Conjugated Molecules Based Multi-Component Artificial Photosynthesis System for Producing Multi-Objective Products.

The development of artificial photosynthesis systems that mimics natural photosynthesis can help address the issue of energy scarcity by efficiently utilizing solar energy. Here, it presents liposomes-based artificial photosynthetic nanocapsules (PSNC) integrating photocatalytic, chemical catalytic, and biocatalytic systems through one-pot method. The PSNC contains 5,10,15,20-tetra(4-pyridyl) cobalt-porphyrin, tridipyridyl-ruthenium nitrate, oligo-pphenyl-ethylene-rhodium complex, and creatine kinase, efficiently generating oxygen, nicotinamide adenine dinucleotide (NADH), and adenosine triphosphate with remarkable enhancements of 231%, 30%, and 86%, compared with that of molecules mixing in aqueous solution. Additionally, the versatile PSNC enables simulation of light-independent reactions, achieving a controllable output of various target products. The regenerated NADH within PSNC further facilitates alcohol dehydrogenase, yielding methanol with a notable efficiency improvement of 37%. This work introduces a promising platform for sustainable solar energy conversion and the simultaneous synthesis of multiple valuable products in an ingenious and straightforward way.

Oxidative Dissolution of Sulfide Minerals Tends to Accumulate More Dissolved Heavy Metals in Deep Seawater Environments than in Shallow Seawater Environments.

Deep-sea mining magnifies the release of heavy metals into seawater through oxidative dissolution of seafloor massive sulfide (SMS). At present, there is little information about how the metals released into seawater might be affected by the mineral assemblages, seawater conditions, and solid percentages. Here, leaching experiments were carried out to examine the behavior of three sulfides from the Southwest Indian Ridge, under conditions that replicated deep and shallow seawater environments at three solid-liquid ratios. The results demonstrated that sphalerite dissolved rapidly, and the metals released in both experimental conditions were comparable, potentially reflecting galvanic interactions between the sulfide minerals. Large quantities of the released metals were removed from the solutions when hydrous ferric oxides formed, especially for shallow seawater conditions. A comparison of metal concentrations in the leachates with the baseline metal concentrations in natural seawater indicated that most of the released metals, when diluted with seawater, would not have widespread impacts on ecosystems. Based on the obtained unique oxidative dissolution properties of each SMS at variable solid-liquid ratios, targeted wastewater discharge treatments are proposed to minimize impacts from the dissolved metals. This study will support the development of robust guidelines for deep-sea mining activities.

Self-Powered Biohybrid Systems Based on Organic Materials for Sustainable Biosynthesis.

Sustainable energy conversion and effective biosynthesis for value-added chemicals have attracted considerable attention, but most biosynthesis systems cannot work independently without external power. In this work, a self-powered biohybrid system based on organic materials is designed and constructed successfully by integrating electroactive microorganisms with electrochemical devices. Among them, the hybrid living materials based on S. oneidensis/poly[3-(3'-N,N,N-triethylamino-1'-propyloxy)-4-methyl-2,5-thiophene chloride] (PMNT) biofilms for microbial fuel cells played a crucial role in electrocatalytic biocurrent generation by using biowaste as the only energy source. Without any external power supplies, the self-powered biohybrid systems could generate, convert, and store electrical energy for effective photosynthetic regulation and sustained chemical production. This work provides a new strategy to combine comprehensive renewable energy production with chemical manufacturing without an external power source in the future.

Phosphorus-Doped Hollow Tubular g-C3N4 for Enhanced Photocatalytic CO2 Reduction.

Photocatalytic CO2 reduction is a tactic for solving the environmental pollution caused by greenhouse gases. Herein, NH4H2PO4 was added as a phosphorus source in the process of the hydrothermal treatment of melamine for the first time, and phosphorus-doped hollow tubular g-C3N4 (x-P-HCN) was fabricated and used for photocatalytic CO2 reduction. Here, 1.0-P-HCN exhibited the largest CO production rate of 9.00 µmol·g-1·h-1, which was 10.22 times higher than that of bulk g-C3N4. After doping with phosphorus, the light absorption range, the CO2 adsorption capacity, and the specific surface area of the 1.0-P-HCN sample were greatly improved. In addition, the separation of photogenerated electron-hole pairs was enhanced. Furthermore, the phosphorus-doped g-C3N4 effectively activated the CO2 adsorbed on the surface of phosphorus-doped g-C3N4 photocatalysts, which greatly enhanced the CO production rate of photocatalytic CO2 reduction over that of g-C3N4.

Zinc Stable Isotope Fractionation Mechanisms during Adsorption on and Substitution in Iron (Hydr)oxides.

The Zn isotope fingerprint is widely used as a proxy of various environmental geochemical processes, so it is crucial to determine which are the mechanisms responsible for isotopic fractionation. Iron (Fe) (hydr)oxides greatly control the cycling and fate and thus isotope fractionation factors of Zn in terrestrial environments. Here, Zn isotope fractionation and related mechanisms during adsorption on and substitution in three FeOOH polymorphs are explored. Results demonstrate that heavy Zn isotopes are preferentially enriched onto solids, with almost similar isotopic offsets (Δ66/64Znsolid-solution = 0.25-0.36‰) for goethite, lepidocrocite, and feroxyhyte. This is consistent with the same average Zn-O bond lengths for adsorbed Zn on these solids as revealed by Zn K-edge X-ray absorption fine structure spectroscopy. In contrast, at an initial Zn/Fe molar ratio of 0.02, incorporation of Zn into goethite and lepidocrocite by substituting for lattice Fe preferentially sequesters light Zn isotopes with Δ66/64Znsubstituted-stock solution of -1.52 ± 0.09‰ and -1.18 ± 0.15‰, while Zn-substituted feroxyhyte (0.06 ± 0.11‰) indicates almost no isotope fractionation. This is closely related to the different crystal nucleation and growth rates during the Zn-doped FeOOH formation processes. These results provide direct experimental evidence of incorporation of isotopically light Zn into Fe (hydr)oxides and improve our understanding of Zn isotope fractionation mechanisms during mineral-solution interface processes.

Water-soluble conjugated polymers for bioelectronic systems.

Bioelectronics is an interdisciplinary field of research that aims to establish a synergy between electronics and biology. Contributing to a deeper understanding of bioelectronic processes and the built bioelectronic systems, a variety of new phenomena, mechanisms and concepts have been derived in the field of biology, medicine, energy, artificial intelligence science, etc. Organic semiconductors can promote the applications of bioelectronics in improving original performance and creating new features for organisms due to their excellent photoelectric and electrical properties. Recently, water-soluble conjugated polymers (WSCPs) have been employed as a class of ideal interface materials to regulate bioelectronic processes between biological systems and electronic systems, relying on their satisfying ionic conductivity, water-solubility, good biocompatibility and the additional mechanical and electrical properties. In this review, we summarize the prominent contributions of WSCPs in the aspect of the regulation of bioelectronic processes and highlight the latest advances in WSCPs for bioelectronic applications, involving biosynthetic systems, photosynthetic systems, biophotovoltaic systems, and bioelectronic devices. The challenges and outlooks of WSCPs in designing high-performance bioelectronic systems are also discussed.

Flexible bioelectronic device fabricated by conductive polymer-based living material.

Living materials are worked as an inside collaborative system that could naturally respond to changing environmental conditions. The regulation of bioelectronic processes in living materials could be effective for collecting biological signals and detecting biomarkers. Here, we constructed a living material with conjugated polymers poly[3-(3'-N,N,N-triethylamino-1'-propyloxy)-4-methyl-2,5-thiophene chloride] (PMNT) and Shewanella oneidensis MR-1 biofilm. In addition, the living material was integrated as a flexible bioelectronic device for lactate detection in physiological fluids (sweat, urine, and plasma). Owing to the electroconductivity of conjugated polymers, PMNT could optimize the bioelectronic process in the living material. The collected electrical signal could be wirelessly transferred to a portable smartphone for reading and analyzing. Because lactate is also a biomarker for cancer treatment, the flexible bioelectronic device was further used to detect and count the cancer cells. The proof of the bioelectronic device using conductive polymer-based living material exhibits promising applications in the next-generation personal health monitoring systems.

Mantle Hg isotopic heterogeneity and evidence of oceanic Hg recycling into the mantle.

The geochemical cycle of mercury in Earth's surface environment (atmosphere, hydrosphere, biosphere) has been extensively studied; however, the deep geological cycling of this element is less well known. Here we document distinct mass-independent mercury isotope fractionation (expressed as Δ199Hg) in island arc basalts and mid-ocean ridge basalts. Both rock groups show positive Δ199Hg values up to 0.34‰ and 0.22‰, respectively, which deviate from recent estimates of the primitive mantle (Δ199Hg: 0.00 ± 0.10‰, 2 SD)1. The positive Δ199Hg values indicate recycling of marine Hg into the asthenospheric mantle. Such a crustal Hg isotope signature was not observed in our samples of ocean island basalts and continental flood basalts, but has recently been identified in canonical end-member samples of the deep mantle1, therefore demonstrating that recycling of mercury can affect both the upper and lower mantle. Our study reveals large-scale translithospheric Hg recycling via plate tectonics.

Transformation of minerals and mobility of heavy metals during oxidative weathering of seafloor massive sulfide and their environmental significance.

Seafloor massive sulfide (SMS) deposits have received widespread attention because of their potential as available metal resources. Deep-sea mining operations significantly increase the exposure of fresh sulfide to oxygenated seawater. Knowledge about mineral transformation and the fate of heavy metals during sulfide oxidation remains insufficient, which is unfavorable for eco-friendly deep-sea mining. Here, a series of partially or completely oxidized sulfide samples collected from the Yuhuang hydrothermal field, Southwest Indian Ridge, were examined for detailed mineralogical, geochemical, and morphological analyses. Models for mineral conversion and heavy metal mobility over time were established through the obtained results to assess the potential environmental impacts associated with deep-sea mining. The absence of hydrous ferric sulfates in the pure oxide samples suggests that they were transformed into iron (oxy)hydroxides after long-term exposure in seawater. There are also indications that amorphous iron (oxy)hydroxides dehydrated to layer-like goethite and that schwertmannite hydrolyzed to globular goethite. The microorganism-related morphology of secondary minerals strengthens the case that sulfide oxidation is a microbially mediated process. The enrichment of Cu, Zn, V, and U in oxidation products indicates that they can serve as effective purification agents to retain heavy metals originated from sulfide and seawater. Heavy metal contents display a progressively increasing trend in the oxide profiles, which can be well explained by our models for oxide crust accumulation. Because secondary minerals have excellent adsorption capability and mineral transformation is a reaction removal of sulfate radicals, we conclude that sulfide oxidation provides a sink for oceanic heavy metal cycles and a sulfur source in balancing the global biogeochemical sulfur cycle. In addition, mining SMS deposits containing a large quantity of Fe-bearing sulfide minerals or iron oxides from inactive hydrothermal fields are conducive to reducing environmental hazards and maintaining the economic value of remaining deposits.

Selective Fluorescence Imaging of Cancer Cells Based on ROS-Triggered Intracellular Cross-Linking of Artificial Enzyme.

Inside living cells, regulation of catalytic activity of artificial enzymes remains challenging due to issues such as biocompatibility, efficiency, and stability of the catalyst, by which the practical applications of artificial enzymes have been severely hindered. Here, an artificial enzyme, PTT-SGH, with responsiveness to reactive oxygen species (ROS), was obtained by introducing a catalytic histidine residue to pentaerythritol tetra(3-mercaptopropionate) (PTT). The artificial enzyme formed large aggregates in cells via the intracellular ROS-mediated oxidation of thiol groups. The process was significantly facilitated in tumor cells because of the higher ROS concentration in the tumor microenvironment. The catalytic activity of this artificial enzyme was intensively enhanced through deprotonation of cross-linked PTT-SGH, which showed typical esterase activities. Selective fluorescence imaging of tumor cells was achieved using the artificial enzyme to trigger the cleavage of the ester bond of the caged fluorophore inside living cells.

Cadmium Isotope Fractionation during Adsorption and Substitution with Iron (Oxyhydr)oxides.

Cadmium (Cd) isotopes have great potential for understanding Cd geochemical cycling in soil and aquatic systems. Iron (oxyhydr)oxides can sequester Cd via adsorption and isomorphous substitution, but how these interactions affect Cd isotope fractionation remains unknown. Here, we show that adsorption preferentially enriches lighter Cd isotopes on iron (oxyhydr)oxide surfaces through equilibrium fractionation, with a similar fractionation magnitude (Δ114/110Cdsolid-solution) for goethite (Goe) (-0.51 ± 0.04‰), hematite (Hem) (-0.54 ± 0.10‰), and ferrihydrite (Fh) (-0.55 ± 0.03‰). Neither the initial Cd2+ concentration or ionic strength nor the pH influence the fractionation magnitude. The enrichment of the light isotope is attributed to the adsorption of highly distorted [CdO6] on solids, as indicated by Cd K-edge extended X-ray absorption fine-structure analysis. In contrast, Cd incorporation into Goe by substitution for lattice Fe at a Cd/Fe molar ratio of 0.05 preferentially sequesters heavy Cd isotopes, with a Δ114/110Cdsolid-solution of 0.22 ± 0.01‰. The fractionation probably occurs during the transformation of Fh into Goe via dissolution and reprecipitation. These results improve the understanding of the Cd isotope fractionation behavior being affected by iron (oxyhydr)oxides in Earth's critical zone and demonstrate that interactions with minerals can obscure anthropogenic and natural Cd isotope characteristics, which should be carefully considered when applying Cd isotopes as environmental tracers.

Cadmium isotope constraints on heavy metal sources in a riverine system impacted by multiple anthropogenic activities.

Heavy metals pollutants are global concern due to their toxicities and persistence in the environment. Cd isotope signatures in soils and sediments change during weathering, and it remains unclear if Cd isotopes can effectively trace Cd sources in a riverine system. In this study, we investigate Cd concentration and its isotope compositions, as well as other heavy metals of sediments and related potential Cd sources in a riverine system. The results showed that the two river sediments evaluated were moderately polluted by Zn, Cr, and Cd, while the source samples (soil, sludge, waste, and raw materials) were seriously polluted by heavy metals derived from anthropogenic activities. According to comprehensive ecological risks, the two sediments have a moderate to low potential risk and more than half of all anthropogenic activities in the study area were at considerable or moderate potential risk. We determined that Cd pollution in river sediments was primarily derived from sewage treatment and outlets based on river flow direction and the isotope geochemical behaviors of the Cd isotope in nature conditions. This study further confirmed that analyzing Cd isotopes could be a powerful tool for tracing the source and destination of environmental Cd for multiple sources with similar Cd concentrations.

Cd isotope fractionation during sulfide mineral weathering in the Fule Zn-Pb-Cd deposit, Yunnan Province, Southwest China.

Zinc (Zn)-Lead (Pb) deposits are generally rich in cadmium (Cd), and the weathering of sulfide minerals in such deposits results in large releases of Cd into the environment. From an environmental and public health standpoint, understanding Cd sources and cycling is critical to identifying potential hazards to humans. In this study, the Cd isotope compositions (expressed as δ114/110Cd) of secondary minerals such as anglesite (-0.57±0.03‰; 2S.D.), granular smithsonite (0.04±0.14‰; 2S.D.), layered smithsonite (0.15±0.40‰; 2S.D.), hydrozincite (0.26±0.01‰; 2S.D.) and clay minerals (-0.01±0.06‰; 2S.D.) from the Fule Zn-Pb-Cd deposit, Southwest China, are investigated to better understand the Cd sources and cycling in this area. Combined with our previous study (Zhu et al., 2017), the work herein elucidates the patterns of Cd isotopic fractionation during the formation processes of such secondary minerals and traces the weathering of these minerals into the ecosystem. The δ114/110Cd values of secondary minerals exhibit the following decreasing trend: hydrozincite>large granular smithsonite>small granular smithsonite>anglesite. Although different amounts of Cd were lost during the formation of equally sized samples, no or minor variations in Cd isotopic composition were observed. However, significant isotopic differences were observed between different size fractions. These results demonstrate that the particle size of secondary minerals and weathering products of sulfide significantly influence Cd isotope composition and fractionation during natural weathering. This systematic fractionation provides an initial foundation for the use of Cd isotopes as environmental tracers in ecosystems and in the global Cd isotope budget.

Cd isotope fractionation during simulated and natural weathering.

In practice, stable Cd isotope ratios are being applied to trace pollution sources in the natural environment. However, Cd isotope fractionation during weathering processes is not yet fully understood. We investigated Cd isotope fractionation of PbZn ore in leaching experiments and in the environment under natural weathering processes. Our leaching experiments demonstrated that the leachate was enriched with heavy Cd isotopes, relative to initial and residual samples (Δ(114/110)Cdleachate - initial state = 0.40-0.50‰, Δ(114/110)Cdleachate -residual state = 0.36-0.53‰). For natural samples, δ(114/110)Cd values of stream sediments were higher than those of the corresponding soil samples collected from the riverbank, Δ(114/110)Cdstream sediment -soil can be up to 0.50‰. This observation is consistent with our leaching experiments, which indicate significant Cd isotope fractionation during natural weathering processes. Therefore, natural contributions should be considered when using Cd isotopes to trace anthropogenic pollution in water and sediment systems.

Fractionation of Stable Cadmium Isotopes in the Cadmium Tolerant Ricinus communis and Hyperaccumulator Solanum nigrum.

Cadmium (Cd) isotopes provide new insights into Cd uptake, transport and storage mechanisms in plants. Therefore, the present study adopted the Cd-tolerant Ricinus communis and Cd-hyperaccumulator Solanum nigrum, which were cultured under controlled conditions in a nutrient solution with variable Cd supply, to test the isotopic fractionation of Cd during plant uptake. The Cd isotope compositions of nutrient solutions and organs of the plants were measured by multiple collector inductively coupled plasma mass spectrometry (MC-ICPMS). The mass balance of Cd isotope yields isotope fractionations between plant and Cd source (δ(114/110)Cdorgans-solution) of -0.70‰ to -0.22‰ in Ricinus communis and -0.51‰ to -0.33‰ in Solanum nigrum. Moreover, Cd isotope fractionation during Cd transport from stem to leaf differs between the Cd-tolerant and -hyperaccumulator species. Based on these results, the processes (diffusion, adsorption, uptake or complexation), which may induce Cd isotope fractionation in plants, have been discussed. Overall, the present study indicates potential applications of Cd isotopes for investigating plant physiology.

Zn/Cd ratios and cadmium isotope evidence for the classification of lead-zinc deposits.

Lead-zinc deposits are often difficult to classify because clear criteria are lacking. In recent years, new tools, such as Cd and Zn isotopes, have been used to better understand the ore-formation processes and to classify Pb-Zn deposits. Herein, we investigate Cd concentrations, Cd isotope systematics and Zn/Cd ratios in sphalerite from nine Pb-Zn deposits divided into high-temperature systems (e.g., porphyry), low-temperature systems (e.g., Mississippi Valley type [MVT]) and exhalative systems (e.g., sedimentary exhalative [SEDEX]). Our results showed little evidence of fractionation in the high-temperature systems. In the low-temperature systems, Cd concentrations were the highest, but were also highly variable, a result consistent with the higher fractionation of Cd at low temperatures. The δ(114/110)Cd values in low-temperature systems were enriched in heavier isotopes (mean of 0.32 ± 0.31‰). Exhalative systems had the lowest Cd concentrations, with a mean δ(114/110)Cd value of 0.12 ± 0.50‰. We thus conclude that different ore-formation systems result in different characteristic Cd concentrations and fraction levels and that low-temperature processes lead to the most significant fractionation of Cd. Therefore, Cd distribution and isotopic studies can support better understanding of the geochemistry of ore-formation processes and the classification of Pb-Zn deposits.