Enhanced efficiencies on purifying acid mine drainage in constructed wetlands based on synergistic adsorption of attapulgite-soda residue composites and microbial sulfate reduction.

Constructed wetlands (CWs) are a promising approach for treating acid mine drainage (AMD). However, the extreme acidity and high loads of heavy metals in AMD can easily lead to the collapse of CWs without proper pre-treatment. Therefore, it is considered essential to maintain efficient and stable performance for AMD treatment in CWs. In this study, pre-prepared attapulgite-soda residue (ASR) composites were used to improve the substrate of CWs. Compared with CWs filled with gravel (CWs-G), the removal efficiencies of sulfate and Fe, Mn, Cu, Zn Cd and Pb in CWs filled with ASR composites (CWs-ASR) were increased by 30% and 10-70%, respectively. These metals were mainly retained in the substrate in stable forms, such as carbonate-, Fe/Mn (oxide)hydroxide-, and sulfide-bound forms. Additionally, higher levels of photosynthetic pigments and antioxidant enzyme activities in plants, along with a richer microbial community, were observed in CWs-ASR than in CWs-G. The application of ASR composites alleviated the adverse effects of AMD stresses on wetland plants and microorganisms. In return, the increased bacteria abundance, particularly SRB genera (e.g., Thermodesulfovibrionia and Desulfobacca), promoted the formation of metal sulfides, enabling the saturated ASR adsorbed with metals to regenerate and continuously capture heavy metals. The synergistic adsorption of ASR composites and microbial sulfate reduction maintained the stable and efficient operation of CWs. This study contributes to the resource utilization of industrial alkaline by-products and promotes the breakthrough of new techniques for low-cost and passive treatment systems such as CWs.

Acid modified attapulgite loaded with bacillomycin D for mold inhibition and mycotoxin removal.

Molds and mycotoxins pose severe threats to health. Bacillomycin D (BD) can effectively inhibit mold growth. Attapulgite (ATP) can provide a good carrier for antimicrobial agents. Natural ATP was acid-modified to obtain H-ATP. It was used to load BD to obtain a novel composite material (H-ATP-BD). The results showed H-ATP had better adsorption performance than ATP. BD was adsorbed up to 93.13 % by adding 30 mg H-ATP and stirring at 40 ℃ for 120 min. Fourier transform infrared spectra (FTIR), size and zeta potential, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) results confirmed successful loading of BD onto H-ATP. The composite showed good inhibition of Aspergillus and adding 0.6 % H-ATP-BD composite was effective in removing 89.06 % of aflatoxin B1 (AFB1) at 50 °C. Model fitting indicated that AFB1 removal was a spontaneous exothermic reaction. This research will lay the foundation for the development of efficient and green antimicrobial and toxin-reducing materials.

Light-Driven Conversion of Silicon Nitride Nanopore to Nanonet for Single-Protein Trapping Analysis.

The single-molecule technique for investigation of an unlabeled protein in solution is very attractive but with great challenges. Nanopore sensing as a label-free tool can be used for collecting the structural information of individual proteins, but currently offers only limited capabilities due to the fast translocation of the target. Here, a reliable and facile method is developed to convert the silicon nitride nanopore to a stable nanonet platform for single-entity sensing by electrophoretic or electroosmotic trapping. A nanonet is fabricated based on a material reorganization process caused by electron-beam and light-irradiation treatment. Using protein molecules as a model, it is revealed that the solid-state nanonet can produce collision and trapping flipping signals of the protein, which provides more structural information than traditional nanopore sensing. More importantly, thanks to the excellent stability of the solid-state silicon nitride nanonet, it is demonstrated that the ultraviolet-light-irradiation-induced structural-change process of an individual protein can be captured. The developed nanonet supplies a robust platform for single-entity studies but is not limited to proteins.

Morphofunctional reaction of leukocytes and platelets in in vitro contact with a-C:H:SiOx -coated Ti-6Al-4V substrate.

The article deals with the plasma-assisted chemical vapor deposition of 0.3-1.4 µm thick a-C:H:SiOx films in a mixture of argon and polyphenylmethylsiloxane vapor onto the Ti-6Al-4V alloy substrate, which is often used as an implant material. The a-C:H:SiOx film structure is studied by the Fourier-transform infrared and Raman spectroscopies. The pull-off adhesion test assesses the adhesive strength of a-C:H:SiOx films, and the ball-on-disk method is employed to measure their wear rate and friction coefficient. According to these studies, a-C:H:SiOx films are highly adhesive to the Ti-6Al-4V substrate, have low (0.056) friction coefficient and wear rate (9.8 × 10-8  mm3  N-1  m-1 ) in phosphate-buffered saline at 40°C. In vitro studies show neither thrombogenicity nor cytotoxicity of the a-C:H:SiOx film for the human blood mononuclear cells (hBMNCs). The in vitro contact between the hBMNC culture and a-C:H:SiOx films 0.8-1.4 µm thick deposited onto Ti-6Al-4V substrates reduces a 24-hour secretion of pro-inflammatory cytokines and chemokines IL-8, IL-17, TNFα, RANTES, and MCP-1. This reduction is more significant when the film thickness is 1.4 µm and implies its potential anti-inflammatory effect and possible application in cardiovascular surgery. The dependence is suggested for the concentration of anti-inflammatory cytokines and chemokines and the a-C:H:SiOx film thickness, which correlates with the surface wettability and electrostatic potential. The article discusses the possible applications of the anti-inflammatory effect and low thrombogenicity of a-C:H:SiOx films in cardiovascular surgery.

Microfluidic Liquid Cell with Silicon Nitride Super-Thin Membrane for Electron Microscopy of Samples in Liquid.

Microfluidic liquid cells have been developed to visualize nanoscaled biological samples in liquid using a scanning electron microscope (SEM) through an electron-transparent membrane (ETM). However, despite the combination of the high-resolution visualization of SEM and the high experimental capability of microfluidics, the image is unclear because of the scattering of the electron beam in the ETM. Thus, this study developed a microfluidic liquid cell with a super-thin ETM of thickness 10 nm. Because the super-thin ETM is excessively fragile, the bonding of a silicon-nitride-deposited substrate and a polydimethylsiloxane microchannel before silicon anisotropic etching was proposed prevented the super-thin ETM from damage and breakage due to etching. With this protection against etchant using the microchannel, the yield of the fabricated super-thin ETM increased from 0 to 87%. Further, the scattering of the electron beam was suppressed using a microfluidic liquid cell with a super-thin ETM, resulting in high-resolution visualization. In addition, T4 bacteriophages were visualized using a super-thin ETM in vacuum. Furthermore, the cyanobacterium Synechocystis sp. PCC6803 in liquid was visualized using a super-thin ETM, and sub-microscopic structures on the surface were observed.

Silicon Nitride Nanopores Formed by Simple Chemical Etching: DNA Translocations and TEM Imaging.

We demonstrate DNA translocations through silicon nitride pores formed by simple chemical etching on glass substrates using microscopic amounts of hydrofluoric acid. DNA translocations and transmission electron microscopy (TEM) prove the fabrication of nanopores and allow their characterization. From ionic measurements on 318 chips, we report the effective pore diameters ranging from zero (pristine membranes) and sub-nm to over 100 nm, within 50 µm diameter membranes. The combination of ionic conductance, DNA current blockades, TEM imaging, and electron energy loss spectroscopy (EELS) provides comprehensive information about the pore area and number, from single to few pores, and pore structure. We also show the formation of thinned membrane regions as precursors of pores. The average pore density, about 5 × 10-4 pores/µm2, allows pore number adjustment statistically (0, 1, or more). This simple and affordable chemical method for making solid-state nanopores accelerates their adoption for DNA sensing and characterization applications.

Immobilization of EreB on Acid-Modified Palygorskite for Highly Efficient Degradation of Erythromycin.

Erythromycin is one of the most commonly used macrolide antibiotics. However, its pollution of the ecosystem is a significant risk to human health worldwide. Currently, there are no effective and environmentally friendly methods to resolve this issue. Although erythromycin esterase B (EreB) specifically degrades erythromycin, its non-recyclability and fragility limit the large-scale application of this enzyme. In this work, palygorskite was selected as a carrier for enzyme immobilization. The enzyme was attached to palygorskite via a crosslinking reaction to construct an effective erythromycin-degradation material (i.e., EreB@modified palygorskite), which was characterized using FT-IR, SEM, XRD, and Brunauer-Emmett-Teller techniques. The results suggested the successful modification of the material and the loading of the enzyme. The immobilized enzyme had a higher stability over varying temperatures (25-65 °C) and pH values (6.5-10.0) than the free enzyme, and the maximum rate of reaction (Vmax) and the turnover number (kcat) of the enzyme increased to 0.01 mM min-1 and 169 min-1, respectively, according to the enzyme-kinetics measurements. The EreB@modified palygorskite maintained about 45% of its activity after 10 cycles, and degraded erythromycin in polluted water to 20 mg L-1 within 300 min. These results indicate that EreB could serve as an effective immobilizing carrier for erythromycin degradation at the industrial scale.

Wide bandgap semiconductor nanomembranes as a long-term biointerface for flexible, implanted neuromodulator.

Electrical neuron stimulation holds promise for treating chronic neurological disorders, including spinal cord injury, epilepsy, and Parkinson's disease. The implementation of ultrathin, flexible electrodes that can offer noninvasive attachment to soft neural tissues is a breakthrough for timely, continuous, programable, and spatial stimulations. With strict flexibility requirements in neural implanted stimulations, the use of conventional thick and bulky packages is no longer applicable, posing major technical issues such as short device lifetime and long-term stability. We introduce herein a concept of long-lived flexible neural electrodes using silicon carbide (SiC) nanomembranes as a faradic interface and thermal oxide thin films as an electrical barrier layer. The SiC nanomembranes were developed using a chemical vapor deposition (CVD) process at the wafer level, and thermal oxide was grown using a high-quality wet oxidation technique. The proposed material developments are highly scalable and compatible with MEMS technologies, facilitating the mass production of long-lived implanted bioelectrodes. Our experimental results showed excellent stability of the SiC/silicon dioxide (SiO2) bioelectronic system that can potentially last for several decades with well-maintained electronic properties in biofluid environments. We demonstrated the capability of the proposed material system for peripheral nerve stimulation in an animal model, showing muscle contraction responses comparable to those of a standard non-implanted nerve stimulation device. The design concept, scalable fabrication approach, and multimodal functionalities of SiC/SiO2 flexible electronics offer an exciting possibility for fundamental neuroscience studies, as well as for neural stimulation-based therapies.

In vitro antibacterial effect of forsterite nanopowder: synthesis and characterization.

The aims of this study were the preparation, characterization, and in vitro antibacterial activity evaluation of forsterite (FS, Mg2SiO4) nanopowder obtained by two major methods, namely sol-gel (FSsg) and co-precipitation (FSpp). The main aim was to determine the influence of preparation methodologies on physical properties and in vitro antibacterial activity of obtained forsterite nanopowder. To assess the best working temperature for the preparation of FSsg and FSpp, the synthesis and thermal treatment conditions were optimized on the basis of thermal gravimetric (TG) and differential scanning calorimetric (DSC) analysis performed on the dried gel and dried co-precipitated solid, respectively. The FSsg and FSpp powders were characterized by X-ray powder diffraction (XRD), indicating a high purity for both FSsg and FSpp powders. The morphology of FSsg and FSpp nanopowders was explored by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). In vitro antibacterial activity was investigated using a targeted pathogen, namely Staphylococcus aureus (S. aureus) ATCC 6538 P as tested strain by broth dilution technique and inoculations on nutrient agar to highlight the bactericidal inhibitory effect. FSsg nanopowder has no inhibitory capacity, while FSpp produced inhibition, the effect being bactericidal at a concentration of 10 mg/mL. The superior bactericidal activity of FSpp against FSsg is due to variation in the own surface properties, such as specific surface area (SSA) and nano-regime particle size. The FSpp nanoparticles, NPs, obtained by co-precipitation method are reported for the first time as a novel bactericidal nanomaterial against S. aureus.

Anticancer and biological properties of new axially disubstituted silicon phthalocyanines.

This study reports the synthesis of three novel axially disubstituted silicon phthalocyanines (1-3-Si) and their quaternized phthalocyanines (1-3-QSi). The resulting compounds were characterized by applying spectroscopic techniques including 1H NMR, FT-IR, UV-vis, and mass spectroscopy. The biological properties of compounds 1-3-QSi, including DNA cleavage activities, DNA binding modes, and topoisomerase enzyme inhibition activities, were investigated using agarose gel electrophoresis. pBR322 plasmid DNA, CT-DNA, and AL-DNA (isolated from apricot leaf) were used for DNA studies. All the quaternized compounds exhibited acceptable DNA cleavage activities. Human topoisomerase I and E. coli topoisomerase enzymes were used for the topoisomerase I inhibition studies. All the quaternized complexes inhibited topoisomerase I activity. Moreover, these compounds were screened for cytotoxic and apoptotic effects against a human colon cancer cell line (DLD-1) by performing MTT and Annexin V assays. They exhibited toxicity and apoptotic effect on the DLD-1 cell line. The findings reveal that the compounds can be utilized for cancer therapy after further investigations.

Synthesis of ß-Silyl-α-amino Acid Derivatives by Cu-Catalyzed Regio- and Enantioselective Silylamination of α,ß-Unsaturated Esters.

A copper-catalyzed silylamination of α,ß-unsaturated esters with silylboranes and hydroxylamines has been developed to afford the corresponding ß-silyl-α-amino acid derivatives, which are of great interest in medicinal and pharmaceutical chemistry. Additionally, by using a suitable chiral bisphosphine ligand, the asymmetric induction is possible, delivering the optically active ß-silyl-α-amino acids with synthetically acceptable diastereomeric ratios (55:45-82:18 dr) and high enantiomeric ratios (81:19-99:1 er).

Resonator nanophotonic standing-wave array trap for single-molecule manipulation and measurement.

Nanophotonic tweezers represent emerging platforms with significant potential for parallel manipulation and measurements of single biological molecules on-chip. However, trapping force generation represents a substantial obstacle for their broader utility. Here, we present a resonator nanophotonic standing-wave array trap (resonator-nSWAT) that demonstrates significant force enhancement. This platform integrates a critically-coupled resonator design to the nSWAT and incorporates a novel trap reset scheme. The nSWAT can now perform standard single-molecule experiments, including stretching DNA molecules to measure their force-extension relations, unzipping DNA molecules, and disrupting and mapping protein-DNA interactions. These experiments have realized trapping forces on the order of 20 pN while demonstrating base-pair resolution with measurements performed on multiple molecules in parallel. Thus, the resonator-nSWAT platform now meets the benchmarks of a table-top precision optical trapping instrument in terms of force generation and resolution. This represents the first demonstration of a nanophotonic platform for such single-molecule experiments.

Development of Chiral Ligands for the Transition-Metal-Catalyzed Enantioselective Silylation and Borylation of C-H Bonds.

Enantioselective reactions that install functional groups at the positions of unactivated C-H bonds can be envisioned to produce intermediates for the synthesis of the active ingredients in pharmaceuticals and agrochemicals directly from simple feedstocks. Among these C-H bond functionalization reactions, those that form carbon-silicon (C-Si) and carbon-boron (C-B) bonds have been pursued because the products of these reactions can be converted to those containing a wide range of functional groups and because compounds containing silicon and boron possess unique properties that can be valuable for medicinal and materials chemistry. Although the silylation and borylation of C-H bonds have undergone extensive development during the past two decades, enantioselective versions of these reactions were not known until a few years ago. In this Minireview, we present the rapid development of enantioselective silylation and borylation of C-H bonds, with an emphasis on the design and development of the types of chiral ligands needed to achieve these reactions and an intention to inspire an expansion of these types of transformations.

Fabrication and nanophotonic waveguide integration of silicon carbide colour centres with preserved spin-optical coherence.

Optically addressable spin defects in silicon carbide (SiC) are an emerging platform for quantum information processing compatible with nanofabrication processes and device control used by the semiconductor industry. System scalability towards large-scale quantum networks demands integration into nanophotonic structures with efficient spin-photon interfaces. However, degradation of the spin-optical coherence after integration in nanophotonic structures has hindered the potential of most colour centre platforms. Here, we demonstrate the implantation of silicon vacancy centres (VSi) in SiC without deterioration of their intrinsic spin-optical properties. In particular, we show nearly lifetime-limited photon emission and high spin-coherence times for single defects implanted in bulk as well as in nanophotonic waveguides created by reactive ion etching. Furthermore, we take advantage of the high spin-optical coherences of VSi centres in waveguides to demonstrate controlled operations on nearby nuclear spin qubits, which is a crucial step towards fault-tolerant quantum information distribution based on cavity quantum electrodynamics.

Tailoring Silicon Nitride Surface Chemistry for Facilitating Odontogenic Differentiation of Rat Dental Pulp Cells.

Silicon nitride (Si3N4) can facilitate bone formation; hence, it is used as a biomaterial in orthopedics. Nevertheless, its usability for dentistry is unexplored. The aim of the present study was to investigate the effect of Si3N4 granules for the proliferation and odontogenic differentiation of rat dental pulp cells (rDPCs). Four different types of Si3N4 granules were prepared, which underwent different treatments to form pristine as-synthesized Si3N4, chemically treated Si3N4, thermally treated Si3N4, and Si3N4 sintered with 3 wt.% yttrium oxide (Y2O3). rDPCs were cultured on or around the Si3N4 granular beds. Compared with the other three types of Si3N4 granules, the sintered Si3N4 granules significantly promoted cellular attachment, upregulated the expression of odontogenic marker genes (Dentin Matrix Acidic Phosphoprotein 1 and Dentin Sialophosphoprotein) in the early phase, and enhanced the formation of mineralization nodules. Furthermore, the water contact angle of sintered Si3N4 was also greatly increased to 40°. These results suggest that the sintering process for Si3N4 with Y2O3 positively altered the surface properties of pristine as-synthesized Si3N4 granules, thereby facilitating the odontogenic differentiation of rDPCs. Thus, the introduction of a sintering treatment for Si3N4 granules is likely to facilitate their use in the clinical application of dentistry.

Reactive Sputtered Silicon Nitride as an Alternative Passivation Layer for Microelectrode Arrays in Sensitive Bioimpedimetric Cell Monitoring.

Microelectrode arrays (MEAs) are widely used to study the behavior of cells noninvasively and in real time. While the design of MEAs focuses mainly on the electrode material or its application-dependent modification, the passivation layer, which is crucial to define the electrode area and to insulate the conducting paths, remains largely unnoticed. Because often most cells are in direct contact with the passivation layer rather than the electrode material, biocompatible photoresists such as SU-8 are almost exclusively used. However, SU-8 is not without limitations in terms of optical transmission, optimal cell support, or compatibility within polymer-based microfluidic lab on chip systems. Here, we established a silicon nitride (SiN) passivation by physical vapor deposition (PVD), which was optimized and evaluated for impedance spectroscopy-based monitoring of cells. Surface characteristics, biocompatibility, and electrical insulation capability were investigated and compared to SU8 in detail. To investigate the influence of the SiN passivation on the impedimetric analysis of cells, HEK-293 A and MCF-7 were chosen as adherent cell models and measured on microelectrodes of 50-200 µm in diameter. The results clearly revealed an overall suitability of SiN as alternative passivation. While for the smallest electrode size a cell line dependent comparable or slightly decreased cell signal could be observed in comparison with SU-8, a significant higher cell signal was observed for microelectrodes larger than 50 µm in diameter. Furthermore, a high suitability for the bonding of PEGDA and PDMS microfluidic structures on the SiN passivation layer without any leakage could be demonstrated.

Low-energy Ar+ and N+ ion beam induced chemical vapor deposition using hexamethyldisilazane for the formation of nitrogen containing SiC and carbon containing SiN films.

We proposed an experimental methodology for producing films on substrates with an ion beam induced chemical vapor deposition (IBICVD) method using hexamethyldisilazane (HMDS) as a source material. In this study, both HMDS and ion beam were simultaneously injected onto a Si substrate. We selected Ar+ and N+ as the ion beam. The energy of the ion beam was 101 eV. Temperature of the Si substrate was set at 540 °C. After the experiments, films were found to be deposited on the substrates. The films were then analyzed by Fourier transform infrared (FTIR) spectroscopy, stylus profilometer, X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy (XPS). The FTIR and XPS results showed that silicon carbide films containing small amount of nitrogen were formed when Ar+ ions were injected in conjunction with HMDS. On the other hand, in the cases of N+ ion beam irradiation, silicon nitride films involving small amount of carbon were formed. It was noted that no film deposition was observed when HMDS alone was supplied to the substrates without any ion beam injections.

Silicon-nitride microring resonators for nonlinear optical and biosensing applications.

We discuss the design, fabrication, and characterization of silicon-nitride microring resonators for nonlinear-photonic and biosensing device applications. The first part presents new theoretical and experimental results that overcome highly normal dispersion of silicon-nitride microresonators by adding a dispersive coupler. The latter parts review our work on highly efficient second-order nonlinear interaction in a hybrid silicon-nitride slot waveguide with nonlinear polymer cladding and silicon-nitride microring application as a biosensor for human stress indicator neuropeptide Y at the nanomolar level.

Multifunctional Ca-Zn-Si-based micro-nano spheres with anti-infective, anti-inflammatory, and dentin regenerative properties for pulp capping application.

While pulp capping using a variety of materials has been applied clinically to preserve the health and vitality of the dental pulp and induce dentin repair no material meets all the anti-infection, anti-inflammation, and promoting pulp tissue regeneration criteria. Micro-nano materials of bioactive glasses (BG) with the biocompatibility and osteogenesis-promoting properties were developed for this study using Zn-doped bioactive glass (BGz) micro-nano spheres for dental pulp capping to control infection and inflammation and promote tissue regeneration. Of three key findings, the co-culture of Porphyromonas gingivalis showed that the BGz had an excellent antibacterial effect, and after being stimulated with BGz in vitro, macrophages showed a significant decrease of pro-inflammatory M1 markers compared with the undoped BG group. It is also noted that the conditioned medium derived from BGz-stimulated macrophages could significantly promote mineralized dentin formation of dental pulp cells (DPCs). In rats, acute pulp restoration experiments proved that BGz used as a pulp capping agent had excellent dentin regenerative properties. This work may provide a novel strategy to promote osteo/dentinogenic differentiation through regulating early inflammation, with potential applications in pulp capping.

Effect of pectin and attapulgite filler on swelling, network parameters and controlled release of diltiazem hydrochloride from polyacrylic copolymer gel.

Pectin grafted polyacrylic copolymer hydrogels were made by free radical crosslink copolymerization of acrylic acid (AA) and acrylamide (AM) in an aqueous solution of pectin. N'N-methylene bis acrylamide (MBA) was used as a crosslinker. During the polymerization reaction the attapulgite (APG) filler was also incorporated in situ into the network of the copolymer gel. Several filled hydrogels were prepared by varying the amount of pectin and APG filler. These hydrogels were characterized by FTIR, 13C NMR, XRD, TGA, SEM, mechanical properties, DMA, swelling, diffusion characteristics and network parameters. The release kinetics of a model drug diltiazem hydrochloride (DT) was studied with these hydrogels. The wt% of pectin, APG and MBA was optimized with a central composite design (CCD) model of response surface methodology (RSM) with equilibrium swelling ratio (ESR), drug adsorption (mg/100 mg gel) and drug release% in 16 h as response. Accordingly, the hydrogel prepared with 5:1 AA:AM molar ratio, 25 wt% monomer concentration, 1% each of initiator and MBA concentration, 18 wt% pectin and 2 wt% APG showed an optimized ESR of 17.75, drug loading of 27.58 and a drug release % of 92.5 in 16 h at a solution pH of 7.4.