Biogated mesoporous silica nanoagents for inhibition of cell migration and combined cancer therapy.

Migration is an initial step in tumor expansion and metastasis; suppressing cellular migration is beneficial to cancer therapy. Herein, we designed a novel biogated nanoagents that integrated the migration inhibitory factor into the mesoporous silica nanoparticle (MSN) drug delivery nanosystem to realize cell migratory inhibition and synergistic treatment. Antisense oligonucleotides (Anti) of microRNA-330-3p, which is positively related with cancer cell proliferation, migration, invasion, and angiogenesis, not only acted as the locker for blocking drugs but also acted as the inhibitory factor for suppressing migration via gene therapy. Synergistic with gene therapy, the biogated nanoagents (termed as MSNs-Gef-Anti) could achieve on-demand drug release based on the intracellular stimulus-recognition and effectively kill tumor cells. Experimental results synchronously demonstrated that the migration suppression ability of MSNs-Gef-Anti nanoagents (nearly 30%) significantly contributed to cancer therapy, and the lethality rate of the non-small-cell lung cancer was up to 70%. This strategy opens avenues for realizing efficacious cancer therapy and should provide an innovative way for pursuing the rational design of advanced nano-therapeutic platforms with the combination of cancer cell migratory inhibition.

Core-shell "loading-type" nanomaterials enabling glucometer readout for portable and sensitive detection of p-aminophenol in real samples.

A one-target-many-trigger signal model sensing strategy is proposed for quickly, sensitive and on-site detection of the environmental pollutant p-aminophenol (PAP) by use of a commercial personal glucose meter (PGM) for signal readout with the core-shell "loading-type" nanomaterial MSNs@MnO2 as amplifiable nanoprobes. In this design, the mesoporous silica nanoparticles (MSNs) nanocontainer with entrapped signal molecule glucose is coated with redoxable manganese dioxide (MnO2) nanosheets to form the amplifiable nanoprobes (Glu-MSNs@MnO2). When encountered with PAP, the redox reaction between the MnO2 and PAP can induce the degradation of the outer layer of MSNs@MnO2, liberating multiple copies of the loaded glucose to light up the PGM signal. Owing to the high loading capability of nanocarriers, a "one-to-many" relationship exists between the target and the signal molecule glucose, which can generate adequate signal outputs to achieve the requirement of on-site determination of environmental pollutants. Taking advantage of this amplification mode, the developed PAP assay owns a dynamic linear range of 10.0-400 µM with a detection limit of 2.78 µM and provides good practical application performance with above 96.7 ± 4.83% recovery in environmental water and soil samples. Therefore, the PGM-based amplifiable sensor for PAP proposed can accommodate these requirements of environment monitoring and has promising potential for evaluating pollutants in real environmental samples.

Self-powered DNA nanomachines for fluorescence detection of lead.

A versatile DNA nanomachine detection system has been developed via the combination of DNAzyme with catalytic hairpin assembly (CHA) technology for achieving accurate and sensitive detection of lead ions (Pb2+). In the presence of target Pb2+, capture DNA nanomachine formed by AuNP and DNAzyme recognized and reacted with Pb2+, which yielded an "active" DNAzyme, that induced the cleavage of substrate strand, and then released the initiator DNA (TT) for CHA. With the help of the initiator DNA TT, self-powered CHA was activated to achieve the signal amplification reaction in the detection of DNA nanomachine. Meanwhile, the initiator DNA TT was released and hybridized with the other H1 strand to initiate another CHA, replacement, and turnovers, producing enhanced fluorescence signal of fluorophore FAM (excitation 490 nm/emission 520 nm) for sensitive determination of Pb2+. Under the optimized conditions, the DNA nanomachine detection system revealed high selectivity toward Pb2+ in the concentration range 50-600 pM, with the limit of detection (LOD) of 31 pM. Recovery tests demonstrated that the DNA nanomachine detection system has excellent detection capability in real samples. Therefore, the proposed strategy can be extended and act as a basic platform for highly accurate and sensitive detection of various heavy metal ions.

Removal of petroleum hydrocarbon-contaminated soil using a solid-phase microbial fuel cell with a 3D corn stem carbon electrode modified with carbon nanotubes.

Solid-phase microbial fuel cell (SMFC) can accelerate the removal of organic pollutants through the electrons transfer between microorganisms and anodes in the process of generating electricity. Thus, the characteristics of the anode material will affect the performance of SMFCs. In this study, corn stem (CS) is first calcined into a 3D macroporous electrode, and then modified with carbon nanotubes (CNTs) through electrochemical deposition method. Scanning electron microscope analysis showed the CS/CNT anode could increase the contact area on the surface. Furthermore, electrochemical impedance spectroscopy and cyclic voltammetry analysis indicated the electrochemical double-layer capacitance of the CS/CNT anode increased while its internal resistance decreased significantly. These characteristics are crucial for increasing bacterial adhesion capability and electron transfer rate. The maximum output voltage of the SMFC with CS/CNT anode was 158.42 mV, and the removal rate of petroleum hydrocarbon (PH) reached 42.17%, 2.72 times that of unmodified CS. In conclusion, CNT-modified CS is conducive to improve electron transfer rate and microbial attachment, enhancing the removal efficiency of PH in soil.

CuO/g-C3N4 heterojunction photocathode enhances the microbial electrosynthesis of acetate through CO2 reduction.

Microbial electrosynthesis (MES) is a novel CO2 utilization technology. Biocatalysts in this process may use electrons obtained from a photovoltaic system to reduce CO2 to chemicals and realize energy conversion from solar energy to chemical energy. The photoelectric material CuO/g-C3N4 was directly introduced into the MES system using mixed culture as biocatalyst in this study. CuO/g-C3N4 can effectively absorb light and presents satisfactory electron and hole separation ability. Photogenerated electrons from CuO/g-C3N4 enhanced the electron transfer rate and reduced cathodic charge transfer resistance. CuO/g-C3N4 mainly improved the electron supply of electroautotrophic microorganisms through direct electron transfer rather than indirect electron transfer via hydrogen. Photogenerated holes can combine electrons from anode and provide extra driving force to improve the MES performance. Furthermore, the CuO/g-C3N4 photocathode also improved the biocatalytic activity by increasing the total amount of biocatalyst and regulating cathodic microbial community composition. Acetate production rate in MES with the CuO/g-C3N4 photocathode was 2.6 times higher than that of the control group. This study provides a new strategy for semiconductor photocathodes to improve the MES performance with mixed culture.

Perovskite-Based Multifunctional Cathode with Simultaneous Supplementation of Substrates and Electrons for Enhanced Microbial Electrosynthesis of Organics.

Microbial electrosynthesis (MES) is an electricity-driven technology for the microbial reduction of CO2 to organic commodities. However, the limited solubility of CO2 in a solution and the inefficient electron transfer make it impossible for microorganisms to obtain an efficient surface for catalytic interaction, thus resulting in the low efficiency of MES. To address this, we introduce a multifunctional perovskite-based cathode material Pr0.5(Ba0.5Sr0.5)0.5Co0.8Fe0.2O3-δ-carbon felt (Pr0.5BSCF-CF), which provides a simultaneously significant increase in CO2 absorption and hydrogen production. As a result, the volumetric acetate production rate of MES obtained by Pr0.5BSCF-CF is 0.24 ± 0.01 g L-1 day-1, and it achieves a maximum acetate titer of 13.74 ± 0.20 g L-1 within 70 days. An adequate supply of CO2 and H2 also provides a sufficient amount of substrates and energy for the self-replication of the biocatalysts in the MES reactor. This effect not only increases the amount of biocatalysts but also optimizes the functions of the biocatalysts; the above benefits further improve the production efficiency of the MES system. This strategy demonstrates that the development of perovskite-based multifunctional cathodes with a simultaneous supplementation of substrates and electrons is a promising approach toward improving the MES efficiency.

Correction to: Modification of carbon felt anode with graphene/Fe2O3 composite for enhancing the performance of microbial fuel cell.

It has been brought to our attention that in our article, explanations about cable bacteria are not rigorous. We apologize for these and note the specific reporting issues and errors below, with their corrections.

Modification of carbon felt anode with graphene/Fe2O3 composite for enhancing the performance of microbial fuel cell.

In this paper, a graphene/Fe2O3 (G/Fe2O3) modified anode was prepared through a simple one-step hydrothermal reduction method to improve the performance of microbial fuel cell (MFC). The power density of MFC with the G/Fe2O3 anode was 334 ± 4 mW/m2, which was 1.72 times and 2.59 times that of MFC with a graphene anode and an unmodified anode, respectively. Scanning electron microscopy and iron reduction rate experiment showed that G/Fe2O3 materials had good biocompatibility. Furthermore, microbial community analysis results indicated that the predominant populations on the anode biofilm belonged to Enterobacteriaceae, and the abundance of Desulfovibrio increased in the presence of the Fe2O3. Thus, the combination of graphene and Fe2O3 provided high electrical conductivity to facilitate extracellular electron transfer (EET) and improved biocompatibility to promote the exoelectrogenic bacteria formation. Therefore, G/Fe2O3 is an effective anode material for enhancing the performance of MFCs.

Mo2C-induced hydrogen production enhances microbial electrosynthesis of acetate from CO2 reduction.

BACKGROUND: Microbial electrosynthesis (MES) is a biocathode-driven process, in which electroautotrophic microorganisms can directly uptake electrons or indirectly via H2 from the cathode as energy sources and CO2 as only carbon source to produce chemicals. RESULTS: This study demonstrates that a hydrogen evolution reaction (HER) catalyst can enhance MES performance. An active HER electrocatalyst molybdenum carbide (Mo2C)-modified electrode was constructed for MES. The volumetric acetate production rate of MES with 12 mg cm-2 Mo2C was 0.19 ± 0.02 g L-1 day-1, which was 2.1 times higher than that of the control. The final acetate concentration reached 5.72 ± 0.6 g L-1 within 30 days, and coulombic efficiencies of 64 ± 0.7% were yielded. Furthermore, electrochemical study, scanning electron microscopy, and microbial community analyses suggested that Mo2C can accelerate the release of hydrogen, promote the formation of biofilms and regulate the mixed microbial flora. CONCLUSION: Coupling a HER catalyst to a cathode of MES system is a promising strategy for improving MES efficiency.

Fe3O4/granular activated carbon as an efficient three-dimensional electrode to enhance the microbial electrosynthesis of acetate from CO2.

Microbial electrosynthesis (MES) allows the transformation of CO2 into value-added products by coupling with renewable energy. The enhancement in the microbial activity and electron transfer rate via a new electrode modification method is essential for developing MES. Here, three groups of granular activated carbon decorated by Fe3O4 (Fe3O4/GAC) with mass fractions of 23%, 38% and 50% were prepared and compared with bare GAC. The volumetric acetate production rate of MES with Fe3O4/GAC-38% was the highest (0.171 g L-1 d-1), which was 1.4 times higher that of the control (bare GAC), and the final acetate concentration reached 5.14 g L-1 within 30 days. Linear sweep voltammetry and microbial community analyses suggested that Fe3O4/GAC facilitates extracellular electron transfer and improves the enrichment of electrochemically active bacteria. Fe3O4/GAC is an effective three-dimensional electrode material that enhances biofilm activity on GAC and improves MES efficiency.

Fluidized granular activated carbon electrode for efficient microbial electrosynthesis of acetate from carbon dioxide.

The electricity-driven bioreduction of carbon dioxide to multi-carbon organic compounds, particularly acetate, has been achieved in microbial electrosynthesis (MES). MES performance can be limited by the amount of cathode surface area available for biofilm formation and slow substrate mass transfer. Here, a fluidized three-dimensional electrode, containing granular activated carbon (GAC) particles, was constructed via MES. The volumetric acetate production rate increased by 2.8 times through MES with 16 g L-1 GAC (0.14 g L-1 d-1) compared with that of the control (no GAC), and the final acetate concentration reached 3.92 g L-1 within 24 days. Electrochemical, scanning electron microscopy, and microbial community analyses suggested that GAC might improve the performance of MES by accelerating direct and indirect (via H2) electron transfer because GAC could provide a high electrode surface and a favorable mass transport. This study attempted to improve the efficiency of MES and presented promising opportunities for MES scale-up.

Bio-Reduction of Graphene Oxide Using Sulfate-Reducing Bacteria and Its Implication on Anti-Biocorrosion.

In this paper, we developed an environmental friendly, cost effective, simple and green approach to reduce graphene oxide (GO) by a sulfate-reducing bacterium Desulfovibrio desulfuricans. The D. desulfuricans reduces exfoliated GO to reduced graphene oxide (rGO) at 25 °C in an aqueous solution without any toxic and environmentally harmful reducing agents. The rGO was characterized with X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Transmission Electron Microscope, X-ray Photoelectron Spectroscopy and Raman Spectroscopy. The analysis results showed that rGO had excellent properties and multi-layer graphene sheets structure. Furthermore, we demonstrated that D. desulfuricans, one of the primary bacteria responsible for the biocorrosion of various metals, might reduce GO to rGO on the surface of copper and prevented the corrosion of copper, which confirmed that electrophoretic deposition of GO on the surface of metals had great potential on the anti-biocorrosion applications.

Degradation characterization and pathway analysis of chlortetracycline and oxytetracycline in a microbial fuel cell.

The wide presence of antibiotics in the environment has raised concerns about their potential impact on ecological and human health. This study was conducted to evaluate the degradation of antibiotics (chlortetracycline (CTC) and oxytetracycline (OTC)) in microbial fuel cells (MFCs) and the change of toxicity. The degradation rates of 60 mg L-1 CTC and OTC in the MFCs were 74.2% and 78%, respectively, within 7 days. The degradation ability of the two antibiotics followed the order of OTC > CTC. Toxicity test results of the zebrafish illustrated the toxicity of OTC and CTC was largely eliminated by MFC treatment. Furthermore, possible degradation pathways of CTC and OTC were speculated using LC-MS analysis. High-throughput sequencing analysis indicated that Petrimonas, Azospirillum, Dokdonella, Burkholderia and Stenotrophomonas were the predominant genera in the MFC anode biofilm. Therefore, this work is of great significance for future studies on the treatment of antibiotics in wastewater by MFCs.

Electrophoretic deposition of carbon nanotube on reticulated vitreous carbon for hexavalent chromium removal in a biocathode microbial fuel cell.

For Cr(VI)-removal microbial fuel cell (MFC), a more efficient biocathode in MFCs is required to improve the Cr(VI) removal and electricity generation. RVC-CNT electrode was prepared through the electrophoretic deposition of carbon nanotube (CNT) on reticulated vitreous carbon (RVC). The power density of MFC with an RVC-CNT electrode increased to 132.1 ± 2.8 mW m-2, and 80.9% removal of Cr(VI) was achieved within 48 h; compared to only 44.5% removal of Cr(VI) in unmodified RVC. Cyclic voltammetry, energy-dispersive spectrometry and X-ray photoelectron spectrometry showed that the RVC-CNT electrode enhanced the electrical conductivity and the electron transfer rate; and provided more reaction sites for Cr(VI) reduction. This approach provides process simplicity and a thickness control method for fabricating three-dimensional biocathodes to improve the performance of MFCs for Cr(VI) removal.

High efficiency microbial electrosynthesis of acetate from carbon dioxide by a self-assembled electroactive biofilm.

Microbial electrosynthesis (MES) is a biocathode-driven process, producing high-value chemicals from CO2. Here, an in situ self-assembled graphene oxide (rGO)/biofilm was constructed, in MES, for high efficient acetate production. GO has been successfully reduced by electroautotrophic bacteria for the first time. An increase, of 1.5 times, in the volumetric acetate production rate, was obtained by self-assembling rGO/biofilm, as compared to the control group. In MES with rGO/biofilm, a volumetric acetate production rate of 0.17gl-1d-1 has been achieved, 77% of the electrons consumed, were recovered and the final acetate concentration reached 7.1gl-1, within 40days. A three-dimensional rGO/biofilm was constructed enabling highly efficient electron transfer rates within biofilms, and between biofilm and electrode, demonstrating that the development of 3D electroactive biofilms, with higher extracellular electron transfer rates, is an effective approach to improving MES efficiency.

Graphene/biofilm composites for enhancement of hexavalent chromium reduction and electricity production in a biocathode microbial fuel cell.

In this study, a simple method of biocathode fabrication in a Cr(VI)-reducing microbial fuel cell (MFC) is demonstrated. A self-assembling graphene was decorated onto the biocathode microbially, constructing a graphene/biofilm, in situ. The maximum power density of the MFC with a graphene biocathode is 5.7 times that of the MFC with a graphite felt biocathode. Cr(VI) reduction was also enhanced, resulting in 100% removal of Cr(VI) within 48h, at 40mg/L Cr(VI), compared with only 58.3% removal of Cr(VI) in the MFC with a graphite felt biocathode. Cyclic voltammogram analyses showed that the graphene biocathode had faster electron transfer kinetics than the graphite felt version. Energy dispersive spectrometer (EDS) and X-ray photoelectron spectra (XPS) analysis revealed a possible adsorption-reduction mechanism for Cr(VI) reduction via the graphene biocathode. This study attempts to improve the efficiency of the biocathode in the Cr(VI)-reducing MFC, and provides a useful candidate method for the treatment of Cr(VI) contaminated wastewater, under neutral conditions.

Enhancement of cellulose degradation in freshwater sediments by a sediment microbial fuel cell.

OBJECTIVE: To demonstrate that an enhanced sediment microbial fuel cell (SMFC) system can accelerate the degradation of cellulose in fresh water sediments as the accumulation of cellulose in lake sediments may aggravate the lake marsh, increase organic matter content and result in rapid deterioration of water quality and damage the ecosystem. RESULTS: After 330 days the highest cellulose removal efficiency (72.7 ± 2.1 %) was achieved in the presence of a SMFC with a carbon nanotube decorated cathode, followed by a SMFC without the cathode decoration (64.4 ± 2.8 %). The lowest cellulose removal efficiency (47.9 ± 2.1 %) was in the absence of SMFC. The sediment characterization analysis confirmed that the carbon nanotube decorated cathode enhances the electron transfer rate in the SMFC and improves the dissolved organic matter oxidation rate. CONCLUSION: This study offers a relatively simple and promising new method for cellulose degradation in sediment.

Effect of carbon nanotube modified cathode by electrophoretic deposition method on the performance of sediment microbial fuel cells.

A multi-walled, carbon nanotube (MWNT)-modified graphite felt (GF) cathode was fabricated to improve the performance of sediment microbial fuel cells (SMFC). Three types of MWNT-modified GF cathodes were prepared by different electrophoretic deposition (EPD) times. Maximum power density of SMFC with MWNT-GF*** cathode at 60 min EPD was 215 ± 9.9 mW m(-2). This was 1.6 times that of SMFC with a bare GF cathode. Cyclic voltammetry and the amount of biomass showed that biomass density and electrochemical activity increased as the electrophoretic deposition time extended. Therefore the electrode possesses the highest catalytic behavior toward O2 reduction reaction. This simple process of carbon nanotube modification of a cathode by EPD can serve as an effective technique to improve the performance of SMFC.

Simultaneous carbon and nitrogen removal using a litre-scale upflow microbial fuel cell.

A 10 L upflow microbial fuel cell (UMFC) was constructed for simultaneous carbon and nitrogen removal. During the 6-month operation, the UMFC constantly removed carbon and nitrogen, and then generated electricity with synthetic wastewater as substrate. At 5.0 mg L(-1) dissolved oxygen, 100 Ω external resistance, and pH 6.5, the maximum power density (Pmax) and nitrification rate for the UMFC was 19.5 mW m(-2) and 17.9 mg·(L d)(-1), respectively. In addition, Pmax in the UMFC with chicken manure wastewater as substrate was 16 mW m(-2), and a high chemical oxygen demand (COD) removal efficiency of 94.1% in the UMFC was achieved at 50 mM phosphate-buffered saline. Almost all ammonia in the cathode effluent was effectively degraded after biological denitrification in the UMFC cathode. The results can help to further develop pilot-scale microbial fuel cells for simultaneous carbon and nitrogen removal.

Effect of different acclimation methods on the performance of microbial fuel cells using phenol as substrate.

Single-chamber microbial fuel cells (MFCs) with air-cathode were constructed. MFCs were fed different feedstocks during their inoculation, their role on phenol degradation and MFC performance were investigated. The results showed that the MFC inoculated using glucose exhibited the highest power density (31.3 mW m(-2)) when phenol was used as the sole substrate for MFC. The corresponding biodegradation kinetic constant was obtained at 0.035 h(-1), at an initial phenol concentration of 600 mg L(-1). Moreover, the phenol degradation rates in this MFC with closed circuit were 9.8-16.5% higher than those in MFC with opened circuit. The cyclic voltammograms revealed a different electrochemical activity of the anode biofilms in the MFC, and this led to differences in performance of the MFCs with phenol as sole substrate. These results demonstrated that phenol degradation and power production are affected by current generation and type of acclimation.