Tumour cell identification by means of Raman spectroscopy in combination with optical traps and microfluidic environments

Raman spectroscopy has been recognized to be a powerful tool for label-free discrimination of cells. Sampling methods are under development to utilize the unique capabilities to identify cells in body fluids such as saliva, urine or blood. The current study applied optical traps in combination with Raman spectroscopy to acquire spectra of single cells in microfluidic glass channels. Optical traps were realized by two 1070 nm single mode fibre lasers. Microflows were controlled by a syringe pump system. A novel microfluidic glass chip was designed to inject single cells, modify the flow speed, accommodate the laser fibres and sort cells after Raman based identification. Whereas the integrated microchip setup used 514 nm for excitation of Raman spectra, a quartz capillary setup excited spectra with 785 nm laser wavelength. Classification models were trained using linear discriminant analysis to differentiate erythrocytes, leukocytes, acute myeloid leukaemia cells (OCI-AML3), and breast tumour cells BT-20 and MCF-7 with accuracies that are comparable with previous Raman experiments of dried cells and fixed cells in a Petri dish. Implementation into microfluidic environments enables a high degree of automation that is required to improve the throughput of the approach for Raman activated cell sorting.     

Aconitum lipo-alkaloids--semisynthetic products of the traditional medicine

The term lipo-alkaloid is used for C19 aconitane alkaloids containing one or two long-chain fatty acid residues. Lipo-alkaloids are transesterified derivatives of the most toxic and highly effective diester-type diterpene alkaloids, such as aconitine, hypaconitine, mesaconitine. Lipo-alkaloids are native minor compounds of aconite drugs, but their amount significantly increases after traditional processing, which is a general method in the Far Eastern traditional medicinal systems. Analytical works demonstrated that cautious processing (usually boiling) of crude aconite roots decreases the amount of normal diterpene alkaloids and increases the concentration of lipo-alkaloids resulting in the reduction of toxicity of the drugs. Many papers reported that lipo-alkaloids occur as a complex mixture in the drugs, and the isolation of the individual components is extremely difficult. These compounds have been identified using highly sensitive analytical methods (HPLC-MS, NMR), and semisynthetic approaches have been developed to ensure lipo-alkaloids in pure form for pharmacological studies. This review summarizes the structure, chemistry, semisynthesis, analytics and bioactivities of lipo-alkaloids. On the basis of 32 references this is the first comprehensive study on this topic, covering the data of 173 compounds.     

Reversible hydrogenation restores defected graphene to graphene

Graphene as a two-dimensional material is prone to hydrocarbon contaminations,which can significantly alter its intrinsic electrical properties.Herein,we implem...     

Determination of Arsenic Species in Fish Oil After Acid Digestion

Arsenic speciation is of increasing interest to the food industry, as concerns about high total arsenic concentrations in food can often be alleviated to a great extent if the ratio of toxic, less toxic and non-toxic arsenic compounds in the sample is known. The lipid matrix of fish oil is a challenge in the determination of arsenic species, as current methods for this type of analysis require the analyte to be water-soluble. In this study, two sample preparation techniques were applied. One the one hand water-soluble species were extracted with methanol/water, on the other, acid digestion was applied to release lipid-soluble arsenic compounds into the aqueous phase. Ion chromatography – inductively coupled plasma mass spectrometry (IC-ICP-MS) was used for separation and sensitive element-specific detection of arsenic compounds. Additional experiments, including alkaline hydrolysis, were carried out to find out more about the type of lipids arsenic is bound to in fish oil. Up to eight different arsenic species were detected and quantified in fish oil with dimethylarsinate being the major compound both in the aqueous extract and in the acid digest. No inorganic arsenic was detected in the aqueous extract, and the maximum concentration of arsenate determined in the acid digest was 0.05 μg g⁻¹. The total arsenic concentration determined by ICP-MS ranged from <0.1 to 5 μg g⁻¹. With regard to the mass balance, approximately 1% of the total arsenic content was extractable with methanol/water, whereas the sum of arsenic species quantified after acid digestion yielded 85–100% of the total arsenic content. It was confirmed that the large fraction of arsenic in fish oil not extractable on an aqueous basis consists of organoarsenic compounds. This new approach in sample preparation makes the complete characterization of the arsenic content in the sample possible with regard to the respective species, providing necessary information required for risk assessment.     

Controlling phase formation in solids: rational synthesis of phase separated Co@Fe2O3 heteroparticles and CoFe2O4 nanoparticles

A wet chemical approach from organometallic reactants allowed the targeted synthesis of Co@Fe(2)O(3) heterodimer and CoFe(2)O(4) ferrite nanoparticles. They display magnetic properties that are useful for magnetic MRI detection.     

Binding structure of elastase inhibitor scyptolin A

Natural bioactive compounds are of general interest to pharmaceutical research because they may be used as leads in drug development campaigns. Among them, scyptolin A and B from Scytonema hofmanni PCC 7110 are known to inhibit porcine pancreatic elastase, which in turn resembles the attractive drug target neutrophil elastase. The crystal structure of scyptolin A as bound to pancreatic elastase was solved at 2.8 A resolution. The inhibitor occupies the most prominent subsites S1 through S4 of the elastase and prevents a hydrolytic attack by covering the active center with its rigid ring structure. The observed binding structure may help to design potent elastase inhibitors.