1H NMR metabolite fingerprinting as a new tool for body fluid identification in forensic science

In this feasibility study, we propose, for the first time, ¹H NMR spectroscopy coupled with mathematical strategies as a valid tool for body fluid (BF) trace identification in forensic science. In order to assess the ability of this approach to identify traces composed either by a single or by two different BFs, samples of blood, urine, saliva, and semen were collected from different donors, and binary mixtures were prepared. ¹H NMR analyses were carried out for all samples. Spectral data of the whole set were firstly submitted to unsupervised principal component analysis (PCA); it showed that samples of the same BF cluster well on the basis of their characterizing molecular components and that mixtures exhibit intermediate characteristics among BF typologies. Furthermore, samples were divided into a training set and a test set. An average NMR spectral profile for each typology of BF was obtained from the training set and validated as representative of each BF class. Finally, a fitting procedure, based on a system of linear equations with the four obtained average spectral profiles, was applied to the test set and the mixture samples; it showed that BFs can be unambiguously identified, even as components of a mixture. The successful use of this mathematical procedure has the advantage, in forensics, of overcoming bias due to the analyst's personal judgment. We therefore propose this combined approach as a valid, fast, and non‐destructive tool for addressing the challenges in the identification of composite traces in forensics. Copyright © 2013 John Wiley & Sons, Ltd.     

High field NMR,a powerful new analytical tool

The use of high fields in NMR spectroscopy can result in extra fine structure in the spectrum as a consequence of alignment of the molecules by the magnetic field of the spectrometer. The new information available provides a powerful tool in the analysis of structure and interactions of molecules in liquid solution.     

79Br NMR spectroscopy as a practical tool for kinetic analysis

⁷⁹Br NMR spectroscopy has been used to monitor a series of reactions in which the bromide ion is produced, including the Menschutkin reaction of pyridine with a range of substituted benzyl bromides and a Heck coupling process. In cases where the process could also be monitored using ¹H NMR spectroscopy, the kinetic analyses using heteronuclear magnetic resonance spectroscopy were shown to be completely consistent. Both the utility of the process in following reactions which may be difficult to analyse using other techniques and the practical limitations associated with solvent choice are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Calculated NMR as a tool for structural elucidation of jungianol and mutisianthol

Theoretical methods were used for the correct structure assignments of the natural products jungianol and mutisianthol. A three stage protocol for the calculation was used: a conformational search using molecular mechanics (MM3), a DFT (B3LYP) structure optimization and ab initio (HF/GIAO) or DFT (B3LYP/GIAO) calculation of magnetic properties.     

Gas—phase high resolution NMR as a potential tool for conformational studies

Gas—phase high resolution NMR is a potentially useful new tool for the study of rotational isomerism. The methods of measurement are explained, with the care necessary for sample preparations. The main areas of application at present are a) dynamic NMR study of conformational interconversion processes and b) conformational analysis for populations and energies through coupling constants. For the latter, our recent results on 1,2-disubstituted propanes such as 1,2-dichloropropane, 1,2-di(methoxy-d₃)propane and 1-methoxy-2-propanol are discussed.     

13C NMR as a general tool for the assignment of absolute configuration

(13)C NMR, alone or in combination with (1)H NMR, allows the assignment of the absolute configuration of chiral alcohols, amines, carboxylic acids, thiols, cyanohydrins, sec,sec-diols and sec,sec-aminoalcohols, derivatized with appropriate chiral auxiliaries. This extends the assignment possibilities of NMR to fully deuterated and to nonproton containing compounds.     

Mass spectrometry imaging as a tool for surgical decision‐making

Despite significant advances in image‐guided therapy, surgeons are still too often left with uncertainty when deciding to remove tissue. This binary decision between removing and leaving tissue during surgery implies that the surgeon should be able to distinguish tumor from healthy tissue. In neurosurgery, current image‐guidance approaches such as magnetic resonance imaging (MRI) combined with neuronavigation offer a map as to where the tumor should be, but the only definitive method to characterize the tissue at stake is histopathology. Although extremely valuable information is derived from this gold standard approach, it is limited to very few samples during surgery and is not practically used for the delineation of tumor margins. The development and implementation of faster, comprehensive, and complementary approaches for tissue characterization are required to support surgical decision‐making – an incremental and iterative process with tumor removed in multiple and often minute biopsies. The development of atmospheric pressure ionization sources makes it possible to analyze tissue specimens with little to no sample preparation. Here, we highlight the value of desorption electrospray ionization as one of many available approaches for the analysis of surgical tissue. Twelve surgical samples resected from a patient during surgery were analyzed and diagnosed as glioblastoma tumor or necrotic tissue by standard histopathology, and mass spectrometry results were further correlated to histopathology for critical validation of the approach. The use of a robust statistical approach reiterated results from the qualitative detection of potential biomarkers of these tissue types. The correlation of the mass spectrometry and histopathology results to MRI brings significant insight into tumor presentation that could not only serve to guide tumor resection, but that is also worthy of more detailed studies on our understanding of tumor presentation on MRI. Copyright © 2013 John Wiley & Sons, Ltd.     

Swallow-tailed perylene derivative: a new tool for fluorescent imaging of lipid hydroperoxides

A swallow-tailed perylene derivative including a triphenylphosphine moiety was synthesized and applied to the detection and the live-cell imaging of lipid hydroperoxides. The novel probe, named Spy-LHP, reacted rapidly and quantitatively with lipid hydroperoxides to form the corresponding oxide, Spy-LHPOx, which emits extremely strong fluorescence (Phi approximately 1) in the visible range (lambda(em) = 535 nm, 574 nm). Spy-LHP was highly selective for lipid hydroperoxides, and the addition of other reactive oxygen species (ROS) including hydrogen peroxides, hydroxyl radical, superoxide anion, nitric oxide, peroxynitrite, and alkylperoxyl radical, caused no significant increase in the fluorescence intensity. The probe exhibited good localization to cellular membranes and was successfully applied to the confocal laser scanning microscopy (CLSM) imaging of lipid hydroperoxides in live J774A.1 cells, in which lipid peroxidation was proceeded by the stimulation of 2,2-azobis(2-amidinopropane)dihydrochloride (AAPH). These findings establish Spy-LHP as a promising new tool for investigating the physiology of lipid hydroperoxides.     

Dilatometry as a tool to study a new synthesis for calcium hexaluminate

By using a wet chemical route, pure calcium hexaluminate (CA₆) was yielded, significantly lowering the reaction temperature and shortening the synthesis time if compared to usual industrial procedures. owever, dilatometric studies performed on compacts made of the as-prepared powder, just after pre-heating at 450°C, has shown a superposition between sintering shrinkage and expansion related to CA₂ formation, an intermediate phase formed during calcination and phase evolution to CA₆. oupling of such opposite phenomena led to microcracking of the material, mainly if the heating rates (10°C min^-1) were high. However, lower heating rates (1-5°C min^-1) could quite avoid microcracking but also limit densification. This revised version was published online in July 2006 with corrections to the Cover Date.     

Affinity capillary electrophoresis with a DNA-nanoparticle conjugate as a new tool for genotyping

We have developed a novel method for genotyping based on free solution affinity capillary electrophoresis. We prepared DNA-nanoparticle conjugates by mixing biotin-modified DNA and NeutrAvidin-modified polystyrene nanoparticles; this mixture was then injected into a capillary. Subsequently, we injected the fluorescent-labeled sample DNAs into the capillary, applied the voltage, increased its temperature after 7 min, and detected the fluorescence at its anodic end. This novel method was applied for genotyping human c-K-ras, and the three genotypes were definitely distinguishable with high reproducibility. This method can be easily automated, and it is useful for high-throughput gene mutation analysis.     

Silicon-29 diffusion-ordered NMR spectroscopy (DOSY) as a tool for studying aqueous silicates

The first use of silicon-29 diffusion-ordered NMR spectroscopy (DOSY) is reported, in a study of the speciation of aqueous silicates.     

1H-Detected 13C photo-CIDNP as a sensitivity enhancement tool in solution NMR

NMR is a powerful yet intrinsically insensitive technique. The applicability of NMR to chemical and biological systems would be substantially extended by new approaches going beyond current signal-to-noise capabilities. Here, we exploit the large enhancements arising from (13)C photochemically induced dynamic nuclear polarization ((13)C photo-CIDNP) in solution to improve biomolecular NMR sensitivity in the context of heteronuclear correlation spectroscopy. The (13)C-PRINT pulse sequence presented here involves an initial (13)C nuclear spin polarization via photo-CIDNP followed by conversion to anti-phase coherence and transfer to (1)H for detection. We observe substantial enhancements, up to ?200-fold, relative to the dark (laser off) experiment. Resonances of both side-chain and backbone CH pairs are enhanced for the three aromatic residues Trp, His, and Tyr, the σ(32) peptide, and the drkN SH3 protein. The sensitivity of this experiment, defined as signal-to-noise per square root of unit time (S/N)(t), is unprecedented in the NMR polarization enhancement literature dealing with polypeptides in solution. Up to a 16-fold larger (S/N)(t) than for the (1)H-(13)C SE-HSQC reference sequence is achieved, for the σ(32) peptide. Data collection time is reduced up to 256-fold, highlighting the advantages of (1)H-detected (13)C photo-CIDNP in solution NMR.     

Weakly oriented liquid-crystal NMR solvents as a general tool to determine relative configurations

A new NMR method to determine the relative configuration of asymmetric centres is presented. It proceeds through the use of a weakly ordered solvent and the measurement of orientational order parameters. The method is illustrated by using dihydropyridone derivatives for which the orientations and the relative configurations of the asymmetric carbon atoms are determined unambiguously.     

Reversible Michael addition of thiols as a new tool for dynamic combinatorial chemistry

The Michael addition of thiols to enones is reported as a new method for dynamic combinatorial library synthesis.     

A near-infrared fluorescent calcium probe: a new tool for intracellular multicolour Ca2+ imaging

We report a novel near-infrared fluorescent calcium probe (KFCA), which has good optical properties such as intense NIR fluorescence emission (670 nm, QY: 0.24), excellent ON/OFF ratio (120-fold), and good wavelength-compatibility with visible-light-emissive fluorophores (Fluo-4, DsRed2), and which is applicable for real-time dual-colour intracellular Ca(2+) imaging.     

Manipulation of the director in bicellar mesophases by sample spinning: a new tool for NMR spectroscopy.

It is shown that bicellar nematic liquid-crystalline phases can be oriented with the director (the normal to the bicellar plane) at an arbitrary angle to the applied magnetic field by sample rotation around one axis (variable-angle sample spinning) or around two axes successively (switched-angle spinning). This promises to open novel possibilities for NMR studies of bicelles and proteins incorporated into bicelles or dissolved in a solution containing bicelles, including the correlation of several orientations in a two-dimensional NMR experiment.