Publication

2020
Sheng A, Liu J, Li X, Qafoku O, Collins RN, Jones AM, Pearce CI, Wang C, Ni J, Lu A, et al. Labile Fe(III) from sorbed Fe(II) oxidation is the key intermediate in Fe(II)-catalyzed ferrihydrite transformation. Geochimica et Cosmochimica Acta [Internet]. 2020;272:105 - 120. 访问链接Abstract
Ferrihydrite (Fh) is a major Fe(III)-(oxyhydr)oxide nanomineral distinguished by its poor crystallinity and thermodynamic metastability. While it is well known that in suboxic conditions aqueous Fe(II) rapidly catalyzes Fh transformation to more stable crystalline Fe(III) phases such as lepidocrocite (Lp) and goethite (Gt), because of the low solubility of Fe(III) the mass transfer pathways enabling these rapid transformations have remained unclear for decades. Here, using a selective extractant, we isolated and quantified a critical labile Fe(III) species, one that is more reactive than Fe(III) in Fh, formed by the oxidation of aqueous Fe(II) on the Fh surface. Experiments that compared time-dependent concentrations of solid-associated Fe(II) and this labile Fe(III) against the kinetics of phase transformation showed that its accumulation is directly related to Lp/Gt formation in a manner consistent with the classical nucleation theory. 57Fe isotope tracer experiments confirm the oxidized Fe(II) origin of labile Fe(III). The transformation pathway as well as the accelerating effect of Fe(II) can now all be explained on a unified basis of the kinetics of Fe(III) olation and oxolation reactions necessary to nucleate and sustain growth of Lp/Gt products, rates of which are greatly accelerated by labile Fe(III).
Sheng A, Liu J, Li X, Qafoku O, Collins RN, Jones AM, Pearce CI, Wang C, Ni J, Lu A, et al. Labile Fe(III) from sorbed Fe(II) oxidation is the key intermediate in Fe(II)-catalyzed ferrihydrite transformation. Geochimica et Cosmochimica Acta [Internet]. 2020;272:105 - 120. 访问链接Abstract
Ferrihydrite (Fh) is a major Fe(III)-(oxyhydr)oxide nanomineral distinguished by its poor crystallinity and thermodynamic metastability. While it is well known that in suboxic conditions aqueous Fe(II) rapidly catalyzes Fh transformation to more stable crystalline Fe(III) phases such as lepidocrocite (Lp) and goethite (Gt), because of the low solubility of Fe(III) the mass transfer pathways enabling these rapid transformations have remained unclear for decades. Here, using a selective extractant, we isolated and quantified a critical labile Fe(III) species, one that is more reactive than Fe(III) in Fh, formed by the oxidation of aqueous Fe(II) on the Fh surface. Experiments that compared time-dependent concentrations of solid-associated Fe(II) and this labile Fe(III) against the kinetics of phase transformation showed that its accumulation is directly related to Lp/Gt formation in a manner consistent with the classical nucleation theory. 57Fe isotope tracer experiments confirm the oxidized Fe(II) origin of labile Fe(III). The transformation pathway as well as the accelerating effect of Fe(II) can now all be explained on a unified basis of the kinetics of Fe(III) olation and oxolation reactions necessary to nucleate and sustain growth of Lp/Gt products, rates of which are greatly accelerated by labile Fe(III).
2019
Liu F, Li X, Sheng A, Shang J, Wang Z, Liu J. Kinetics and Mechanisms of Protein Adsorption and Conformational Change on Hematite Particles. Environmental Science & Technology [Internet]. 2019;53(17):10157-10165. 访问链接Abstract
Adsorption kinetics and conformational changes of a model protein, bovine serum albumin (BSA, 0.1, 0.5, or 1.0 g/L), on the surface of hematite (α-Fe2O3) particles in 39 ± 9, 68 ± 9, and 103 ± 8 nm, respectively, were measured using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. As the particle size increases, the amount of adsorbed BSA decreases, but the loss in the helical structure of adsorbed BSA increases due to the stronger interaction forces between adsorbed BSA and the larger particles. On 39 or 68 nm hematite particles, refolding of adsorbed BSA can be induced by protein–protein interactions, when the protein surface coverage exceeds certain critical values. Two-dimensional correlation spectroscopy (2D-COS) analysis of time-dependent ATR-FTIR spectra indicate that the increase in the amount of adsorbed BSA occurs prior to the loss in the BSA helical structure in the initial stage of adsorption processes, whereas an opposite sequence of the changes to BSA conformation and surface coverage is observed during the subsequent refolding processes. Desorption experiments show that replacing the protein solution with water can quench the refolding, but not the unfolding, of adsorbed BSA. A kinetic model was proposed to quantitatively describe the interplay of adsorption kinetics and conformational change, as well as the effects of particle size and initial protein concentration on the rate constants of elementary steps in protein adsorption onto a mineral surface.
Li X, Qin F, Chen X, Sheng A, Wang Z, Liu J. Dissolution Behavior of Isolated and Aggregated Hematite Particles Revealed by in Situ Liquid Cell Transmission Electron Microscopy. Environmental Science & Technology [Internet]. 2019. 访问链接
Peng H, Pearce CI, N'Diaye AT, Zhu Z, Ni J, Rosso KM, Liu J. Redistribution of Electron Equivalents between Magnetite and Aqueous Fe2+ Induced by a Model Quinone Compound AQDS. Environmental Science and Technology [Internet]. 2019. 访问链接
2018
刘娟∗, 盛安旭, 刘枫, 李晓旭, 琚宜文*, 刘国恒. 纳米矿物及其环境效应. 地球科学. 2018;43(5):1450-1463.PKU 
Peng H, Pearce CI, Huang W, Zhu Z*, N’Diaye AT, Rosso KM, Liu J*. Reversible Fe(II) uptake/release by magnetite nanoparticles. Environmental Science: Nano. Environmental Science: Nano [Internet]. 2018. 访问链接
You Y, Zheng S, Zang H, Liu F, Liu F, Liu J*. Stimulatory effect of magnetite on the syntrophic metabolism of Geobacter co-cultures: Influences of surface coating. Geochimica et Cosmochimica Acta [Internet]. 2018. 访问链接Abstract
Magnetite-mediated direct interspecies electron transfer (DIET) can facilitate syntrophic metabolism in natural microbial communities and also promote the performance of the engineered systems based on syntrophic interactions. In this study, the stimulatory effect of bare synthetic magnetite (Mt), humic acid coated magnetite, and SiO2 coated magnetite (Mt-SiO2) on DIET in defined co-cultures of Geobacter metallireducens/Geobacter sulfurreducens were studied. Magnetite coated with Aldrich humic acid (HA) and Elliott Soil humic acid (HAES), respectively, were prepared, and the two kinds of humic acid influenced the ability of Mt to promote syntrophic metabolism of the co-cultures in a similar way. When weight concentration was the same, pure humic acid presented the stimulatory effect on DIET similar to bare magnetite. However, the presence of HA coating on magnetite surface caused 50% and 61%, respectively, decrease in the rates of ethanol consumption (Re) and succinate production (Rs) in DIET processes. Pure HA in the same weight concentration as the HA coating in Mt-HA induced the similar metabolism rates as Mt-HA. In the Mt-HA mediated DIET, most electrons from ethanol metabolism were transferred to G. sulfurreducens selectively through the HA coating, and magnetite core hardly contributed to DIET processes. The SiO2 coating on magnetite resulted in 81% and 89%, respectively, decreases in Re and Rs, mainly because the non-conductive SiO2 layer hindered electron transfer between magnetite core and bacteria. After eight-day incubation with the co-cultures, bare magnetite nanoparticles formed relatively larger and more compact aggregates with cells than Mt-HA and Mt-SiO2, due to the different surface charge between bare and coated Mt. The generation of dissolved Fe(II) and HCl-extractable Fe(II) due to microbial reduction of magnetite by G. metallireducens and vivianite formation were observed along with DIET processes in all DIET experiments. Based on these results, different pathways of electron transfer in defined co-cultures of Geobacters with bare and coated magnetite nanoparticles were proposed. The findings in this study demonstrate the significant effects of surface properties on the ability of magnetite to stimulate DIET, which needs to be considered in order to comprehensively understand the role and mechanisms of mineral-mediated DIET in natural and engineered systems.
Zang H, Miao C, Shang J, Liu Y, Liu J*. Structural effects on the catalytic activity ofcarbon-supported magnetite nanocomposites inheterogeneous Fenton-like reactions. RSC Adv [Internet]. 2018. 访问链接Abstract
The catalytic reactivity of synthetic bare magnetite nanoparticles, activated carbon supported magnetite (AC-Mt), and graphene oxide supported magnetite (GO-Mt) for heterogeneous Fenton-like oxidation of methylene blue (MB) were compared, in order to investigate how the structural features of the support impact catalytic activity of the nanocomposites. The different effects of AC and GO on MB removal rate, hydroxyl radical ([radical dot]OH) production, iron leaching, and surface deactivation have been systematically studied. The rate constant of MB removal by AC-Mt was 0.1161 min-1, one order of magnitude larger than the value of bare magnetite nanoparticles (0.0566 min-1). The higher catalytic activity of AC-Mt might be attributed to the larger reactive surface area of well-dispersed magnetite for [radical dot]OH production and the recharge of the magnetite surface by the AC support via Fe-O-C bonds. However, the removal rate of MB by GO-Mt was one order of magnitude slower than that of bare magnetite nanoparticles under the same experimental conditions, presumably due to the wrapping of GO around magnetite nanoparticles or extensive aggregation of GO-Mt composites. These findings revealed the significant influence of support structure on the catalytic activity of carbon-supported magnetite nanocomposites, which is important for the development of efficient magnetite-based catalysts for wastewater treatments.
刘娟, 李晓旭, 刘枫, 张逸潇. 铁氧化物-微生物界面电子传递的分子机制研究进展. 矿物岩石地球化学通报 [Internet]. 2018;37(1):39-47. 访问链接PKU 
2017
Zhang Y, Liu C, Zhu G, Huang X, Liu W, Hu W, Song M, He W, Liu J*, Zhai J*. Piezotronic-effect-enhanced Ag2S/ZnO photocatalyst for organic dye degradation. RSC Advances. 2017;7(76):48176-48183.
Antagonistic effect of humic acid and naphthalene on biochar colloid transport in saturated porous media
Yang W, Wang Y, Shang J, Liu K, Sharma P, Liu J, Li B. Antagonistic effect of humic acid and naphthalene on biochar colloid transport in saturated porous media. Chemosphere. 2017.
Effect of naphthalene on transport and retention of biochar colloids through saturated porous media
Yang W, Wang Y, Sharma P, Li B, Liu K, Liu J, Flury M, Shang J. Effect of naphthalene on transport and retention of biochar colloids through saturated porous media. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2017;530:146-154.
Zhu G, Yang Y, Liu J*, Liu F, Lu A, He W*. Enhanced photocurrent production by the synergy of hematite nanowire-arrayed photoanode and bioengineered Shewanella oneidensis MR-1. Biosensors and Bioelectronics. 2017;94:227-234.
2016
Aggregation Kinetics of Hematite Particles in the Presence of Outer Membrane Cytochrome OmcA of Shewanella oneidenesis MR-1
Sheng A, Liu F, Shi L, Liu J*. Aggregation Kinetics of Hematite Particles in the Presence of Outer Membrane Cytochrome OmcA of Shewanella oneidenesis MR-1. Environmental Science & Technology. 2016;50(20):11016-11024.Abstract
The aggregation behavior of 9, 36, and 112 nm hematite particles was studied in the presence of OmcA, a bacterial extracellular protein, in aqueous dispersions at pH 5.7 through time-resolved dynamic light scattering, electrophoretic mobility, and circular dichroism spectra, respectively. At low salt concentration, the attachment efficiencies of hematite particles in all sizes first increased, then decreased, and finally remained stable with the increase of OmcA concentration, indicating the dominant interparticle interaction changed along with the increase in the protein-to-particle ratio. Nevertheless, at high salt concentration, the attachment efficiencies of all hematite samples gradually decreased with increasing OmcA concentration, which can be attributed to increasing steric force. Additionally, the aggregation behavior of OmcA–hematite conjugates was more correlated to total particle–surface area than primary particle size. It was further established that OmcA could stabilize hematite nanoparticles more efficiently than bovine serum albumin (BSA), a model plasma protein, due to the higher affinity of OmcA to hematite surface. This study highlighted the effects of particle properties, solution conditions, and protein properties on the complicated aggregation behavior of protein–nanoparticle conjugates in aqueous environments.
Extracellular electron transfer mechanisms between microorganisms and minerals
Shi L, Dong H, Reguera G, Beyenal H, Lu A, Liu J, Yu H-Q, Fredrickson JK. Extracellular electron transfer mechanisms between microorganisms and minerals. Nature Reviews Microbiology [Internet]. 2016;14(10):651-662. 访问链接Abstract
Electrons can be transferred from microorganisms to multivalent metal ions that are associated with minerals and vice versa. As the microbial cell envelope is neither physically permeable to minerals nor electrically conductive, microorganisms have evolved strategies to exchange electrons with extracellular minerals. In this Review, we discuss the molecular mechanisms that underlie the ability of microorganisms to exchange electrons, such as c-type cytochromes and microbial nanowires, with extracellular minerals and with microorganisms of the same or different species. Microorganisms that have extracellular electron transfer capability can be used for biotechnological applications, including bioremediation, biomining and the production of biofuels and nanomaterials.
Impact of Proteins on Aggregation Kinetics and Adsorption Ability of Hematite Nanoparticles in Aqueous Dispersions
Sheng A, Liu F, Xie N, Liu J*. Impact of Proteins on Aggregation Kinetics and Adsorption Ability of Hematite Nanoparticles in Aqueous Dispersions. Environmental science & technology. 2016;50(5):2228.Abstract
The initial aggregation kinetics of hematite nanoparticles (NPs) that were conjugated with two model globular proteins—cytochrome c from bovine heart (Cyt) and bovine serum albumin (BSA)—were investigated over a range of monovalent (NaCl) and divalent (CaCl2) electrolyte concentrations at pH 5.7 and 9. The aggregation behavior of Cyt-NP conjugates was similar to that of bare hematite NPs, but the additional electrosteric repulsion increased the critical coagulation concentration (CCC) values from 69 mM to 113 mM in NaCl at pH 5.7. An unsaturated layer of BSA, a protein larger than Cyt, on hematite NPs resulted in fast aggregation at low salt concentrations and pH 5.7, due to the strong attractive patch-charge interaction. However, the BSA-NP conjugates could be stabilized simply by elevating salt concentrations, owing to the screening of the attractive patch-charge force and the increasing contribution from steric force. This study showed that the aggregation state of protein-conjugated NPs is proved to be completely switchable via ionic strength, pH, protein size, and protein coverage. Macroscopic Cu(II) sorption experiments further established that reducing aggregation of hematite NPs via tailoring ionic strength and protein conjugation could promote the metal uptake by hematite NPs under harsh conditions.
In situ observation of hematite nanoparticle aggregates using liquid cell transmission electron microscopy
Liu J*, Wang Z*, Sheng A, Liu F, Qin F, Wang ZL*. In situ observation of hematite nanoparticle aggregates using liquid cell transmission electron microscopy. Environmental science & technology. 2016;50(11):5606-5613.Abstract
Aggregation of nanoparticles impacts their reactivity, stability, transport, and fate in aqueous environments, but limited methods are available to characterize structural features and movement of aggregates in liquid. Here, liquid cell transmission electron microscopy (LCTEM) was utilized to directly observe the size, morphology, and motion of aggregates that were composed of 9 and 36 nm hematite nanoparticles, respectively, in water or NaCl solution. When mass concentrations were same, the aggregates of 9 nm nanoparticles were statistically more compact and slightly larger than those of 36 nm nanoparticles. Aggregates in both samples were typically nonspherical. Increasing ionic strength resulted in larger aggregates, and also enhanced the stability of aggregates under electron-beam irradiation. In water, small aggregates moved randomly and approached repeatedly to large aggregates before final attachment. In NaCl solution, small aggregates moved directly toward large aggregates and attached to the latter quickly. This observation provided a direct confirmation of the DLVO theory that the energy barrier to aggregation is higher in water than in salt solutions. This study not only presented the influences of particle size and ionic strength on aggregation state, but also demonstrated that LCTEM is a promising method to link aggregation state to dynamic processes of nanoparticles.
Liu J*, Pearce CI, Shi L, Wang Z, Shi Z, Arenholz E, Rosso KM*. Particle size effect and the mechanism of hematite reduction by the outer membrane cytochrome OmcA of Shewanella oneidensis MR-1. Geochimica et Cosmochimica Acta. 2016;193:160-175.Abstract
The cycling of iron at the Earth’s near surface is profoundly influenced by dissimilatory metal reducing microorganisms, and many studies have focused on unraveling electron transfer mechanisms between these bacteria and Fe(III)-(oxyhydr)oxides. However, these efforts have been complicated by the fact that these minerals often occur in the micro- to nanosize regime, and in relevant natural environments as well as in the laboratory are subject to aggregation. The nature of the physical interface between the cellular envelope, the outer-membrane cytochromesresponsible for facilitating the interfacial electron transfer step, and these complex mineral particulates is thus difficult to probe. Previous studies using whole cells have reported reduction rates that do not correlate with particle size. In the present study we isolate the interaction between the decaheme outer-membrane cytochrome OmcA of Shewanella oneidensisand nanoparticulate hematite, examining the reduction rate as a function of particle size and reaction products through detailed characterization of the electron balance and the structure and valence of iron at particle surfaces. By comparison with abiotic reduction via the smaller molecule ascorbic acid, we show that the reduction rate is systematically controlled by the sterically accessible interfacial contact area between OmcA and hematite in particle aggregates; rates increase once pore throat sizes in aggregates become as large as OmcA. Simultaneous measure of OmcA oxidation against Fe(II) release shows a ratio of 1:10, consistent with a cascade OmcA oxidation mechanism heme by heme. X-ray absorption spectroscopies reveal incipient magnetite on the reacted surfaces of the hematite nanoparticles after reaction. The collective findings establish the importance of accessibility of physical contact between the terminal reductases and iron oxide surfaces, and through apparent consistency of observations help reconcile behavior reported at the larger more complex scale of whole cell studies.
Liu JY, Zhang Y, Liu C, Peng M, Yu A, Kou J, Liu W, Zhai J*, Liu J*. Piezo-phototronic effect enhanced UV photodetector based on CuI/ZnO double-shell grown on flexible copper microwire. Nanoscale research letters. 2016;11(1):281.Abstract
In this work, we present a facile, low-cost, and effective approach to fabricate the UV photodetector with a CuI/ZnO double-shell nanostructure which was grown on common copper microwire. The enhanced performances of Cu/CuI/ZnO core/double-shell microwire photodetector resulted from the formation of heterojunction. Benefiting from the piezo-phototronic effect, the presentation of piezocharges can lower the barrier height and facilitate the charge transport across heterojunction. The photosensing abilities of the Cu/CuI/ZnO core/double-shell microwire detector are investigated under different UV light densities and strain conditions. We demonstrate the I-V characteristic of the as-prepared core/double-shell device; it is quite sensitive to applied strain, which indicates that the piezo-phototronic effect plays an essential role in facilitating charge carrier transport across the CuI/ZnO heterojunction, then the performance of the device is further boosted under external strain.

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