In-Situ Growth of Gadolinium Phthalocyaninato Sandwich Complexes on the Ag(111) Surface

We report a low-temperature scanning tunneling microscopy investigation of the in-situ growth of gadolinium phthalocyaninato complexes by combined deposition of free-base phthalocyanines and gadolinium atoms on a smooth Ag(111) substrate. A careful control of the stoichiometry allows the expression of a multilevel structurecomposed of irregularly distributed Gd_x-1(Pc)_x complexes, x=2–5, thus paving new avenues for surface-confined columnar growth.     

Chiral kagomé lattice from simple ditopic molecular bricks

Self-assembly techniques allow for the fabrication of highly organized architectures with atomic-level precision. Here, we report on molecular-level scanning tunneling microscopy observations demonstrating the supramolecular engineering of complex, regular, and long-range ordered periodic networks on a surface atomic lattice using simple linear molecular bricks. The length variation of the employed de novo synthesized linear dicarbonitrile polyphenyl molecules translates to distinct changes of the bonding motifs that lead to hierarchic order phenomena and unexpected changes of the surface tessellations. The achieved 2D organic networks range from a close-packed chevron pattern via a rhombic network to a hitherto unobserved supramolecular chiral kagomé lattice.     

On-Surface Synthesis of Polyphenylene Wires Comprising Rigid Aliphatic Bicyclo[1.1.1]Pentane Isolator Units

Bicyclo[1.1.1]pentane (BCP) motifs are of growing importance to the pharmaceutical industry as sp³-rich bioisosteres of benzene rings and as molecular building blocks in materials science. Herein we explore the behavior of 1,3-disubstituted BCP moieties on metal surfaces by combining low-temperature scanning tunneling microscopy / non-contact atomic force microscopy studies with density functional theory modeling. We examine the configuration of individual BCP-containing precursors on Au(111), their supramolecular assembly and thermally activated dehalogenative coupling reactions, affording polymeric chains with incorporated electronically isolating units. Our studies not only provide the first sub-molecular insights of the BCP scaffold behavior on surfaces, but also extend the potential application of BCP derivatives towards integration in custom-designed surface architectures.     

Continuous microfluidic DNA extraction using phase-transfer magnetophoresis

This paper reports a novel microfluidic-chip based platform using "phase-transfer magnetophoresis" enabling continuous biomolecule processing. As an example we demonstrate for the first time continuous DNA extraction from cell lysate on a microfluidic chip. After mixing bacterial Escherichia coli culture with superparamagnetic bead suspension, lysis and binding buffers, DNA is released from cells and captured by the beads. These DNA carrying beads are continuously transported across the interfaces between co-flowing laminar streams of sample mixture, washing and elution buffer. Bead actuation is achieved by applying a time-varying magnetic field generated by a rotating permanent magnet. Flagella-like chains of magnetic beads are formed and transported along the microfluidic channels by an interplay of fluid drag and periodic magnetic entrapment. The turnover time for DNA extraction was approximately 2 minutes with a sample flow rate of 0.75 μl s(-1) and an eluate flow rate of 0.35 μl s(-1). DNA recovery was 147% (on average) compared to bead based batch-wise extraction in reference tubes within a dilution series experiment over 7 orders of magnitude. The novel platform is suggested for automation of various magnetic bead based applications that require continuous sample processing, e.g. continuous DNA extraction for flow-through PCR, capture and analysis of cells and continuous immunoassays. Potential applications are seen in the field of biological safety monitoring, bioprocess control, environmental monitoring, or epidemiological studies such as monitoring the load of antibiotic resistant bacteria in waste water from hospitals.     

Identification of the major urinary metabolites in man of seven synthetic cannabinoids of the aminoalkylindole type present as adulterants in ‘herbal mixtures’ using LC‐MS/MS techniques

Herbal mixtures, such as ‘Spice’, containing cannabimimetic compounds are easily available on the Internet and have become increasingly popular among people having to undergo urine drug testing, as these compounds are not detected by current immunochemical tests. For analysis of urine samples, knowledge of the main metabolites is necessary as the unchanged compounds are usually not found in urine after consumption. In this paper, the identification of the major metabolites of the currently most common seven synthetic cannabinoids is presented. Urine samples from patients of psychiatric facilities known to have consumed synthetic cannabinoids were screened by LC‐MS/MS and HR‐MS/MS techniques, and the major metabolites for each of the following synthetic cannabinoids were identified by their enhanced product ion spectra and accurate mass measurement: JWH‐018, JWH‐073, JWH‐081, JWH‐122, JWH‐210, JWH‐250 and RCS‐4. The major metabolic pathway is monohydroxylation either at the N‐alkyl side chain, the naphthyl moiety or the indole moiety. In addition, metabolites with carboxylated alkyl chains were identified for some of the compounds. These results facilitate the design of urine screening methods for detecting consumption of synthetic cannabinoids. Copyright © 2012 John Wiley & Sons, Ltd.     

Studies on the metabolism of the Δ9‐tetrahydrocannabinol precursor Δ9‐tetrahydrocannabinolic acid A (Δ9‐THCA‐A) in rat using LC‐MS/MS,LC‐QTOF MS and GC‐MS techniques

In Cannabis sativa, Δ9‐Tetrahydrocannabinolic acid‐A (Δ9‐THCA‐A) is the non‐psychoactive precursor of Δ9‐tetrahydrocannabinol (Δ9‐THC). In fresh plant material, about 90% of the total Δ9‐THC is available as Δ9‐THCA‐A. When heated (smoked or baked), Δ9‐THCA‐A is only partially converted to Δ9‐THC and therefore, Δ9‐THCA‐A can be detected in serum and urine of cannabis consumers. The aim of the presented study was to identify the metabolites of Δ9‐THCA‐A and to examine particularly whether oral intake of Δ9‐THCA‐A leads to in vivo formation of Δ9‐THC in a rat model. After oral application of pure Δ9‐THCA‐A to rats (15 mg/kg body mass), urine samples were collected and metabolites were isolated and identified by liquid chromatography‐mass spectrometry (LC‐MS), liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) and high resolution LC‐MS using time of flight‐mass spectrometry (TOF‐MS) for accurate mass measurement. For detection of Δ9‐THC and its metabolites, urine extracts were analyzed by gas chromatography‐mass spectrometry (GC‐MS). The identified metabolites show that Δ9‐THCA‐A undergoes a hydroxylation in position 11 to 11‐hydroxy‐Δ9‐tetrahydrocannabinolic acid‐A (11‐OH‐Δ9‐THCA‐A), which is further oxidized via the intermediate aldehyde 11‐oxo‐Δ9‐THCA‐A to 11‐nor‐9‐carboxy‐Δ9‐tetrahydrocannabinolic acid‐A (Δ9‐THCA‐A‐COOH). Glucuronides of the parent compound and both main metabolites were identified in the rat urine as well. Furthermore, Δ9‐THCA‐A undergoes hydroxylation in position 8 to 8‐alpha‐ and 8‐beta‐hydroxy‐Δ9‐tetrahydrocannabinolic acid‐A, respectively, (8α‐Hydroxy‐Δ9‐THCA‐A and 8β‐Hydroxy‐Δ9‐THCA‐A, respectively) followed by dehydration. Both monohydroxylated metabolites were further oxidized to their bishydroxylated forms. Several glucuronidation conjugates of these metabolites were identified. In vivo conversion of Δ9‐THCA‐A to Δ9‐THC was not observed. Copyright © 2009 John Wiley & Sons, Ltd.     

LC‐MS/MS analysis of Δ9‐tetrahydrocannabinolic acid A in serum after protein precipitation using an in‐house synthesized deuterated internal standard

An assay based on liquid chromatography/tandem mass spectrometry is presented for the fast, precise and sensitive quantitation of Δ9‐tetrahydrocannabinolic acid A (THCA) in serum. THCA is the biogenetic precursor of Δ9‐tetrahydrocannabinol in cannabis and has aroused interest in the pharmacological and forensic field especially as a potential marker for recent cannabis use. After addition of deuterated THCA, synthesized from D₃‐THC as starting material, and protein precipitation, the analytes were separated using gradient elution on a Luna C18 column (150 × 2.0 mm × 5 µm) with 0.1% formic acid and acetonitrile/0.1% formic acid. Data acquisition was performed on a triple quadrupole linear ion trap mass spectrometer in multiple reaction monitoring mode with negative electrospray ionization. After optimization, the following sample preparation procedure was used: 200 μL serum was spiked with internal standard solution and methanol and then precipitated ‘in fractions’ with 500 μL ice‐cold acetonitrile. After storage and centrifugation, the supernatant was evaporated and the residue redissolved in mobile phase. The assay was fully validated according to international guidelines including, for the first time, the assessment of matrix effects and stability experiments. Limit of detection was 0.1 ng/mL, and limit of quantification was 1.0 ng/mL. The method was found to be selective and proved to be linear over a range of 1.0 to 100 ng/mL using a 1/x weighted calibration model with regression coefficients >0.9996. Accuracy and precision data were within the required limits (RSD ≤ 8.6%, bias: 2.4 to 11.4%), extractive yield was greater than 84%. The analytes were stable in serum samples after three freeze/thaw cycles and storage at ?20 °C for one month. Copyright © 2012 John Wiley & Sons, Ltd.     

A comprehensive library‐based,automated screening procedure for 46 synthetic cannabinoids in serum employing liquid chromatography‐quadrupole ion trap mass spectrometry with high‐temperature electrospray ionization

Considering the vast variety of synthetic cannabinoids and herbal mixtures – commonly known as ‘Spice’ or ‘K2’ – on the market and the resulting increase of severe intoxications related to their consumption, there is a need in clinical and forensic toxicology for comprehensive up‐to‐date screening methods. The focus of this project aimed at developing and implementing an automated screening procedure for the detection of synthetic cannabinoids in serum using a liquid chromatography‐ion trap‐MS (LC‐MSⁿ) system and a spectra library‐based approach, currently including 46 synthetic cannabinoids and 8 isotope labelled analogues. In the process of method development, a high‐temperature ESI source (IonBooster^TM, Bruker Daltonik) and its effects on the ionization efficiency of the investigated synthetic cannabinoids were evaluated and compared to a conventional ESI source. Despite their structural diversity, all investigated synthetic cannabinoids benefitted from high‐temperature ionization by showing remarkably higher MS intensities compared to conventional ESI. The employed search algorithm matches retention time, MS and MS²/MS³ spectra. With the utilization of the ionBooster source, limits for the automated detection comparable to cut‐off values of routine MRM methods were achieved for the majority of analytes. Even compounds not identified when using a conventional ESI source were detected using the ionBooster‐source. LODs in serum range from 0.1 ng/ml to 0.5 ng/ml. The use of parent compounds as analytical targets offers the possibility of instantly adding new emerging compounds to the library and immediately applying the updated method to serum samples, allowing the rapid adaptation of the screening method to ongoing forensic or clinical requirements. The presented approach can also be applied to other specimens, such as oral fluid or hair, and herbal mixtures and was successfully applied to authentic serum samples. Quantitative MRM results of samples with analyte concentrations above the determined LOD were confirmed as positive findings by the presented method. Copyright © 2014 John Wiley & Sons, Ltd.     

Orthogonal Insertion of Lanthanide and Transition‐Metal Atoms in Metal–Organic Networks on Surfaces

The orthogonal coordinative properties of tetrapyrrole macrocycles and nitrile ligands have been used in a multistep procedure towards interfacial d‐f hetero‐bimetallic nanoarchitectures based on a free‐base porphyrin derivative functionalized with meso‐cyanobiphenylene substituents. Molecular‐level scanning tunneling microscopy studies reveal that the porphyrin module alone self‐assembles on Ag(111) in a close‐packed layer with a square unit cell. Upon co‐deposition of Gd atoms, a square‐planar motif is formed that reflects the fourfold coordination of CN ligands to the rare‐earth centers. The resulting nanoporous network morphology is retained following exposure to a beam of Co atoms, which induces selective porphyrin metalation and ultimately yields a gridlike 2D metallosupramolecular architecture.