Name: multiplexed fluorescent microarray for human salivary protein analysis using polymer microspheres and fiber-optic bundles
Uploaded: 2013-10-10T21:00:00
Description: Watch this Scientific Journal Video about Multiplexed Fluorescent Microarray for Human Salivary Protein Analysis Using Polymer Microspheres and Fiber-optic Bundles at JoVE.com

This work was supported by the National Institutes of Health (grant 08UDE017788-05). E.B.P. also acknowledges support from the Spanish Foundation for Science and Technology (FECYT). The authors thank Shonda T. Gaylord and Pratyusha Mogalisetti for critical reading of the manuscript.

<img alt="Figure 1" fo:content-width="5in" width="500" src="/files/ftp_upload/50726/50726fig1highres.jpg" /> 
Figure 1. Workflow for applying fiber-optic microsphere antibody array to saliva profiling.
 (1) Microspheres are internally encoded with two fluorescent dyes; (2) the encoded microspheres are externally modified with protein-specific monoclonal antibodies; (3) the multiplexed microspheres are mixed, and (4) randomly deposited in microwells etched at th...

<ol>
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Methods. 261 (01), 157-165 (2002).</li><li>Wang, C. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Array-based+multiplexed+screening+and+quantitation+of+human+cytokines+and+chemokines.">Array-based multiplexed screening and quantitation of human cytokines and chemokines.</a> J. Proteome Res. 1, 337-343 (2002).</li><li>de Jager, W., Velthuis, t. e., Prakken, H., Kuis, B. J., W, G. T., Rijkers, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+detection+of+15+human+cytokines+in+a+single+sample+of+stimulated+peripheral+blood+mononuclear+cells.">Simultaneous detection of 15 human cytokines in a single sample of stimulated peripheral blood mononuclear cells.</a> Clin. Diagn. Lab. Immunol. 10, 133-139 (2003).</li><li>Lee, H. J., Nedelkov, D., Corn, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+plasmon+resonance+imaging+measurements+of+antibody+arrays+for+the+multiplexed+detection+of+low+molecular+weight+protein+biomarkers.">Surface plasmon resonance imaging measurements of antibody arrays for the multiplexed detection of low molecular weight protein biomarkers.</a> Anal. Chem. 78, 6504-6510 (2006).</li><li>Vignali, D. A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiplexed+particle-based+flow+cytometric+assays.">Multiplexed particle-based flow cytometric assays.</a> J. Immunol. Methods. 243 (00), 243-255 (2000).</li><li>Rissin, D. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-molecule+enzyme-linked+immunosorbent+assay+detects+serum+proteins+at+subfemtomolar+concentrations.">Single-molecule enzyme-linked immunosorbent assay detects serum proteins at subfemtomolar concentrations.</a> Nat. Biotechnol. 28, 595-599 (2010).</li><li>Zhang, H., Nie, S., Etson, C. M., Wang, R. M., Walt, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oil-sealed+femtoliter+fiber-optic+arrays+for+single+molecule+analysis.">Oil-sealed femtoliter fiber-optic arrays for single molecule analysis.</a> Lab Chip. 12, 2229-2239 (2012).</li><li>Blicharz, T. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fiber-Optic+Microsphere-Based+Antibody+Array+for+the+Analysis+of+Inflammatory+Cytokines+in+Saliva.">Fiber-Optic Microsphere-Based Antibody Array for the Analysis of Inflammatory Cytokines in Saliva.</a> Anal. Chem. 81, 2106-2114 (2009).</li><li>Mukhopadhyay, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Devices+to+drool+for.">Devices to drool for.</a> Anal. Chem. 78, 4255-4259 (2006).</li><li>Wong, D. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Salivary+diagnostics+powered+by+nanotechnologies,+proteomics+and+genomics.">Salivary diagnostics powered by nanotechnologies, proteomics and genomics.</a> J. Am. Dent. Assoc. 137, 313-321 (2006).</li><li>Segal, A., Wong, D. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Salivary+diagnostics:+enhancing+disease+detection+and+making+medicine+better.">Salivary diagnostics: enhancing disease detection and making medicine better.</a> Eur. J. Dent. Educ. 12, 22-29 (2008).</li><li>St John, M. A. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interleukin+6+and+interleukin+8+as+potential+biomarkers+for+oral+cavity+and+oropharyngeal+squamous+cell+carcinoma.">Interleukin 6 and interleukin 8 as potential biomarkers for oral cavity and oropharyngeal squamous cell carcinoma.</a> Arch. Otolaryngol. Head Neck Surg. 130, 929-935 (2004).</li><li>Herr, A. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+immunoassays+as+rapid+saliva-based+clinical+diagnostics.">Microfluidic immunoassays as rapid saliva-based clinical diagnostics.</a> Proc. Natl. Acad. Sci. U.S.A. 104, 5268-5273 (2007).</li><li>Pantano, P., Walt, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ordered+nanowell+arrays.">Ordered nanowell arrays.</a> Chem. Mater. 8, 2832-2835 (1996).</li><li>Schena, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Protein Microarrays. , (2005).</li></ol>

Researchers should pay extra attention to the following steps: for better decoding accuracy, it is necessary to verify the microspheres were homogeneously suspended in all incubation and wash steps during the microspheres encoding procedure. In addition, the encoded microspheres need to be protected from light throughout the entire experiment. Following proper encoding and storage procedures, we found that overall decoding accuracy was above 99%. The encoded microspheres should be stored at 4 &#176;C. Avoid freez...

Since the first microarray reported by Mark Schena and coworkers in the mid-1990s, this powerful tool has been utilized in many fields of biological research1. Antibody microarrays capable of simultaneously detecting multiple proteins in diagnostic fluids, such as blood, have important applications in clinical diagnostics and biomarker screening2-10. Saliva, containing many of the same analytes as blood, has been considered as a preferable alternative to blood because saliva collection is safe, noninvasive, and can be carried out by minimally-trained medical personnel11-13. Currently, multiplexed protein analysis using saliva samples is limited by several important factors, including the low concentration of target analyte14 and the wide concentration range of different biomarkers15..
Herein, we demonstrate the analysis of six proteins: human vascular endothelial growth factor (VEGF), interferon gamma-induced protein 10 (IP-10), interleukin-8 (IL-8), epidermal growth factor (EGF), matrix metallopeptidase 9 (MMP-9), and interleukin-1 beta (IL-1&#946;). The performance of the method was initially verified using standard solutions constituting recombinant analyte proteins and blocking buffer. Real saliva samples collected from patients of different chronic respiratory diseases as well as healthy controls were also tested with satisfactory performance. The protocol should be applicable to other protein analytes and other microsphere-based assays. This platform offers considerable advantages to the Analytical Chemistry field as it enables fast, accurate, and reproducible simultaneous analysis of low concentrations of several proteins with a broad dynamic range, minimal non-specific interactions, reduced sample consumption, and low cost in comparison to an analogous Enzyme-Linked Immunosorbent Assay (ELISA).

<table border="1">
	<tbody>
		<tr>
			<td>Name of Reagent</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Eu-TTA dye</td>
			<td>Fisher Scientific</td>
			<td>AC42319-0010</td>
			<td></td>
		</tr>
		<tr>
			<td>THF</td>
			<td>Sigma-Aldrich</td>
			<td>34865-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Amber glass vial</td>
			<td>Fisher Scientific</td>
			<td>03-339-23B</td>
			<td></td>
		</tr>
		<tr>
			<td>Coumarin 30 dye</td>
			<td>Sigma-Aldrich</td>
			<td>546127-100MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Microspheres</td>
			<td>Bangslabs</td>
			<td>PC05N/6698</td>
			<td></td>
		</tr>
		<tr>
			<td>1.5 ml microcentrifuge tubes</td>
			<td>Fisher Scientific</td>
			<td>05-408-129</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS 10x concentrate</td>
			<td>Sigma-Aldrich</td>
			<td>P5493-1L</td>
			<td></td>
		</tr>
		<tr>
			<td>Water</td>
			<td>Sigma-Aldrich</td>
			<td>W4502-1L</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Sigma-Aldrich</td>
			<td>34860-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Tw-20</td>
			<td>Sigma-Aldrich</td>
			<td>P7949-100 ml</td>
			<td></td>
		</tr>
		<tr>
			<td>BupH MES buffered saline</td>
			<td>Thermo Scientific</td>
			<td>28390</td>
			<td></td>
		</tr>
		<tr>
			<td>SDS</td>
			<td>Sigma-Aldrich</td>
			<td>05030-500ML-F</td>
			<td></td>
		</tr>
		<tr>
			<td>NaOH solution</td>
			<td>Fisher Scientific</td>
			<td>SS256-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Safe-lock microcentrifuge tube</td>
			<td>VWR labshop</td>
			<td>53511-997</td>
			<td></td>
		</tr>
		<tr>
			<td>EDC</td>
			<td>Thermo Scientific</td>
			<td>22980</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfo-NHS</td>
			<td>Thermo Scientific</td>
			<td>24510</td>
			<td></td>
		</tr>
		<tr>
			<td>Human VEGF capture antibody</td>
			<td>R&#38;D Systems</td>
			<td>MAB293</td>
			<td></td>
		</tr>
		<tr>
			<td>Human IP-10 capture antibody</td>
			<td>R&#38;D Systems</td>
			<td>MAB266</td>
			<td></td>
		</tr>
		<tr>
			<td>Human IL-8 capture antibody</td>
			<td>R&#38;D Systems</td>
			<td>MAB208</td>
			<td></td>
		</tr>
		<tr>
			<td>Human EGF capture antibody</td>
			<td>R&#38;D Systems</td>
			<td>MAB636</td>
			<td></td>
		</tr>
		<tr>
			<td>Human MMP-9 capture antibody</td>
			<td>R&#38;D Systems</td>
			<td>MAB936</td>
			<td></td>
		</tr>
		<tr>
			<td>Human IL-1&#946; capture antibody</td>
			<td>R&#38;D Systems</td>
			<td>MAB601</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse IgG1 isotype control antibody</td>
			<td>R&#38;D Systems</td>
			<td>MAB002</td>
			<td></td>
		</tr>
		<tr>
			<td>StartingBlock (TBS) buffer</td>
			<td>Thermo Scientific</td>
			<td>37542</td>
			<td></td>
		</tr>
		<tr>
			<td>HCl standard solution 1.0 N</td>
			<td>Sigma-Aldrich</td>
			<td>318949-500 ml</td>
			<td></td>
		</tr>
		<tr>
			<td>0.5 ml microcentrifuge tubes</td>
			<td>Fisher Scientific</td>
			<td>05-408-120</td>
			<td></td>
		</tr>
		<tr>
			<td>Protein-free (PBS) buffer</td>
			<td>Thermo Scientific</td>
			<td>37572</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant human VEGF 165</td>
			<td>R&#38;D Systems</td>
			<td>293-VE</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant human IP-10</td>
			<td>R&#38;D Systems</td>
			<td>266-IP</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant human IL-8</td>
			<td>R&#38;D Systems</td>
			<td>208-IL</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant human EGF</td>
			<td>R&#38;D Systems</td>
			<td>236-EG</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant human MMP-9</td>
			<td>R&#38;D Systems</td>
			<td>911-MP</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant human IL-1&#946;</td>
			<td>R&#38;D Systems</td>
			<td>201-LB</td>
			<td></td>
		</tr>
		<tr>
			<td>StartingBlock T20 (PBS) buffer</td>
			<td>Thermo Scientific</td>
			<td>37539</td>
			<td></td>
		</tr>
		<tr>
			<td>Blocker BSA in PBS</td>
			<td>Thermo Scientific</td>
			<td>37525</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotinylated VEGF detection antibody</td>
			<td>R&#38;D Systems</td>
			<td>BAF293</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotinylated IP-10 detection antibody</td>
			<td>R&#38;D Systems</td>
			<td>BAF266</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotinylated IL-8 detection antibody</td>
			<td>R&#38;D Systems</td>
			<td>BAF208</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotinylated EGF detection antibody</td>
			<td>R&#38;D Systems</td>
			<td>BAF236</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotinylated MMP-9 detection antibody</td>
			<td>R&#38;D Systems</td>
			<td>BAF911</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotinylated IL-1&#946; detection antibody</td>
			<td>R&#38;D Systems</td>
			<td>BAF201</td>
			<td></td>
		</tr>
		<tr>
			<td>Streptavidin, R-phycoerythrin</td>
			<td>Invitrogen</td>
			<td>S-21388</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol (200 proof)</td>
			<td>Sigma-Aldrich</td>
			<td>E7023-500ML</td>
			<td></td>
		</tr>
	</tbody>
</table>

multiplexed fluorescent microarray for human salivary protein analysis using polymer microspheres and fiber-optic bundles

Herein, we describe a protocol for simultaneously measuring six proteins in saliva using a fiber-optic microsphere-based antibody array. The immuno-array technology employed combines the advantages of microsphere-based suspension array fabrication with the use of fluorescence microscopy. As described in the video protocol, commercially available 4.5 &#956;m polymer microspheres were encoded into seven different types, differentiated by the concentration of two fluorescent dyes physically trapped inside the microspheres. The encoded microspheres containing surface carboxyl groups were modified with monoclonal capture antibodies through EDC/NHS coupling chemistry. To assemble the protein microarray, the different types of encoded and functionalized microspheres were mixed and randomly deposited in 4.5 &#956;m microwells, which were chemically etched at the proximal end of a fiber-optic bundle. The fiber-optic bundle was used as both a carrier and for imaging the microspheres. Once assembled, the microarray was used to capture proteins in the saliva supernatant collected from the clinic. The detection was based on a sandwich immunoassay using a mixture of biotinylated detection antibodies for different analytes with a streptavidin-conjugated fluorescent probe, R-phycoerythrin. The microarray was imaged by fluorescence microscopy in three different channels, two for microsphere registration and one for the assay signal. The fluorescence micrographs were then decoded and analyzed using a homemade algorithm in MATLAB.

Fluorescence images from three channels showing a small section of the fiber-optic bundle are shown in Figures 2A-C. These images were analyzed using an algorithm written in MATLAB (as described in more detail in the Discussion section). The analysis employs both information from the Eu-TTA encoding image (Figure 2A) and the C30 encoding image (Figure 2B) to decode the microspheres, and the fluorescence intensities of different microspheres in the signal image (F...

Watch this Scientific Journal Video about Multiplexed Fluorescent Microarray for Human Salivary Protein Analysis Using Polymer Microspheres and Fiber-optic Bundles at JoVE.com

Multiplexed Fluorescent Microarray for Human Salivary Protein Analysis Using Polymer Microspheres and Fiber-optic Bundles

We describe a procedure for profiling salivary proteins using multiplexed microsphere-based antibody arrays. Monoclonal antibodies were covalently linked to fluorescent dye-encoded 4.5 &#x03BC;m polymer microspheres using carbodiimide chemistry. The modified microspheres were deposited in fiber-optic microwells to measure protein levels in saliva using fluorescence sandwich immunoassays.

Herein, we describe a protocol for simultaneously measuring six proteins in saliva using a fiber-optic microsphere-based antibody array. The immuno-array ...

multiplexed-fluorescent-microarray-for-human-salivary-protein

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Chemistry

Gyroid Nickel Nanostructures from Diblock Copolymer Supramolecules

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex - polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template&#39;s channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology.

This article describes the preparation of well-ordered nickel nanofoams via electroless metal deposition onto nanoporous templates obtained from self-assembled diblock copolymer based supramolecules.

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, ...

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous solution. In a carbon nanotube/PEO105-PPO70-PEO105 (poloxamer 407) aqueous solution, the amphiphilic poloxamer 407 adsorbs onto the carbon nanotube surfaces and self-assembles into continuous layers, driven by intermolecular interactions between constituent molecules. The addition of 5-methylsalicylic acid changes the self-assembled structure from spherical-micellar to a cylindrical morphology. The fabricated poloxamer 407/carbon nanotube hybrid particles exhibit thermo-responsive structural features so that the density and thickness of poloxamer 407 layers are also reversibly controllable by varying temperature. The detailed structural properties of the poloxamer 407/carbon nanotube particles in suspension can be characterized by small-angle neutron scattering experiments and model fit analyses. The distinct curve shapes of the scattering intensities depending on temperature control or addition of aromatic additives are well described by a modified core-shell cylinder model consisting of a carbon nanotube core cylinder, a hydrophobic shell, and a hydrated polymer layer. This method can provide a simple but efficient way for the fabrication and in-situ characterization of carbon nanotube-based nano particles with a structure-tunable encapsulation.

A method for the functionalization of carbon nanotubes with structure-tunable polymeric encapsulation layers and structural characterization using small-angle neutron scattering is presented.

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous ...

The Preparation and Properties of Thermo-reversibly Cross-linked Rubber Via Diels-Alder Chemistry

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ethylene-propylene rubber, grafted with maleic anhydride, is thermo-reversibly cross-linked in two steps. The pending anhydride moieties are first modified with furfurylamine to graft furan groups to the rubber backbone. These pendant furan groups are then cross-linked with a bis-maleimide via a Diels-Alder coupling reaction. Both reactions can be performed under a broad range of experimental conditions and can easily be applied on a large scale. The material properties of the resulting Diels-Alder cross-linked rubbers are similar to a peroxide-cured ethylene/propylene/diene rubber (EPDM) reference. The cross-links break at elevated temperatures (&#62; 150 &#176;C) via the retro-Diels-Alder reaction and can be reformed by thermal annealing at lower temperatures (50-70 &#176;C). Reversibility of the system was proven with infrared spectroscopy, solubility tests and mechanical properties. Recyclability of the material was also shown in a practical way, i.e., by cutting a cross-linked sample into small parts and compression molding them into new samples displaying comparable mechanical properties, which is not possible for conventionally cross-linked rubbers.

A simple two-step approach involving rubber modification and cross-linking yields fully reworkable, elastic rubber products.

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ...

Using Capillary Electrophoresis to Quantify Organic Acids from Plant Tissue: A Test Case Examining Coffea arabica Seeds

Carboxylic acids are organic acids containing one or more terminal carboxyl (COOH) functional groups. Short chain carboxylic acids (SCCAs; carboxylic acids containing three to six carbons), such as malate and citrate, are critical to the proper functioning of many biological systems, where they function in cellular respiration and can serve as indicators of cell health. In foods, organic acid content can have significant impact on taste, with increased SCCA levels resulting in a sour or &#34;acid&#34; taste. Because of this, methods for the rapid analysis of organic acid levels are of particular interest to the food and beverage industries. Unfortunately, however, most methods used for SCCA quantification are dependent on time-consuming protocols requiring the derivatization of samples with hazardous reagents, followed by costly chromatographic and/or mass spectrometric analyses. This method details an alternate method for the detection and quantification of organic acids from plant material and food samples using free zonal capillary electrophoresis (CZE), sometimes simply referred to as capillary electrophoresis (CE). CZE provides a cost-effective method for measuring SCCAs with a low limit of detection (0.005 mg/ml). This article details the extraction and quantification of SCCAs from plant samples. While the method provided focuses on measurement of SCCAs from coffee beans, the method provided can be applied to multiple plant-based food materials.

Using Capillary Electrophoresis to Quantify Organic Acids from Plant Tissue: A Test Case Examining Coffea arabica Seeds

This article presents a method for the detection and quantification of organic acids from plant material using free zonal capillary electrophoresis. An example of the potential application of this method, determining the effects of a secondary fermentation on organic acid levels in coffee seeds, is provided.

Carboxylic acids are organic acids containing one or more terminal carboxyl (COOH) functional groups. Short chain carboxylic acids (SCCAs; carboxylic ...

Microfluidic Dry-spinning and Characterization of Regenerated Silk Fibroin Fibers

The protocol demonstrates a method for mimicking the spinning process of silkworm. In the native spinning process, the contracting spinning duct enables the silk proteins to be compact and ordered by shearing and elongation forces. Here, a biomimetic microfluidic channel was designed to mimic the specific geometry of the spinning duct of the silkworm. Regenerated silk fibroin (RSF) spinning doped with high concentration, was extruded through the microchannel to dry-spin fibers at ambient temperature and pressure. In the post-treated process, the as-spun fibers were drawn and stored in ethanol aqueous solution. Synchrotron radiation wide-angle X-ray diffraction (SR-WAXD) technology was used to investigate the microstructure of single RSF fibers, which were fixed to a sample holder with the RSF fiber axis normal to the microbeam of the X-ray. The crystallinity, crystallite size, and crystalline orientation of the fiber were calculated from the WAXD data. The diffraction arcs near the equator of the two-dimensional WAXD pattern indicate that the post-treated RSF fiber has a high orientation degree.

A protocol for the microfluidic spinning and microstructure characterization of regenerated silk fibroin monofilament is presented.

The protocol demonstrates a method for mimicking the spinning process of silkworm. In the native spinning process, the contracting spinning duct enables ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Time-resolved Photophysical Characterization of Triplet-harvesting Organic Compounds at an Oxygen-free Environment Using an iCCD Camera

Here, we present a sensible method of the acquisition and analysis of time-resolved photoluminescence using an ultrafast iCCD camera. This system enables the acquisition of photoluminescence spectra covering the time regime from nanoseconds up to 0.1 s. This enables us to follow the changes in the intensity (decay) and emission of the spectra over time. Using this method, it is possible to study diverse photophysical phenomena, such as the emission of phosphorescence, and the contributions of prompt and delayed fluorescence in molecules showing thermally activated delayed fluorescence (TADF). Remarkably, all spectra and decays are obtained in a single experiment. This can be done for solids (thin film, powder, crystal) and liquid samples, where the only limitations are the spectral sensitivity of the camera and the excitation wavelength (532 nm, 355 nm, 337 nm, and 266 nm). This technique is, thus, very important when investigating the excited state dynamics in organic emitters for their application in organic light-emitting diodes and other areas where triplet harvesting is of paramount importance. Since triplet states are strongly quenched by oxygen, emitters with efficient TADF luminescence, or those showing room temperature phosphorescence (RTP), must be correctly prepared in order to remove any dissolved oxygen from solutions and films. Otherwise, no long-lived emission will be observed. The method of degassing solid samples as presented in this work is basic and simple, but the degassing of liquid samples creates additional difficulties and is particularly interesting. A method of minimizing solvent loss and changing the sample concentration, while still enabling to remove oxygen in a very efficient and a repeatable manner, is presented in this work.

Here, we present a method of the spectroscopic characterization of organic molecules by means of time-resolved photoluminescence spectroscopy on the nanosecond-to-millisecond timescale in oxygen-free conditions. Methods to efficiently remove oxygen from the samples and, thus, limit luminescence quenching are also described.

Here, we present a sensible method of the acquisition and analysis of time-resolved photoluminescence using an ultrafast iCCD camera. This system enables ...

Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds

Cyclic voltammetry (CV) is a technique used in the analysis of organic compounds. When this technique is combined with electron paramagnetic resonance (EPR) or ultraviolet-visible and near-infrared (UV-Vis-NIR) spectroscopies, we obtain useful information such as electron affinity, ionization potential, band-gap energies, the type of charge carriers, and degradation information that can be used to synthesize stable organic electronic devices. In this study, we present electrochemical and spectroelectrochemical methods to analyze the processes occurring in active layers of an organic device as well as the generated charge carriers.

In this article, we describe electrochemical, electron paramagnetic resonance, and ultraviolet-visible and near-infrared spectroelectrochemical methods to analyze organic compounds for application in organic electronics.

Cyclic voltammetry (CV) is a technique used in the analysis of organic compounds. When this technique is combined with electron paramagnetic resonance ...

Sample Preparation in Quartz Crystal Microbalance Measurements of Protein Adsorption and Polymer Mechanics

In this study, we present various examples of how thin film preparation for quartz crystal microbalance experiments informs the appropriate modeling of the data and determines which properties of the film can be quantified. The quartz crystal microbalance offers a uniquely sensitive platform for measuring fine changes in mass and/or mechanical properties of an applied film by observing the changes in mechanical resonance of a quartz crystal oscillating at high frequency. The advantages of this approach include its experimental versatility, ability to study changes in properties over a wide range of experimental time lengths, and the use of small sample sizes. We demonstrate that, based on the thickness and shear modulus of the layer deposited on the sensor, we can acquire different information from the material. Here, this concept is specifically exploited to display experimental parameters resulting in mass and viscoelastic calculations of adsorbed collagen on gold and polyelectrolyte complexes during swelling as a function of salt concentration.

The quartz crystal microbalance can provide accurate mass and viscoelastic properties for films in the micron or submicron range, which is relevant for investigations in biomedical and environmental sensing, coatings, and polymer science. The sample thickness influences which information can be obtained from the material in contact with the sensor.

In this study, we present various examples of how thin film preparation for quartz crystal microbalance experiments informs the appropriate modeling of ...