Financial support provided by National Science Foundation (CAREER award CHE-0847262. We thank Vapourtec Ltd and Enwave Optronics for equipment support, and Daniel Daleb of the University of Connecticut for his assistance in construction of the flow cell apparatus.

1. Find Suitable Signals for Reaction Monitoring
<ol>
	<li>Obtain Raman spectra for all starting materials and the product.</li>
	<li>Overlay spectra and identify an intense band that is unique to the product.</li>
	<li>Use this Raman band to monitor the progress of the reaction. A band at 1,608&#160;cm-1 was selected in this case.</li>
</ol>
2. Set up the Flow Cell
<ol>
	<li>Obtain a suitable flow cell. Here use one with the following dimensions: width of 6.5 mm, height of 20 mm, and a path length of 5 mm (Figure 2A).</li>
	<li>Place the flow cell in a container that provides an environment free of ambient light.</li>
	<li>Connect tubing to the inlet and outlet of the flow cell (in this case 1 mm I.D. PFA tubing).</li>
</ol>
3. Interface the Raman Spectrometer with the Flow Cell
<ol>
	<li>Obtain a suitable Raman spectrometer with a flexible optical assembly that can be placed in close proximity to the flow cell.</li>
	<li>Place the optical assembly through a suitably sized aperture in the box containing the flow cell assembly (Figure 2B).</li>
	<li>Slide the optical assembly until it touches the flow cell and then pull it back leaving a gap of ~ 2 mm.</li>
	<li>Fill the flow cell with 100% acetone.</li>
	<li>Turn on the Raman spectrometer and acquire spectra in continuous-scan mode.</li>
	<li>Focus the laser by gently moving the light pipe a fraction at a time. Keep moving the light pipe until the signal is at its greatest intensity and the peaks are sharp and well defined.</li>
</ol>
<img alt="Figure 2" src="/files/ftp_upload/52393/52393fig2.jpg" /> 
Figure 2. (A) Flow cell and (B) Raman interface used. <a href="https://www.jove.com/files/ftp_upload/52393/52393fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
4. Prepare Reagent and Solvent Solutions
<ol>
	<li>Add salicylaldehyde (6.106 g, 50 mmol, 1 equiv) and ethyl acetoacetate (6.507 g, 50 mmol, 1 equiv) to a 50 ml volumetric flask.</li>
	<li>Add ethyl acetate to a total volume of 50 ml and then thoroughly mix the contents.</li>
	<li>Transfer a 10 ml aliquot of the stock solution to a 20 ml glass vial containing a magnetic stir bar. Label this vial &#8220;reagent.&#8221;</li>
	<li>In a 100 ml bottle place 90 ml of ethyl acetate. Label this bottle &#8220;solvent&#8221;. In a 100 ml bottle place 90 ml of acetone. Label this bottle &#8220;solvent intercept&#8221;.</li>
</ol>
5. Prepare the Flow Apparatus
<ol>
	<li>Ensure that the flow unit has at least two pumps and label them &#8220;P1&#8221; and &#8220;P2&#8221;. Identify solvent and reagent inlet lines for each pump. Place the exit lines from the &#8220;collect&#8221; and &#8220;waste&#8221; lines into two individual 100 ml bottles labeled &#8220;product&#8221; and &#8220;waste&#8221;, respectively.</li>
	<li>As a reactor, use a 10 ml capacity PFA coil capable of being heated.</li>
	<li>Connect the tube exiting P1 to the inlet of the PFA reactor coil.</li>
	<li>Install a three-port polyether ether ketone (PEEK) tee-mixer after the reactor coil.</li>
	<li>Connect the tube exiting P2 to the tee-mixer, 180&#176; from the reactor coil exit tubing. Connect a piece of tubing to the third port of the Tee-mixer. On the other end of this tube place a back-pressure regulator.</li>
	<li>Connect a line from the output of the back-pressure regulator to the input of the flow cell. Connect a line from the output of the flow cell to the &#8220;waste/collect&#8221; switch.</li>
	<li>Prime the solvent lines for both P1 and P2 as well as the reagent line for P1 with solvent. Move the reagent line for P1 from the solvent bottle to the reagent bottle.</li>
	<li>Using P1, pass ethyl acetate through the reactor coil at 2 ml/min until it is filled. Pass acetone through P2 at a flow rate of 2 ml/min for 2 min.</li>
	<li>Adjust the solvent flow rates for both P1 and P2 to 1 ml/min. Set the back-pressure regulator to a pressure of 7 bar. Set the reactor coil temperature to the desired temperature.</li>
	<li>Double-check the equipment is configured as shown in the schematic in Figure 3.</li>
	<li>Once the system reaches constant temperature and pressure, check for leaks and then run the reaction.</li>
</ol>
<img alt="Figure 3" src="/files/ftp_upload/52393/52393fig3.jpg" /> 
Figure 3. Schematic of the equipment configuration used for reaction monitoring experiments. <a href="https://www.jove.com/files/ftp_upload/52393/52393fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
6. Monitor the Reaction
<ol>
	<li>Take a background scan of the ethyl acetate/acetone solvent system as it passed through the flow cell. This will be automatically subtracted from all subsequent scans.</li>
	<li>Configure the spectrometer to take scans every 15 sec (in this case the Raman spectrometer was set to a 10 sec integration time, boxcar = 3, and average = 1).</li>
	<li>Inject piperidine (0.05 ml, 0.05 mmol, 0.1 equiv) all at once into the glass vial labeled &#8220;reagent&#8221;.</li>
	<li>After thoroughly mixing, switch P1 from &#8220;solvent&#8221; to &#8220;reagent.&#8221; Set the exit stream to &#8220;collect.&#8221;</li>
	<li>When all material is completely loaded, switch P1 from &#8220;reagent&#8221; back to &#8220;solvent.&#8221; Continue flowing solvent through the reactor coil for another 30 min. Once this time has elapsed, turn off the heating.</li>
	<li>Turn pumps P1 and P2 off when the reactor coil temperature has cooled to below 50 &#176;C.</li>
</ol>
7. Analyze the Data
<ol>
	<li>Export the Raman spectrometer data to a spreadsheet and plot Raman intensity at 1,608 cm-1 vs. time.</li>
	<li>To optimize conditions, perform the reaction across a number of flow rates and reactor temperatures in an iterative manner.</li>
	<li>Overlay plots of Raman intensity at 1,608 cm-1 vs. time. 
	Note: Higher Raman intensity correlates with higher product conversion.</li>
</ol>
8. Run the Reaction Using Optimized Conditions
<ol>
	<li>Having screened various conditions (varying flow rates / reactor temperatures), run the reaction using the optimized conditions to afford the highest product conversion.&#160;</li>
</ol>
9. Isolate the Product
<ol>
	<li>Take the contents of the product flask and pour it into a beaker containing 100 ml of ice and 20 ml of 2 M HCl.</li>
	<li>Rinse the product flask with a minimal amount of ethyl acetate (2 ml) and transfer to the beaker.</li>
	<li>Stir the icy mixture until all the ice is completely melted.</li>
	<li>Set up a filtration system with a Hirsch funnel, side-arm flask, rubber collar and a length of rubber vacuum tubing.</li>
	<li>Filter the resulting precipitate under vacuum, rinse with cold diethyl ether (10 ml) and allow it to dry under a heat lamp (2-3 hr) or dry O/N under vacuum.</li>
	<li>Confirm the identity of the product by 1H nuclear magnetic resonance (NMR) spectroscopy using CDCl3 as the solvent. For a 500 MHz NMR spectrometer, the 1H NMR data of 3-acetylcoumarin is as follows: &#948; = 2.73 (s, 3 H) 7.31 - 7.40 (m, 2 H) 7.65 (ddd, J = 7.53, 4.37, 2.60 Hz, 2 H) 8.51 (s, 1 H) ppm, 13C NMR data: &#948; = 30.84 (CH3) 117.00 (CH) 118.56 (C) 124.86 (CH) 125.27 (CH) 130.51 (CH) 134.68 (C) 147.74 (CH) 155.64 (C) 159.52 (C) 195.77 (C) ppm.</li>
</ol>

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The authors have nothing to disclose.

The ease in which the Raman spectrometer can be interfaced with the flow unit makes this inline technique valuable for reaction monitoring. A number of reaction variables can be probed in an expedited manner, allowing the user to arrive at optimized reaction conditions faster than when using offline methods. Application of the techniques described herein also allows for monitoring of the formation of side products, assuming a suitable band can be found. Conditions can be screened and selected, which allow both for the hi...

By using continuous-flow processing, chemists are finding that they can perform a range of chemical reactions safely, effectively, and with ease1,2. As a result, flow chemistry equipment is becoming an integral tool for running reactions both in industrial settings as well as research labs in academic institutions. A wide variety of synthetic chemistry transformations have been carried out in flow reactors3,4. In select cases, reactions that do not work in batch have been shown to proceed smoothly under continuous-flow conditions5. For both reaction optimization and quality control, incorporation of in-line reaction monitoring with flow processing offers significant advantages. In-line monitoring provides continuous analysis with real-time response to actual sample conditions. This is faster and, in some cases, more reliable than comparable off-line techniques. A number of in-line analytical techniques have been interfaced with flow reactors7. Examples include infrared8,9, UV-visible10,11, NMR12,13, Raman spectroscopy14,15, and mass spectrometry16,17.
Our research group has interfaced a Raman spectrometer with a scientific microwave unit18. Using this, a range of reactions have been monitored from both a qualitative19 and quantitative20 standpoint. Building on this success, we have recently interfaced our Raman spectrometer with one of our continuous-flow units and employed it for in-line reaction monitoring of a number of key medicinally-relevant organic transformations.21 In each case it was possible to monitor the reactions and also in one example, by means of a calibration curve, we could determine product conversion from Raman spectral data. In Here we describe how to set up the apparatus and use it to monitor reactions. We use the piperidine-catalyzed synthesis of 3-acetylcoumarin (1) from salicylaldehyde with ethyl acetoacetate (Figure 1) as the model reaction here.
<img alt="Figure 1" src="/files/ftp_upload/52393/52393fig1.jpg" /> 
Figure 1. Base catalyzed condensation reaction between salicylaldehyde and ethyl acetoacetate to yield 3-acetylcoumarin (1). <a href="https://www.jove.com/files/ftp_upload/52393/52393fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<table border="0">
	<tbody>
		<tr>
			<td>Salicylaldehyde</td>
			<td>Sigma-Aldrich</td>
			<td>S356</td>
			<td>Reagent Grade, 98%</td>
		</tr>
		<tr>
			<td>Ethyl acetoacetate</td>
			<td>Acros Organics</td>
			<td>117970010</td>
			<td>99%</td>
		</tr>
		<tr>
			<td>Piperidine</td>
			<td>Sigma-Aldrich</td>
			<td>104094</td>
			<td>Reagent Plus, 99%</td>
		</tr>
		<tr>
			<td>Hydrochloric acid</td>
			<td>Sigma-Aldrich</td>
			<td>320331</td>
			<td>ACS Reagent, 37%</td>
		</tr>
		<tr>
			<td>Ethyl acetate</td>
			<td>Sigma-Aldrich</td>
			<td>34858</td>
			<td>CHROMASOLV, for HPLC, &#62;99.7%</td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>Sigma-Aldrich</td>
			<td>650501</td>
			<td>CHROMASOLV, for HPLC, &#62;99.9%</td>
		</tr>
		<tr>
			<td>Flow cell</td>
			<td>Starna Cells</td>
			<td></td>
			<td>583.65.65-Q-5/Z20</td>
		</tr>
		<tr>
			<td>Flow unit</td>
			<td>Vapourtec</td>
			<td></td>
			<td>E-series system</td>
		</tr>
		<tr>
			<td>Raman spectrometer</td>
			<td>Enwave Optronics Inc</td>
			<td></td>
			<td>Model EZRaman-L</td>
		</tr>
	</tbody>
</table>

real-time monitoring of reactions performed using continuous-flow processing: the preparation of 3-acetylcoumarin as an example

By using inline monitoring, it is possible to optimize reactions performed using continuous-flow processing in a simple and rapid way. It is also possible to ensure consistent product quality over time using this technique. We here show how to interface a commercially available flow unit with a Raman spectrometer. The Raman flow cell is placed after the back-pressure regulator, meaning that it can be operated at atmospheric pressure. In addition, the fact that the product stream passes through a length of tubing before entering the flow cell means that the material is at RT. It is important that the spectra are acquired under isothermal conditions since Raman signal intensity is temperature dependent. Having assembled the apparatus, we then show how to monitor a chemical reaction, the piperidine-catalyzed synthesis of 3-acetylcoumarin from salicylaldehyde and ethyl acetoacetate being used as an example. The reaction can be performed over a range of flow rates and temperatures, the in-situ monitoring tool being used to optimize conditions simply and easily.

The continuous-flow preparation of 3-acetylcoumarin was chosen as a representative reaction for in-line monitoring. In batch, the reaction proceeds well when using ethyl acetate as the solvent. However, the product (1) is not completely soluble at RT. To prevent potential clogging of the back-pressure regulator, as well as mitigate the risk of having solid particles in the flow cell which would perturb signal acquisition, we used a technique we developed previously for this and other reactions22</su...

Watch this Scientific Journal Video about Real-time Monitoring of Reactions Performed Using Continuous-flow Processing: The Preparation of 3-Acetylcoumarin as an Example at JoVE.com

Real-time Monitoring of Reactions Performed Using Continuous-flow Processing: The Preparation of 3-Acetylcoumarin as an Example

Real-time monitoring allows for fast optimization of reactions performed using continuous-flow processing. Here the preparation of 3-acetylcoumarin is used as an example. The apparatus for performing in-situ Raman monitoring is described, as are the steps required to optimize the reaction.

By using inline monitoring, it is possible to optimize reactions performed using continuous-flow processing in a simple and rapid way. It is also possible ...

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9.6K Views.  University of Connecticut. Real-time monitoring allows for fast optimization of reactions performed using continuous-flow processing. Here the preparation of 3-acetylcoumarin is used as an example. The apparatus for performing in-situ Raman monitoring is described, as are the steps required to optimize the reaction.

Video: Real-time Monitoring of Reactions Performed Using Continuous-flow Processing: The Preparation of 3-Acetylcoumarin as an Example

Rapid High-throughput Species Identification of Botanical Material Using Direct Analysis in Real Time High Resolution Mass Spectrometry

We demonstrate that direct analysis in real time-high resolution mass spectrometry can be used to produce mass spectral profiles of botanical material, and that these chemical fingerprints can be used for plant species identification. The mass spectral data can be acquired rapidly and in a high throughput manner without the need for sample extraction, derivatization or pH adjustment steps. The use of this technique bypasses challenges presented by more conventional techniques including lengthy chromatography analysis times and resource intensive methods. The high throughput capabilities of the direct analysis in real time-high resolution mass spectrometry protocol, coupled with multivariate statistical analysis processing of the data, provide not only class characterization of plants, but also yield species and varietal information. Here, the technique is demonstrated with two psychoactive plant products, Mitragyna speciosa (Kratom) and Datura (Jimsonweed), which were subjected to direct analysis in real time-high resolution mass spectrometry followed by statistical analysis processing of the mass spectral data. The application of these tools in tandem enabled the plant materials to be rapidly identified at the level of variety and species.

A method for species identification of botanical material by direct analysis in real time-high resolution mass spectrometry and multivariate statistical analysis is presented.

We demonstrate that direct analysis in real time-high resolution mass spectrometry can be used to produce mass spectral profiles of botanical material, ...

Capillary Electrophoresis to Monitor Peptide Grafting onto Chitosan Films in Real Time

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. Compared to other analytical separation techniques, such as chromatography, CE is cheap, robust and effectively requires no sample preparation (for a number of complex natural matrices or polymeric samples). CE is fast and can be used to follow the evolution of mixtures in real time (e.g., chemical reaction kinetics), as the signals observed for the separated compounds are directly proportional to their quantity in solution.
Here, the efficiency of CE is demonstrated for monitoring the covalent grafting of peptides onto chitosan films for subsequent biomedical applications. Chitosan&#39;s antimicrobial and biocompatible properties make it an attractive material for biomedical applications such as cell growth substrates. Covalently grafting the peptide RGDS (arginine - glycine - aspartic acid - serine) onto the surface of chitosan films aims at improving cell attachment. Historically, chromatography and amino acid analysis have been used to provide a direct measurement of the amount of grafted peptide. However, the fast separation and absence of sample preparation provided by CE enables equally accurate yet real-time monitoring of the peptide grafting process. CE is able to separate and quantify the different components of the reaction mixture: the (non-grafted) peptide and the chemical coupling agents. In this way the use of CE results in improved films for downstream applications.
The chitosan films were characterized through solid-state NMR (nuclear magnetic resonance) spectroscopy. This technique is more time-consuming and cannot be applied in real time, but yields a direct measurement of the peptide and thus validates the CE technique.

Free solution capillary electrophoresis is a fast, cheap and robust analytical method that enables the quantitative monitoring of chemical reactions in real time. Its utility for rapid, convenient and precise analysis is demonstrated here through analysis of covalent peptide grafting onto chitosan films for improved cell adhesion.

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. ...

A Protocol for Safe Lithiation Reactions Using Organolithium Reagents

Organolithium reagents are powerful tools in the synthetic chemist&#39;s toolbox. However, the extreme pyrophoric nature of the most reactive reagents warrants proper technique, thorough training, and proper personal protective equipment. To aid in the training of researchers using organolithium reagents, a thorough, step-by-step protocol for the safe and effective use of tert-butyllithium on an inert gas line or within a glovebox is described. As a model reaction, preparation of lithium tert-butyl amide by the reaction of tert-butyl amine with one equivalent of tert-butyl lithium is presented.

The safe and proper use of organolithium reagents is described.

Organolithium reagents are powerful tools in the synthetic chemist&#39;s toolbox. However, the extreme pyrophoric nature of the most reactive reagents ...

Monitoring the Effects of Illumination on the Structure of Conjugated Polymer Gels Using Neutron Scattering

We demonstrate a protocol to effectively monitor the gelation process of a high concentration solution of conjugated polymer both in the presence and absence of white light exposure. By instituting a controlled temperature ramp, the gelation of these materials can be precisely monitored as they proceed through this structural evolution, which effectively mirrors the conditions experienced during the solution deposition phase of organic electronic device fabrication. Using small angle neutron scattering (SANS) and ultra-small angle neutron scattering (USANS) along with appropriate fitting protocols we quantify the evolution of select structural parameters throughout this process. Thorough analysis indicates that continued light exposure throughout the gelation process significantly alters the structure of the ultimately formed gel. Specifically, the aggregation process of poly(3-hexylthiophene-2,5-diyl) (P3HT) nano-scale aggregates is negatively affected by the presence of illumination, ultimately resulting in the retardation of growth in conjugated polymer microstructures and the formation of smaller scale macro-aggregate clusters.

A protocol for the analysis of gels formed from the optoelectronic conjugated polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) using small and ultra-small angle neutron scattering in both the presence and absence of illumination is presented.

We demonstrate a protocol to effectively monitor the gelation process of a high concentration solution of conjugated polymer both in the presence and ...

Measurements of Long-range Electronic Correlations During Femtosecond Diffraction Experiments Performed on Nanocrystals of Buckminsterfullerene

The precise details of the interaction of intense X-ray pulses with matter are a topic of intense interest to researchers attempting to interpret the results of femtosecond X-ray free electron laser (XFEL) experiments. An increasing number of experimental observations have shown that although nuclear motion can be negligible, given a short enough incident pulse duration, electronic motion cannot be ignored. The current and widely accepted models assume that although electrons undergo dynamics driven by interaction with the pulse, their motion could largely be considered &#39;random&#39;. This would then allow the supposedly incoherent contribution from the electronic motion to be treated as a continuous background signal and thus ignored. The original aim of our experiment was to precisely measure the change in intensity of individual Bragg peaks, due to X-ray induced electronic damage in a model system, crystalline C60. Contrary to this expectation, we observed that at the highest X-ray intensities, the electron dynamics in C60 were in fact highly correlated, and over sufficiently long distances that the positions of the Bragg reflections are significantly altered. This paper describes in detail the methods and protocols used for these experiments, which were conducted both at the Linac Coherent Light Source (LCLS) and the Australian Synchrotron (AS) as well as the crystallographic approaches used to analyse the data.

We describe an experiment designed to probe the electronic damage induced in nanocrystals of Buckminsterfullerene (C60) by intense, femtosecond pulses of X-rays. The experiment found that, surprisingly, rather than being stochastic, the X-ray induced electron dynamics in C60 are highly correlated, extending over hundreds of unit cells within the crystals1.

The precise details of the interaction of intense X-ray pulses with matter are a topic of intense interest to researchers attempting to interpret the ...

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 ...

Continuous Flow Chemistry: Reaction of Diphenyldiazomethane with p-Nitrobenzoic Acid

Continuous flow technology has been identified as instrumental for its environmental and economic advantages leveraging superior mixing, heat transfer and cost savings through the &#34;scaling out&#34; strategy as opposed to the traditional &#34;scaling up&#34;. Herein, we report the reaction of diphenyldiazomethane with p-nitrobenzoic acid in both batch and flow modes. To effectively transfer the reaction from batch to flow mode, it is essential to first conduct the reaction in batch. As a consequence, the reaction of diphenyldiazomethane was first studied in batch as a function of temperature, reaction time, and concentration to obtain kinetic information and process parameters. The glass flow reactor set-up is described and combines two types of reaction modules with &#34;mixing&#34; and &#34;linear&#34; microstructures. Finally, the reaction of diphenyldiazomethane with p-nitrobenzoic acid was successfully conducted in the flow reactor, with up to 95% conversion of the diphenyldiazomethane in 11 min. This proof of concept reaction aims to provide insight for scientists to consider flow technology&#39;s competitiveness, sustainability, and versatility in their research.

Continuous Flow Chemistry: Reaction of Diphenyldiazomethane with p-Nitrobenzoic Acid

Flow chemistry carries environmental and economic advantages by leveraging superior mixing, heat transfer and cost benefits. Herein, we provide a blueprint to transfer chemical processes from batch to flow mode. The reaction of diphenyldiazomethane (DDM) with p-nitrobenzoic acid, conducted in batch and flow, was chosen for proof of concept.

Continuous flow technology has been identified as instrumental for its environmental and economic advantages leveraging superior mixing, heat transfer and ...

A Continuous-flow Photocatalytic Reactor for the Precisely Controlled Deposition of Metallic Nanoparticles

In this work, a novel photocatalytic reactor for the pulsed and controlled excitation of the photocatalyst and the precise deposition of metallic nanoparticles is developed. Guidelines for the replication of the reactor and its operation are provided in detail. Three different composite systems (Pt/graphene, Pt/TiO2, and Au/TiO2) with monodisperse and uniformly distributed particles are produced by this reactor, and the photodeposition mechanism, as well as the synthesis optimization strategy, are discussed. The synthesis methods and their technical aspects are described comprehensively. The role of the ultraviolet (UV) dose (in each excitation pulse) on the photodeposition process is investigated and the optimum values for each composite system are provided.

For a continuous and scalable synthesis of noble-metal-based nanocomposites, a novel photocatalytic reactor is developed and its structure, operation principles, and product quality optimization strategies are described.

In this work, a novel photocatalytic reactor for the pulsed and controlled excitation of the photocatalyst and the precise deposition of metallic ...

Technical Aspect of the Automated Synthesis and Real-Time Kinetic Evaluation of [11C]SNAP-7941

Positron emission tomography (PET) is an essential molecular imaging technique providing insights into pathways and using specific targeted radioligands for in vivo investigations. Within this protocol, a robust and reliable remote-controlled radiosynthesis of [11C]SNAP-7941, an antagonist to the melanin-concentrating hormone receptor 1, is described. The radiosynthesis starts with cyclotron produced [11C]CO2 that is subsequently further reacted via a gas-phase transition to [11C]CH3OTf. Then, this reactive intermediate is introduced to the precursor solution and forms the respective radiotracer. Chemical as well as the radiochemical purity are determined by means of RP-HPLC, routinely implemented in the radiopharmaceutical quality control process. Additionally, the molar activity is calculated as it is a necessity for the following real-time kinetic investigations. Furthermore, [11C]SNAP-7941 is applied to MDCKII-WT and MDCKII-hMDR1 cells for evaluating the impact of P-glycoprotein (P-gp) expression on cell accumulation. For this reason, the P-gp expressing cell line (MDCKII-hMDR1) is either used without or with blocking prior to experiments by means of the P-gp substrate (&#177;)-verapamil and the results are compared to the ones observed for the wildtype cells. The overall experimental approach demonstrates the importance of a precise time-management that is essential for every preclinical and clinical study using PET tracers radiolabelled with short-lived nuclides, such as carbon-11 (half-life: 20 min).

Technical Aspect of the Automated Synthesis and Real-Time Kinetic Evaluation of [11C]SNAP-7941

Here, we represent a protocol for the fully automated radiolabelling of [11C]SNAP-7941 and the analysis of the real-time kinetics of this PET-tracer on P-gp expressing and non-expressing cells.

Positron emission tomography (PET) is an essential molecular imaging technique providing insights into pathways and using specific targeted radioligands ...

Optimization of Radiochemical Reactions using Droplet Arrays

Current automated radiosynthesizers are designed to produce large clinical batches of radiopharmaceuticals. They are not well suited for reaction optimization or novel radiopharmaceutical development since each data point involves significant reagent consumption, and contamination of the apparatus requires time for radioactive decay before the next use. To address these limitations, a platform for performing arrays of miniature droplet-based reactions in parallel, each confined within a surface-tension trap on a patterned polytetrafluoroethylene-coated silicon "chip", was developed. These chips enable rapid and convenient studies of reaction parameters including reagent concentrations, reaction solvent, reaction temperature and time. This platform permits the completion of hundreds of reactions in a few days with minimal reagent consumption, instead of taking months using a conventional radiosynthesizer.

This method describes the use of a novel high-throughput methodology, based on droplet chemical reactions, for the rapid and economical optimization of radiopharmaceuticals using nanomole amounts of reagents.