage and processing of insulin., Graphical Abstract, Highlights • BPQDs inhibit insulin amyloid fibrillation at an ultralow concentration • BPQDs can depolymerize protofibrils and even mature fibers • BPQDs inhibit aggregation mainly by van der Waals' force and hydrophobic interaction • BPQDs are biocompatible and can reduce insulin fibrils-induced cytotoxicity, Drugs; Cell Biology

Nanoscale zero-valent iron has been widely applied in environmental remediation and toxic waste treatment, especially for the degradation of persistent organic pollutants (POPs). However, the dechlorination activity of Fe nanoparticles (Fe NPs) can be suppressed by the precipitation of iron oxides generated from the corrosion of Fe-Pd NPs under alkaline conditions, leading to a decreased dechlorination efficiency. Faced with this challenge, we report a highly effective dechlorination system that functions over a broad pH range and especially well under alkaline conditions in this work. Procyanidin (PROC), a natural polyphenol, was utilized as a stabilizer to manipulate the size distribution of Fe-Pd NPs and, more importantly, as a scavenger of Fe ions to prevent iron oxide precipitation. Experiments and theoretical calculations reveal that the generated Fe ions was mainly present in the form of bis- and tris-PROC-Fe complexes in the reaction solution. Compared with pristine Fe-Pd NPs, the PROC-modified Fe-Pd NPs had a dechlorination efficiency that was increased 20-fold (pH 9.0). Notably, a normalized rate constant was enhanced by more than 2 orders of magnitude compared to the previously reported dechlorination systems. The PROC-modified Fe-Pd NPs showed excellent dechlorination efficiency over a wide pH range (2.3–13.0). Nanyang Technological University This work was supported by the National Natural Science Foundation of China (21621004, 51473115, 21776212), Tianjin Municipal Science and Technology Bureau, China (16JCZDJC37900, 18YFHBZC00010, 18YFZCSF00590), and the Ministry of Education (grant No. NCET-11-0372). JY thanks to a start-up grant of NTU, M4082049.070.

The fates and detrimental effects of particles entering the body have gained increasingly notable attention worldwide because of the burgeoning applications of various particles and wide existence of ambient particulate matter. Studies on the interaction of particles with biological interfaces demonstrate the potential risks and hazards to the health of living organisms. This review aims to provide a systematic overview of the interaction between particles and typical biological interfaces, with an emphasis on the effects of particle properties and microenvironment, and the potential adverse results arising from these interactions. First, we describe the major entry routes of particles into the human body to understand the main exposure pathways and the fates and impacts of particles. Different behaviors of particles interacting with mucosae and cell membranes are then reviewed. Finally, the knowledge gaps are identified and the long-term development of interaction research is proposed.