Syringe Filter Research Articles

Separation and determination of cadmium in water samples based on functionalized carbon nanotube by syringe filter membrane- micro solid-phase extraction

A simple and fast separation of cadmium (Cd) based on functionalized carbon nanotubes with 2,3-dimercapto-1-propanol (CNTs@DHSP) was achieved in water samples before a determination by atom trap flame atomic absorption spectrometry (AT-FAAS). In this study, Cd(II) ions were extracted by syringe filter membrane-micro solid phase extraction procedure(SFM-μ-SPE). Firstly, 20 mg of the CNTs@DHSP as solid-phase added to 20 mL of water sample in a syringe, then dispersed for 3 min after adjusting pH up to 7 and pass through SFM very slowly. After extraction, the Cd(II) ions were back-extracted from SFM/CNTs@DHSP by 1.0 mL of eluent in acidic pH. Finally, the cadmium concentration was measured by AT-FAAS. Under the optimal conditions, the linear range (2–90 µg L−1), LOD (0.75 µg L−1) and enrichment factor (19.6) were obtained (RSD<1.5%). The adsorption capacity of Cd(II) with the CNTs@DHSP was obtained about 152.6 mg g-1. The method was validated by certified reference materials (SRM, NIST) and ET-AAS in water samples.

Emulsion-free chitosan-genipin microgels for growth plate cartilage regeneration.

The growth plate is a cartilage tissue near the ends of children's long bones and is responsible for bone growth. Injury to the growth plate can result in the formation of a 'bony bar' which can span the growth plate and result in bone growth abnormalities in children. Biomaterials such as chitosan microgels could be a potential treatment for growth plate injuries due to their chondrogenic properties, which can be enhanced through loading with biologics. They are commonly fabricated via an emulsion method, which involves solvent rinses that are cytotoxic. Here, we present a high throughput, non-cytotoxic, non-emulsion-based method to fabricate chitosan-genipin microgels. Chitosan was crosslinked with genipin to form a hydrogel network, and then pressed through a syringe filter using mesh with various pore sizes to produce a range of microgel particle sizes. The microgels were then loaded with chemokines and growth factors and their release was studied in vitro. To assess the applicability of the microgels for growth plate cartilage regeneration, they were injected into a rat growth plate injury. They led to increased cartilage repair tissue and were fully degraded by 28 days in vivo. This work demonstrates that chitosan microgels can be fabricated without solvent rinses and demonstrates their potential for the treatment of growth plate injuries.

Polyadenine-based fluorescent probe for high-selective determination of copper ion in freshwater

ABSTRACT In this work, a polyadenine-based fluorescent probe (pAFP) was designed for highly selective determination of Cu2+ in various freshwater sources. The pAFP contained a fluorescent group carboxyfluorescein (FAM) and a guanine-cytosine-guanine-cytosine (GCGC) sequence which was linked to the ends of a polyadenine strand. The complexation between polyadenine strand and Cu2+ induced the transition of polyadenine strand from a loose random coil to a compact structure, resulting in the proximity of the GCGC to the FAM and subsequent fluorescent quench of the FAM. Our work identified the polyadenine strand as a novel recognization element for Cu2+, which displayed high selectivity and appropriate affinity (104 ~ 105 M−1) to Cu2+, with a stoichiometric ratio of 1:1. Based on it, the pAFP provided a dynamic range from 80 nM to 20 µM for the determination of Cu2+and a detection limit of 62 nM, meeting the requirements of the World Health Organization (WHO) and Environmental Protection Agency (EPA). The analysis of Cu2+-spiked real samples from lentic (Yudai Lake) and a lotic freshwater system (Xiangjiang River) revealed the high accuracy of the method, evidencing the application of this proposed sensor towards wide-field freshwater detection. Compared to other reported fluorescent probes, our pAFP displays a much simpler composition and structure. Meanwhile, in the actual procedure, our method only requires a simple pretreatment of the water sample by a 0.22 μm syringe filter, and the whole test procedure can be completed within 10 min. Such a convenient, low-cost and time-saving method for the determination of Cu2+will greatly facilitates the on-site and real-time monitoring of Cu2+ in different freshwater sources and subsequent water quality control.

First surveillance of SARS-CoV-2 and organic tracers in community wastewater during post lockdown in Chennai, South India: Methods, occurrence and concurrence.

Surveillance of SARS-CoV-2 and organic tracers (OTs) were conducted in the community wastewater of Chennai city and the suburbs, South India, during partial and post lockdown phases (August–September 2020) as a response to the coronavirus disease 2019 (COVID-19) pandemic. Wastewater samples were collected from four sewage treatment plants (STPs), five sewage pumping stations (SPSs) and at different time intervals from a suburban hospital wastewater (HWW). Four different methods of wastewater concentrations viz., composite (COM), supernatant (SUP), sediment (SED), and syringe filtration (SYR) were subjected to quantitative real time-polymerase chain reaction (qRT-PCR). Unlike HWW, STP inlet, sludge and SPS samples were found with higher loading of SARS-CoV-2 by SED followed by SUP method. Given the higher levels of dissolved and suspended solids in STPs and SPSs over HWW, we suspect that this enveloped virus might exhibit the tendency of higher partitioning in solid phase. Cycle threshold (Ct) values were < 30 in 50% of the HWW samples indicating higher viral load from the COVID-19 infected patients. In the STP outlets, a strict decline of biochemical oxygen demand, >95% removal of caffeine, and absence of viral copies reflect the efficiency of the treatment plants in Chennai city. Among the detected OTs, a combination of maximum dynamic range and high concurrence percentage was observed for caffeine and N1 gene of SARS-CoV-2. Hence, we suggest that caffeine can be used as an indicator for the removal of SARS-CoV-2 by STPs. Our predicted estimated number of cases are in line with the available clinical data from the catchments. Densely distributed population of the Koyambedu catchment could be partly responsible for the high proportion of estimated infected individuals during the study period.

Cucurbituril-Functionalized Nanocomposite as a Promising Industrial Adsorbent for Rapid Cationic Dye Removal.

A supramolecular cucurbit[6]uril (CB[6])-enriched magnetic montmorillonite (CBCM) nanocomposite was prepared and characterized. CB[6] played a prominent role as a capping agent, helping in better distribution of the nanoparticles, and as a binder between nanoparticles. Montmorillonite provided structural stability and fortified ultrafast adsorption toward dyes. Its application in the removal of cationic dyes from wastewater was systematically assessed. Process parameters such as pH, initial dye concentration, dosage, temperature, and time were optimized. Kinetics and isotherms of the process were described using pseudo-second-order kinetics and the Langmuir isotherm, respectively. CBCM exhibited rapid dye removal capacity in short reaction times with qmax of 199.20, 78.31, and 55.62 mg g–1 and K2 of 0.0281, 0.0.0823, and 0.0953 L mg–1 min–1 for crystal violet, methylene blue, and rhodamine B, respectively. Benefiting from the synergetic effects of montmorillonite surface hydrophobicity, abundant carbonyl groups of CB[6], and magnetic properties of copper ferrite, CBCM demonstrated outstanding dye removal capacity, negligible leaching at saturation, and high tolerance toward harsh conditions. This intrinsic nature is expedient in prolonged industrial operations. To demonstrate industrial viability, syringe filtration and continuous flow fixed-bed column operations were validated. The CBCM fixed-bed column demonstrated stable dye removal efficiency with 10–100 mg mL–1 dye at 10–50 mL min–1 flow rates. Utilizing the magnetic and catalytic activities of the copper ferrite nanoparticles, CBCM was recycled using a magnet, regenerated, and reused for several cycles. CB[6] remarkably improved the performance of the nanocomposite and made it suitable for different effluent treatment techniques. This may pave a sustainable way toward the efficient onsite treatment of effluent at the industrial scale.

A comparative study of three conventional methods for diagnosis urinary schistosomiasis.

The general objective of this comparative study was the evaluation of three diagnostic techniques (sedimentation technique using centrifugation, filtration techniques using millipore filter and Ninhydrine stained filter paper) conventional approaches. This was carried out at Alzaidab, River Nile State, Northern Sudan on 93 school children. The study involved the collection of samples from school children of 7 years age and above. A questionnaire was distributed to collect data on gender, age and water contact activities. The examinations on all samples were carried out applying the methods previously mentioned. The results revealed that the overall prevalence rates of Schistosomahaematobium in Alzaidab Nile State were 16.1%, 24.7% and 24.7% using the centrifugation, syringe filtration millipore, ninhydrin – filter paper staining method respectively. According to gender, males showed higher prevalence rates than females using all the techniques mentioned and the highest prevalence rate in males (36.1%) was reported by the syringe filtration millipore and ninhydrin – filter paper staining method. According to age groups, the highest prevalence rate was reported among the group of children over 13 years of age, using all the techniques. The high prevalence rate (64.3%) among the above mentioned group (over 13 year’s of age) was shown by the syringe filtration millipore and ninhydrin – filter paper staining method. The highest prevalence among those who had water contact (32.9%) was shown by the syringe filtration millipore and ninhydrin – filter paper staining method.It was found that the syringe filtration millipore and ninhydrin – filter paper staining methods gave identical and reproducible results, yet the ninhydrin – filter paper staining does not fit for field practice since it can only be carried out in the laboratory.

Ultrasensitive Point-of-Care Test for Tumor Marker in Human Saliva Based on Luminescence-Amplification Strategy of Lanthanide Nanoprobes.

The point‐of‐care detection of tumor markers in saliva with high sensitivity and specificity remains a daunting challenge in biomedical research and clinical applications. Herein, a facile and ultrasensitive detection of tumor marker in saliva based on luminescence‐amplification strategy of lanthanide nanoprobes is proposed. Eu2O3 nanocrystals are employed as bioprobes, which can be easily dissolved in acidic enhancer solution and transform into a large number of highly luminescent Eu3+ micelles. Meanwhile, disposable syringe filter equipped with nitrocellulose membrane is used as bioassay platform, which facilitates the accomplishment of detection process within 10 min. The rational integration of dissolution enhanced luminescent bioassay strategy and miniaturized detection device enables the unique lab‐in‐syringe assay of tumor marker like carcinoembryonic antigen (CEA, an important tumor marker in clinic diagnosis and prognosis of cancer) with a detection limit down to 1.47 pg mL−1 (7.35 × 10−15 m). Upon illumination with a portable UV flashlight, the photoluminescence intensity change above 0.1 ng mL−1 (0.5 × 10−12 m) of CEA can be visually detected by naked eyes, which allows one to qualitatively evaluate the CEA level. Moreover, we confirm the reliability of using the amplified luminescence of Eu2O3 nanoprobes for direct quantitation of CEA in patient saliva samples, thus validates the practicality of the proposed strategy for both clinical diagnosis and home self‐monitoring of tumor marker in human saliva.

Impact of Membranes on In Vitro Release Assessment: a Case Study Using Dexamethasone.

In vitro release studies are commonly used to assess the product performance of topical dosage forms. In such studies, the mass transport of drugs through synthetic membranes into a receiving chamber filled with a release medium is measured. The release medium is also passed through filtration membranes prior to chromatographic analysis. There are no official guidelines directing membrane selection for in vitro release studies or for filtration. Considering the diversity in membrane materials and their physical properties, the aim of this study was to investigate membrane-drug binding and the effect of various membranes on the release performance of a model drug dexamethasone (DEX) using USP dissolution apparatus IV. Seven membranes of different pore sizes (0.45 and 1.2μm) and materials (cellulose acetate, polyethersulfone, and nylon) were assessed. Two different methods, syringe filter and 24-h incubation, were used for the determination of membrane-drug binding effects at low drug concentrations and saturated concentration conditions. Cellulose acetate and nylon membranes showed significant drug binding after 24-h incubations at both drug concentrations. DEX diffusion through membranes was significantly slowed down in all the tested membranes when compared with DEX solution without membranes. The extent of the retardation varied due to the differences in membrane structures. In conclusion, materials and sources of membranes affected drug dissolution profiles and the results showed membrane-drug binding effects. Proper selection of membranes with low drug binding ability and low diffusion resistance is essential to ensure appropriate and reproducible in vitro release assessments and filtration studies. Graphical Abstract.

Culture and Differentiation of Human Umbilical Cord-Derived Mesenchymal Stem Cells on Growth Factor-Rich Fibrin Scaffolds to Produce Engineered Cartilages.

After injuries, the cartilage healing capacity is limited owing to its nature as a particular connective tissue without blood vessels, lymphatics, or nerves. The creation of artificial cartilage tissue mimics the biological properties of native cartilage and can reduce the need for donated tissue. Fibrin is a type of biodegradable scaffold that has great potential in tissue engineering applications. It can become good material for cell adhesion and proliferation in vitro. Therefore, this study aimed to create a cartilage tissue in vitro using umbilical cord-derived mesenchymal stem cells (UCMSC) and growth factor-rich fibrin (GRF) scaffolds. UCMSCs were isolated and expanded, and platelet-rich plasma (PRP) preparations were performed following previously published protocols. PRP was activated (aPRP) by a 0.45-μm syringe filter to release growth factors inside the platelets. Each 2.105 of the UCMSCs were suspended in 2ml of aPRP to make the mixture of MSC and PRP (MSC-PRP). Then, Ca2+ solution was added to this mixture to produce the fibril scaffold with UCMSCs inside. UCMSCs' adhesion and proliferation inside the scaffold were evaluated by observation under inverted microscopy, H-E staining, MTT assays, and scanning electron microscopy (SEM). The fibril structure containing UCMSCs was cultured, and chondrogenesis was induced using commercial chondrogenesis media for 21days (iMSC-GRF). The differentiation in efficacy toward cartilage was evaluated based on the accumulation of aggrecan (acan), glycosaminoglycans (GAGs), and collagen type II (Col II). The results showed that we successfully created a cartilage tissue with some characteristics that mimic the properties of natural cartilage. The engineered cartilage tissue was positive with some cartilage protein, such as acan, GAG, and Coll II. In vitro cartilage presented some natural chondrocyte-like cells. The artificial cartilage tissue was positive for CD14, CD34, CD90, CD105, and HLA-DR and negative for CD44, CD45, and CD73. These results showed that using UCMSCs and growth factor-rich fibril from platelet-rich plasma was feasible to produce engineered cartilage tissue for further experiments or clinical usage.

Triazine and Porphyrin-Based Cross-Linked Conjugated Polymers: Protonation-Assisted Dissolution and Thermoelectric Properties

As two pivotal functional segments, triazine and porphyrin can be coupled to form a highly cross-linked conjugated polymer. Although the obtained conjugated polymers are almost insoluble in most so...

Effects of Filter-Membrane Materials on Concentrations of Trace Elements in Acidic Solutions

Filtration is commonly used to separate liquids from solid materials before the determination of trace element concentrations in aqueous solutions. Therefore, it is important to determine how much elemental content is extracted from the filter itself or lost via absorption into the filter. In this study, we investigated three types of disposable syringe filters (polyvinylidene difluoride, PVDF; polytetrafluoroethylene, PTFE; PTFE with glass microfiber prefiltration media, GD/X) and their acid-cleaned versions using ammonium nitrate (NH4NO3) and acetic acid (HOAc) solutions. The concentrations of most trace elements (Li, Al, Cr, Mn, Co, Ni, Cu, Zn, Rb, Sr, Mo, Cd, Cs, Ba, Pb, and U) were higher in filtrates that had passed through acid-cleaned filters than those that had passed through uncleaned filters. In filtrates from PVDF and PTFE filters, many trace elements were below the detection limit. However, regardless of the filter type and acid cleaning, Li, Cu, Zn, Mo, and Ba concentrations in filtrates of NH4NO3 solutions, and Al, Cr, Mn, Cu, Zn, and Ba concentrations in filtrates of HOAc solutions were much higher than those of other trace elements. These differences were particularly noticeable in filtrates from GD/X filters containing glass microfiber layers. These data indicate that certain trace elements can be released from membrane materials by reacting with acid in the filtered solution. Furthermore, the amounts of each trace element were associated with the membrane type. These findings suggest that filter type should be carefully selected to obtain the required accuracy, in consideration of the target elements and whether an acid-cleaned filter is needed.

An Improved Reflection Colorimeter Integrated with a Coaxial Optical-fiber Cable for Highly Sensitive Solid-phase Colorimetry Using a Membrane Filter.

Highly sensitive solid-phase colorimetry for nickel ion was demonstrated using an improved reflection colorimeter equipped with a coaxial optical-fiber cable. The nickel complex with α-furil dioxime was collected on a small-size membrane filter embedded in a disposable syringe filter unit. The leading edge of the optical-fiber cable was connected to the syringe filter unit via a Luer-lock fitting, and the color intensity of the sample on the filter was evaluated accurately. The detection limit was 0.8 ng in 2.5 mL of the complex solution (0.3 μg L-1). This improved configuration is applicable to highly sensitive on-site analysis without expensive instruments nor high laboratory skills.

144 Rumen Fluid Metabolites as Potential Biomarkers of Feed Efficiency in Angus Steers

Abstract Beef cattle is the most consumed red meat in the United States, and the United States is the largest producer and consumer of beef cattle globally. Feed is one of the largest input costs for the beef cattle industry, accounting for 40–60% of the total input costs. Identifying methods for improving feed efficiency in beef cattle herds could result in decreased cost to both producers and consumers, as well as increased animal protein available for global consumption. Identification of feed efficiency biomarkers could aid in the selection of more feed-efficient animals. To identify potential biomarkers of feed efficiency, rumen fluid was collected from low- (n = 14) and high-RFI (n = 15) Angus steers based on RFI ± 0.5 SD around the mean following a 70d feed efficiency trial to determine rumen metabolites associated with variations in feed efficiency. Steers were 7 months of age, weighing 264±2.7 kg. Rumen fluid was collected via gastric tubing, filtered through a 0.22 µM syringe filter, extracted for metabolomic analysis using 0.1% formic acid in acetonitrile:water:methanol (2:2:1), and injected into the Dionex UltiMate 3000 UHPLC system with an Exactive Plus Orbitrap MS. Peaks for known metabolites were identified using MAVEN and analyzed using MetaboAnalyst 4.0 and SAS. Significance was determined using an α ≤ 0.05. Based on fold change (high/low RFI), eight metabolites were greater in low-RFI steers compared to high-RFI steers, including 3,4-dihydroxyphenylacetate, 4-pyridoxate, citraconate, hypoxanthine, succinate/methylmalonate, thymine, uracil, and xylose (P ≤ 0.05), while 12 metabolites differed by ≥ 2-fold. These metabolites were predominantly involved in amino acid and lipid metabolism. Rumen fluid metabolomes differed in steers of varying feed efficiencies. These metabolites may be used as biomarkers of feed efficiency and may provide insight as to factors contributing to differences in feed efficiency that may be exploited to improve feed efficiency in beef cattle herds.

(144) Rumen Fluid Metabolites as Potential Biomarkers of Feed Efficiency in Angus Steers

Abstract Beef cattle is the most consumed red meat in the United States, and the United States is the largest producer and consumer of beef cattle globally. Feed is one of the largest input costs for the beef cattle industry, accounting for 40–60% of the total input costs. Identifying methods for improving feed efficiency in beef cattle herds could result in decreased cost to both producers and consumers, as well as increased animal protein available for global consumption. Identification of feed efficiency biomarkers could aid in the selection of more feed-efficient animals. To identify potential biomarkers of feed efficiency, rumen fluid was collected from low- (n = 14) and high-RFI (n = 15) Angus steers based on RFI ± 0.5 SD around the mean following a 70d feed efficiency trial to determine rumen metabolites associated with variations in feed efficiency. Steers were 7 months of age, weighing 264±2.7 kg. Rumen fluid was collected via gastric tubing, filtered through a 0.22 µM syringe filter, extracted for metabolomic analysis using 0.1% formic acid in acetonitrile:water:methanol (2:2:1), and injected into the Dionex UltiMate 3000 UHPLC system with an Exactive Plus Orbitrap MS. Peaks for known metabolites were identified using MAVEN and analyzed using MetaboAnalyst 4.0 and SAS. Significance was determined using an α ≤ 0.05. Based on fold change (high/low RFI), eight metabolites were greater in low-RFI steers compared to high-RFI steers, including 3,4-dihydroxyphenylacetate, 4-pyridoxate, citraconate, hypoxanthine, succinate/methylmalonate, thymine, uracil, and xylose (P ≤ 0.05), while 12 metabolites differed by ≥ 2-fold. These metabolites were predominantly involved in amino acid and lipid metabolism. Rumen fluid metabolomes differed in steers of varying feed efficiencies. These metabolites may be used as biomarkers of feed efficiency and may provide insight as to factors contributing to differences in feed efficiency that may be exploited to improve feed efficiency in beef cattle herds.

143 Rumen Fluid Metabolites as Potential Biomarkers of Feed Efficiency in Angus Steers

Abstract Beef cattle is the most consumed red meat in the United States, and the United States is the largest producer and consumer of beef cattle globally. Feed is one of the largest input costs for the beef cattle industry, accounting for 40–60% of the total input costs. Identifying methods for improving feed efficiency in beef cattle herds could result in decreased cost to both producers and consumers, as well as increased animal protein available for global consumption. Identification of feed efficiency biomarkers could aid in the selection of more feed-efficient animals. To identify potential biomarkers of feed efficiency, rumen fluid was collected from low- (n = 14) and high-RFI (n = 15) Angus steers based on RFI ± 0.5 SD around the mean following a 70-d feed efficiency trial to determine rumen metabolites associated with variations in feed efficiency. Steers were 7 mo of age, weighing 264±2.7 kg. Rumen fluid was collected via gastric tubing, filtered through a 0.22 µM syringe filter, extracted for metabolomic analysis using 0.1% formic acid in acetonitrile:water:methanol (2:2:1), and injected into the Dionex UltiMate 3000 UHPLC system with an Exactive Plus Orbitrap MS. Peaks for known metabolites were identified using MAVEN and analyzed using MetaboAnalyst 4.0 and SAS. Significance was determined using an α ≤ 0.05. Based on fold change (high/low RFI), eight metabolites were greater in low-RFI steers compared to high-RFI steers, including 3,4-dihydroxyphenylacetate, 4-pyridoxate, citraconate, hypoxanthine, succinate/methylmalonate, thymine, uracil, and xylose (P ≤ 0.05), while 12 metabolites differed by ≥ 2-fold. These metabolites were predominantly involved in amino acid and lipid metabolism. Rumen fluid metabolomes differed in steers of varying feed efficiencies. These metabolites may be used as biomarkers of feed efficiency and may provide insight as to factors contributing to differences in feed efficiency that may be exploited to improve feed efficiency in beef cattle herds.

Electrochemical Impedance Spectroscopy to Evaluate the Adsorption and Structural Changes of Liposome Dependent with Surface Charge

Liposome is well known as mimicking a cell, which is composed of lipid bilayer membrane. Liposome is spherical shape and formed by amphiphilic molecules, meaning that outer layer is composed of hydrophilic molecules and inner layer is composed of hydrophobic molecules. Evaluation of adsorption and rupture of liposome on a surface is very important to drug delivery system (DDS) or understand the capability of the cell.Many studies reported the adsorption and interaction of lipid bilayer using highly sensitive sensing methods without labeling such as quartz crystal microbalance (QCM), plasmonic devices such as SPR, LSPR and SERS, and electrochemical impedance spectroscopy (EIS). We focus on EIS as an evaluation tool for adsorption and rupture of liposome, since EIS is highly sensitive to the surface condition of the electrode and electrochemical measurement is simple.EIS is very sensitive to the surface condition of the electrode. We report here that surface charge is very important to evaluate the adsorption and interaction of liposome on the electrode surface, which are controlled by using self–assembled monolayer (SAM). So far as we know, there are little reports focusing on surface charge evaluate the adsorption and interaction of liposome on the electrode surface. Here, we report the effect of surface charge on electrochemical reactions due to SAMs which were coated on the Au electrode.Liposome preparation was described below. Thin organic film was formed with 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC). Then we obtained solution including DOPC which diameter was lower than 220 nm because the solution was filtered 20 times through the syringe filter (pore diameter was 220 nm). We used 1-Dodecanethiol (DDT), 11-Mercapto-1-undecanol (MUD or 11–HUT: 11–Hydroxy–1–undecanthiol) and 11-Amino-1-undecanthiol (11–AUT) for the SAM. These chemicals have same straight–chain alkane with thiol group to bind with Au surface, but head group is changed as CH3 for DDT meaning that the surface is neutral and hydrophobic, CH2OH for MUD meaning that the surface is charged negative and hydrophilic and CH2NH2 for 11–AUT meaning that the surface is charged positive and hydrophilic. Thus, we can discuss about the characteristics of Rct dependent with head group of SAM on the detection of liposome adsorption and rupture. As the results, most sensitive surface was obtained on use of 11–AUT in this study. In addition, we estimated the critical micelle concentration (CMC) of a surfactant, Triton–X 100, on the rupture process of liposome.As an example of results, we show two type of hydrophilic surface, type A and B. Type A was coated with 11-Mercapto-1-undecanol, which surface had hydroxy group and was negatively charged. Type B was coated with 11-Amino-1-undecanol, which surface had amino group and was positively charged.At first, we discussed about the results on type A. Fig. 1(Type A) shows Nyquist plots according to adsorption and rupture of liposome. After the adsorption of liposome, Rct decreased drastically. This characteristic was caused by surface charge after the liposome adsorption. As written above, the hydroxyl surface was charged negatively which repel the redox probe. After the liposome adsorption, surface charge changed to positive because the surface of DOPC was charged positively, which attracted the redox probes by charge polarity. After adding the surfactant, Rct increased and was almost same as that before the liposome adsorption. Next, we discussed about the results on type B. Fig. 1(Type B) shows Nyquist plots according to adsorption and rupture of liposome. After the adsorption of liposome, Rct increased drastically due to steric barrier of liposome. In this case, liposome adhered on the surface by hydrophilic interaction. Surface charge was not changed via liposome adsorption. After adding the surfactant, Rct decreased and was almost twice comparing with that before the liposome adsorption. This data show that ruptured liposome and/or surfactant adhered on the electrode surface. As discussed above, the amino surface was superior to detect adhesion and rupture of liposome comparing with other electrodes which coated with/without methyl and hydroxy SAM, when [Fe(CN)6]3-/4- was used as redox probes because of mixed surface conditions such as hydrophilicity and electric charge. Figure 1

Stability of TiO2-Based Materials under PEFC Operation Condition for Non-Platinum Cathodes

1. Background Pt/C catalysts used for cathodes of polymer electrolyte fuel cells (PEFCs) have problems such as high cost and insufficient durability against potential change [1]. Therefore, we have developed a non-platinum catalyst based on group 4 and 5 transition metal oxides because they are inexpensive and stable in acidic solution [2]. We successfully demonstrated that Nb-doped TiOx catalyst showed high onset potential for oxygen reduction reaction (ORR) and higher electrochemical durability than platinum [3]. However, the ORR current was much smaller than that of platinum catalyst. An increase in the surface area of oxides is effective to increase the ORR current. Nano-sizing of oxide particles is one of the solutions to increase the surface area of oxides. In general, the solubilities of nanoparticles are larger than those of large particles. Therefore, we need to evaluate the stability of nanoparticles in acidic solution. Some investigations regarding the stability of titanium oxide nanoparticle which is one candidate of group 4 oxide cathodes [4, 5, 6] have been already performed. However, the stability in PEFC operating condition has not been evaluated in detail. Therefore, in this study, the chemical stability was evaluated by measuring the dissolution behavior of titanium oxide nanoparticles in an acidic electrolyte simulating the operating environment of PEFC. 2. ExperimentalA 600 mg of TiO2 nanopowder (US Research Nanomaterials, mean particle size: 6.0 nm, Anatase) was immersed in 1.0 M (pH = 0.25), or 0.32 M (pH = 0.66), or 0.10 M HClO4 (pH = 1.06) and stirred. The temperature was controlled by using a water or an oil bath in the temperature range from 30 to 90 ℃. At the desired time, the stirring was stopped, then a small amount of the solution (2 mL) was sampled and filtered through a 0.22 µm syringe filter. The sample solution was immediately diluted. The remaining solution was stirred again. This procedure was repeated. The concentration of titanium in the sample was measured by ICP-AES (Seiko Instruments).3. Results and DiscussionFigure 1 shows the concentration of titanium of TiO2 nanopowder with diameter of 6.0 nm as a function of immersion time in 0.1 M HClO4 under air at 30, 50, 70, and 90 ℃. The concentration of titanium became constant after 800, 500, 300, and 150 h immersion at 30, 50, 70 and 90 ℃, respectively, meaning that dissolution reached equilibrium. The solubility of TiO2 nanopowder in 0.1 M HClO4 were 16, 6.2, 3.2, and 2.2 µmol dm-3 at 30, 50, 70, and 90 ℃, respectively. The solubility of TiO2 nanopowder decreases with increase in temperature and becomes chemically stable, which indicates that TiO2 nanoparticles are more suitable for PEFC operating condition at high temperature.Figure 2 shows the van't Hoff plots of the solubility of the TiO2 nanopowder in HClO4 and the solubility of platinum black powder in 0.1 M HClO4 [7] is also plotted. The solubility of TiO2 decreases with increase in temperature, while the solubility of platinum black increases with increase in temperature in acidic electrolytes. From the slope of the approximate line of the van't Hoff plot of the solubility of TiO2 nanopowder, the apparent standard enthalpy change of dissolution of TiO2 nanoparticles, ΔHº , in 0.10 M HClO4 is estimated to be -29.1 kJ mol-1, and the dissolution reaction of TiO2 nanoparticles in an acidic electrolytes is exothermal. Furthermore, from the value of the standard Gibbs energy change of the dissolution reaction, ΔGº , calculated from the solubility of TiO2 nanopowder at 30 ℃, the apparent standard dissolution entropy change, ΔSº , in 0.10 M HClO4 was calculated to be -151 J mol-1 K-1.AcknowledgmentsThis research is conducted with the support of the National Research and Development Corporation New Energy and Industrial Technology Development Organization (NEDO). In addition, the authors wish to thank the support of JSPS grants-in-aid for scientific research, Suzuki Foundation and Tonen General Sekiyu Research / Development Encouragement & Scholarship Foundation.Reference[1] S. Kawahara, S. Mitsushima, K. Ota, N. Kamiya, ECS Trans., 3(1), 625(2006).[2] A. Ishihara, Y. Ohgi, K. Matsuzawa, S. Mitsushima, and K. Ota, Electrochim. Acta, 55, 8005 (2010).[3] M. Hamazaki, A. Ishihara, Y. Kohno, K. Matsuzawa, S. Mitsushima, K. Ota, Electrochemistry, 83(10), 817(2015).[4] J. Schmidt, W. Vogelsberger, J. Solution Chem., 38, 1267 (2009).[5] J. Schmidt, W. Vogelsberger, J. Phys. Chem., 110, 3955(2006).[6] S. E. Ziemniak, M. E. Jones, K. E. S. Combs, J. Solution Chem., 22(7), 601(1993).[7] S. Mitsushima, Y. Koizumi, S. Uzuka, K. Ota, Electrochim. Acta, 54, 455 (2008). Figure 1

Highly Sensitive and Rapid Quantitative Detection of Plasmodium falciparum Using an Image Cytometer.

The gold standard for malaria diagnosis is microscopic examination of blood films by expert microscopists. It is important to detect submicroscopic and asymptomatic Plasmodium infections in people, therefore the development of highly sensitive devices for diagnosing malaria is required. In the present study, we investigated whether an imaging cytometer was useful for the highly sensitive quantitative detection of parasites. Whole blood samples were prepared from uninfected individuals spiked with Plasmodium falciparum-infected erythrocytes. Thereafter, erythrocytes were purified using a push column comprising of a syringe filter unit with SiO2-nanofiber filters. After adding the erythrocytes, stained with nuclear stain, to a six-well plate, quantitative detection of the parasites was performed using an image cytometer, CQ1. Imaging of 2.6 × 106 erythrocytes was completed in 3 min, and the limit of detection indicated parasitemia of 0.00010% (≈5 parasites/μL of blood). In addition to rapid, highly sensitive, and quantitative detection, the ease of application and economic costs, image cytometry could be efficiently applied to diagnose submicroscopic parasites in infected people from endemic countries.

A Syringe-Filter-based Portable Microreactor for Size-selective Proteolysis of Low Molecular-weight Proteins

Abstract Portable microreactors (PMRs) have valuable applications in the field of proteomics. However, no PMRs have been developed for the size-selective proteolysis of low molecular-weight proteins (LWPs) with mass less than 30 kDa, which are of great importance in biomarkers, biomolecular signaling and the field of pathology. In this study, a novel syringe-filter-based PMR using core-shell mesoporous silica (CSMS) microspheres as an enzyme support was reported. Because of the unique properties of CSMS microspheres, the PMR was easily fabricated by on-site physical adsorption even without any incubation, which was accomplished by simply pushing trypsin solution through a syringe filter containing the microspheres. Efficient immobilization of trypsin was demonstrated by characterizing the PMR using various spectroscopic techniques. The PMR loading amount was approximately 2.9 mg/g trypsin/CSMS microspheres with negligible leaching. The capability of the proposed PMR for size-selective proteolysis was assessed by investigating the digestion of proteins with different molecular weights, i.e., cytochrome C (12.38 kDa), lysozyme (14.39 kDa), myoglobin (17.00 kDa) and ferritin (440.00 kDa). The results of capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) analysis showed that, by using the proposed PMR, the peptide numbers and sequence coverage of LWPs in the sample were enhanced owing to the size-exclusion interaction of the mesopores against large proteins. The proposed PMRs had essential features of easy fabrication, low cost, reusability and efficient size-selective proteolysis, and performing multiple functions including size-exclusion of LWPs, trypsin digestion and filtration in a single injection step of protein samples. This study provided a robust approach for fabricating PMRs that could perform rapid size-selective digestion of LWPs.

Combining Ion Chromatography and Total Reflection X-ray Fluorescence for Detection of Major, Minor and Trace Elements in Quartz-Hosted Fluid Inclusions

The crush-leach technique is a frequently used method to determine the bulk composition of fluid inclusions trapped in a range of geological samples. We present a modified crush-leach technique combining ion chromatography (IC) and total reflection X-ray fluorescence spectroscopy (TXRF) which allows to determine a range of major, minor and trace elements out of one leachate. To date, trace element detection by means of TXRF is barely used in geosciences, although it combines the advantages of low to very low detection limits (µg/L to ng/L range), small sample amount needed (µL-range) and a fast and inexpensive analytical procedure. Previously described problems of adsorption of polyvalent cations at sample surfaces have been overcome by using acidified water as a leachate. Instead, it has been demonstrated that, for example, the syringe filter type used for IC measurements influences contamination and/or adsorption for a number of elements. The proposed method combination was evaluated for accuracy, reproducibility and system blanks and subsequently applied to quartz samples from hydrothermal vein deposits of the Schwarzwald ore district, SW Germany.