A Novel UHPLC-MS/MS Method for the Quantification of Seven Opioids in Different Human Tissues.

Background: Opioids are considered the cornerstone of pain management: they show good efficacy as a first-line therapy for moderate to severe cancer pain. Since pharmacokinetic/pharmacodynamic information about the tissue-specific effect and toxicity of opioids is still scarce, their quantification in post-mortem autoptic specimens could give interesting insights.

Methods: We describe an ultra-high-performance liquid chromatography coupled with tandem mass spectrometry method for the simultaneous quantification of methadone, morphine, oxycodone, hydrocodone, oxymorphone, hydromorphone and fentanyl in several tissues: liver, brain, kidney, abdominal adipose tissue, lung and blood plasma.

An ultrahigh-resolution soft x-ray microscope for quantitative analysis of chemically heterogeneous nanomaterials.

The analysis of chemical states and morphology in nanomaterials is central to many areas of science. We address this need with an ultrahigh-resolution scanning transmission soft x-ray microscope. Our instrument provides multiple analysis tools in a compact assembly and can achieve few-nanometer spatial resolution and high chemical sensitivity via x-ray ptychography and conventional scanning microscopy.

Switchable resolution in soft x-ray tomography of single cells.

The diversity of living cells, in both size and internal complexity, calls for imaging methods with adaptable spatial resolution. Soft x-ray tomography (SXT) is a three-dimensional imaging technique ideally suited to visualizing and quantifying the internal organization of single cells of varying sizes in a near-native state. The achievable resolution of the soft x-ray microscope is largely determined by the objective lens, but switching between objectives is extremely time-consuming and typically undertaken only during microscope maintenance procedures.

Piezoelectric polymer multilayer on flexible substrate for energy harvesting.

A piezoelectric polymer multilayer structure formed on a flexible substrate is investigated for mechanical energy harvesting under bending mode. Analytical and numerical models are developed to clarify the effect of material parameters critical to the energy harvesting performance of the bending multilayer structure. It is shown that the maximum power is proportional to the square of the piezoelectric stress coefficient and the inverse of dielectric permittivity of the piezoelectric polymer.

Miniaturized acceleration sensors with in-plane polarized piezoelectric thin films produced by micromachining.

Miniaturized acceleration sensors employing piezoelectric thin films were fabricated through batch micromachining with silicon and silicon-on-insulator (SOI) wafers. The acceleration sensors comprised multiple suspension beams supporting a central seismic mass. Ferroelectric (Pb,La)(Zr,Ti) O(3) (PLZT) thin films were coated and in-plane polarized on the surfaces of the suspension beams for realizing electromechanical conversion through the piezoelectric effect.

Isolation and identification of thiohomosildenafil and thiosildenafil in health supplements.

Two unknown compounds are detected and isolated from health supplements for the enhancement of sexual function. The structures of the unknown compounds are elucidated using high-resolution MS, ESI-MS/MS, NMR, UV and IR. One compound is identified as an analogue of sildenafil in which the oxygen atom is substituted with a sulfur atom in the pyrazolopyrimidine moiety, and an ethyl group instead of a methyl group is attached to the piperazinyl nitrogen.

Identification of benzamidenafil, a new class of phosphodiesterase-5 inhibitor, as an adulterant in a dietary supplement.

A sample labeled to be a natural herbal supplement for the enhancement of sexual function, was sent to Health Sciences Authority (HSA) of Singapore for testing. An unknown compound was detected and isolated from the product. The structure of the unknown compound was identified using LC-UV, high-resolution MS, ESI-MS/MS, IR, and NMR.

Liquid chromatography ion trap/time-of-flight mass spectrometric study on the fragmentation of an acetildenafil analogue.

Liquid chromatography ion-trap time-of-flight mass spectrometry was employed to elucidate the fragmentation pathways of an analogue of acetildenafil. Based on the accurate masses of the parent ion, product ions and neutral losses of acetildenafil analogue, its fragmentation pathways were proposed. The information is useful for the on-line structural identification of unknown analogues of acetildenafil found as adulterants in herbal products.

Detection of dehydroepiandrosterone and androsterone in a traditional Chinese herbal product.

Dehydroepiandrosterone (DHEA) and androsterone (ADT) were detected in a traditional Chinese herbal product by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS). DHEA and ADT were tentatively identified by comparing their electron ionization (EI) mass spectra with those in the GC-MS Wiley database. A multiple reaction monitoring (MRM) scan was performed in LC-MS/MS to confirm the presence of the DHEA and ADT in the herbal product extract.

Detection of sildenafil analogues in herbal products for erectile dysfunction.

Sildenafil, the active ingredient in Viagra (Pfizer), is a prescription medicine used for erectile dysfunction. Compounds with chemical structures similar to that of sildenafil were isolated and purified during the analysis of some herbal products marketed for treatment of erectile dysfunction. Structural elucidation using liquid chromatography-diode array detection, infrared spectroscopy, liquid chromatography-tandem mass spectrometry, and nuclear magnetic resonance spectroscopy confirmed that the compounds were homosildenafil, hydroxyhomosildenafil, and acetildenafil.

Ultra fast miniaturized real-time PCR: 40 cycles in less than six minutes.

We have designed, fabricated and tested a real-time PCR chip capable of conducting one thermal cycle in 8.5 s. This corresponds to 40 cycles of PCR in 5 min and 40 s.

Simultaneous determination of synthetic phosphodiesterase-5 inhibitors found in a dietary supplement and pre-mixed bulk powders for dietary supplements using high-performance liquid chromatography with diode array detection and liquid chromatography-electrospray ionization tandem mass spectrometry.

A high-performance liquid chromatography-diode array detection (HPLC-DAD) method and a liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method were developed to screen for the presence of synthetic phosphodiesterase-5 (PDE-5) inhibitors and their analogues, namely sildenafil, vardenafil, tadalafil, homosildenafil, acetildenafil and hydroxyhomosildenafil. The methods were applied to pre-market samples submitted to the Health Sciences Authority of Singapore (HSA) for testing. One sample was in the form of capsules while six other samples were pre-mixed bulk powder samples for dietary supplements to be repackaged or formulated into the final dosage forms (usually capsules).

The nature of the gecko lizard adhesive force.

The extraordinary climbing skills of gecko lizards have been under investigation for a long time. Here we report results of direct measurement of single spatula forces in air with varying relative humidities and in water, by the force-distance method using an atomic force microscope. We have found that the presence of water strongly affects the adhesion force and from analysis of our results, we have demonstrated that the dominant force involved is the capillary force.