Evaluating the use of fatty acid profiles to identify Francisella tularensis

Rapid capillary gas chromatography (GC) with flame-ionization detection was used to determine the cellular fatty acid profiles of Francisella tularensis. Two subspecies of F. tularensis, the live vaccine strain (LVS) derived from holarctica and a novicida strain Utah 112 (U112), were used to compare the extracted fatty acid methyl esters (FAMEs). A data set for the 2 subspecies was prepared using fatty acid profiles of bacteria grown on 2 types of media, Mueller-Hinton and cysteine heart agar supplemented with 5% rabbit blood (CHAB), and harvested at various time intervals (Day 1 through Day 4) with replicates prepared on different days. A total of 204 samples were analyzed. The results showed that these fatty acid quantitative profiles were unique for each of the subspecies and could be used as a fingerprint for the organism. It was determined by this rapid method that approximately 88% of the fatty acids in both the LVS and U112 strains included 6 saturated fatty acids: 10:0, 12:0, 14:0, 16:0, 18:0, and 20:0; and 4 hydroxy fatty acids 10:0 2OH, 16:0 3OH, 17:0 3OH, and 18:0 3OH. Data analysis and determination of clustering were performed by principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). Both PCA and SIMCA showed clear separation of the LVS and U112 strain and would be useful for prediction of unknowns. It was determined that the incubation time can be reduced from 48 to 24 h, and results are highly predictive for the identification of F. tularensis. In summary, analysis of FAMEs from F. tularensis subspecies LVS and U112 grown on CHAB or Mueller-Hinton media, and using a rapid GC method can provide a sensitive procedure for identification of these organisms.     

Templating core-shell particles using metal ion-chelating biosurfactants

Designer biosurfactants can be used to stabilise and functionalise interfaces.One particularly promising use is the stabilisation of oil-in-water emulsions,enab...     

A robust method for the Hiyama-type coupling of arylsiloxanes and disiloxanes with aryl halides

Palladium catalysed Hiyama-type coupling of aryl disiloxanes or aryl silanols with aryl halides in the presence of stoichiometric silver(I) oxide and catalytic TBAF allows the rapid preparation of biaryls in moderate to high yield under mild thermal or microwave irradiation conditions.     

Adsorption of well-defined fluorine-containing polymers onto poly(tetrafluoroethylene)

Adsorption of well-defined fluorinated polymers onto clinically relevant poly(tetrafluoroethylene) (PTFE) substrates offers an attractive method for modifying the surface properties of chemically inert PTFE. Reversible addition-fragmentation chain transfer (RAFT) was successfully used for synthesis of the polymers in this study: the homopolymers poly(2,3,4,5,6-pentafluorostyrene) (PFS), poly(2,2,3,3-tetrafluoropropyl acrylate) (PTFPA), and poly(2,2,3,3-tetrafluoropropyl methacrylate) (PTFPMA) as well as their block copolymers with tert-butyl acrylate ( (t)BA). Water-soluble blocks were synthesized through the hydrolysis of the t-butyl side groups of P( (t)BA) to the corresponding carboxylic acid. Adsorption of selected polymers onto PTFE from a series of solvents (methyl ethyl ketone (MEK), dimethylformamide (DMF), fluorobenzene (FB), dichloromethane (DCM)) was investigated using X-ray photoelectron spectroscopy (XPS) and sessile water drop measurements. The three homopolymers studied all adsorbed irreversibly (i.e., were not removed by washing) from organic solvents at ambient temperature. PFS displayed the highest adsorption, and was attributed to strong hydrophobic interactions. From angle-resolved XPS it was concluded that PFS became impregnated into the PTFE substrate down to depths of 100 A when using FB as a solvent. The carboxylic acid-containing block copolymers adsorbed more effectively from DMF (a good solvent for the poly(acrylic acid) block) compared to MEK. The resulting modified PTFE substrates displayed high stability with respect to desorption in aqueous solution, yet conformational changes of the adsorbed polymer resulted in a switchable hydrophobic-hydrophilic surface (in air or water, respectively). These results highlight the success of a facile and simple approach to irreversibly adsorb functional polymers to a nonfunctional fluorinated surface.     

Modification of graphene/graphene oxide with polymer brushes using controlled/living radical polymerization

Graphene nanosheets possess a range of extraordinary physical and electrical properties with enormous potential for applications in microelectronics, photonic devices, and nanocomposite materials. However, single graphene platelets tend to undergo agglomeration due to strong π–π and Van der Waals interactions, which significantly compromises the final material properties. One of the strategies to overcome this problem, and to increase graphene compatibility with a receiving polymer host matrix, is to modify graphene (or graphene oxide (GO)) with polymer brushes. The research to date can be grouped into approaches involving grafting‐from and grafting‐to techniques, and further into approaches relying on covalent or noncovalent attachment of polymer chains to the suitably modified graphene/GO. The present Highlight article describes research efforts to date in this area, focusing on the use of controlled/living radical polymerization techniques. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Hyperbranched polymers for molecular imaging: designing polymers for parahydrogen induced polarisation (PHIP)

The first hyperpolarisation of polymers using parahydrogen induced polarisation (PHIP) is reported by hydrogenation of terminal alkyne groups in a biocompatible hyperbranched polymer. Signal enhancements of 1500-fold could be obtained depending on the structure of the polymer, thus opening new potential avenues for polymeric molecular imaging.     

Combining a DS-DBR laser with QPM-DFG for mid-infrared spectroscopy

Studies into the suitability of a novel, widely tunable telecom L-band (1563?C1613?nm) digital supermode distributed Bragg reflector (DS-DBR) laser for spectroscopy in the mid-IR are presented. Light from the DS-DBR laser was mixed with 1064?nm radiation in a periodically poled lithium niobate (PPLN) crystal to generate mid-IR light by quasi phase matching difference frequency generation (QPM-DFG). The resultant continuous wave radiation covered the range 3000?C3200?cm^?1 with powers of up to 2.6???W. The use of such laser light for spectroscopic applications was illustrated by performing absorption experiments on both narrow-band and broad-band absorbers, namely methane (CH₄) and methanethiol (CH₃SH). Wavelength modulation spectroscopy (WMS) on CH₄ demonstrated that the modulation characteristics of the DS-DBR laser observed in the near-IR were transposed to the mid-IR and yielded a sensitivity of 3.1×10^?6?cm^?1?Hz^?1/2 over a 47?cm path length. In the CH₃SH spectrum, the absorption feature at 3040?cm^?1 was identified as a potential useful region for monitoring this biomarker in exhaled breath at reduced pressures.     

The influence of casting parameters on the surface morphology of PS‐b‐P4VP honeycomb films

The “breath figures” method provides an efficient and cost‐effective method to produce highly ordered honeycomb patterns in polymeric films at micrometer and sub‐micrometer dimensions. The size and regularity of the pores can be adjusted through a series of physical and chemical parameters. In this study, amphiphilic diblock copolymers, polystyrene‐block‐poly(4‐vinyl pyridine) (PS‐b‐P4VP) with different lengths of P4VP, were synthesized through Reversible Addition‐Fragmentation Chain Transfer polymerization. The honeycomb‐patterned films were prepared from these well‐defined polymers through the dynamic breath figures method. A series of physical parameters including solution concentration, flow rate, humidity of the flow, and the humidity of the casting environment, were delicately adjusted to systematically investigate their effects on the morphology of the films. These studies identified four key factors which were found to influence the formation of the pattern. No obvious effect was found on the pore size by changing the length of P4VP block. The result provides clear direction on the fabrication of PS‐b‐P4VP honeycomb‐patterned films and more broadly contributes a deeper understanding of the processes involved in the formation of honeycomb patterns. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3721–3732