In Vitro Microvessel Models

Lab Chip, 2015, Accepted ManuscriptDOI: 10.1039/C5LC00832H, Critical ReviewMax Bogorad, Jackson DeStefano, Johann Karlsson, Andrew Wong, Sharon Gerecht, Peter SearsonA wide range of perfusable microvessel models have been developed, exploiting advances…



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A lab-on-a-chip system integrating tissue sample preparation and multiplex RT-qPCR for gene expression analysis in point-of-care hepatotoxicity assessment

Lab Chip, 2015, Advance ArticleDOI: 10.1039/C5LC00798D, PaperGeok Soon Lim, Joseph S. Chang, Zhang Lei, Ruige Wu, Zhiping Wang, Kemi Cui, Stephen WongIn this study, we realize an integrated lab-on-a-chip system with “sample-in-answer-out” multiplex gen…



Simultaneous determination of multiple platycosides with a single reference standard in Platycodi Radix by high-performance liquid chromatography coupled with evaporative light scattering detection

A traditional external standard method using high-performance liquid chromatography coupled with evaporative light scattering detection has been developed for fast and accurate determination of seven platycosides in Platycodi Radix. However, inevitabl…



Recent advances in chemiluminescence detection coupled with capillary electrophoresis and microchip capillary electrophoresis

Capillary electrophoresis (CE) is an ideal analytical method for extremely volume limited biological microenvironments. However, the small injection volume makes it a challenge to achieve highly sensitive detection. Chemiluminescence (CL) detection is…



Development and validation of polymerized high internal phase emulsion monoliths coupled with high-performance liquid chromatography and fluorescence detection for the determination of trace tetracycline antibiotics in environmental water samples

A polymerized high internal phase emulsion monolith was used as a novel sorbent for solid-phase extraction coupled with high-performance liquid chromatography and fluorescence detection for the determination of oxytetracycline, tetracycline, doxycycli…



Highly sensitive electrochemical sensor based on β-cyclodextrin–gold@3, 4, 9, 10-perylene tetracarboxylic acid functionalized single-walled carbon nanohorns for simultaneous determination of myricetin and rutin

Publication date: Available online 1 September 2015
Source:Analytica Chimica Acta
Author(s): Xin Ran, Long Yang, Jianqiang Zhang, Guogang Deng, Yucong Li, Xiaoguang Xie, Hui Zhao, Can-Peng Li
The application of macrocyclic hosts for construction of different electrochemical devices and separation matrices has attracted much attentions due to their benign biocompatibility and simplicity of synthesis. Myricetin and rutin are considered two of the most bioactive flavonoids, which have been proved to exhibit various physiological functions. This work reports a simple and facile approach for the synthesis of β-cyclodextrin-gold@3, 4, 9, 10-perylene tetracarboxylic acid functionalized single-walled carbon nanohorns (β-CD–Au@PTCA–SWCNHs) nanohybrids. The simultaneous electrochemical determination of myricetin and rutin using a β-CD–Au@PTCA–SWCNHs-modified glassy carbon electrode was established. The results show that the β-CD–Au@PTCA–SWCNHs-modified electrode displayed electrochemical signal superior to those of Au@PTCA–;SWCNHs and SWCNHs towards myricetin and rutin. The proposed modified electrode has a linear response range of 0.01 to 10.00 μM both for myricetin and rutin with relatively low detection limits of 0.0038 μM for myricetin and 0.0044 μM (S/N=3) for rutin, respectively. The excellent performance of the sensing platform is considered to be the synergic effects of the SWCNHs (e.g. their good electrochemical properties and large surface area) and β-CD (e.g. a hydrophilic external surface, a high supramolecular recognition, and a good enrichment capability).

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Turnover Rates in Microorganisms by Laser Ablation Electrospray Ionization Mass Spectrometry and Pulse-chase Analysis

Publication date: Available online 1 September 2015
Source:Analytica Chimica Acta
Author(s): Sylwia A. Stopka, Tarek R. Mansour, Bindesh Shrestha, Éric Maréchal, Denis Falconet, Akos Vertes
Biochemical processes rely on elaborate networks containing thousands of compounds participating in thousands of reaction. Rapid turnover of diverse metabolites and lipids in an organism is an essential part of homeostasis. It affects energy production and storage, two important processes utilized in bioengineering. Conventional approaches to simultaneously quantify a large number of turnover rates in biological systems are currently not feasible. Here we show that pulse-chase analysis followed by laser ablation electrospray ionization mass spectrometry (LAESI-MS) enable the simultaneous and rapid determination of metabolic turnover rates. The incorporation of ion mobility separation (IMS) allowed an additional dimension of analysis, i.e., the detection and identification of isotopologs based on their collision cross sections. We demonstrated these capabilities by determining metabolite, lipid, and peptide turnover in the photosynthetic green algae, Chlamydomonas reinhardtii, in the presence of 15N-labeled ammonium chloride as the main nitrogen source. Following the reversal of isotope patterns in the chase phase by LAESI-IMS-MS revealed the turnover rates and half-lives for biochemical species with a wide range of natural concentrations, e.g., chlorophyll metabolites, lipids, and peptides. For example, the half-lives of lyso-DGTS(16:0) and DGTS(18:3/16:0), t1/2 = 43.6±4.5 h and 47.6±2.2 h, respectively, provided insight into lipid synthesis and degradation in this organism. Within the same experiment, half-lives for chlorophyll a, t1/2 = 24.1± 2.2 h, and a 2.8 kDa peptide, t1/2 = 10.4±3.6 h, were also determined.

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Automated on-line liquid-liquid extraction system for temporal mass spectrometric analysis of dynamic samples

Publication date: Available online 1 September 2015
Source:Analytica Chimica Acta
Author(s): Kai-Ta Hsieh, Pei-Han Liu, Pawel L. Urban
Most real samples cannot directly be infused to mass spectrometers because they could contaminate delicate parts of ion source and guides, or cause ion suppression. Conventional sample preparation procedures limit temporal resolution of analysis. We have developed an automated liquid-liquid extraction system that enables unsupervised repetitive treatment of dynamic samples and instantaneous analysis by mass spectrometry (MS). It incorporates inexpensive open-source microcontroller boards (Arduino and Netduino) to guide the extraction and analysis process. Duration of every extraction cycle is 17 minutes. The system enables monitoring of dynamic processes over many hours. The extracts are automatically transferred to the ion source incorporating a Venturi pump. Operation of the device has been characterized (repeatability, RSD = 15%, n = 20; concentration range for ibuprofen, 0.053 – 2.000 mM; LOD for ibuprofen, ∼ 0.005 mM; including extraction and detection). To exemplify its usefulness in real-world applications, we implemented this device in chemical profiling of pharmaceutical formulation dissolution process. Temporal dissolution profiles of commercial ibuprofen and acetaminophen tablets were recorded during 10 h. The extraction-MS datasets were fitted with exponential functions to characterize the rates of release of the main and auxiliary ingredients (e.g. ibuprofen, k = 0.43 ± 0.01 h-1). The electronic control unit of this system interacts with the operator via touch screen, internet, voice, and short text messages sent to the mobile phone, which is helpful when launching long-term (e.g. overnight) measurements. Due to these interactive features, the platform brings the concept of the Internet-of-Things (IoT) to the chemistry laboratory environment.

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Dried blood spot analysis without dilution: Application to the LC–MS/MS determination of BMS-986001 in rat dried blood spot

Publication date: 1 October 2015
Source:Journal of Chromatography B, Volume 1002
Author(s): Long Yuan, Alan Schuster, Jim X. Shen, Pamela Garrison-Borowski, Anne-Françoise Aubry
Sample dilution is one major challenge in dried blood spot (DBS) bioanalysis. To resolve this issue, we applied a no-dilution strategy for DBS analysis by using a calibration curve with very wide linear range. We developed an LC–MS/MS DBS assay with a linear range of 5 orders of magnitude (50–5000,000ng/mL) for BMS-986001, an HIV drug under development, by simultaneously monitoring two selective reaction monitoring transitions of different intensity. The assay was validated and successfully applied to the analysis of DBS samples collected in a toxicology study in rats dosed with BMS-986001. All samples were analyzed without any dilution. We also compared the concentration data generated from the DBS method and a validated plasma assay for the same study. The two sets of data agreed well with each other, demonstrating the validity of this strategy for DBS analysis. This approach provides an effective and convenient way to eliminate complicated dilution for DBS and other sample collection techniques.



Pharmacokinetic and protein binding profile of peptidomimetic DPP-4 inhibitor – Teneligliptin in rats using liquid chromatography–tandem mass spectrometry

Publication date: 1 October 2015
Source:Journal of Chromatography B, Volume 1002
Author(s): S. Shantikumar, N. Satheeshkumar, R. Srinivas
The aim of the present study is to explore pharmacokinetic and protein binding characteristics of a novel dipeptidylpeptidase-4 (DPP-4) inhibitor, teneligliptin in rats using an ultra high performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UHPLC–QTOF-MS). It is required for demonstrating the high protein binding nature of teneligliptin which can be extended for drug repositioning to brain disorders. Sample preparation was accomplished through a protein precipitation procedure using acetonitrile. Separation of teneligliptin and sitagliptin (IS) from endogenous components with high selectivity and sensitivity (0.5ng/mL) was achieved within 4min using Poroshell 120 EC-C18 column (100×3.0mm, 2.7μ). A gradient mobile phase consisting of 10mM ammonium formate and acetonitrile was applied at a flow rate of 0.45mL/min. Detection of target ions [M+H]+ at m/z 427.2274 for teneligliptin and m/z 408.1258 for IS was performed in selective ion mode using positive ion electrospray ionization high resolution accurate mass spectrometry. The linearity of the method was found to be in the range of 0.5–1000ng/mL. The matrix effect was 88.7–94.5% for teneligliptin. Plasma samples were found to stable under different storage conditions. It was successfully applied to pharmacokinetic and plasma protein binding study of drug in rats. Results showed linear dose proportionality of pharmacokinetics at 0.1 and 1mg/kg and relatively high protein binding of teneligliptin (85.46 ± 0.24 %) compared with other DPP-4 inhibitors.



Determination of putrescine, cadaverine, spermidine and spermine in different chemical matrices by high performance liquid chromatography–electrospray ionization–ion trap tandem mass spectrometry (HPLC–ESI–ITMS/MS)

Publication date: 1 October 2015
Source:Journal of Chromatography B, Volume 1002
Author(s): Alan Alexander González Ibarra, Katarzyna Wrobel, Alma Rosa Corrales Escobosa, Julio Cesar Torres Elguera, Ma Eugenia Garay-Sevilla, Kazimierz Wrobel
The goal of this work was to establish a simple HPLC–ESI–ITMS/MS procedure, suitable for the determination of four common aliphatic polyamines in two different types of biological matrices. To this end, 1,6-diaminohexane was used as the internal standard (IS) and 4-fluoro-3-nitrobenzenotrifluoride (FNBT) as the derivatizing agent. Formation of fully derivatized compounds was confirmed by high resolution ESI–QTOFMS and MS/MS analysis. Reversed phase chromatographic separation was carried out by gradient elution with 0.1% (v/v) formic acid and methanol. In a positive ESI mode, the following pairs of precursor/quantifier ions were used for multiple reaction monitoring: 467.4/261.0 for PUT, 481.2/461.1 for CAD, 713.7/261.0 for SPD, 959.8/507.2 for SPM and 495.3/475.2 for IS. On-column instrumental detection limits of four polyamines were in the range 0.62–2.14fmol (0.039–0.215ng/ml). Versatility was demonstrated by analyzing plant extracts and human urine; prior to derivatization, all samples were cleaned-up by dichloromethane extraction. The evaluated signal suppression/enhancement was in the range 82.3–115.4% and the percentage recoveries obtained in the method of standard addition were in the range 83.7–114.4%. Statistically significant differences in polyamines concentrations were found in garden cress exposed to Cd(II) versus control seedlings (t-test, p<0.05); results obtained for urine from healthy volunteers and diabetic patients at different clinical conditions suggested possible utility of free polyamines as biomarkers of progressive diabetes.



Hydrophilic strips for preventing air bubble formation in a microfluidic chamber

In a microfluidic chamber, unwanted formation of air bubbles is a critical problem. Here, we present a hydrophilic strip array that prevents air bubble formation in a microfluidic chamber. The array is located on the top surface of the chamber, which …



Efficient separation of tanshinones by polyvinylpyrrolidone-stabilized graphene modified micellar electrokinetic chromatography

In this work, a polyvinylpyrrolidone (PVP)-stabilized graphene was used in micellar electrokinetic chromatography (MEKC) for the separation of tanshinones. Seven structurally similar tanshinones were studied, i.e., tanshinone IIB, dihydrotanshinone I,…



Self-aligning subatmospheric hybrid liquid junction electrospray interface for capillary electrophoresis

We report a construction of a self-aligning subatmospheric hybrid liquid junction electrospray interface for capillary electrophoresis eliminating the need for manual adjustment by guiding the capillaries in a microfabricated liquid junction glass chi…



Genetic diversity and haplotype structure of 21 Y-STRs, including nine non-core loci, in South Tunisian Population: Forensic Relevance

Y chromosome short tandem repeats (Y-STRs) are being used frequently in forensic laboratories. Previous studies of Y-STR polymorphisms in different groups of the Tunisian population identified low levels of diversity and discrimination capacity using …



Multi-constituent determination and fingerprint analysis of Scutellaria indica L. using ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

An ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry method integrating multi-constituent determination and fingerprint analysis has been established for quality assessment and control of Scutellaria indi…