Alkaline Buffer Research Articles

Zoogenic mechanisms of ecological rehabilitation of urban soils of the park zone of megapolis: Earthworms and Soil Buffer Capacity

Earthworms (Oligochaeta: Lumbricidae) are typical representatives of the funcitional group of ecosystem engineers. They actively participate in formation and stabilization of soil fertility through their effect on its buffer capacity. Buffer capacity defines in many aspects soil potential, supports immobilization and mobilization of certain elements of fertility – first of all mineral elements essential for plants, productive moisture, heat energy of soil, gas composition of soil air. Park soils within megapolises territory are their integral components and this defines conditions of growth and development for green plants. To evaluate the contribution of the earthworms’ coprolites into acidic-base (pH) buffer capacity of two categories of soil within the city – urban soils and urban grounds (urbanozems) of the park zones within the plots planted with Norway maple (Acer platanoides L.) trees on the territory of two parks – “Zeleny gai” and Pisarzhevsky Park (city Dnipro, Ukraine), soil and coprolites samples were collected. Buffer capacity of coprolites and anthropogenically transformed soils (urban soils) was evaluated according to Arrhenius method after “buffer area”. It was established that acid-base buffer capacity of coprolites (earthworms’ excretes), which are new formations of zoogenic origin in soil statistically significantly higher than for initial types soil within city parks. For urban soil with upper humified layer of calcic chernozem within the acidic diapason of external load it was 22.9% higher, which, in average, accordingly was 22.9 and 18.7 convectional units, within alkaline – 18.4% higher and was, accordingly, 24.2 and 20,4 convectional units, in sum (acidic-alkaline) – 20.6% higher and was 47.1 and 39.1 convectional units. For urban ground (urbanozem) with within the acidic diapason of external load it was 44.9% higher and acidic–alkaline buffering capacity, in average, accordingly, was 25.5 and 17.6 convectional units, in sum (acidic-alkaline) – 20.6% higher and was 42.8 and 35.4 convectional units accordingly. Thus, soil saprophagues, such as earthworms, in the conditions of magapolises in the recreation zones within the territories of city parks’ green plantations is one of the natural factors of ecological rehabilitation of urban soils. This, in general, improves ecological state of green plantations on the urban soils within park areas and recreation zone edaphotopes revitalization and support optimization of human living and recreation environment. DOI: http://dx.doi.org/10.5755/j01.erem.75.1.21121

Isolation of IgG Associated with Human Placenta.

We optimized the method of isolation of antibodies from placental tissue of a conventionally healthy patient. Four protocols of antibody isolation were evaluated and a protocol with tissue grinding (without homogenization) and successive elution of the antibodies with acidic and alkaline buffers was recommended for use. The repertoire of the isolated antibodies was characterized using a glycan array. Partial coincidence of the specificity of the isolated antibodies with antibodies in the peripheral blood was demonstrated, which indicates their possible association with carbohydrate antigens in the placenta. Identification of potential molecular targets of resident antibodies in the placenta is necessary for understanding the mechanisms of formation of immunological tolerance to the fetus.

Cloning, Expression, and Characterization of a Novel Thermostable and Alkaline-stable Esterase from Stenotrophomonas maltophilia OUC_Est10 Catalytically Active in Organic Solvents

A thermostable and alkaline-stable novel esterase (Est7) was identified through the whole genome sequencing of Stenotrophomonas maltophilia OUC_Est10. The open reading frame of this gene encoded 617 amino acid residues. After heterologous expression in Escherichia coli BL21 (DE3), the purified Est7 was separated as a single protein and presented a molecular mass of 70.6 kDa. Multiple sequence alignment indicated that Est7 had a typical catalytic triad (Ser-Asp-His) and the conserved sequence (GDSL) typical of the family II lipid hydrolase proteins. Est7 showed good stability in alkaline buffers, especially in Tris-HCl buffer at pH 9.0 (residual activity 93.8% after 96 h at 4 °C) and in the medium temperature conditions (residual activity 70.2% after 96 h at 45 °C and pH 8.0). The enzyme also retained higher stability toward several hydrophilic and hydrophobic organic solvents (e.g., after incubation in 100% acetonitrile or in n-hexane the enzyme retained about 97% and 84% of the activity in the absence of organic solvent, respectively). Furthermore, Est7 could catalyze the transesterification reaction of vinylacetate with 2-phenylethanol and cis-3-hexen-1-ol to their corresponding acetate esters in petroleum ether or tert-butyl methyl ether. These results indicate Est7 as a promising biocatalyst for applications of Est7 in non-aqueous media.

Drivers of pH Variability in Coastal Ecosystems.

A synthesis of long-term changes in pH of coastal ecosystems shows that, in contrast to the uniform trends of open-ocean acidification (-0.0004 to -0.0026 pH units yr-1) driven by increased atmospheric CO2, coastal ecosystems display a much broader range of trends (-0.023 to 0.023 pH units yr-1) and are as likely to show long-term increase as decline in pH. The majority of the 83 investigated coastal ecosystems displayed nonlinear trends, with seasonal and interannual variations exceeding 1 pH unit for some sites. The high pH variability of coastal ecosystems is primarily driven by inputs from land. These include freshwater inputs that typically dilute the alkalinity of seawater thereby resulting in reduced buffering, nutrients enhancing productivity and pH, as well as organic matter supporting excess respiration driving acidification. For some coastal ecosystems, upwelling of nutrient-rich and corrosive water may also contribute to variability in pH. Metabolic control of pH was the main factor governing variability for the majority of coastal sites, displaying larger variations in coastal ecosystems with low alkalinity buffering. pH variability was particularly pronounced in coastal ecosystems with strong decoupling of production and respiration processes, seasonally or through stratification. Our analysis demonstrate that coastal pH can be managed by controlling inputs of nutrients, organic matter, and alkalinity. In well-mixed coastal waters, increasing productivity can improve resistance to ocean acidification, whereas increasing productivity enhances acidification in bottom waters of stratified coastal ecosystems. Environmental management should consider the balance between the negative consequences of eutrophication versus those of acidification, to maintain biodiversity and ecosystem services of our coastal ecosystems.

Capillary electrophoresis-mass spectrometry using robust poly(ether ether ketone) capillary for tolerance to high content of organic solvents

Nonaqueous capillary electrophoresis (CE) and organic-aqueous CE using high content of organic solvents are common techniques in capillary electrophoresis-mass spectrometry (CE-MS) due to various advantages. However, the long-term stability of commonly used polyimide coated fused silica capillary remains a major problem that polyimide coating is prone to swelling in organic solvents and aminolysis in alkaline buffer, which cause serious problems like irregular electrospray, current drop or clogging event. In this work, robust PEEK capillary was used as separation capillary for tolerance to high content of organic solvents in CE-MS system. It is interesting that the high mechanical and chemical stability of PEEK capillary ensured stable CE separation and electrospray when used in CE-MS. All quantitative experiments were accomplished by single PEEK capillary. In addition, the using of organic solvents as running buffer reduced adsorption of hydrophobic compounds on PEEK capillary wall and improved the symmetry of peak shape. The PEEK-based CE-MS method showed good separation performance in analysis of several groups of active alkaloids in traditional Chinese medicines and was applied for quantitative analysis of peimine and peiminine in Bulbus Fritillariae thunbergii herb with high sensitivity. Based on the advantages like simple pretreatment, easy to cut, stable and good separation performance of PEEK column in CE-MS, this study provides an effective way for improving the stability and employment of high content of organic solvents in CE-MS analysis.

Quantifying Cigarette Smoke Induced Oxidative DNA Damage of Wild Type & XPC Knockdown Human Bronchial Cells Using Human 8-oxoguanine DNA Glycosylase 1

Background and Hypothesis: 
 Chronic exposure to cigarette smoke (CS) induces DNA lesions and oxidative damage leading to the development of lung diseases such as emphysema and lung cancer. Xeroderma Pigmentosum group C (XPC) is a protein which repairs CS bulky DNA lesions and oxidative DNA damage, including 8-OHdG. We hypothesize that in vitro CS exposure will result in increased 8-OhdG and that XPC knockdown (KD) leads to higher levels of 8-OHdG. 
 Experimental Methods: 
 Briefly, immortalized normal human bronchial epithelial cells (Beas2B), were cultured and subsequently exposed to CS extract to induce DNA damage. Cells in agarose were then gently lysed, immersed in an alkaline buffer, incubated with hOGG1 enzyme, and analyzed for DNA damage using single cell electrophoresis (Comet Assay). Slides were stained and viewed by fluorescence microscopy. DNA damage is expressed as tail moment, measured by CometScore. Statistical analysis was performed using 2-way ANOVA (SigmaStat) with p-value < 0.05 indicating statistical significance. 
 Results and Conclusion: 
 Both XPC KD and wild-type (WT) Beas2B cells treated with 2.5% CS measured higher levels of DNA damage than air control. The addition of hOGG1 lead to an increase in the tail moment in both AC and CS-exposed cells, indicating an increase in the oxidative DNA lesion, 8-OHdG. Finally, XPC KD exposed to 2.5% CS demonstrated an increase in DNA damage and in 8-OHdG compared to WT (p<0.001). In conclusion, these results further support that CS leads to increased oxidative DNA damage and suggests a role for XPC in regulation and repair of the oxidative DNA lesion, 8-OHdG.

Downstream processing of Cry4AaCter-induced inclusion bodies containing insect-derived antimicrobial peptides produced in Escherichia coli

The Cry4AaCter tag is a pull-down tag which promotes the formation of inclusion bodies (IBs) that can be resolubilized in an alkaline buffer. Here, we used the Cry4AaCter tag to create a platform for the production of antimicrobial peptides (AMPs) in Escherichia coli featuring a uniform resolubilization process independent of the peptide fused to the pull-down tag. The Cry4AaCter tag conserves the bioactivity of fusion proteins and thus allows the purification of simple AMPs and more complex AMPs stabilized by disulfide bonds. We developed a downstream process (DSP) for the purification of IBs containing the mutated Galleria mellonella insect metalloprotease inhibitor IMPI(I38V), which has a globular structure stabilized by five disulfide bonds. IMPI(I38V) is a potent inhibitor of the M4 metalloproteases used as virulence factors by several human pathogens. We used a single crossflow filtration for the washing and resolubilization of the Cry4AaCter-induced IBs and obtained bioactive IMPI(I38V) after tag removal. We achieved a 68-fold higher protein yield using our IB system compared to an alternative DSP approach in which a GST-fusion strategy was used to produce soluble IMPI(I38V). The Cry4AaCter-based process was transferable to gloverin (another G. mellonella AMP) and the visible marker green fluorescent protein, which accumulated in fluorescent IBs, confirming it is a broadly applicable strategy for the recovery of functional proteins.

Penetration model for chemical reactivation for resin-embedded green fluorescent protein imaging.

.In the so-called surface microscopy, serial block-face imaging is combined with mechanic sectioning to obtain volumetric imaging. While mapping a resin-embedded green fluorescent protein (GFP)-labeled specimen, it has been recently reported that an alkaline buffer is used to chemically reactivate the protonated GFP molecules, and thus improve the signal-to-noise ratio. In such a procedure, the image quality is highly affected by the penetration rate of a solution. We propose a reliable penetration model to describe the penetration process of the solution into the resin. The experimental results are consistent with the parameters predicted using this model. Thus, this model provides a valuable theoretical explanation and aids in optimizing the system parameters for mapping resin-embedded GFP biological samples.

Dopamine hydrochloride and carboxymethyl chitosan coatings for multifilament surgical suture and their influence on friction during sliding contact with skin substitute

In order to reduce the damage to tissue and fill the interstices between fibers, multifilament sutures are frequently treated with certain coating materials. The objective of this study was to create and characterize dopamine hydrochloride (DA) and carboxymethyl chitosan (CMCS) coatings on surgical sutures and investigate their effects on the frictional performance of the surgical sutures during sliding through a skin substitute. The effects of the treatment on the physical and chemical characteristics of the surgical sutures were evaluated. The friction force of the surgical sutures during sliding through the skin substitute was experimentally determined using a penetration friction apparatus. The coefficient of friction (COF) was calculated using a linear elastic model and was used to estimate the frictional behavior of the surgical suture-skin interactions.The results showed that the DA coating could evenly deposit on the surface of the etched multifilament surgical suture surfaces in a weakly alkaline buffer solution. The CMCS coating material could form a uniform film on the surface of the sutures. Minor changes in the surface roughness of the multifilament surgical sutures with different treatments occurred in this study. The friction force and the COF of the multifilament surgical sutures with DA and CMCS coating showed little change when compared with untreated multifilament surgical sutures.

Treatment with carbonate buffer decreases antigenicity of nervous necrosis virus (NNV)

Antigens are commonly immobilized after suspending them in an alkaline buffer such as carbonate buffer (pH 9.6) for enzyme-linked immunosorbent assay (ELISA). The objective of this study was to determine the effect of 100 mM carbonate buffer (pH 9.6) on antigenicity of nervous necrosis virus (NNV) known to be pathogenic to fish. ELISA values of NNV antigens immobilized using carbonate buffer (pH 9.6) were ≤ 0.23, significantly lower than those by dry immobilization (ELISA values of approximately 1.0). NNV antigenicity was drastically decreased by treatment with carbonate buffer (pH 9.6), but not by treatment with Tris-HCl buffers at pH 8.0 or pH 9.6. Thus, the decrease of NNV antigenicity was due to carbonate/bicarbonate, not pH. NNV infectivity was also decreased after treatment with carbonate buffer (pH 9.6). The anti-NNV serum could recognize conformational structures of NNV surface protrusions related to NNV infection. Therefore, NNV surface protrusions might have been denatured by treatment with carbonate buffer (pH 9.6). Results of this study also demonstrate that coating NNV antigens by buffer immobilization might be far from practical. However, the sensitivity of ELISA detecting NNV antigens can be greatly improved by dry immobilization of antigens.

Temperature/pH dual-responsive poly (N-isopropylacrylamide)/chitosan-coated luminescent composite nanospheres: Fabrication and controllable luminescence

Thermo/pH dual-responsive luminescent composites consisting of lanthanide-polyoxometalates and Poly (N-isopropylacrylamide)/Chitosan were synthesized. The dual-responsive nanoparticles are characterized by the FT-IR, UV–vis, TEM, SEM, TGA, DLS and luminescence. The prepared composites exhibit the thermo/pH-responsive properties and the controllable and switchable luminescence in solution in response to the simple changes in temperature and pH values. For instance, the composite hydrogels exhibit intense red luminescence under UV irradiation below 34 °C, and the luminescence become much weaker in solution above 34 °C. Moreover, the hydrogel could not show red luminescence in the buffer solution with low pH value. However, it shows bright red luminescence in neutral and alkaline buffer solution. The possible reasons for controllable luminescence are discussed in the research. The results suggest that the multifunctional nanoparticles could be potentially used in biomedical fields such as luminescent switches, biological labeling and imaging.

Electrochemical Biosensor for the Determination of Amlodipine Besylate Based on Gelatin–Polyaniline Iron Oxide Biocomposite Film

In the present study, a new biosensor based on lipase from Candida rugosa (CRL) was developed for amlodipine besylate drug (AMD) with biodegradable material using a mixture of polyaniline iron oxide and gelatin. Polyaniline/Fe2O3 (PANI@Fe2O3) was prepared by a chemical polymerization method in a medium of ammonium persulfate as an oxidant and characterized by employing Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), and Ultra-violet (UV) spectroscopy. The purified enzyme was entrapped in the biocomposite matrix film with the aid of a glutaraldehyde cross-linking reagent to establish the immobilization of the lipase. The principle of the biosensor is based on the electrochemical properties of amlodipine besylate (AMD), which were studied for the first time using the cyclic voltammetric method. The cathodic behavior of AMD was measured on the irreversible reduction signal at −0.185 V versus Ag/AgCl at pH 7.4 and 30 °C in a phosphate alkaline buffer.

Alkaline Phosphatase Assay Based on the Chromogenic Interaction of Diethanolamine with 4-Aminophenol.

Diethanolamine (DEA) has been extensively utilized as an alkaline buffer in current assays of alkaline phosphatase (ALP) activity in the past decades. While playing the role of a buffer, the chemical reactivity of DEA has been widely ignored in such assays. Herein, we report an interesting chromogenic interaction between DEA and 4-aminophenol (AP) in the presence of H2O for the first time, which inspires us to develop a novel DEA-participated ALP activity assay by using 4-aminophenyl phosphate (APP) as a substrate. This APP/DEA-based colorimetric approach has been proved to be comparable and even superior to the conventional p-nitrophenyl phosphate (pNPP)-based one, especially in the low ALP activity region, due to its higher sensitivity. The clear response mechanism and excellent sensing performance ensure that it can be further applied to determining ALP activity in real biological samples, screening potential ALP inhibitors in vitro, establishing ALP-enabled ELISA, and even fluorophore-assisted fluorescent ALP activity assay. It is demonstrated that this strategy not only possesses a good feasibility, but also exhibits a promising outlook for a series of ALP-related and -extended detections.

Application of Mg(OH)2 Nanosheets for Conservation and Restoration of Precious Documents and Cultural Archives

Magnesium hydroxide (Mg(OH)2) nanosheets were explored as an effective material for the restoration and conservation of paper-based cultural archives and compared with the commonly used Ca(OH)2 nanoparticles. The (Mg(OH)2) nanosheets were applied to filter paper as a reference, as well as to new and old paper samples. The effectiveness of Mg(OH)2 nanosheets was evaluated by (i) a pH test of the surface and the bulk extracts, (ii) measuring the alkaline reserve and correlating it with the enhancement in life expectancy, and (iii) in terms of mechanical strength. The alkaline reserve test indicated an increase in the alkaline buffer, which resulted in markedly reduced acidic content of the samples. It was inferred from the improved properties that Mg(OH)2 nanosheets coated the paper as a lamination sheet and protected it as the first line of defense against acidic environmental attack. Moreover, its presence within the paper acted as an alkaline reserve and also as reinforcement in the form of an inorganic nanosheet. The results suggest that the nanosheets are an innovative, compatible, and efficient material for the consolidation and restoration of old and new paper samples.

Biomimetic Synthesis of Polydopamine Coated ZnFe2O4 Composites as Anode Materials for Lithium-Ion Batteries.

Metal oxides as anode materials for lithium storage suffer from poor cycling stability due to their conversion mechanisms. Here, we report an efficient biomimetic method to fabricate a conformal coating of conductive polymer on ZnFe2O4 nanoparticles, which shows outstanding electrochemical performance as anode material for lithium storage. Polydopamine (PDA) film, a bionic ionic permeable film, was successfully coated on the surfaces of ZnFe2O4 particles by the self-polymerization of dopamine in the presence of an alkaline buffer solution. The thickness of PDA coating layer was tunable by controlling the reaction time, and the obtained ZnFe2O4/PDA sample with 8 nm coating layer exhibited an outstanding electrochemical performance in terms of cycling stability and rate capability. ZnFe2O4/PDA composites delivered an initial discharge capacity of 2079 mAh g–1 at 1 A g–1 and showed a minimum capacity decay after 150 cycles. Importantly, the coating layer improved the rate capability of composites compared to that of its counterpart, the bare ZnFe2O4 particle materials. The outstanding electrochemical performance was because of the buffering and protective effects of the PDA coating layer, which could be a general protection strategy for electrode materials in lithium-ion batteries.

Identification of a Novel Esterase from Marine Environmental Genomic DNA Libraries and Its Application in Production of Free All- trans-Astaxanthin.

Astaxanthin is a pigment with various functions. Free astaxanthin is obtained mainly through saponification methods, which could result in many byproducts. Enzymatic methods using lipases have been used in a few cases, while there are no reports on the use of esterases for the production of free astaxanthin. Herein we present the screening and identification of a novel esterase (Est3-14) from a marine mud metagenomic library. Est3-14 is pH-sensitive and keeps good stability in alkaline buffers (residual activity 94%, pH 8.0, 4 °C, and 36 h). Meanwhile, Est3-14 keeps a good stability in the medium temperature condition (residual activity 56.7%, pH 8.0, 40 °C, and 84 h). Est3-14 displayed high hydrolysis activity to prepare free all- trans-astaxanthin in biphasic systems. Furthermore, under optimal conditions (0.5 mL ethanol, 6 mL 0.1 M Tris-HCl buffer, pH 8.0, 0.5% (w/v) H. pluvialis oil, 40 °C), the hydrolytic conversion ratio was 99.3% after 36 h.

Chemical reactivation of fluorescein isothiocyanate immunofluorescence-labeled resin-embedded samples.

Resin embedding is widely used and facilitates microscopic imaging of biological tissues. In contrast, quenching of fluorescence during embedding process hinders the application of resin embedding for imaging of fluorescence-labeled samples. For samples expressing fluorescent proteins, it has been demonstrated that the weakened fluorescence could be recovered by reactivating the fluorophore with alkaline buffer. We extended this idea to immunofluorescence-labeling technology. We showed that the fluorescence of pH-sensitive fluorescein isothiocyanate (FITC) was quenched after resin embedding but reactivated after treating by alkaline buffer. We observed 138.5% fluorescence preservation ratio of reactivated state, sixfold compared with the quenched state in embedding resin, which indicated its application for fluorescence imaging of high signal-to-background ratio. Furthermore, we analyzed the chemical reactivation mechanism of FITC fluorophore. This work would show a way for high-resolution imaging of immunofluorescence-labeled samples embedded in resin.

Influence of Alkaline Additives and Buffers on Mineral Trapping of CO2 under Mild Conditions

AbstractCarbon dioxide (CO2) gas is the main contributor to climate change. CO2 storage in underground brines and oil‐field brines by mineral trapping has been considered as a promising alternative in order to reduce CO2 emissions. However, permanent storage of CO2 in stable carbonate minerals is greatly dependent on brine pH, being favored over an alkaline pH. The effect of alkaline additives (NaOH, KOH, CaO) and buffer solutions (NaHCO3/NaOH, Na2HPO4/NaOH, NH4Cl/NH4OH) on the mineral trapping of CO2 under mild conditions using a synthetic brine is investigated. The results indicate that both NaOH+NH4Cl/NH4OH and KOH+NH4Cl/NH4OH mixtures promote precipitation mainly of calcium carbonate (CaCO3).

DNA Diffusion Assay Applied to Plant Cells.

DNA diffusion assay is a simple, sensitive and reliable technique which allows the assessment of programmed cell death (PCD) or necrosis events based on nuclear morphology. It consists in isolating nuclei from plant material, which are then embedded in agarose and subjected to lysis in alkaline buffers. Under these conditions, and due to the presence of abundant alkali-labile sites in the DNA, small pieces of DNA diffuse in the agarose gel giving a specific halo appearance when stained with fluorescent dyes like DAPI (4',6-diamidino-2-phenylindole). Here, we describe an optimized protocol for DNA diffusion assay applied to different types of plant cells/tissues, indicating all the critical steps required for a successful experimental procedure.

Impact of pH and temperature on the electrochemical and semiconducting properties of zinc in alkaline buffer media.

The electrochemical and semiconductive properties of spontaneously formed passive films on pure Zn were investigated in alkaline carbonate/bicarbonate buffer solutions as functions of pH and temperature. The study was performed in 0.1 M (CO32− + HCO3−) mixtures over the pH range 9.2 to 9.8 using open circuit potential, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and Mott–Schottky analysis techniques. Generally, zinc passivation is enhanced with either increasing pH or decreasing the ambient temperature. The steady state potential (Ess) value reveals that in pH 9.8 buffer the propensity of Zn for passivation is superior when compared with those in the other tested buffer solutions. The total surface film resistance (Rt) derived from the impedance data proves this result, which is likely attributed to changes in composition and/or microstructure of the film. In pH 9.8 buffer solution the passivation tendency always decreases with temperature increase. However, in pH 9.2 the system behaves similarly up to 25 °C; afterwards zinc passivation trend was found to re-increase once more. The apparent activation energy for the corrosion process was evaluated and discussed. Analysis of Mott–Schottky plots was found to be suitable for characterizing the semiconductor properties of the naturally deposited barrier layers which are all consistent with the well-known n-type character of the oxide film on zinc. The absence of any evidences for the p-type semiconductive behavior indicates a preponderance of oxygen vacancies and zinc interstitials over metal vacancies. Moreover, Mott–Schottky results demonstrate that the donor concentration increases with either increasing pH or deceasing temperature commensurate with the increasing trends in the passive film thickness.