Plating Efficiency Research Articles

Protein Expression Modifications in Phage-Resistant Mutants of Aeromonas salmonicida after AS-A Phage Treatment.

The occurrence of infections by pathogenic bacteria is one of the main sources of financial loss for the aquaculture industry. This problem often cannot be solved with antibiotic treatment or vaccination. Phage therapy seems to be an alternative environmentally-friendly strategy to control infections. Recognizing the cellular modifications that bacteriophage therapy may cause to the host is essential in order to confirm microbial inactivation, while understanding the mechanisms that drive the development of phage-resistant strains. The aim of this work was to detect cellular modifications that occur after phage AS-A treatment in A. salmonicida, an important fish pathogen. Phage-resistant and susceptible cells were subjected to five successive streak-plating steps and analysed with infrared spectroscopy, a fast and powerful tool for cell study. The spectral differences of both populations were investigated and compared with a phage sensitivity profile, obtained through the spot test and efficiency of plating. Changes in protein associated peaks were found, and these results were corroborated by 1-D electrophoresis of intracellular proteins analysis and by phage sensitivity profiles. Phage AS-A treatment before the first streaking-plate step clearly affected the intracellular proteins expression levels of phage-resistant clones, altering the expression of distinct proteins during the subsequent five successive streak-plating steps, making these clones recover and be phenotypically more similar to the sensitive cells.

Methods for Expansion of Three-Dimensional Cultures of Human Embryonic Stem Cells Using a Thermoresponsive Polymer.

Human pluripotent stem cells (hPSCs) are viewed as promising candidates for applications in regenerative medicine and therapy due to their proliferative and pluripotent properties. However, obtaining clinically significant numbers of hPSCs remains a limiting factor and impedes their use in therapeutic applications. Conventionally, hPSCs are cultured on two-dimensional surfaces coated with a suitable substrate, such as Matrigel™. This method, however, requires a large surface area to generate sufficient cell numbers to meet clinical needs and is therefore impractical as a manufacturing platform for cell expansion. In addition, the use of enzymes for cell detachment and small molecule inhibitors to increase plating efficiency may impact future cell behavior when used for routine subculturing. In this study, we describe a protocol to generate and maintain hPSC aggregates in a three-dimensional suspension culture by utilizing thermoresponsive nanobridges. The property of the polymer used in the nanobridges enables passaging and expansion through a temperature change in combination with mechanically applied shear to dissociate aggregates; thus, we eliminate the need of enzymes or small molecules for cell dissociation and viability, respectively. Utilizing this platform, maintenance of human embryonic stem cells for three continuous passages demonstrated high expression levels in key pluripotent markers.

The first known virus isolates from Antarctic sea ice have complex infection patterns.

Viruses are recognized as important actors in ocean ecology and biogeochemical cycles, but many details are not yet understood. We participated in a winter expedition to the Weddell Sea, Antarctica, to isolate viruses and to measure virus-like particle abundance (flow cytometry) in sea ice. We isolated 59 bacterial strains and the first four Antarctic sea-ice viruses known (PANV1, PANV2, OANV1 and OANV2), which grow in bacterial hosts belonging to the typical sea-ice genera Paraglaciecola and Octadecabacter. The viruses were specific for bacteria at the strain level, although OANV1 was able to infect strains from two different classes. Both PANV1 and PANV2 infected 11/15 isolated Paraglaciecola strains that had almost identical 16S rRNA gene sequences, but the plating efficiencies differed among the strains, whereas OANV1 infected 3/7 Octadecabacter and 1/15 Paraglaciecola strains and OANV2 1/7 Octadecabacter strains. All the phages were cold-active and able to infect their original host at 0°C and 4°C, but not at higher temperatures. The results showed that virus-host interactions can be very complex and that the viral community can also be dynamic in the winter-sea ice.

Evaluation of cyclophosphamide-induced genotoxicity and cytotoxicity in cultured human lymphocytes

Aim: The present study was aimed to examine and evaluate the genotoxicity and cytotoxicity induced by different doses of cyclophosphamide (CP) in normal healthy cultured human peripheral blood lymphocytes. Materials and Methods: Genotoxicity and cytotoxicity was evaluated through mitotic index (MI), chromosomal aberrations, micronuclei frequency, and colony formation assay (plating efficiency [PE] and survival fraction), respectively. Results: It has been observed that CP (1, 2.5, and 5 μg/ml)) induced a dose-dependent increase in chromosomal aberrations and micronuclei frequencies in cultured human peripheral blood lymphocyte as compared to normal. A significant increase was observed in the percentage of aberrant cells and dicentrics/exchanges at 1 and 2.5 μg/ml CP and aberrant cells, breaks, fragments, and dicentrics/exchanges at 5/μg/ml CP. A dose-dependent decrease in values of MI and nuclear division index was also observed in CP-treated group. The frequency of micronuclei in binucleated cells showed a dose-dependent increase. In colony formation assay, PE and surviving fraction values showed significant (P

THE N-HEXANE FRACTION OF MYRMECODIA PENDANS INHIBITS CELL SURVIVAL AND PROLIFERATION IN COLON CANCER CELL LINE

Objective: Despite advanced treatment options available for colorectal cancer, many reported resistance and unresponsiveness to conventional chemotherapeutic agents. Therefore, it is urgent to discover a novel drug for colon cancer. Sarang Semut (Myrmecodia pendans), an Indonesian native plant, has been studied extensively due to its anti-cancer profiles. This study aimed to evaluate the anti-tumour activity of Sarang Semut in colon cancer cells.Methods: We evaluated cytotoxic activity of methanol extract as well as n-hexane and ethyl acetate fraction towards colon cancer cell lines (Caco-2 and HCT-116 cells) utilizing 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. The most potent fraction was evaluated further in inhibiting cell survival using MTT assay and cell proliferation using trypan blue exclusion assay as well as a clonogenic assay.Results: Our data showed that the n-hexane fraction of Sarang Semut induces more cell death than the methanol extract and ethyl acetate fraction. Therefore, we analyzed the n-hexane fraction further and found that the inhibitory concentration 50% (IC50) of the n-hexane fraction was 24 and 30 parts per million (ppm) for Caco-2 and HCT-116 cells, respectively. Moreover, it inhibited cell growth as well as cell colony formation, in particular, shown by the plating efficiency (P<0.05) and colony area per seed (P<0.01) of the control group were different to the treatment group.Conclusion: The n-hexane fraction of Sarang Semut demonstrates a high potential antitumor activity in colon cancer cell line.

Establishment and Characterization of gc-006-03, a Novel Human Signet Ring Cell Gastric Cancer Cell Line Derived from Metastatic Ascites.

Signet ring cell gastric cancer (SRCGC) is a special type of gastric cancer with rapid progression and poor prognosis. However, few available SRCGC cell lines from Chinese patients can be used for research, the molecular mechanism of its growth and metastasis is still incompletely understood. In this study, we established and characterized a novel SRCGC cell line, gc-006-03.The cells showed a tendency to pile up without contact inhibition. G-band karyotypes of gc-006-03 were revealed hypotriploid with a modal chromosome number of 51. Immunohistochemistry analysis showed that the cells were positive for CEA, CK7, CDX2 and Ki-67(45%), and negative for CK20, TTF1and Li-cadherin. Flow cytometry analysis showed that gc-006-3 had 25% of CD44+ cells. The cells possessed strong clonality and high plating efficiency, and the doubling time was 36h. The cells grew vigorously for more than 100 passages in serial culture. Meanwhile, the cells showed a high rate of tumor formation. Tumors were observed in all of the nude mice (5/5) given injections of the cells. The metastatic capability of the cell line was found in zebrafish injected the cells. The results of whole genome sequencing revealed the unique genomic characteristics of gc-006-03. In summary, this new stable cell line may be useful in basic and clinical research on gastric signet ring cell carcinoma.

Lithium-Mediated Ammonia Electro-Synthesis: Effect of CsClO4 on Lithium Plating Efficiency and Ammonia Synthesis

Electro-reduction of nitrogen aided by lithium offers a new route for ammonia synthesis. In this novel approach, the first step of lithium plating plays a determining role in faradaic efficiency (FE) of the electro-synthesis process. It was found that the simple addition of cesium salt in a conventional organic electrolyte enhanced Li plating performance (FE of 82.3% for ammonia synthesis) to a substantial extent. This improvement appeared to have a lot to do with a Cs-caused change in morphology of Li deposit, which brought about the suppression of parasitic side reactions between metallic Li and propylene carbonate. This study proves that FE enhancement can be made possible via a simple change in electrolyte composition, an approach that is collectively called electrolyte engineering, and this approach can serve as effective means for making the best of Li-mediated ammonia synthesis.

Effects of STC1 overexpression on tumorigenicity and metabolism of hepatocellular carcinoma

Stanniocalcin-1 (STC1) is a paracrine factor associated with inflammation and carcinogenesis. Using clinicopathological data, we previously reported that a greater expression of STC1 in hepatocellular carcinoma (HCC) was significantly correlated with smaller tumor size. The underlying mechanism on the correlation is not known. In this study, using a metastatic HCC cell-line (MHCC-97L, P) and lentiviral vector mediated-STC1 overexpression, the inoculation of STC1-overexpressing MHCC-97L (S1) cells in a nude mice xenograft model demonstrated reductions in tumor mass and volume. As compared with P cells, S1 cells exhibited epithelial phenotype with significantly lower plating efficiency and reduced migratory and proliferative potential. Using coulter counter for cell-sizing, S1 cells (17.6 μm) were significantly smaller than P cells (19.6 μm). Western blot analysis revealed that S1 cells exhibited reduced expression level of phosphorylated ribosomal protein S6 (p-rpS6). Moreover, an inhibition of the upstream kinase p70S6K was evident with the dephosphorylation of Thr389 in the linker domain of the kinase. The inhibition of p70S6K/p-rpS6 pathway was accompanied with reduced cellular ATP level and increase of p-AMPK in S1 cells. Significantly lower rates of glycolysis and extracellular O2 consumption in S1 cells exhibited a lower cellular energy status. Since a faster rate of ATP production is essential to support cancer growth and metastasis, the present study identified the effect of STC1-overexpression on reducing energy metabolism, leading to an activation of AMPK pathway but an inhibition of p70S6K/p-rpS6 signaling to reduce tumor growth.

Interlocking Intramedullary Nailing Versus Locked Dual-Plating Fixation for Femoral Shaft Fractures in Patients with Multiple Injuries: A Retrospective Comparative Study

ABSTRACTPurpose: Intramedullary nailing (IMN) is a popular method in the management of femoral shaft fractures (FSFs). However, whether the association of IMN with pulmonary fat emboli can compromise the pulmonary and nervous systems is debatable. The purpose of this study is to compare IMN with the locked dual plating (LDP) method by assessing the clinical outcomes of FSF patients with head or chest injury. Method: A total of 126 FSF patients were included in this study between January 2010 and July 2016 and divided into LDP and IMN groups. Patient demographic characteristics, operative time, blood loss, Harris Hip Score, Lysholm Knee Score, radiological outcomes, and systemic complications were collected and compared between the two treatment groups. Patients were followed up for at least 12 months. Results: The LDP group performed better than IMN in terms of operative time, estimated blood loss amount, and malunion rate. Differences in function scores, fracture union rate, overall pulmonary complication rate, and in-hospital mortality between the two groups were not significant. Average radiographic union time was significantly longer in the LDP group (36.3 weeks) than in the IMN group (32.5 weeks). One case of fixation failure occurred postoperatively in the LDP group, whereas one case of fracture nonunion took place in the IMN group. Conclusion: Our findings suggest that dual-plating fixation is a promising method for FSFs with multiple injuries. However, the retrospective nature of this study necessitates high-quality trials to be performed to assess the clinical efficiency of dual plating.

Testing Serum Batches for Mouse Embryonic Stem Cell Culture.

The variability in embryonic stem (ES) cell culture is due primarily to serum. Serum is typically produced in large batches from many animals. However, samples may differ depending on the age and diet of the animals, the country of origin, and other factors creating lot-to-lot variations. Some vendors test FBS lots for compatibility with ES cell culture. Many laboratories prefer to test serum batches themselves to identify the lot giving optimal growth. In this protocol, small quantities of specific serum batches are obtained from different suppliers and tested for their ability to support ES cells in an undifferentiated state. A complete test includes the serum batches' influence on plating efficiency, cell morphology, toxicity, and, if possible, their ability to support generation of chimeras.

Herbicide ingredients change Salmonella enterica sv. Typhimurium and Escherichia coli antibiotic responses.

Herbicides are frequently released into both rural and urban environments. Commercial herbicide formulations induce adaptive changes in the way bacteria respond to antibiotics. Salmonella enterica sv. Typhimurium and Escherichia coli were exposed to common co-formulants of formulations, and S. enterica sv. Typhimurium was exposed to active ingredients dicamba, 2,4-D and glyphosate to determine what ingredients of the commercial formulations caused this effect. Co-formulants Tween80 and carboxymethyl cellulose induced changes in response, but the pattern of the responses differed from the active ingredients, and effect sizes were smaller. A commercial wetting agent did not affect antibiotic responses. Active ingredients induced changes in antibiotic responses similar to those caused by complete formulations. This occurred at or below recommended application concentrations. Targeted deletion of efflux pump genes largely neutralized the adaptive response in the cases of increased survival in antibiotics, indicating that the biochemistry of induced resistance was the same for formulations and specific ingredients. We found that glyphosate, dicamba, and 2,4-D, as well as co-formulants in commercial herbicides, induced a change in susceptibility of the potentially pathogenic bacteria E. coli and S. enterica to multiple antibiotics. This was measured using the efficiency of plating (EOP), the relative survival of the bacteria when exposed to herbicide and antibiotic, or just antibiotic, compared to survival on permissive media. This work will help to inform the use of non-medicinal chemical agents that induce changes in antibiotic responses.

Evaluation of the combined effect of NIR laser and ionizing radiation on cellular damages induced by IUdR-loaded PLGA-coated Nano-graphene oxide.

Glioma is one of the most common malignant cancers of the central nervous system (CNS). Radiatherapy and chemotherapy may be used to slow the growth of tumors that cannot be removed with surgery. The current study developed a combination therapy tool using Nanographene oxide (NGO) functionalized with poly lactic-co-glycolic acid (PLGA) as a carrier of 5-iodo-2-deoxyuridine (IUdR) for glioma cancer treatment. U87MG cells were treated in different groups with IUdR, PLGA-coated Nanographene oxide (PLGA-NGO), IUdR-loaded PLGA-coated Nanographene oxide (IUdR-PLGA-NGO), 2Gy 6MV X-ray radiation, and near-infrared region (NIR) laser radiation. PLGA-NGO showed excellent biocompatibility, high storage capacity for IUdR and high photothermal conversion efficiency. It was effectively employed to create cell damage in the U87MG cell line in the presence of X-ray (6 MV) and NIR laser. Moreover, IUdR-PLGA-NGO+X-ray+NIR laser significantly reduced the plating efficiency of the cells in comparison with IUdR-PLGA-NGO+X-ray and IUdR-PLGA-NGO+NIR laser. Furthermore, Prussian blue staining showed that IUdR-PLGA-NGO-SPIONs were delivered into glioblastoma cells. The PLGA-NGO loaded with IUdR under NIR and X-ray radiation exhibited the highest cytotoxicity toward U87MG cells when compared with other treatment methods, indicating efficient radio-photothermal targeted therapy.

Effect of E1A gene on radiosensitivity of human nasopharyngeal carcinoma cells and its possible mechanism

Objective To investigate the effect of E1A gene on the radiosensitivity of human nasopharyngeal carcinoma cells and its possible mechanism. Methods The E1A gene was transfected into nasopharyngeal carcinoma CNE-2R cells by adenovirus vector. The expression of E1A gene was detected by RT-PCR. Untransfected CNE-2R cells (PBS group) and CNE-2R cells transfected with empty vector Ad-β-gal (Ad-β-gal group) and E1A (Ad-E1A group) were given 0 Gy, 2 Gy, 4 Gy, 6 Gy, 8 Gy 6 MV X-ray irradiation. The changes in radiosensitivity of CNE-2R cells were determined by colony-forming assay. Flow cytometry was used to analyze cell apoptosis in each group. The expression of NF-κB, CK2α, Bcl-2, and cleaved caspase-3 was measured by Western blot. Results RT-PCR confirmed that the E1A gene was transfected into CNE-2R cells and stably expressed. The Ad-E1A group had a significantly lower plating efficiency than the PBS group and the Ad-β-gal group (P<0.05). The Ad-E1A group had significantly lower cell survival rate at 2 Gy irradiation than the PBS group and the Ad-β-gal group (0.217 vs. 0.602, P<0.05; 0.217 vs. 0.585, P<0.05). The Ad-E1A group had a significantly higher α/β value than the PBS group and the Ad-β-gal group (24.680 vs. 5.268, P<0.05; 24.680 vs. 5.132, P<0.05). Flow cytometry results showed that irradiation alone could promote the apoptosis of CNE-2R cells, when combined with E1A gene, the apoptosis rate was significantly increased (P<0.05). Western blot results showed that E1A gene down-regulated the expression of NF-κB/p65, CK2α, and Bcl-2 and up-regulated the expression of cleaved caspase-3. Conclusions E1A gene can enhance the radiosensitivity of nasopharyngeal carcinoma cells by inhibiting the expression of CK2 to block the NF-κB signaling pathway and promoting cell apoptosis. Key words: E1A gene; NF-κB; Casein Kinase 2; Nasopharyngeal Carcinoma Cell; Radiosensitivity; Apoptosis

Combined treatment of pancreatic cancer xenograft with 90Y-ITGA6B4-mediated radioimmunotherapy and PI3K/mTOR inhibitor.

AIMTo investigate the therapeutic effect of combined integrin α6β4-targeted radioimmunotherapy (RIT) and PI3K/mTOR inhibitor BEZ235 in a pancreatic cancer model.METHODSPhosphorylation of Akt, mTOR, the downstream effectors eukaryotic initiation factor 4E binding protein 1 (4EBP1) and S6 ribosomal protein (S6) were evaluated in BxPC-3 human pancreatic cancer cells treated with Yttrium-90 (90Y) labeled anti-integrin α6β4 antibody (ITGA6B4) and BEZ235 by western blotting. The cytotoxic effect of BEZ235 was investigated using a colony formation assay. Therapeutic efficacy enhancement by oral BEZ235 administration was assessed using mice bearing BxPC-3 xenograft tumors. Tumor volume measurements and immunohistochemical analyses (cell proliferation marker Ki-67, DNA damage marker p-H2AX and p-4EBP1 staining) of tumors were performed for evaluation of combined treatment with 90Y-ITGA6B4 plus BEZ235, or each arm alone.RESULTSWe found that phosphorylation of Akt (p-Akt), 4EBP1 (p-4EBP1) and S6 (p-S6) was inhibited by BEZ235. Colony formation in BxPC-3 cells was additively suppressed by the combination of 90Y-ITGA6B4 and BEZ235. Pretreatment with BEZ235 before 90Y-ITGA6B4 exposure resulted in significant reduction of cells plating efficiency (PE) (0.54 ± 0.11 vs 2.81 ± 0.14 with 185 kBq/mL 90Y-ITGA6B4 exposure, P < 0.01; 0.39 ± 0.08 vs 1.88 ± 0.09 with 370 kBq/mL 90Y-ITGA6B4 exposure, P < 0.01) when 5 × 103 cells per dish were plated. In vivo, the combined treatment with 90Y-ITGA6B4 plus BEZ235 enhanced the inhibition of tumor growth and statistically significant differences of relative tumor volume were observed for 27 d after the treatment start date when compared with the 90Y-ITGA6B4 single injection treatment (1.03 ± 0.38 vs 1.5 ± 0.15 at Day 27, P < 0.05), and for 41 d when compared with the BEZ235 treatment alone (1.8 ± 0.7 vs 3.14 ± 1.19 at Day 41, P < 0.05). Tumors from treatment groups showed reduction in volumes, decreased Ki-67-positive cells, increased p-H2AX-positive cells and decreased p-4EBP1 expression.CONCLUSIONThe therapeutic efficacy of 90Y-ITGA6B4-RIT can be improved by combining with dual PI3K and mTOR inhibitor, BEZ235, in a pancreatic cancer model suggesting potential clinical application.

MicroRNA-378 enhances radiation response in ectopic and orthotopic implantation models of glioblastoma.

Glioblastoma multiforme (GBM) is the most common and highly malignant primary brain tumor, which is virtually incurable due to its therapeutic resistance to radiation and chemotherapy. To develop novel therapeutic approaches for treatment of GBM, we examined the role of miR-378 on tumor growth, angiogenesis, and radiation response in ectopic and orthotopic U87 glioblastoma models. Cell and tumor growth rates, in vitro and in vivo radiation sensitivities, and tumor vascular density were evaluated in U87-GFP and U87-miR-378 tumor lines. Ectopic tumor response to radiation was evaluated under normal blood flow and clamp hypoxic conditions. Results show that in vitro, miR-378 expression moderately increased cell growth rate and plating efficiency, but did not alter radiation sensitivity. U87-miR-378 tumors exhibited a higher transplantation take rate than U87-GFP tumors. In vivo, under oxygenated condition, subcutaneous U87-miR-378 tumors receiving 25Gy showed a tendency for longer tumor growth delay (TGD) than control U87-GFP tumors. In contrast, under hypoxic condition, U87-miR-378 xenografts exhibited substantially shorter TGD than U87-GFP tumors, indicating that under normal blood flow conditions, U87-miR-378 tumors were substantially more oxygenated than U87-GFP tumors. Intracranial multi-photon laser-scanning microscopy demonstrated increased vascular density of U87-miR-378 versus control U87-GFP tumors. Finally, miR-378 increased TGD following 12Gy irradiation in U87 intracranial xenografts, and significantly prolonged survival of U87-miR-378 tumor-bearing mice (P = 0.04). In conclusion, higher miR-378 expression in U87-miR-378 cells promotes tumor growth, angiogenesis, radiation-induced TGD, and prolongs survival of orthotopic tumor-bearing hosts. Regulation of VEGFR2 by miR-378 significantly increased vascular density and oxygenation in U87 xenografts.

Theranostic Applications of Pair-Production for Enhancing Radiation Therapy

To enhance radiotherapy by utilizing pair-production, the probability of which increases with X-ray energy and atomic Z number. Introducing high Z metals during 18MV irradiation should result in increased cell killing compared to 18MV irradiation without metal or 6MV with/without metal. This effect will be due to increased pair-production near high Z nuclei which increases locally absorbed radiation dose. This effect requires metal, preferably nontoxic, to be present during irradiation and will be measured in vitro with clonogenic survival assays. Clonogenic survival assays were carried out using A549 human lung cancer cells. Tissue culture plates were irradiated with 2Gy of either 6MV or 18MV photons with or without metal drugs (100 uM sodium phosphotungstate hydrate, 4ug/ml cisplain, and 12ug/ml carboplatin) present during radiotherapy. Metal drugs were introduced to culture media 2 hours prior to irradiation and left in place during irradiation. The media was replaced immediately after irradiation with metal-free media. Calibrated output factors were used to ensure the same absorbed dose between the two beam energies under identical experimental setup conditions. Mean plating efficiency was determined to be 41% on average for A549. Incubating cells in 100uM tungsten for 4 hours without irradiation produced no significant toxicity (>95% survival). In the absence of metal drug, the 2Gy 6MV and 18MV plates showed similar survival (64% vs 67%). When tungsten compound was introduced, the 6MV plate again showed 66% survival, however the 18MV plate showed 34% survival, approximately double cell killing. These experiments were repeated at 4, 6, and 8Gy to generate cell survival curves and the radiation sensitization enhancement ratio (SER) was found to be approximately 1.5. The tungsten 18MV survival curve shows a minimal shoulder region compared to the 6MV with/without tungsten and 18MV without tungsten curves, suggesting inhibition of sublethal damage repair. The 2Gy 6MV vs 18MV clonogenic survival studies were carried out for 4ug/ml cisplatin and 12ug/ml carboplatin which similarly showed approximately 40% enhancement of cell killing for both drugs at 18MV compared to 6MV. Cells treated with 18MV irradiation in the presence of 100uM sodium phosphotungstate hydrate showed approximately 50% less cell survival at 2, 4, 6, and 8Gy compared to 6MV with/without metal and 18MV without metal. Cisplatin and carboplatin show similar radiosensitization at 18MV yielding 40% more cell killing than 6MV. This effect is due to pair-production leading to increased photon-matter interaction and requires metal to be present at time of irradiation. The survival curves at 2, 4, 6, and 8Gy show loss of initial shoulder region suggesting impaired sublethal damage repair or increased effective LET. The generation of 511keV annihilation photons in situ may allow tumor imaging and dose measurement via PET technology. Confirmatory in vivo studies are planned.

Cr3O(O2CCH2CH3)6(H2O)3]NO3·H2O (Cr3) Toxicity Potential in Bacterial and Mammalian Cells.

Chromium(III) has generally been considered to be essential for proper carbohydrate and lipid metabolism, and, despite recent evidence to the contrary, chromium(III)-containing compounds remain one of the most popular commercial dietary supplements. Cr3, or [Cr3O(O2CCH2CH3)6(H2O)3]NO3·H2O, is a trivalent chromium compound that is a promising chromium nutritional supplement. Studies with Cr3 have indicated that it is non-toxic in developmental and short- and long-term exposure studies in rodents, but the safety of this compound to chromosomes and cells has not been explored. The current study evaluates the mutagenicity, cytotoxicity, and clastogenicity of Cr3 in bacterial and mammalian cells and compares these results with similar studies using the bestselling Cr(III) nutritional supplement, chromium picolinate (CrPic). The mutagenicity of CrPic and Cr3 was tested in Escherichia coli FX-11 and Salmonella typhimurium (TA 98 and TA 100). Cytotoxicity was measured as a decrease in plating efficiency relative to controls after treatment with Cr3 and CrPic for 24h in CHO K1 cells. Clastogenicity was measured by counting the number of metaphases damaged and of the total number chromosomal aberrations in CHO K1 cells. Mutagenesis assays in E. coli and S. typhimurium were negative. All treatments of Cr3 produced ≥84% plating efficiency except 80μg/cm2, which reduced the plating efficiency to 62%. Cr3 at any treatment level did not produce a significant increase in the number of cells with abnormal metaphases, while treatments using ≥40μg/cm2 of CrPic elevated the number significantly. These data suggest that Cr3 is significantly less mutagenic in bacteria cells and less clastogenic in CHO K1 cells, while CrPic is clastogenic in CHO K1 cells.

Funtionalization and Electrocatalytic Application of Electrolessly Deposited Silver Nanoplatelet Films

Facile wet-chemical functionalization techniques, which enable the direct modification of device parts without separate synthesis, purification and assembly steps, are promising choices for nanofabrication [1]. Regarding nanostructured metal films, electroless plating displays an interesting option for this task [2]. During electroless plating, metal reduction is sustained by the electrocatalytically active deposit, which brings the main components of the metastable plating baths to reaction. However, the technique has to be adapted to nanomaterial production. For instance, without the use of templates, the conformal growth mode favors the formation of relatively smooth, polycrystalline films, which do not possess anisotropic nanoscale features [2, 3]. In this contribution, we outline the efficiency of shape-controlled electroless silver plating for the realization of functional nanomaterials. First, we demonstrate the simplicity and flexibility of the technique, followed by a discussion of strategies for application-oriented synthesis optimization. We then show how the obtained materials can be derivatized to introduce new functionalities. By adding an iron-tartrate complex to a silver plating bath, we achieve selective two-dimensional growth without templates. Using this reaction, homogeneous films of high aspect ratio silver nanoplatelets can be deposited on various substrate materials in a short time. Moreover, recessed and curved substrates can be coated, such as the interior of glass microcapillaries (Fig. 1 a, b). Also, the nucleation behavior of the reaction can be tuned: Homogeneous nucleation and bath decomposition can be either enforced to obtain powders of sand-rose shaped silver particles (Fig. 1 c), which can be used to formulate catalyst inks or composites, or suppressed to achieve selective heterogeneous deposition of platelet films. When sufficiently developed, the films possess continuous conduction paths. Together with the large, easily accessible and well-defined surface of the platelets, this renders them particularly interesting for electrochemical applications. The films can be used as supporting, nanostructured electrodes, or employed directly as electrocatalyst. As an example for the latter case, we used different silver structures for amperometric detection of hydrogen peroxide, in which a strong, selective and fast response to the analyte could be achieved. The sensitivity of the silver catalyst could be enhanced by tuning the deposit morphology, such as in the case of porous platelets of high aspect ratio and surface area (Fig. 1 d). Electrolessly plated nanomaterials can be conveniently derivatized [4] using reactions such as thermal oxidation, galvanic replacement or chemical bath deposition. Several modification options for the silver nanoplatelet films will be presented. For example, by using the silver structures as substrate for subsequent cuprite plating, they can be decorated with Cu2O nanoparticles (Fig. 1 e, f). Due to the wide functionality range of silver nanostructures and the shape-sensitivity of many of their properties [5], the approach described here provides a highly productive route toward materials for heterogeneous catalysis, sensing, plasmonics and (photo)electrochemistry, especially considering miniaturized designs such as microreactors and lab-on-a-chip sensors. F. M. acknowledges funding by a Research Fellowship of the German Research Foundation (MU 4125/1-1). [1] Kim, J.; Li, Z.; Park, I. Lab on a Chip 11, 2011, 1946–1951. [3] Gabardo, C. M.; Adams-McGavin, R. C.; Fung, B. C.; Mahoney, E. J.; Fang, Q.; Soleymani, L. Scientific Reports 7, 2017, 42543. [3] Muench, F.; Oezaslan, M.; Svoboda, I.; Ensinger, W. Materials Research Express 2, 2015, 105010. [4] Muench, F.; Sun, L.; Kottakkat, T.; Antoni, M.; Schaefer, S.; Kunz, U.; Molina-Luna, L.; Duerrschnabel, M.; Kleebe, H.-J.; Ayata, S.; Roth, C.; Ensinger, W. ACS Applied Materials and Interfaces 9, 2017, 771–781. [5] Wiley, B.; Sun, Y.; Xia, Y. Accounts of Chemical Research 40, 2007, 1067–1076. Figure 1

High Concentrated Electrolytes for Li Metal Anodes

Li metal is seen as the ultimate anode for LIBs due to its extremely high theoretical energy density (3860 mAh g-1) and low negative redox potential (-3.04 V vs. standard hydrogen electrode). Making Li metal a ubiquitous anode is the key in propelling energy storage and conversion systems. It is one of the key components that will further the development of next-generation batteries, such as Li-S, Li-O2, and high energy density batteries (500Wh/kg) for the automotive industry. One way to address the dendritic growth and low coloumbic efficiency of the Li metal, is to focus on the electrolyte to form a robust and stable solid electrolyte interphase (SEI). There are several types of electrolytes that one can use for Li metal, each serving its purpose to fulfill a need in high voltage and low voltage applications. Herein, the focus on electrolytes for both high and low voltage applications. Simple electrolyte formulations containing LiFSI, yield a robust and stable SEI that is primarily composed of inorganic functionalities due to salt reduction. A bisalt formulations yield high plating and stripping efficiencies (98.5 at 0.5mA/cm2), even higher efficiencies at elevated temperatures. We further demonstrate the use of a high concentrated carbonate based electrolyte in a high voltage anode free and half cell that out performs the conventional carbonate electrolyte.

Cycle Life Study and Failure Analysis of the Rechargeable Porous Zinc Electrode in Alkaline Electrolyte

Metallic zinc (Zn) is an attractive negative electrode material for rechargeable batteries because it is a non-toxic, earth abundant metal. It has a low equilibrium potential of -1.35 V vs. mercury-mercuric oxide (Hg/HgO) in concentrated alkaline electrolyte and a high theoretical gravimetric charge capacity of 820 mAh/g. During discharge, Zn oxidizes and forms a dissolved complex known as the zincate ion, Zn(OH)4 2-, from which zinc oxide (ZnO) precipitates as a solid. On charge, Zn(OH)4 2- is reduced to metallic Zn. Motivation to study the Zn electrode in rechargeable batteries is driven by a target overall battery energy density of 200 Wh/L that is sustainable for 1000 or more charge-discharge cycles. This corresponds to a Zn electrode charge density in the range of 650 mAh/mL. The percentage of charge capacity of Zn accessed is known as the depth of discharge (DOD). Battery energy density of 200 Wh/L motivates zinc electrode improvement to 20% Zn DOD. However, increased Zn DOD leads to a decrease in cycle life. A negative exponential relationship between cycle life and Zn DOD for the range of 1% to 15% Zn DOD for zinc-manganese dioxide (Zn-MnO2) batteries was observed experimentally. Over 2800 cycles were achieved in a Zn-MnO2 battery at 1% Zn DOD. The effect of additives on the Zn electrode at Zn DOD values in the range of 15% to 30% was studied in zinc-nickel (Zn-Ni) battery cycle tests. Additives used were surfactant cetyltrimethylammonium bromide (CTAB), bismuth oxide (Bi2O3), synthetic layered silicate Laponite, and calcium hydroxide (Ca(OH)2). A cycle life of 542 at 15% Zn DOD was observed for a Zn electrode containing CTAB, bismuth oxide, and Laponite. In both Zn-MnO2 and Zn-Ni batteries, absolute value of Zn potential vs. Hg/HgO on discharge decreased as cycle number increased, even before discharge capacity faded. The Zn electrode is associated with multiple failure mechanisms. Electrolyte depletion is due to a lack of hydroxide ions (OH-), either because of OH- consumption during battery discharge or an insufficient electrolyte reservoir. Pore plugging results from decreased electrode porosity associated with ZnO precipitation. Zn passivation occurs when precipitated ZnO films completely surround Zn. Shape change of the Zn electrode is a phenomenon in which Zn is not deposited uniformly during charge. The Zn electrode is also susceptible to gassing, in which the hydrogen (H2) evolution reaction occurs during charge. Water is reduced to gaseous H2, thus the flow of electrons into the electrode is not used to deposit metallic Zn, resulting in lower Zn plating efficiency. In order to further understand underlying physical, chemical, and electrochemical behavior of the Zn electrode as well as improve energy density and cycle life, future experimental and theoretical work is proposed. The effect of additives on the cycle life of Zn-MnO2 batteries will be studied. Additionally, electrode performance for Zn DOD values in the range of 15% to 30% Zn DOD will be investigated. A theoretical mathematical model of the Zn electrode will be formulated based on the governing equations of the system. Numerical solutions will be obtained for the spatial profiles of Zn(OH)4 2- concentration, OH- concentration, current density, potential, and porosity at extended cycle number. [1] Ingale, Nilesh D.; Gallaway, Joshua W.; Nyce, Michael; Couzis, Alexander; Banerjee, Sanjoy, “Rechargeability and economic aspects of alkaline zinc-manganese dioxide cells for electrical storage and load leveling,” Journal of Power Sources, 276 (2015), 7-18. [2] Wei, Xia; Desai, Divyaraj; Yadav, Gautam G.; Turney, Damn E.; Couzis, Alexander; Banerjee, Sanjoy. "Impact of anode substrates on electrodeposited zinc over cycling in zinc-anode rechargeable batteries," Electrochimica Acta, 212 (2016), 603-613. [3] Yadav, Gautam G.; Gallaway, Joshua W.; Turney, Damon E.; Nyce, Michael; Huang, Jinchao; Wei, Xia; Banerjee, Sanjoy. " Regenerable Cu-intercalated MnO2 layered cathode for highly cyclable energy dense batteries," Nature Communications, 8 (2017) 14424. [4] Turney, Damon; Gallaway, Joshua; Yadav, Gautam; Ramirez, Rodolfo; D'Ambrose, Michael; Kolhekar, Snehal; Nyce, Michael; Wei, Xia; Huang, Jinchao; Chen-Wiegart, Yu-chen; Wang, Jun; Banerjee, Sanjoy. "Rechargeable zinc alkaline anodes for long-cycle energy storage," Chemistry of Materials, under review.