Buffer Fluids Research Articles

BSA nanoclusters-based sensor for detection of dopamine in schizophrenia from biofluids

Objective To develop nontoxic and stable fluorescent emission B-Cu nanoclusters (NCs) for the specific detection of dopamine at low concentrations in cerebrospinal fluid (CSF). Significance Fluorescent gold and copper NCs conjugated with proteins, such as bovine serum albumin (BSA), offer photostability and healthcare potential. This study focused on fabricating B-Cu NCs that exhibited superior characteristics for sensitive dopamine detection. Methods The study employed various instrumental techniques including attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), spectrofluorometry, and transmission electron microscopy (TEM) to characterize the formulated B-Cu NCs. The NCs were synthesized, resulting in particle size ∼300 nm. The highest observed fluorescence was recorded at 24542.81 relative fluorescence units (RFU). Results The introduction of dopamine at concentrations of 0.1, 0.2, 0.3, and 0.4 ng/mL led to decreased fluorescence in both B-Au and B-Cu NCs due to an electron transport system. This reduction in fluorescence allowed dopamine concentration analysis in phosphate buffer and biological fluids such as blood plasma and CSF. B-Cu NCs showed potential as a biosensing system for point-of-care (POC) applications, specifically for diagnosing schizophrenia. Conclusion The study successfully synthesized stable and nontoxic B-Cu NCs with enhanced fluorescent emission properties. These NCs exhibited the capacity to detect dopamine at low concentrations in CSF. The study’s findings hold promise for future applications, particularly in the development of a B-Cu NCs-based biosensing system for convenient POC detection of schizophrenia by both patients and clinicians. The potential impact of this technology on healthcare and biomedical fields is substantial.

MODELLING OF DEEP WELL CEMENTING PROCESS

The research aims to simulate Managed Pressure Cementing (MPC) for a deepwater field, focusing on optimizing the cementing process to ensure structural integrity and wellbore stability. The study addresses the challenges associated with conventional cementing methods, providing insights into the pressure dynamics, fluid properties, and pump performance crucial for deep well cementing operations. The methodology involves conducting a simulation to model the cementing process for a deep well with a total length of 9144 meters, where the previous casing's shoe is located at a depth of 6096 meters. Real data is utilized to obtain profiles of reservoir pressure, hydraulic fracturing pressure, and viscosities of essential fluids, including cement, drilling fluid, and buffer fluid. The simulation considers factors such as annular pressure loss, Equivalent Circulating Density (ECD) calculation, and pump performance under varying conditions. Additionally, the density of the cement slurry in the annulus during pumping is established. The study reveals that pump performance under the given conditions is 57 m³/h for drilling and buffer fluids, while for cement solutions, it can vary from 19 m³/h to 38 m³/h. These results offer actionable insights for operational planning and optimization of the cementing process in deep wells. The simulation successfully models the cementing process for a deep well, providing valuable data on equivalent circulation density and cement slurry density in the annulus. The determined pump performance under different conditions is critical for understanding the dynamics of fluid circulation during cementing operations. Practical implications of the research include the optimization of cementing processes, contributing to enhanced structural integrity, reduced wellbore instability, and improved efficiency in deepwater field operations. In conclusion, the study not only contributes to theoretical understanding but also provides practical data for optimizing the cementing process in deep wells, reflecting the industry's commitment to continuous improvement in drilling technologies and ensuring the reliability and efficiency of wellbore operations in challenging environments. Keywords: managed pressure drilling (MPD), wellbore stability, downhole conditions, real-time monitoring, managed pressure cementing (MPC), zonal isolation.

Additive manufacturing a novel bioceramic bone scaffold with MgO/Ca3(PO4)2: Microstructure, mechanical property and controllable degradation behavior

Biodegradable bone grafts have gained considerable attention in the field of clinical research as they can be used to avoid re-surgery to remove scaffolds. We fabricated biodegradable composite ceramic scaffolds using magnesium oxide and calcium phosphate following the vat photopolymerization technology. We studied the effects of different magnesium oxide content on the process of in vitro degradation of the composite scaffolds and discussed the degradation process by comparing the extent of degradation realized in Tris-HCl buffer and simulated body fluids. We also explored the variations in the mechanical properties of the scaffolds during degradation. The results revealed that the composite scaffolds maintained the strength standard for spongy bone (compressive strength σ: 2–20 MPa) even after 28 d of degradation. Additionally, the strength of the composite scaffold containing 80 wt% magnesium oxide was comparable to the strength standard recommended for cortical bones (σ: 100–200 MPa). Controllable degradation rates were recorded, and acceptable mechanical properties were observed for these scaffolds during degradation. The results reported herein can be potentially used to expand the application prospects of biodegradable scaffolds.

Enhancing of spacer fluids compositions for well cementing

Currently, almost all researchers believe that turbulent flow is the most preferred displacement mode. However, when it comes to cementing, where practical limitations prevent obtaining turbulent flow, opinions begin to differ. In general, either «very slow» flow or «very fast» flow is recommended for all wells in the annulus. There are mainly two types of buffer liquids used – «wash» and «space». The first buffer liquid is «wash», which washes away and removes the remnants of drilling fluid, clay cake, etc., and the second is «space», a thicker system, entering the cavities, cleans them and also pulls out all the remnants of the first buffer liquid to the surface. The first buffer fluid is «wash», basically a thinner, of the drilling fluid, which may contain surfactants - surfactants or liquid-restraining agents, the preferred mode of motion is turbulent. The second buffer liquid – «space», can mainly contain polymeric materials, weighting agents, the preferred mode of movement is laminar (cork). The choice of these fluids is determined by their chemical compatibility with drilling and cement slurries, their effectiveness in removing the drilling fluid. Very important postulates adopted by almost all leading oil firms are given. A new and very affordable composition of the buffer liquid of the following composition has been proposed: «wash» - FLS - 4%, diesel fuel - 2%, the rest is water - 9%; «space» - carboxymethylcellulose (CMC) - 0.5%, bentonite solution with a density of 1030 kg/m3 - 99.5%. If necessary, these buffer fluids can be weighted, for example, with barite, to an average density between the densities of drilling and cement slurries in a given well.. Keywords: buffer fluid; drilling fluid; cement mortar;turbulent flow; mode of motion; mud cake; centralizer; casing string.

IMPROVING THE METHOD OF SELECTING BUFFER TO IMPROVE THE QUALITY OF WELL ANCHORING WITH THE USE HYDROCARBON-BASED DRILLING FLUID

Currently, when cementing casing strings, various formulations of buffer fluids are used, the choice of which is based on laboratory testing of its compatibility with specific drilling and grouting solutions. The development of market relations evolutionarily pushed manufacturers to obtain and use the most efficient, durable materials and technologies that meet the requirements of ISO 13500:2008 [11], ISO 10426-2:2003(R) [12].In foreign and Russian practice, leading oil and gas companies use integrated quality management systems. However, due to the influence of a number of socio-economic factors, there has been a sharp rise in the cost and reduction in the production of components, along with a continuous increase in the need for efficient materials in many industries. The use of components produced by domestic enterprises in industrial volumes makes them deficit-free, and in terms of price quite affordable and competitive raw materials [6].«RN-BashNIPIneft» LLC together with the «USPTU has developed a methodology to establish uniform requirements for the evaluation of buffer fluids for hydrocarbon-based drilling fluids when cementing casing strings. The methodological basis for achieving this goal is the concept of a systematic approach in the quality management of buffer fluids [8].

A non-faradaic impedimetric biosensor for monitoring of caspase 9 in mammalian cell culture

Lower yields and poorer quality of biopharmaceutical products result from cell death in bioreactors. Such cell death is commonly associated with programmed cell death or apoptosis. During apoptosis, caspases are activated and cause a cascade of events that eventually lead to cell destruction. We report on an impedance spectroscopy measurement technique for the detection of total caspase-9 in buffer and complex fluids, such as cell culture media. Enhanced sensitivity is achieved by leveraging the physiochemical properties of zinc oxide and copper oxide at the electrode-solution interface. Characterisation of the biosensor surface was performed using scanning electron microscopy and indirectly using an enzyme-linked immunosorbent assay. The characteristic biomolecular interactions between the target analyte and specific capture probe of the biosensor are quantified using non-faradaic electrical impedance spectroscopy (nfEIS). The proof-of-concept biosensor demonstrated a detection limit of 0.07 U/mL (0.032 µM) in buffer. The sensor requires a low sample volume of 50 μL without the need for sample dilution facilitating rapid analysis. Using a luminescence-based assay, the presence of active caspase-9 was detected in the culture media following exposure to a pro-apoptotic agent. We envision that the caspase-9 biosensor will be useful as a cell stress screening device for apoptosis monitoring.

Synthesis and characterization of citric acid crosslinked carboxymethyl tamarind gum-polyvinyl alcohol hydrogel films

The aim of present work was to synthesize and characterize carboxymethyl tamarind gum-polyvinyl alcohol (CMTG-PVA) hydrogel films using citric acid (CA) as a crosslinker. Hydrogel films were prepared by solvent casting technique. The films were evaluated for total carboxyl content (TCC), tensile strength, protein adsorption, permeability properties, hemocompatibility, swellability, moxifloxacin (MFX) loading and release, in-vivo wound healing activity and characterized using instrumental techniques. An optimal increase in amount of PVA and CA increased the TCC and tensile strength of the hydrogel films. Hydrogel films exhibited low protein adsorption and microbial permeation, good permeability to water vapour and oxygen, and sufficient hemocompatibility. The films prepared using high concentration of PVA and low concentration of CA showed good swellability in phosphate buffer and simulated wound fluids. MFX loading in the hydrogel films was found in the range of 384–440 mg/g. The hydrogel films sustained the release of MFX up to 24 h. The release followed Non-Fickian mechanism. ATR-FTIR, solid state 13C NMR and TGA analysis indicated formation of ester crosslinks. In-vivo study revealed good wound healing activity for hydrogel films. From the overall study, it can be concluded that the citric acid crosslinked CMTG-PVA hydrogel films can be effectively used for wound treatment.

Experimental dissolution of carbonaceous materials in water at 1 GPa and 550°C: Assessing the role of carbon forms and redox state on COH fluid production and composition during forearc subduction of organic matter

Biogenic carbonaceous material (CM) is the main carrier of organic carbon in the subduction zone and contributes to COH fluid production and volcanic arc gaseous emissions. Here we investigated the effect of the structural, textural and chemical heterogeneity of CM on its reactivity and redox dissolution by conducting short-lived (1 h) experiments, where synthetic analogues of CM [ordered graphite, graphite oxide (GO), mesoporous carbon (MC), Vulcan® carbon (VC) and glass-like carbon (GC)], are reacted with water at p = 1GPa and T = 550°C–conditions typical of a warm forearc subduction–and fO2 buffered from ▵FMQ ≈ +4 to −7. We show that the amount of dissolved CM (CMdissolved) and the proportion of volatile carbon species (Cvolatile) in the fluid is related both to the structure and the peculiar surficial properties of the carbon forms, such as carbon sp2-and sp3-hybridization, amount of oxygen heteroatoms, presence of oxygenated functional groups (OFGs) and of active sites. MC and graphite (C(sp2) > 94 at%, O < 1 at%, OFGs < 2.2 at %, high proportion of active sites) are relatively inert (CMdissolved < 0.4 mol%) but the former reacts more extensively at extreme redox conditions (producing CO2 + CO and CO2 + CH4 Cvolatile mixtures at ▵FMQ ≈ +4 and −7, respectively), while the latter has a maximum of Cvolatile production (CO2 + CH4) at ▵FMQ ≈ 0, which is not observed in a 10-day long run; partly-ordered GO (C(sp3) ∼ 92 at%, O ∼31 at%, OFGs ∼41 at%) is the most reactive material at all redox conditions (CMdissolved < 2.6 mol%) and produces CO2 as the dominant Cvolatile species; disordered GC, and VC (C(sp3) < 18 at%, O < 8 at%, OFGs < 30 at%) are more reactive at ▵FMQ ≈ +4 (CMdissolved ∼ 1mol%) and ▵FMQ ≈ −7 (CMdissolved < 1 mol%), where Cvolatile is dominantly CO2 and CH4, respectively. Besides the significant deviations from thermodynamically predicted graphite-saturated COH fluid composition and speciation, our results suggests that: 1) immature CM [disordered, rich in C(sp3), O, OFGs] is preferentially dissolved under high fluid fluxes and may buffer fluids to rather oxidizing conditions; 2) a descending flux of oxygen (and hydrogen) bond to CM may exist.

УДОСКОНАЛЕННЯ ВЛАСТИВОСТЕЙ СПЕЦІАЛЬНИХ СВЕРДЛОВИННИХ ТЕХНОЛОГІЧНИХ РІДИН ПРИ РОЗРОБЦІ РОДОВИЩ

Purpose. Analytical, laboratory and industrial study, as well as analysis of the basic factors of rationalization of the use of special process fluids in the processes of cleaning, casing and cementing of boreholes drilled in difficult geological and lithological conditions, through the development and implementation of innovative technical and technological techniques and methods. Methodology. The study of borehole circulation, rock cutting and regime-technological processes was carried out using modern methods of physical bench modeling, instrumentation and related materials, as well as processing the results of studies in the EXCEL, MATHCAD environment. Laboratory control methods were used to study the technological characteristics of special fluids and the patterns of operation of the drilling tool, which are working methods for determining the main characteristics of the formation processes of the wellbore at different stages of its construction. The design of the stabilized buffer mixture was carried out using the method of orthogonal central compositional planning. Findings. The physicochemical properties and influence of washing liquids of various compositions on the rocks of the sedimentary and metamorphic complexes have been studied from the standpoint of their hydration and the ability for surface adsorption interaction. The mechanism of the flow of well circulation processes with the participation of flushing fluids, as well as its consequences for the appearance of prerequisites for reducing the strength of the rock mass and reducing the loss of mechanical power in the wellbore, has been studied. The principles of constructing optimal schemes for the regeneration of a flushing liquid based on the use of sedimentation phenomena are considered. The development and clarification of downhole factors in the behavior of buffer fluids, taking into account their provision for the complete exclusion of the manifestation of violations of the integrity of the cement stone. Originality. Rationalization of indicators of the well construction process can be successfully achieved on the basis of directed regulation and adaptation of the main physical and chemical properties (density, viscosity, surface tension, content of lubricating impurities) of special process fluids for specific well geological and technical conditions. Practical value. The presented research results provide the basis for building a closed engineering cycle for designing and using special process fluids in order to reduce the time for well construction and eliminate the cost of complex repair and restoration work in them. Keywords: flushing liquid, surfactant, well, drilling, buffer system, fastening, cement stone, mine.

Effects of Transport Medium Composition on In vitro Drug Permeation Across Excised Pig Intestinal Tissue

Background:: Knowledge of the permeation characteristics of new chemical entities across biological membranes is essential to drug research and development. Transport medium composition may affect the absorption of compounds during in vitro drug transport testing. To preserve the predictive values of screening tests, the possible influence of transport media on the solubility of model drugs and on the activities of tight junctions and efflux transporter proteins (e.g., Pglycoprotein) must be known. Objective:: The aim of this study was to compare the impact of different transport media on the bidirectional transport of standard compounds, selected from the four classes of the Biopharmaceutical Classification System (BCS), across excised pig intestinal tissue. Methods:: The Sweetana-Grass diffusion apparatus was used for transport studies. Krebs-Ringer bicarbonate (KRB) buffer and simulated intestinal fluids in the fed (FeSSIF) and fasted (FaSSIF) states were used as the three transport media, while the chosen compounds were abacavir (BCS class 1), dapsone (BCS class 2), lamivudine (BCS class 3) and furosemide (BCS class 4). Results:: Abacavir exhibited lower permeability in both the simulated intestinal fluids than in the KRB buffer. Dapsone showed similar permeability in all media. Lamivudine exhibited lower permeability in FaSSIF than in the other two media. Furosemide exhibited improved transport with pronounced efflux in FaSSIF. Conclusion:: Different permeation behaviors were observed for the selected drugs in the respective media, which may have resulted from their different physico-chemical properties, as well as from the effects that dissimilar transport media components had on excised pig intestinal tissue.

Investigation of the Factors Responsible for the Poor Oral Bioavailability of Acacetin in Rats: Physicochemical and Biopharmaceutical Aspects.

Acacetin, an important ingredient of acacia honey and a component of several medicinal plants, exhibits therapeutic effects such as antioxidative, anticancer, anti-inflammatory, and anti-plasmodial activities. However, to date, studies reporting a systematic investigation of the in vivo fate of orally administered acacetin are limited. Moreover, the in vitro physicochemical and biopharmaceutical properties of acacetin in the gastrointestinal (GI) tract and their pharmacokinetic impacts remain unclear. Therefore, in this study, we aimed to systematically investigate the oral absorption and disposition of acacetin using relevant rat models. Acacetin exhibited poor solubility (≤119 ng/mL) and relatively low stability (27.5–62.0% remaining after 24 h) in pH 7 phosphate buffer and simulated GI fluids. A major portion (97.1%) of the initially injected acacetin dose remained unabsorbed in the jejunal segments, and the oral bioavailability of acacetin was very low at 2.34%. The systemic metabolism of acacetin occurred ubiquitously in various tissues (particularly in the liver, where it occurred most extensively), resulting in very high total plasma clearance of 199 ± 36 mL/min/kg. Collectively, the poor oral bioavailability of acacetin could be attributed mainly to its poor solubility and low GI luminal stability.

Subduction zone sulfur mobilization and redistribution by intraslab fluid–rock interaction

Subduction zones mediate the sulfur exchange between Earth’s interior and surface, and play a critical role in the long-term global sulfur cycle. Dehydration of the subducted slab releases aqueous fluids, which in turn interact with the surrounding wall-rocks during reactive flow through the slab. Fluids are regarded as the key agent for sulfur transfer within the slab and subsequently into the mantle wedge. However, the mechanisms underlying sulfur mobilization and redistribution during fluid–rock interaction are not fully understood. Here, we investigate three high-pressure blueschist/eclogite–selvage–vein systems from the Southwestern Tianshan metamorphic belt in northwestern China to explore sulfur behavior during fluid–rock interaction along channelized fluid pathways and within their alteration halos. Petrologic observations on mineral parageneses and δ34S compositions of sulfides reveal two different scenarios of sulfur mobilization and redistribution during fluid–rock interaction at HP conditions. Fe-rich and medium-fS2 (near the pyrite–pyrrhotite buffer) fluids favor pyrrhotite stability over pyrite and can trigger the pyrite–to–pyrrhotite transition in the reaction halo. In this case the bulk-rock sulfur budget may not vary but the sulfur isotope exchange is still effective, producing a δ34S mixing trend in the metasomatic zones. In contrast, Fe-poor and high-fS2 fluids cause conversion of pyrrhotite to pyrite, significant sulfur addition, and sulfur isotope exchange in alteration selvages. Medium-fS2 fluids can transport sulfur and thus are effective in transferring sulfur out of the slab, whereas high-fS2 fluids cause sulfur sequestration along fluid pathways and considerably reduce long-distance sulfur transfer. Multiple fluid infiltration events with different fluid sources result in several pyrite overgrowth sequences, recorded by contrasting Co–Ni element distributions and in-situ δ34S zoning of pyrite. The heaviest δ34S value (+25‰) thus far reported in HP rocks has been found in vein pyrite, suggesting that a seawater sulfate-derived δ34S signature can be transported to great depths in a subduction zone, even though the timing and mechanism of sulfate–to–sulfide reduction in the subduction zone remain unconstrained. Our study provides natural evidence for fluid-mediated sulfide transformation, sulfur transport/storage, and sulfur isotope exchange during fluid–rock interaction, and illuminates the role these processes play in sulfur release from the subducting slab and sulfur subduction into the deep mantle.

On a Novel, Simplified Model Framework Describing Ascorbic Acid Concentration Dynamics.

Ascorbic acid is an essential aminoacid which interacts in several parts of the human body metabolism. The ascorbic acid concentration is controlled by homeostasis, a biological, autonomous control function in the body. Humans are not able to produce ascorbic acid, and the ascorbic acid concentration is maintained by daily oral digestion. Ascorbic acid is buffered in various tissues, such as the adrenal glands, brain, muscles, and other. Excessive ascorbic acid is extracted from the body through urine and intestines. Measuring ascorbic acid concentration in the body is challenging, and special procedures must be followed when extracting a blood sample and performing a concentration analysis. This paper presents a novel, simplified model framework of the ascorbic acid homeostasis in the human body plasma and tissues, including tissues such as adrenal glands, brain, liver, muscles and bone marrow. These tissues also act as ascorbic acid concentration buffers, in case of low oral supply. The dynamic model framework is based on mass balances of ascorbate acid in various tissues, including tissue buffer terms involving the intestine, kidney, adrenal glands, and other critical and noncritical tissues. The interaction between buffer tissues and fluids is maintained by the body homeostasis using chemical transport protein molecules. Additional usage terms describing energy metabolism, body growth, and immune system response are also included. This dynamic model framework, including the ascorbic acid concentration control system, is simulated with assumed parameters based on available literature. The results indicates that further investigations using experiments, in addition to adaptive model parameter estimation schemes and additional model verification tests are needed in order to identify the various model framework parameters to fit the human body ascorbic acid homeostasis and pharmacokinetics.

The choice of components for buffer fluids at the completion well with drilling fluids on oil-based

The choice of components for buffer fluids at the completion well with drilling fluids on oil-based

Sensitive and specific detection of E. coli using biomimetic receptors in combination with a modified heat-transfer method

We report on a novel biomimetic sensor that allows sensitive and specific detection of Escherichia coli (E. coli) bacteria in a broad concentration range from 102 up to 106 CFU/mL in both buffer fluids and relevant food samples (i.e. apple juice). The receptors are surface-imprinted polyurethane layers deposited on stainless-steel chips. Regarding the transducer principle, the sensor measures the increase in thermal resistance between the chip and the liquid due to the presence of bacteria captured on the receptor surface. The low noise level that enables the low detection limit originates from a planar meander element that serves as both a heater and a temperature sensor. Furthermore, the experiments show that the presence of bacteria in a liquid enhances the thermal conductivity of the liquid itself. Reference tests with a set of other representative species of Enterobacteriaceae, closely related to E. coli, indicate a very low cross-sensitivity with a sensor response at or below the noise level.

Fluorescence Correlation Spectroscopy to find the critical balance between extracellular association and intracellular dissociation of mRNA complexes

Fluorescence Correlation Spectroscopy (FCS) is a promising tool to study interactions on a single molecule level. The diffusion of fluorescent molecules in and out of the excitation volume of a confocal microscope leads to the fluorescence fluctuations that give information on the average number of fluorescent molecules present in the excitation volume and their diffusion coefficients. In this context, we complexed mRNA into lipoplexes and polyplexes and explored the association/dissociation degree of complexes by using gel electrophoresis and FCS. FCS enabled us to measure the association and dissociation degree of mRNA-based complexes both in buffer and protein-rich biological fluids such as human serum and ascitic fluid, which is a clear advantage over gel electrophoresis that was only applicable in protein-free buffer solutions. Furthermore, following the complex stability in buffer and biological fluids by FCS assisted to understand how complex characteristics, such as charge ratio and strength of mRNA binding, correlated to the transfection efficiency. We found that linear polyethyleneimine prevented efficient translation of mRNA, most likely due to a too strong mRNA binding, whereas the lipid based carrier Lipofectamine® messengerMAX did succeed in efficient release and subsequent translation of mRNA in the cytoplasm of the cells. Overall, FCS is a reliable tool for the in depth characterization of mRNA complexes and can help us to find the critical balance keeping mRNA bound in complexes in the extracellular environment and efficient intracellular mRNA release leading to protein production. Statement of SignificanceThe delivery of messenger RNA (mRNA) to cells is promising to treat a variety of diseases. Therefore, the mRNA is typically packed in small lipid particles or polymer particles that help the mRNA to reach the cytoplasm of the cells. These particles should bind and carry the mRNA in the extracellular environment (e.g. blood, peritoneal fluid, …), but should release the mRNA again in the intracellular environment. In this paper, we evaluated a method (Fluorescence Correlation Spectroscopy) that allows for the in depth characterization of mRNA complexes and can help us to find the critical balance keeping mRNA bound in complexes in the extracellular environment and efficient intracellular mRNA release leading to protein production.

Surface Assay for Specific Detection of Soluble Amyloid Oligomers Utilizing Pronucleon Peptides Instead of Antibodies.

Immunoassays such as enzyme-linked immunosorbent assays (ELISAs) are widely used for diagnostics; however, antibodies as detection reagents may be insufficiently selective and have other shortcomings. We present a novel non-antibody-based detection method based on binding target molecules to peptides (used as recognition molecules): a surface assay for A-β oligomers employing a peptide comprising amino acid residues of the human β-amyloid protein (Pronucleon peptide) as the capture agent. For the sake of convenience, we term this the "Pronucleon peptide-linked immunosorbent assay", or PLISA. Pronucleon peptides are amino acid sequences matched to target amyloids of interest, in particular soluble Aβ-1-42 amyloid protein oligomers, which are widely considered as an early biomarker for Alzheimer's disease in body fluids. The Pronucleon peptide in a PLISA is immobilized on the surface and substitutes for the capture antibody used in an ELISA for binding the Aβ-1-42 oligomers present in the sample. We present data comparing synthetic oligomer PLISAs in spiked buffer and body fluids (such as cerebrospinal fluid, brain extracts, or whole blood) to those from an ELISA and demonstrate better selectivity of the PLISA for amyloid β-42 oligomers versus monomers and fibrils. The detection limit, calculated as the mean (blank) plus three standard deviations, was in the range of 0.35-1.5 pM (32-135 ng/L) (oligomers contained approximately 20 monomers on average).

Effects of geodynamic setting on the redox state of fluids released by subducted mantle lithosphere

Magnetite breakdown during subduction of serpentinised ultramafic rocks may produce oxidised fluids that oxidise the deep Earth and/or the sub-arc mantle, either via direct transport of ferric iron, or via redox reactions between ferric iron and other elements, such as sulfur. However, so far, there is no consensus on the oxidation state of fluids released during subduction of ultramafic rocks, or the factors that control this oxidation state.Subducted samples from a magma-poor rifted margin and a supra-subduction zone geodynamic setting were compared to examine evidence of changes in opaque phase assemblage and ferric iron content as a consequence of subduction, and as a function of geodynamic setting. Thermodynamic calculations in the system Fe–Ni–O–H–S and Fe–Ni–O–S at the pressures and temperatures of interest were used to constrain oxygen activities and fluid compositions.Samples from New Caledonia, which exemplify supra-subduction zone mantle, contain awaruite (FeNi3) and equilibrated with hydrogen-bearing fluids at oxygen activity less than the FMQ (fayalite–magnetite–quartz) buffer. In contrast, samples from the Zermatt Saas Zone ophiolite, Western Alps, which are thought to represent mantle from a subducted magma-poor rifted margin, contain magnetite plus sulfur-rich phases such as pyrite (FeS2), and are inferred to have equilibrated with hydrogen-poor fluids at oxygen activity greater than FMQ. This major difference is independent of differences in subduction pressure–temperature conditions, variation in peridotite protolith composition, or the nature of adjacent units. We propose that the Zermatt Saas Zone samples would have undergone more complete serpentinisation prior to subduction than the supra-subduction zone (SSZ) New Caledonian samples. This difference explains the different fluid compositions, because incompletely serpentinised rocks containing olivine and brucite retain or evolve awaruite-bearing assemblages that buffer fluid compositions to high hydrogen activity (aH2).Ultramafic rocks are associated with two distinctly different fluid compositions during pre-subduction and subduction serpentinisation. Initially, while olivine is in equilibrium with infiltrating fluid, mineral assemblages that include awaruite in the rocks buffer fluids to H2-bearing, low aO2 compositions. Deserpentinisation of incompletely serpentinised rocks in which awaruite is present also produces H2-bearing fluids. Once awaruite is exhausted, H2-poor, high aO2 fluids co-exist with awaruite-absent assemblages, and deserpentinisation of such rocks would produce H2O-rich fluids.Thus, deserpentinisation of ultramafic rocks could produce either hydrogen-bearing fluids that could infiltrate and reduce the sub-arc mantle, or more oxidised fluids, which could transfer redox budget to other geochemical reservoirs such as the sub-arc mantle. Therefore, the redox contribution of subducted ultramafic rocks to the deep Earth and sub-arc mantle depends on the extent of protolith serpentinisation. Pre-subduction settings that promote extensive serpentinisation by oxidised fluids at high fluid:rock ratios in open systems, such as slow and ultraslow spreading ridges, transform faults, oceanic core complexes, and exhumed mantle at rifted continental margins, may produce more oxidised fluids than those associated with less pervasive serpentinisation and fluids that may be rock-buffered to a reduced state.

Growth arrest and rapid capture of select pathogens following magnetic nanoparticle treatment

Thorough understanding of magnetic nanoparticle (MNP) properties is essential for developing new theranostics. In this study, we provide evidence that non-modified magnetic iron oxide nanoparticles and their functionalized derivatives may be used to restrict growth and capture different pathogens. Coprecipitation of Fe2+ and Fe3+ ions in an alkaline solution was used to synthesize MNPs that subsequently were functionalized by gold and aminosilane coating. Transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) were used to assess their physicochemical properties. A significant decrease of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans outgrown from medium after addition of MNPs or their derivatives was observed during 24h culture. Measurement of optical density revealed that using MNPs, these pathogens can be quickly captured and removed (with efficiency reaching almost 100%) from purposely infected saline buffer and body fluids such as human blood plasma, serum, abdominal fluids and cerebrospinal fluids. These effects depend on nanoparticle concentration, surface chemistry, the type of pathogen, as well as the surrounding environment.

High-throughput nanoscale lipid vesicle synthesis in a semicircular contraction-expansion array microchannel

Towards potential applications in the field of nanomedicine, a new high-throughput synthesis method of lipid vesicles with tunable size as well as enhanced monodispersity is demonstrated using a semicircular contraction-expansion array (CEA) microchannel. Lipid vesicles are generated in the CEA microchannel by injecting lipids in isopropyl alcohol as a sample flow and phosphate buffered saline as a buffer flow, leading to spontaneous formation of lipid vesicles. In the CEA microchannel, Dean vortices cause three-dimensional (3D) lamination by continuously splitting and redirecting fluid streams, resulting in enhancement of fluid mixing. When considered only 3D laminating effect, it showed the best mixing efficiency in the range of flow rates of 12–15 mL/h. However, shear force effect also gives a strong influence on the formation of lipid vesicles, leading to the smallest size and uniform size distribution of lipid vesicles at a total flow rate of 18 mL/h. Consequently, from the interplay between high shear stress and 3D laminating effect, the lipid vesicles were generated with monodispersity and high throughput. The formation of lipid vesicles can be controlled with a total flow rate and a flow rate ratio between the sample and buffer fluids. The throughput of the lipid generation in the CEA microchannel was 10 times higher than previous works. In addition, the generated lipid vesicle populations were confirmed using a cryogenic transmission electron microscopy (cryo-TEM) technique.