Isolation and Enrichment of Pathogens with a Surface‐Modified Aluminium Chip for Raman Spectroscopic Applications

We developed a Raman‐compatible chip for isolating microorganisms from complex media. The isolation of bacteria is achieved by using antibodies as capture molecules. Due to the very specific interaction with the targets, this approach is promising for isolation of bacteria even from complex matrices such as body fluids. Our choice of capture molecules also enabled the investigation of samples containing yet unidentified bacteria, as the antibodies can capture a large variety of bacteria based on their analogue cell wall surface structures. The capability of our system is demonstrated for a broad range of different Gram‐positive and Gram‐negative germs. Subsequent identification is done by recording Raman spectra of the bacteria. Further, it is shown that classification with chemometric methods is possible.     

Poly(2‐oxazoline)‐derived Contact Biocides: Contributions to the Understanding of Antimicrobial Activity

A set of poly(2‐oxazoline)‐derived (co‐)polymers was prepared by microwave‐assisted polymerizations and acid‐mediated hydrolysis and tested for antimicrobial activity in 50 × 50 × 2 mm PP compound plates containing 5 wt% of the polymers. Antimicrobial activity against gram‐negative E. coli and P. aeruginosa as well as C. albicans depended only on the degree of hydrolysis, while antimicrobial activity against gram‐positive S. aureus was only observed for hydrolyzed poly(2‐nonyl‐2‐oxazoline)s. The surface energies of the compound plates compared to pure PP were hardly altered, and the compounds can be considered as alternatives for PP. The presence of the biocide additives at the surface of the PP compound plates could be shown by combined ATR‐IR, zeta potential, and SEM‐EDX measurements. Antimicrobial activity was maintained during double incubation as well as for lowered amounts of the biocide additive of 1% in PP compound plates.

     

A high-sensitivity ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry (UHPLC-HR-TOFMS) method for screening synthetic cannabinoids and other drugs of abuse in urine

The continuing emergence of designer drugs imposes high demands on the scope and sensitivity of toxicological drug screening procedures. An ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry (UHPLC-HR-TOFMS) method was developed for screening and simultaneous confirmation of both designer drugs and other drugs of abuse in urine samples in a single run. The method covered selected synthetic cannabinoids and cathinones, amphetamines, natural cannabinoids, opioids, cocaine and other important drugs of abuse, together with their main urinary metabolites. The database consisted of 277 compounds with molecular formula and exact monoisotopic mass; retention time was included for 192 compounds, and primary and secondary qualifier ion exact mass for 191 and 95 compounds, respectively. Following a solid-phase extraction, separation was performed by UHPLC and mass analysis by HR-TOFMS. MS, and broad-band collision-induced dissociation data were acquired at m/z range 50–700. Compound identification was based on a reverse database search with acceptance criteria for retention time, precursor ion mass accuracy, isotopic pattern and abundance of qualifier ions. Mass resolving power in spiked urine samples was on average FWHM 23,500 and mass accuracy 0.3 mDa. The mean and median cut-off concentrations determined for 75 compounds were 4.2 and 1 ng/mL, respectively. The range of cut-off concentrations for synthetic cannabinoids was 0.2–60 ng/mL and for cathinones 0.7–15 ng/mL. The method proved to combine high sensitivity and a wide scope in a manner not previously reported in drugs of abuse screening. The method’s feasibility was demonstrated with 50 authentic urine samples.

Dual Enzyme‐Responsive Capsules of Hyaluronic Acid‐block‐Poly(Lactic Acid) for Sensing Bacterial Enzymes

The synthesis of novel amphiphilic hyaluronic acid (HYA) and poly(lactic acid) (PLA) block copolymers is reported as the key element of a strategy to detect the presence of pathogenic bacterial enzymes. In addition to the formation of defined HYA‐block‐PLA assemblies, the encapsulation of fluorescent reporter dyes and the selective enzymatic degradation of the capsules by hyaluronidase and proteinase K are studied. The synthesis of the dual enzyme‐responsive HYA‐b‐PLA is carried out by copper–catalyzed Huisgen 1,3‐dipolar cycloaddition. The resulting copolymers are assembled in water to form vesicular structures, which are characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering (DLS), and fluorescence lifetime imaging microscopy (FLIM). DLS measurements show that both enzymes cause a rapid decrease in the hydrodynamic diameter of the nanocapsules. Fluorescence spectroscopy data confirm the liberation of encapsulated dye, which indicates the disintegration of the capsules and validates the concept of enzymatically triggered payload release. Finally, cytotoxicity assays confirm that the HYA‐b‐PLA nanocapsules are biocompatible with primary human dermal microvascular endothelial cells.     

Deracemization By Simultaneous Bio‐oxidative Kinetic Resolution and Stereoinversion

Deracemization, that is, the transformation of a racemate into a single product enantiomer with theoretically 100 % conversion and 100 % ee, is an appealing but also challenging option for asymmetric synthesis. Herein a novel chemo‐enzymatic deracemization concept by a cascade is described: the pathway involves two enantioselective oxidation steps and one non‐stereoselective reduction step, enabling stereoinversion and a simultaneous kinetic resolution. The concept was exemplified for the transformation of rac‐benzylisoquinolines to optically pure (S)‐berbines. The racemic substrates were transformed to optically pure products (ee>97 %) with up to 98 % conversion and up to 88 % yield of isolated product.     

Highly Luminescent and Color‐Tunable Salicylate Ionic Liquids

High quantum yields of up to 40.5 % can be achieved in salicylate‐bearing ionic liquids. A range of these ionic liquids have been synthesized and their photoluminescent properties studied in detail. The differences noted can be related back to the structure of the ionic liquid cation and possible interionic interactions. It is found that shifts of emission, particularly in the pyridinium‐based ionic liquids, can be related to cation–anion pairing interactions. Facile and controlled emission color mixing is demonstrated through combining different ILs, with emission colors ranging from blue to yellow.     

Stereocontrol in Dinuclear Triple Lithium‐Bridged Titanium(IV) Complexes: Solving Some Stereochemical Mysteries

Compounds 1 a – f ‐H₂ form “monomeric” triscatecholate titanium(IV) complexes [Ti( 1 a – f )₃]^2?, which in the presence of Li cations are in equilibrium with the triple lithium‐bridged “dimers” [Li₃(Ti( 1 a – f )₃)₂]^?. The equilibrium strongly depends on the donor ability of the solvent. Usually, in solvents with high donor ability, the stereochemically labile monomer is preferred, whereas in nondonor solvents, the dimer is the major species. In the latter, the stereochemistry at the complex units is “locked”. The configuration at the titanium(IV) triscatecholates is influenced by addition of chiral ammonium countercations. In this case, the induced stereochemical information at the monomer is transferred to the dimer. Alternatively, the configuration at the metal complexes can be controlled by enantiomerically pure ester side chains. Due to the different orientation of the ester groups in the monomer or dimer, opposite configurations of the triscatecholates were observed by circular dichroism (CD) spectroscopy for [Ti( 1 c – e )₃]^2? or [Li₃(Ti( 1 c – e )₃)₂]^?. A surprising exception was found for the dimer [Li₃(Ti( 1 f )₃)₂]^?. Herein, the dimer is the dominating species in weak donor (methanol), as well as strong donor (DMSO), solvents. This is due to the bulkiness of the ester substituent destabilizing the monomer. Due to the size of the substituent in [Li₃(Ti( 1 f )₃)₂]^? the esters have to adopt an unusual conformation in the dimer resulting in a stereocontrol of the small methyl group. Following this, opposite stereocontrol mechanisms were observed for the central metal‐complex units of [Li₃(Ti( 1 c – e )₃)₂]^? or [Li₃(Ti( 1 f )₃)₂]^?.     

Polysulfates [SnO3n+1]2−: With the [S6O19]2− Anion,has the End been Reached?

The S₆O₁₉^2? ion was obtained both as rubidium and ammonium salt from the reaction of the respective sulfate with SO₃. It is the largest polysulfate ion known to date and exhibits a chain of six vertex‐connected [SO₄] tetrahedra. The unique compound was comprehensively characterized and the bonding within the anion was elucidated by theoretical investigations.