Synthesis of 2D cobalt oxide nanosheets using a room temperature liquid metal

Room temperature liquid metals based on Ga can be used as a synthesis medium for the creation of metal oxide nanomaterials, however one thermodynamic limitation is that metals that are more easily oxidised than Ga are required to ensure their preferential formation. In this work we demonstrate a proof of principle approach whereby exposing the liquid metal alloyed with the required metal to acidic conditions circumvents preferential formation of Ga₂O₃ and allows for the formation of the required 2D transition metal oxide nanosheets. The synthesis procedure is straightforward in that it only requires bubbling oxygen gas through the liquid metal alloy into a solution of 10 mM HCl. We show that the formation of thin nanosheets of ca. 1 nm in thickness of CoO is possible. The material is characterised using transmission electron microscopy, atomic force microscopy, X-ray photoelectron and Raman spectroscopy. The electrocatalytic activity of the CoO nanosheets was investigated for the oxygen evolution reaction where the nanosheet thickness was found to be a factor influencing the activity. This proof of principle offers a route to the possible formation of many other 2D transition metal oxides from metals that are less readily oxidised than Ga by taking advantage of the interesting properties of room temperature liquid metals.

A RT liquid metal based on Ga can be used as a synthesis medium for creation of 2D nanosheets of cobalt oxide via expulsion of the sheets from the liquid metal surface into an acidic aqueous solution. The 2D nanosheets are shown to be active for OER.

Sequence analysis of a gene family encoding Taenia ovis vaccine antigens expressed during embryogenesis of eggs

The 45W vaccine antigen of the cestode parasite Taenia ovis is a member of a small gene family estimated to comprise six members. All six genes were cloned and characterised. Nucleotide sequence analysis of the different family members identified a set of closely related genes exhibiting between 75.2 and 98.6% DNA sequence homology. Intron/exon structure for the various genes constituting the family was found to be conserved. Open reading frame analysis and pairwise alignments of predicted polypeptides from the various members of the family revealed that the encoded proteins share between 51.8 and 96.5% amino acid identity with the host-protective 45W antigen. Polymerase chain reaction (PCR) primers were designed which allowed amplification of individual family members in a transcript-specific manner. These were used to investigate gene expression in different developmental stages of the parasite by reverse-transcription polymerase chain reaction (RT-PCR). All members of the gene family were expressed during the T. ovis life-cycle. 45W gene family transcription correlates with embryogenesis of eggs and expression is increased in activated eggs (oncospheres). One family member, ToW3S, was expressed in the early larvae (cysticercus) stages. Expression of genes closely related to the 45W vaccine antigen has important implications for immune evasion under selection from the application of a 45W-based vaccine.

Assessment of pfmdr 1 gene copy number by tandem competitive polymerase chain reaction

The pfmdr 1 gene encodes a Plasmodium falciparum homologue of the human P-glycoprotein expressed on the surface of the parasite food vacuole. Variation in copy number and specific codon mutations of pfmdr 1 have been implicated in the development of parasite resistance to antimalarial drugs. We describe here the technique of Tandem-Competitive Polymerase Chain Reaction (TC-PCR), which allows accurate measurement of pfmdr 1 copy number in parasite DNA obtained directly from small quantities (100 microliters) of red blood cells. We reliably quantified pfmdr1 in previously well characterised strains of Plasmodium falciparum with differing pfmdr1 gene copy numbers using starting amounts of between 3,000 and 40,000 gene copies. We then used TC-PCR to determine pfmdr1 gene copy number in field specimens of venous blood taken from 10 patients with malaria contracted along the Thai-Burmese border. In this region of high grade parasite resistance to mefloquine greater than 70% of samples had a copy number greater than 1 of pfmdr1 determined with a repeatability coefficient of 0.58.

Rapid up-regulation of mdr1 expression by anthracyclines in a classical multidrug-resistant cell line

Studies were carried out in a variant human multidrug-resistant (MDR) cell line CEM/A7R, which expresses very low levels of mdr1 mRNA and P-glycoprotein (P-gp). The induction of mdr1 RNA expression by three anthracyclines, (doxorubicin, daunorubicin, epirubicin), VP-16 and two vinca alkaloids (vincristine, vinblastine) was semiquantitatively assessed by scanning Northern blots on a phosphorimager. The relative level of mdr1 expression was expressed as ratio of mdr1 to the internal RNA (actin). A significant increase (P < 0.02) in expression of mdr1 was noted within 4 hrs of exposure to 1.5 micrograms ml-1 daunorubicin or epirubicin. Neither vinblastine nor vincristine had any effect on mdr1 levels after an 8 h exposure. With increasing concentrations of daunorubicin or epirubicin in a fixed 24 h time period, mdr1 expression increased, although a biphasic response was seen. Based on MRK 16 binding, an increase in P-gp levels was seen in the CEM/A7R line after a 24 h exposure to 1 microgram ml-1 daunorubicin or epirubicin. The rapid increase in mdr1 expression after a short period of exposure to doxorubicin, daunorubicin or epirubicin suggests that induction of mdr1 expression may have an important role in the development of drug-resistant tumours.