Name: an intestine/liver microphysiological system for drug pharmacokinetic and toxicological assessment
Uploaded: 2020-12-03T12:30:00
Description: Watch this Scientific Journal Video about An Intestine/Liver Microphysiological System for Drug Pharmacokinetic and Toxicological Assessment at JoVE.com

We thanks to Dr. Christie Guguen-Guillouzo, Dr. Philippe Gripon at Unit 522 INSERM and to Dr. Christian Trepo at Unit 271 INSERM for the use of the Biological Material (Hepa RG cells) and for making then available for us in order to perform the academic research.

1. Production of tissue equivalents for cultivation in the 2-OC
<ol>
	<li>Small intestine barrier equivalent production
	<ol>
		<li>Maintain Caco-2 and HT-29 cells using the intestine equivalent medium: DMEM supplemented with 10% FBS, 1% penicillin and streptomycin, and 1% non-essential amino acids, which is named as &#8220;DMEM S&#8221; in this manuscript.</li>
		<li>Remove the medium, wash twice with 1x DPBS and add 8 mL of 0.25% Trypsin/EDTA to dissociate Caco-2 cells grown in cell culture flasks (175 cm2...

<ol>
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The accurate and reliable assessment of the pharmacologic properties of investigative new drugs is critical for reducing the risk in the following development steps. The MPS is a relatively new technology, that aims at improving the predictive power and reducing the costs and time spent with preclinical tests. Our group is advancing in the assessment of pharmacokinetic and toxicological properties mostly needed for lead optimization. We worked with the 2-OC microfluidic device, which has two chambers, allowing the integr...

Due to genomic and proteomic differences, animal models have limited predictive value for several human outcomes. Moreover, they are time-consuming, expensive and ethically questionable1. MPS is a relatively new technology that aims at improving the predictive power and reduce the costs and time spent with pre-clinical tests. They are microfluidic devices cultivating organoids (artificial mimetics functional units of organs) under media flow that promotes organoid-organoid communication. Organoids made of human cells increase translational relevance2,3,4. MPS is expected to perform better than the animal tests because they are genetically human and recapitulate the interplay among tissues. When fully functional, the MPS will provide more meaningful results, at higher speed and lower costs and risks4. Many groups are developing MPS for several purposes, especially disease models to tests drug&#8217;s efficacy.
Exposure level is one of the most critical parameters for evaluating drug efficacy and toxicity5,6,7,8,9,10,11,12. MPS allows organoid integration that emulates systemic exposure and is expected to perform better than the traditional 2D human tissue culture. This technology can significantly improve the prediction of compound intestinal absorption and liver metabolism4.
An MPS integrating human equivalent model of intestine and liver is a good starting point, considering the central role of these two organs in drug bioavailability and systemic exposure13,14,15. APAP is an attractive drug for studying an MPS without a kidney equivalent because its metabolization is done mainly by the liver16,17.
The 2-OC is a two-chamber microfluidic device suitable for the culture of two different human equivalent tissues/organoids interconnected by microchannels16. In order to emulate an in vitro human oral/intravenous administration of a drug and assess the effects of the cross-talk between the intestine and liver equivalents on APAP pharmacokinetics, besides the organoids functionality and viability, three different MPS assemblies were performed: (1) an &#8220;Intestine 2-OC MPS&#8221; comprised of an intestine equivalent based in a culture insert containing a Caco-2 + HT-29 cells coculture, integrated into the 2-OC device; (2) a &#8220;Liver 2-OC MPS&#8221; comprised of liver spheroids made of HepaRG + HHSteC (Human Hepatic Stellate Cells) integrated in the 2-OC device; and (3) an &#8220;Intestine/Liver 2-OC MPS&#8221; comprised of the intestine equivalent in one device compartment communicating with the liver equivalent in the other by the media flow through&#160;the microfluidic channels.
All assays were performed under static (no flow) and dynamic (with flow) conditions due to the impact of the mechanical stimuli (compression, stretching, and shear) on the cell viability and functionalities18,19,20. The present article describes the protocol for APAP oral/intravenous administration emulation and the respective absorption/metabolism and toxicological analyses in the 2-OC MPS containing human intestine and liver equivalent models.

<table>
	<tbody>
		<tr>
			<td>1x DPBS</td>
			<td>Thermo Fisher Scientific</td>
			<td>14190235</td>
			<td>No calcium, no magnesium</td>
		</tr>
		<tr>
			<td>2-OC</td>
			<td>TissUse GmbH</td>
			<td></td>
			<td>Two-organ chip</td>
		</tr>
		<tr>
			<td>384-well Spheroid Microplate</td>
			<td>Corning</td>
			<td>3830</td>
			<td>Black/Clear, Round Bottom, Ultra-Low Attachment</td>
		</tr>
		<tr>
			<td>4% Paraformaldehyde</td>
			<td></td>
			<td></td>
			<td>Use to fix cell</td>
		</tr>
		<tr>
			<td>Acetaminophen</td>
			<td>Sigma Aldrich</td>
			<td>A7085</td>
			<td>Use to MPS assays</td>
		</tr>
		<tr>
			<td>Acetonitrile</td>
			<td>Tedia</td>
			<td></td>
			<td>Used to perform HPLC</td>
		</tr>
		<tr>
			<td>Alexa Fluor 647 phalloidin</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td>confocal experiment</td>
		</tr>
		<tr>
			<td>Ammonium acetate</td>
			<td>Sigma Aldrich</td>
			<td></td>
			<td>Used to perform HPLC</td>
		</tr>
		<tr>
			<td>Caco-2 cells</td>
			<td>Sigma Aldrich</td>
			<td>86010202</td>
			<td></td>
		</tr>
		<tr>
			<td>Cacodylate buffer</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cell culture flasks</td>
			<td>Sarstedt</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Confocal Fluorescence microscope</td>
			<td>Leica</td>
			<td>DMI6000</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryostat</td>
			<td>Leica</td>
			<td>CM1950</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM high glucose</td>
			<td>Thermo Fisher Scientific</td>
			<td>12800017</td>
			<td>Add supplements: 10% fetal bovine serum, 100 units per mL penicillin, 100 &#181;g/mL streptomycin, and 1% non-essential amino acids</td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Sigma Aldrich</td>
			<td>D4540</td>
			<td>Add 2% to HepaRG media</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Synth</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Thermo Fisher Scientific</td>
			<td>12657029</td>
			<td></td>
		</tr>
		<tr>
			<td>Freezing medium OCT</td>
			<td>Tissue-Tek</td>
			<td></td>
			<td>Tissue-Tek&#174; O.C.T.&#8482; Compound is a formulation of watersoluble glycols and resins, providing a convenient specimen matrix for cryostat sectioning at temperatures of -10&#176;C and below.</td>
		</tr>
		<tr>
			<td>Hematoxylin &#38; Eosin</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>HepaRG cells</td>
			<td>Biopredic International</td>
			<td>HPR101</td>
			<td>Undifferentiated cells</td>
		</tr>
		<tr>
			<td>HHSTeC</td>
			<td>ScienCell Research Laboratories</td>
			<td>5300</td>
			<td>Cells and all culture supplements</td>
		</tr>
		<tr>
			<td>Hoechst 33342</td>
			<td></td>
			<td></td>
			<td>HCA experiments</td>
		</tr>
		<tr>
			<td>HT-29 cells</td>
			<td>Sigma Aldrich</td>
			<td>85061109</td>
			<td></td>
		</tr>
		<tr>
			<td>Human Insulin</td>
			<td>Invitrogen - Thermo Fisher Scientific</td>
			<td>12585014</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrocortisone</td>
			<td>Sigma Aldrich</td>
			<td>H0888</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropanol</td>
			<td>Merck</td>
			<td>278475</td>
			<td></td>
		</tr>
		<tr>
			<td>Karnovsky&#8217;s fixative</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>L-glutamine</td>
			<td>Thermo Fisher Scientific</td>
			<td>A2916801</td>
			<td></td>
		</tr>
		<tr>
			<td>Luna C18 guard column SS</td>
			<td>Phenomenex</td>
			<td></td>
			<td>Used to perform HPLC</td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Leica</td>
			<td>DMi4000</td>
			<td></td>
		</tr>
		<tr>
			<td>Microtome</td>
			<td>Leica</td>
			<td>RM2245</td>
			<td></td>
		</tr>
		<tr>
			<td>Millicell 0.4 &#181;m pore size inserts</td>
			<td>Merck</td>
			<td>PIHP01250</td>
			<td></td>
		</tr>
		<tr>
			<td>Millicell ERS-2 meter</td>
			<td>Merck</td>
			<td>MERS00002</td>
			<td>Used to TEER measurement</td>
		</tr>
		<tr>
			<td>MitoTracker Deep Red</td>
			<td></td>
			<td></td>
			<td>HCA experiments</td>
		</tr>
		<tr>
			<td>MTT</td>
			<td>Thermo Fisher Scientific</td>
			<td>M6494</td>
			<td></td>
		</tr>
		<tr>
			<td>MX3000P system</td>
			<td>Agilent Technologies</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Neubauer chamber</td>
			<td></td>
			<td></td>
			<td>Counting cells</td>
		</tr>
		<tr>
			<td>Operetta High Content Imaging System</td>
			<td>Perkin Elmer</td>
			<td></td>
			<td>Used to perform HCA</td>
		</tr>
		<tr>
			<td>P450-Glo CYP3A4 Assay with Luciferin-IPA</td>
			<td>Promega</td>
			<td>Cat.# V9001</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin</td>
			<td>Thermo Fisher Scientific</td>
			<td>15070063</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Permount</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td>Histology</td>
		</tr>
		<tr>
			<td>Primers</td>
			<td></td>
			<td></td>
			<td>RT-qPCR</td>
		</tr>
		<tr>
			<td>PVDF membrane</td>
			<td>BioRad</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PVDF Syringe filter</td>
			<td></td>
			<td></td>
			<td>0.22 &#956;m pore size</td>
		</tr>
		<tr>
			<td>Reversed-phase Luna C18 column</td>
			<td>Phenomenex</td>
			<td></td>
			<td>Used to perform HPLC</td>
		</tr>
		<tr>
			<td>Shaker (IKA VXR Basic Vibrax)</td>
			<td>IKA Works GmbH &#38; Co</td>
			<td>2819000</td>
			<td>Used for spheroids to improve MTT assay</td>
		</tr>
		<tr>
			<td>Stellate Cell Media (STeC CM)</td>
			<td>ScienCell</td>
			<td>5301</td>
			<td>Add STeC CM supplements</td>
		</tr>
		<tr>
			<td>SuperScriptIITM Reverse Transcriptase</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SYBR Green PCR Master Mix</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TRizol TM reagent</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td>Trizol is a monophasic solution of phenol and guanidine isothiocyanate.</td>
		</tr>
		<tr>
			<td>Trypsin/EDTA solution</td>
			<td>Thermo Fisher Scientific</td>
			<td>R001100</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra-low-attachment plates</td>
			<td>Corning</td>
			<td>CLS3471-24EA</td>
			<td>6 wells</td>
		</tr>
		<tr>
			<td>Vectashield plus DAPI mounting media</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>White Opaque 96-well Microplate</td>
			<td>PerkinHelmer</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Wide-bore tips</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Williams E</td>
			<td>Pan Biotech</td>
			<td>P04-29510</td>
			<td>Add supplements: 10% fetal bovine serum, 2 mM L-glutamine, 100 units per ml penicillin, 100 &#181;g/mL streptomycin and 5 &#181;g/mL human insulin</td>
		</tr>
	</tbody>
</table>

an intestine/liver microphysiological system for drug pharmacokinetic and toxicological assessment

The recently introduced microphysiological systems (MPS) cultivating human organoids are expected to perform better than animals in the preclinical tests phase of drug developing process because they are genetically human and recapitulate the interplay among tissues. In this study, the human intestinal barrier (emulated by a co-culture of Caco-2 and HT-29 cells) and the liver equivalent (emulated by spheroids made of differentiated HepaRG cells and human hepatic stellate cells) were integrated into a two-organ chip (2-OC) microfluidic device to assess some acetaminophen (APAP) pharmacokinetic (PK) and toxicological properties. The MPS had three assemblies: Intestine only 2-OC, Liver only 2-OC, and Intestine/Liver 2-OC with the same media perfusing both organoids. For PK assessments, we dosed the APAP in the media at preset timepoints after administering it either over the intestinal barrier (emulating the oral route) or in the media (emulating the intravenous route), at 12 &#181;M and 2 &#181;M respectively. The media samples were analyzed by reversed-phase high-pressure liquid chromatography (HPLC). Organoids were analyzed for gene expression, for TEER values, for protein expression and activity, and then collected, fixed, and submitted to a set of morphological evaluations. The MTT technique performed well in assessing the organoid viability, but the high content analyses (HCA) were able to detect very early toxic events in response to APAP treatment. We verified that the media flow does not significantly affect the APAP absorption whereas it significantly improves the liver equivalent functionality. The APAP human intestinal absorption and hepatic metabolism could be emulated in the MPS. The association between MPS data and in silico modeling has great potential to improve the predictability of the in vitro methods and provide better accuracy than animal models in pharmacokinetic and toxicological studies.

To perform the PK APAP tests in the 2-OC MPS, the first step is to manufacture the human intestine and liver equivalents (organoids). They are integrated into the 2-OC microfluidic device (Figure 1A) 24 h before starting of the PK APAP assay. The next day, the medium is changed, and the model is exposed to APAP. Figure 1 illustrates the intestine and liver equivalents placed inside the 2-OC device (Figure 1B) and the APAP PK experim...

Watch this Scientific Journal Video about An Intestine/Liver Microphysiological System for Drug Pharmacokinetic and Toxicological Assessment at JoVE.com

An Intestine/Liver Microphysiological System for Drug Pharmacokinetic and Toxicological Assessment

We exposed a microphysiological system (MPS) with intestine and liver organoids to acetaminophen (APAP). This article describes the methods for organoid production and APAP pharmacokinetic and toxicological property assessments in the MPS. It also describes the tissue functionality analyses necessary to validate the results.

The recently introduced microphysiological systems (MPS) cultivating human organoids are expected to perform better than animals in the preclinical tests ...

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Pharmacokinetics and Pharmacodynamics

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Unit 1

Pharmacokinetics and Pharmacodynamics: Introduction

Pharmacokinetics

SCIENTISTS IN ACTION

Preparation and Characterization of SDF-1&#945;-Chitosan-Dextran Sulfate Nanoparticles

Chitosan (CS) and dextran sulfate (DS) are charged polysaccharides (glycans), which form polyelectrolyte complex-based nanoparticles when mixed under appropriate conditions. The glycan nanoparticles are useful carriers for protein factors, which facilitate the in vivo delivery of the proteins and sustain their retention in the targeted tissue. The glycan polyelectrolyte complexes are also ideal for protein delivery, as the incorporation is carried out in aqueous solution, which reduces the likelihood of inactivation of the proteins. Proteins with a heparin-binding site adhere to dextran sulfate readily, and are, in turn, stabilized by the binding. These particles are also less inflammatory and toxic when delivered in vivo. In the protocol described below, SDF-1&#945; (Stromal cell-derived factor-1&#945;), a stem cell homing factor, is first mixed and incubated with dextran sulfate. Chitosan is added to the mixture to form polyelectrolyte complexes, followed by zinc sulfate to stabilize the complexes with zinc bridges. The resultant SDF-1&#945;-DS-CS particles are measured for size (diameter) and surface charge (zeta potential). The amount of the incorporated SDF-1&#945; is determined, followed by measurements of its in vitro release rate and its chemotactic activity in a particle-bound form.

Preparation and Characterization of SDF-1&amp;#945;-Chitosan-Dextran Sulfate Nanoparticles

The objective of this protocol is to incorporate SDF-1&#945;, a stem cell homing factor, into dextran sulfate-chitosan nanoparticles. The resultant particles are measured for their size and zeta potential, as well as the content, activity, and in vitro release rate of SDF-1&#945; from the nanoparticles.

Chitosan (CS) and dextran sulfate (DS) are charged polysaccharides (glycans), which form polyelectrolyte complex-based nanoparticles when mixed under ...

Preparation and Characterization of Individual and Multi-drug Loaded Physically Entrapped Polymeric Micelles

Amphiphilic block copolymers like polyethyleneglycol-block-polylactic acid (PEG-b-PLA) can self-assemble into micelles above their critical micellar concentration forming hydrophobic cores surrounded by hydrophilic shells in aqueous environments. The core of these micelles can be utilized to load hydrophobic, poorly water soluble drugs like docetaxel (DTX) and everolimus (EVR). Systematic characterization of the micelle structure and drug loading capabilities are important before in vitro and in vivo studies can be conducted. The goal of the protocol described herein is to provide the necessary characterization steps to achieve standardized micellar products. DTX and EVR have intrinsic solubilities of 1.9 and 9.6 &#181;g/ml respectively Preparation of these micelles can be achieved through solvent casting which increases the aqueous solubility of DTX and EVR to 1.86 and 1.85 mg/ml, respectively. Drug stability in micelles evaluated at room temperature over 48 hr indicates that 97% or more of the drugs are retained in solution. Micelle size was assessed using dynamic light scattering and indicated that the size of these micelles was below 50 nm and depended on the molecular weight of the polymer. Drug release from the micelles was assessed using dialysis under sink conditions at pH 7.4 at 37 oC over 48 hr. Curve fitting results indicate that drug release is driven by a first order process indicating that it is diffusion driven.

The goal of this protocol is to describe the preparation and characterization of physically entrapped, poorly water soluble drugs in micellar drug delivery systems composed of amphiphilic block copolymers.

Amphiphilic block copolymers like polyethyleneglycol-block-polylactic acid (PEG-b-PLA) can self-assemble into micelles above their critical micellar ...

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of trifluoromethoxylated aromatic compounds remains a formidable challenge in organic synthesis. Conventional approaches often suffer from poor substrate scope, or require use of highly toxic, difficult-to-handle, and/or thermally labile reagents. Herein, we report a user-friendly protocol for the synthesis of methyl 4-acetamido-3-(trifluoromethoxy)benzoate using 1-trifluoromethyl-1,2-benziodoxol-3(1H)-one (Togni reagent II). Treating methyl 4-(N-hydroxyacetamido)benzoate (1a) with Togni reagent II in the presence of a catalytic amount of cesium carbonate (Cs2CO3) in chloroform at RT afforded methyl 4-(N-(trifluoromethoxy)acetamido)benzoate (2a). This intermediate was then converted to the final product methyl 4-acetamido-3-(trifluoromethoxy)benzoate (3a) in nitromethane at 120 &#176;C. This procedure is general and can be applied to the synthesis of a broad spectrum of ortho-trifluoromethoxylated aniline derivatives, which could serve as useful synthetic building blocks for the discovery and development of new pharmaceuticals, agrochemicals, and functional materials.

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

An operationally simple procedure for the synthesis of ortho-trifluoromethoxylated aniline derivatives via a two-step sequence of O-trifluoromethylation of N-aryl-N-hydroxyacetamide followed by thermally induced intramolecular OCF3-migration is reported.

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of ...

PTR-ToF-MS Coupled with an Automated Sampling System and Tailored Data Analysis for Food Studies: Bioprocess Monitoring, Screening and Nose-space Analysis

Proton Transfer Reaction (PTR), combined with a Time-of-Flight (ToF) Mass Spectrometer (MS) is an analytical approach based on chemical ionization that belongs to the Direct-Injection Mass Spectrometric (DIMS) technologies. These techniques allow the rapid determination of volatile organic compounds (VOCs), assuring high sensitivity and accuracy. In general, PTR-MS requires neither sample preparation nor sample destruction, allowing real time and non-invasive analysis of samples. PTR-MS are exploited in many fields, from environmental and atmospheric chemistry to medical and biological sciences. More recently, we developed a methodology based on coupling PTR-ToF-MS with an automated sampler and tailored data analysis tools, to increase the degree of automation and, consequently, to enhance the potential of the technique. This approach allowed us to monitor bioprocesses (e.g. enzymatic oxidation, alcoholic fermentation), to screen large sample sets (e.g. different origins, entire germoplasms) and to analyze several experimental modes (e.g. different concentrations of a given ingredient, different intensities of a specific technological parameter) in terms of VOC content. Here, we report the experimental protocols exemplifying different possible applications of our methodology: i.e. the detection of VOCs released during lactic acid fermentation of yogurt (on-line bioprocess monitoring), the monitoring of VOCs associated with different apple cultivars (large-scale screening), and the in vivo study of retronasal VOC release during coffee drinking (nosespace analysis).

Proton Transfer Reaction Time of Flight Mass Spectrometry allows high-sensitivity, rapid and non-invasive analysis of volatile organic compounds. To demonstrate its potential, we give three examples: lactic acid fermentation of yogurt (on-line bioprocess monitoring), different apple genotypes (large-scale screening), and retronasal space after drinking coffee (nosespace analysis).

Proton Transfer Reaction (PTR), combined with a Time-of-Flight (ToF) Mass Spectrometer (MS) is an analytical approach based on chemical ionization that ...

An Aptamer-based Sensor for Unchelated Gadolinium(III)

A method for determining the presence of unchelated trivalent gadolinium ion (Gd3+) in aqueous solution is demonstrated. Gd3+ is often present in samples of gadolinium-based contrast agents as a result of incomplete reactions between the ligand and the ion, or as a dissociation product. Since the ion is toxic, its detection is of critical importance. Herein, the design and usage of an aptamer-based sensor (Gd-sensor) for Gd3+ are described. The sensor produces a fluorescence change in response to increasing concentrations of the ion, and has a limit of detection in the nanomolar range (~100 nM with a signal-to-noise ratio of 3). The assay may be run in an aqueous buffer at ambient pH (~7 - 7.4) in a 384-well microplate. The sensor is relatively unreactive toward other physiologically relevant metal ions such as sodium, potassium, and calcium ions, although it is not specific for Gd3+ over other trivalent lanthanides such as europium(III) and terbium(III). Nevertheless, the lanthanides are not commonly found in contrast agents or the biological systems, and the sensor may therefore be used to selectively determine unchelated Gd3+ in aqueous conditions.

An Aptamer-based Sensor for Unchelated GadoliniumIII

The use of polydeoxynucleotide (44-mer aptamer) molecules for sensing unchelated gadolinium(III) ion in an aqueous solution is described. The presence of the ion is detected via an increase in the fluorescence emission of the sensor.

A method for determining the presence of unchelated trivalent gadolinium ion (Gd3+) in aqueous solution is demonstrated. Gd3+ is often present in samples ...

Real-time Breath Analysis by Using Secondary Nanoelectrospray Ionization Coupled to High Resolution Mass Spectrometry

Exhaled volatile organic compounds (VOCs) have aroused considerable interest, since they can serve as biomarkers for disease diagnosis and environmental exposure in a non-invasive manner. In this work, we present a protocol to characterize the exhaled VOCs in real time by using secondary nanoelectrospray ionization coupled to high resolution mass spectrometry (Sec-nanoESI-HRMS). The homemade Sec-nanoESI source was readily set up based on a commercial nanoESI source. Hundreds of peaks were observed in the background-subtracted mass spectra of exhaled breath, and the mass accuracy values are -4.0-13.5 ppm and -20.3-1.3 ppm in the positive and negative ion detection modes, respectively. The peaks were assigned with accurate elemental composition according to the accurate mass and isotopic pattern. Less than 30 s is used for one exhalation measurement, and it takes approximately 7 min for six replicated measurements.

A protocol for characterizing chemical composition of exhaled breath in real time by using secondary nanoelectrospray ionization coupled to high resolution mass spectrometry is demonstrated.

Exhaled volatile organic compounds (VOCs) have aroused considerable interest, since they can serve as biomarkers for disease diagnosis and environmental ...

An Engineered Split-TET2 Enzyme for Chemical-inducible DNA Hydroxymethylation and Epigenetic Remodeling

DNA methylation is a stable and heritable epigenetic modification in the mammalian genome and is involved in regulating gene expression to control cellular functions. The reversal of DNA methylation, or DNA demethylation, is mediated by the ten-eleven translocation (TET) protein family of dioxygenases. Although it has been widely reported that aberrant DNA methylation and demethylation are associated with developmental defects and cancer, how these epigenetic changes directly contribute to the subsequent alteration in gene expression or disease progression remains unclear, largely owing to the lack of reliable tools to accurately add or remove DNA modifications in the genome at defined temporal and spatial resolution. To overcome this hurdle, we designed a split-TET2 enzyme to enable temporal control of 5-methylcytosine (5mC) oxidation and subsequent remodeling of epigenetic states in mammalian cells by simply adding chemicals. Here, we describe methods for introducing a chemical-inducible epigenome remodeling tool (CiDER), based on an engineered split-TET2 enzyme, into mammalian cells and quantifying the chemical inducible production of 5-hydroxymethylcytosine (5hmC) with immunostaining, flow cytometry or a dot-blot assay. This chemical-inducible epigenome remodeling tool will find broad use in interrogating cellular systems without altering the genetic code, as well as in probing the epigenotype&#8722;phenotype relations in various biological systems.

Detailed protocols for introducing an engineered split-TET2 enzyme (CiDER) into mammalian cells for chemical inducible DNA hydroxymethylation and epigenetic remodeling are presented.

DNA methylation is a stable and heritable epigenetic modification in the mammalian genome and is involved in regulating gene expression to control ...

Generation of Electronic Cigarette Aerosol by a Third-Generation Machine-Vaping Device: Application to Toxicological Studies

Electronic-cigarette (e-cig) devices use heat to produce an inhalable aerosol from a liquid (e-liquid) composed mainly of humectants, nicotine, and flavoring chemicals. The aerosol produced includes fine and ultrafine particles, and potentially nicotine and aldehydes, which can be harmful to human health. E-cig users inhale these aerosols and, with the third-generation of e-cig devices, control design features (resistance and voltage) in addition to the choice of e-liquids, and the puffing profile. These are key factors that can significantly impact the toxicity of the inhaled aerosols. E-cig research, however, is challenging and complex mostly due to the absence of standardized assessments and to the numerous varieties of e-cig models and brands, as well as e-liquid flavors and solvents that are available on the market. These considerations highlight the urgent need to harmonize e-cig research protocols, starting with e-cig aerosol generation and characterization techniques. The current study focuses on this challenge by describing a detailed step-by-step e-cig aerosol generation technique with specific experimental parameters that are thought to be realistic and representative of real-life exposure scenarios. The methodology is divided into four sections: preparation, exposure, post-exposure analysis, plus cleaning and maintenance of the device. Representative results from using two types of e-liquid and various voltages are presented in terms of mass concentration, particle size distribution, chemical composition and cotinine levels in mice. These data demonstrate the versatility of the e-cig exposure system used, aside from its value for toxicological studies, as it allows for a broad range of computer-controlled exposure scenarios, including automated representative vaping topography profiles.

Electronic cigarette (e-cig) users are increasing worldwide. Little, however, is known about the health effects induced by inhaled e-cig aerosols. This article describes an e-cig aerosol generation technique suitable for animal exposures and subsequent toxicological studies. Such protocols are required to establish experimentally reproducible and standardized e-cig exposure systems.

Electronic-cigarette (e-cig) devices use heat to produce an inhalable aerosol from a liquid (e-liquid) composed mainly of humectants, nicotine, and ...

High-throughput and Comprehensive Drug Surveillance Using Multisegment Injection-Capillary Electrophoresis-Mass Spectrometry

New analytical methods are urgently needed to enable high-throughput, yet comprehensive drug screening, given an alarming opioid and prescription drug crisis in public health. Conventional urine drug testing based on a two-tier immunoassay screen followed by a gas chromatography-tandem mass spectrometry (GC-MS/MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS) method are expensive and prone to bias while being limited to targeted panels of known drugs of abuse (DoA). Herein, we outline an improved method for drug surveillance that allows for the resolution and detection of an expanded panel of DoA and their metabolites when using multisegment injection-capillary electrophoresis-mass spectrometry (MSI-CE-MS). Multiplexed separations of ten urine samples with a quality control by CE (&lt; 3 min/sample) in conjunction with full-scan data acquisition using a time-of-flight mass spectrometer (TOF-MS) under positive ion mode detection allows for the identification and quantification of DoA above recommended cut-off levels. An excellent resolution of drug isomers and isobars, including background interferences, are achieved when using MSI-CE-MS with an electrokinetic spacer between sample segments, where accurate mass/molecular formula together with the comigration of a matching deuterated internal standard and the detection of one or more bio-transformed metabolites facilitate DoA identification over a wider detection window. Additionally, urine samples can be analyzed directly without enzyme deconjugation for the rapid screening without complicated sample workup. MSI-CE-MS enables the surveillance of a broad spectrum of DoA that is required for the treatment monitoring of high-risk patients, including confirming prescribed drug adherence, revealing illicit drug use/substitution, and evaluating optimal dosage regimes as required for new advances in precision medicine.

Here we describe a high-throughput method for comprehensive drug surveillance that allows for the improved resolution and detection of large panels of drugs of abuse and their metabolites, with quality control based on multisegment injection-capillary electrophoresis-mass spectrometry.

New analytical methods are urgently needed to enable high-throughput, yet comprehensive drug screening, given an alarming opioid and prescription drug ...

An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation

We demonstrate a method for fabricating a prototype reflective display device that contains cholesteric liquid crystal (LC) as an active component. The cholesteric LC is composed of a nematic LC 4&#39;-pentyloxy-4-cyanobiphenyl (5OCB), redox-responsive chiral dopant (FcD), and a supporting electrolyte 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIm-OTf). The most important component is FcD. This molecule changes its helical twisting power (HTP) value in response to redox reactions. Therefore, in situ electrochemical redox reactions in the LC mixture allow for the device to change its reflection color in response to electrical stimuli. The LC mixture was introduced, by a capillary action, into a sandwich-type ITO glass cell comprising two glass slides with patterned indium tin oxide (ITO) electrodes, one of which was coated with poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol) doped with perchlorate (PEDOT+). Upon application of +1.5 V, the reflection color of the device changed from blue (467 nm) to green (485 nm) in 0.4 s. Subsequent application of 0 V made the device recover the original blue color in 2.7 s. This device is characterized by its fastest electrical response and lowest operating voltage among any previously reported cholesteric LC device. This device could pave the way for the development of next generation reflective displays with low energy consumption rates.

A protocol for the fabrication of a reflective cholesteric liquid crystalline display device containing a redox-responsive chiral dopant allowing quick and low-voltage operation is presented.

We demonstrate a method for fabricating a prototype reflective display device that contains cholesteric liquid crystal (LC) as an active component. The ...