Name: Author Spotlight: Porphyrin-Modified Beads for Use as Compensation Controls in Flow Cytometry
Uploaded: 2023-03-24T12:55:00
Description: Watch this Scientific Journal Video about Porphyrin-Modified Beads for Use as Compensation Controls in Flow Cytometry at JoVE.com

We would like to thank David Rodriguez for assistance with the figure preparation and Precision Pathology Services (San Antonio, TX) for the use of its Navios EX flow cytometer.

All procedures need to be done using appropriate personal protective equipment.
1. Preparation of the TCPP stock solution, 1.0 mg/ mL
NOTE: This can be prepared monthly.
<ol>
	<li>Using an analytical balance, spatula, and weighing paper, weigh 49.0-50.9 mg of TCPP. Round the weight to 1/10 of a milligram. Set the measured amount of TCPP aside protected from light. 
	NOTE: Use a static gun if the weight reading is unstable.</li>
	<li>Determine...

Porphyrin-Modified Beads in Flow Cytometry

<ol>
	<li>Josefsen, L. B., Boyle, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unique+diagnostic+and+therapeutic+roles+of+porphyrins+and+phthalocyanines+in+photodynamic+therapy,+imaging+and+theranostics.">Unique diagnostic and therapeutic roles of porphyrins and phthalocyanines in photodynamic therapy, imaging and theranostics.</a> Theranostics. 2 (9), 916-966 (2012).</li><li>Tsolekile, N., Nelana, S., Oluwafemi, O. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Porphyrin+as+diagnostic+and+therapeutic+agent.">Porphyrin as diagnostic and therapeutic agent.</a> Molecules. 24 (14), 2669 (2019).</li><li>Gunaydin, G., Gedik, M. E., Ayan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photodynamic+therapy+for+the+treatment+and+diagnosis+of+cancer-A+review+of+the+current+clinical+status.">Photodynamic therapy for the treatment and diagnosis of cancer-A review of the current clinical status.</a> Frontiers in Chemistry. 9, 686303 (2021).</li><li>Berg, K., 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=Porphyrin-related+photosensitizers+for+cancer+imaging+and+therapeutic+applications.">Porphyrin-related photosensitizers for cancer imaging and therapeutic applications.</a> Journal of Microscopy. 218, 133-147 (2005).</li><li>Kessel, D., Reiners, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-activated+pharmaceuticals:+Mechanisms+and+detection).">Light-activated pharmaceuticals: Mechanisms and detection).</a> Israel Journal of Chemistry. 52 (8-9), 674-680 (2012).</li><li>Didamson, O. C., Abrahamse, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeted+photodynamic+diagnosis+and+therapy+for+esophageal+cancer:+Potential+role+of+functionalized+nanomedicine.">Targeted photodynamic diagnosis and therapy for esophageal cancer: Potential role of functionalized nanomedicine.</a> Pharmaceutics. 13 (11), 1943 (2021).</li><li>Harada, Y., Murayama, Y., Takamatsu, T., Otsuji, E., Tanaka, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=5-Aminolevulinic+acid-induced+protoporphyrin+IX+fluorescence+imaging+for+tumor+detection:+Recent+advances+and+challenges.">5-Aminolevulinic acid-induced protoporphyrin IX fluorescence imaging for tumor detection: Recent advances and challenges.</a> International Journal of Molecular Sciences. 23 (12), 6478 (2022).</li><li>Bochenek, K., Aebisher, D., Mi&#281;dzybrodzka, A., Cie&#347;lar, G., Kawczyk-Krupka, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+bladder+cancer+diagnosis+-+The+role+of+autofluorescence+and+photodynamic+diagnosis.">Methods for bladder cancer diagnosis - The role of autofluorescence and photodynamic diagnosis.</a> Photodiagnosis and Photodynamic Therapy. 27, 141-148 (2019).</li><li>Iwaki, K., 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=Flow+cytometry-based+photodynamic+diagnosis+with+5-aminolevulinic+acid+for+the+detection+of+minimal+residual+disease+in+multiple+myeloma.">Flow cytometry-based photodynamic diagnosis with 5-aminolevulinic acid for the detection of minimal residual disease in multiple myeloma.</a> The Tohoku Journal of Experimental Medicine. 249 (1), 19-28 (2019).</li><li>Patriquin, L., 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=Early+detection+of+lung+cancer+with+meso+tetra+(4-carboxyphenyl)+porphyrin-labeled+sputum.">Early detection of lung cancer with meso tetra (4-carboxyphenyl) porphyrin-labeled sputum.</a> Journal of Thoracic Oncology. 10 (9), 1311-1318 (2015).</li><li>Pan, L., 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=A+brief+introduction+to+porphyrin+compounds+used+in+tumor+imaging+and+therapies.">A brief introduction to porphyrin compounds used in tumor imaging and therapies.</a> Mini Reviews in Medicinal Chemistry. 21 (11), 1303-1313 (2021).</li><li>Nishida, K., Tojo, T., Kondo, T., Yuasa, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+the+correlation+between+porphyrin+accumulation+in+cancer+cells+and+functional+positions+for+application+as+a+drug+carrier.">Evaluation of the correlation between porphyrin accumulation in cancer cells and functional positions for application as a drug carrier.</a> Scientific Reports. 11 (1), 2046 (2021).</li><li>Lin, Y., Zhou, T., Bai, R., Xie, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+approaches+for+the+enhancement+of+porphyrin+skeleton-based+photodynamic+therapy.">Chemical approaches for the enhancement of porphyrin skeleton-based photodynamic therapy.</a> Journal of Enzyme Inhibition and Medicinal Chemistry. 35 (1), 1080-1099 (2020).</li><li>Kou, J., Dou, D., Yang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Porphyrin+photosensitizers+in+photodynamic+therapy+and+its+applications.">Porphyrin photosensitizers in photodynamic therapy and its applications.</a> Oncotarget. 8 (46), 81591-81603 (2017).</li><li>Wezgowiec, J., 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=Electric+field-assisted+delivery+of+photofrin+to+human+breast+carcinoma+cells.">Electric field-assisted delivery of photofrin to human breast carcinoma cells.</a> The Journal of Membrane Biology. 246 (10), 725-735 (2013).</li><li>Palasuberniam, P., 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=Small+molecule+kinase+inhibitors+enhance+aminolevulinic+acid-mediated+protoporphyrin+IX+fluorescence+and+PDT+response+in+triple+negative+breast+cancer+cell+lines.">Small molecule kinase inhibitors enhance aminolevulinic acid-mediated protoporphyrin IX fluorescence and PDT response in triple negative breast cancer cell lines.</a> Journal of Biomedical Optics. 26 (9), 098002 (2021).</li><li>Kim, B., Bohandy, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectroscopy+of+porphyrins.">Spectroscopy of porphyrins.</a> Johns Hopkins APL Technical Digest. 2 (3), 153-163 (1981).</li><li>Uttamlal, M., Sheila Holmes-Smith, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+excitation+wavelength+dependent+fluorescence+of+porphyrins.">The excitation wavelength dependent fluorescence of porphyrins.</a> Chemical Physics Letters. 454 (4), 223-228 (2008).</li><li>Zhang, Y. Z., Kemper, C., Bakke, A., Haugland, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+flow+cytometry+compensation+standards:+internally+stained+fluorescent+microspheres+with+matched+emission+spectra+and+long-term+stability.">Novel flow cytometry compensation standards: internally stained fluorescent microspheres with matched emission spectra and long-term stability.</a> Cytometry. 33 (2), 244-248 (1998).</li><li>Monard, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Building+a+spectral+cytometry+toolbox:+Coupling+fluorescent+proteins+and+antibodies+to+microspheres.">Building a spectral cytometry toolbox: Coupling fluorescent proteins and antibodies to microspheres.</a> Cytometry. Part A. 101 (10), 846-855 (2022).</li><li>Byrd, T., 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=Polystyrene+microspheres+enable+10-color+compensation+for+immunophenotyping+of+primary+human+leukocytes.">Polystyrene microspheres enable 10-color compensation for immunophenotyping of primary human leukocytes.</a> Cytometry. Part A. 87 (11), 1038-1046 (2015).</li><li>Roederer, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Compensation+in+flow+cytometry.">Compensation in flow cytometry.</a> Current Protocols in Cytometry. , (2002).</li><li>Kabe, Y., 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=Porphyrin+accumulation+in+mitochondria+is+mediated+by+2-oxoglutarate+carrier.">Porphyrin accumulation in mitochondria is mediated by 2-oxoglutarate carrier.</a> The Journal of Biological Chemistry. 281 (42), 31729-31735 (2006).</li><li>Bederka, L. H., 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=Sputum+analysis+by+flow+cytometry;+An+effective+platform+to+analyze+the+lung+environment.">Sputum analysis by flow cytometry; An effective platform to analyze the lung environment.</a> PLoS One. 17 (8), e0272069 (2022).</li><li>. US6838248B2 - Compositions and methods for detecting pre-cancerous conditions in cell and tissue samples using 5, 10, 15, 20-tetrakis (carboxyphenyl) porphine Available from: <a target="_blank" href="https://patents.google.com/patent/US68248B2/en?oq=US+patent+6838248+B2">https://patents.google.com/patent/US68248B2/en?oq=US+patent+6838248+B2</a> (2005)</li><li>. Method of using 5,10,15,20-tetrakis(carboxyphenyl)porphine for detecting cancers of the lung Available from: <a target="_blank" href="https://www.osti.gov/deopatents/biblio/7117152">https://www.osti.gov/deopatents/biblio/7117152</a> (1992)</li><li>Grayson, 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=Quality-controlled+sputum+analysis+by+flow+cytometry.">Quality-controlled sputum analysis by flow cytometry.</a> Journal of Visualized Experiments. (174), e62785 (2021).</li><li>Anjali, K., Christopher, J., Sakthivel, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ruthenium-based+macromolecules+as+potential+catalysts+in+homogeneous+and+heterogeneous+phases+for+the+utilization+of+carbon+dioxide.">Ruthenium-based macromolecules as potential catalysts in homogeneous and heterogeneous phases for the utilization of carbon dioxide.</a> ACS Omega. 4 (8), 13454-13464 (2019).</li><li>Yadav, 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=Recent+advances+in+the+preparation+and+applications+of+organo-functionalized+porous+materials.">Recent advances in the preparation and applications of organo-functionalized porous materials.</a> Chemistry. 15 (17), 2588-2621 (2020).</li><li>. US7670799B2 - Method for making 5,10,15,10-tetrakis (carboxyphenyl) porphine (TCPP) solutions and composition compromising TCPP Available from: <a target="_blank" href="https://patents.google.com/patent/US7670799B2/en">https://patents.google.com/patent/US7670799B2/en</a> (2023)</li><li>Shimizu, N., 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=High-performance+affinity+beads+for+identifying+drug+receptors.">High-performance affinity beads for identifying drug receptors.</a> Nature Biotechnology. 18 (8), 877-881 (2000).</li><li>Anderson, G. W., Zimmerman, J. E., Callahan, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+esters+of+N-hydroxysuccinimide+in+peptide+synthesis.">The use of esters of N-hydroxysuccinimide in peptide synthesis.</a> Journal of the American Chemical Society. 86 (9), 1839-1842 (1964).</li><li>Hermanson, G. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Bioconjugate Techniques. , (2013).</li><li>El-Faham, A., Albericio, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peptide+coupling+reagents,+more+than+a+letter+soup.">Peptide coupling reagents, more than a letter soup.</a> Chemical Reviews. 111 (11), 6557-6602 (2011).</li><li>Hulspas, R., O'Gorman, M. R. G., Wood, B. L., Gratama, J. W., Sutherland, 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=Considerations+for+the+control+of+background+fluorescence+in+clinical+flow+cytometry.">Considerations for the control of background fluorescence in clinical flow cytometry.</a> Cytometry Part B. 76 (6), 355-364 (2009).</li><li>Hoffman, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standardization,+calibration,+and+control+in+flow+cytometry.">Standardization, calibration, and control in flow cytometry.</a> Current Protocols in Cytometry. , (2005).</li><li>Ethirajan, M., Chen, Y., Joshi, P., Pandey, R. 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Despite the many applications of porphyrins in cancer diagnosis and therapeutics2, there is limited literature on their potential use as a flow cytometric reagent for the identification of cancerous versus non-cancerous cell populations in primary human tissues24,25,26. Our research on the flow cytometric analysis of human sputum24,27 requires the...

Porphyrins have been of interest for many years in the biomedical field owing to their fluorescence and tumor-targeting properties1,2,3. Therapeutic applications such as photodynamic therapy (PDT) and sonodynamic therapy (SDT) entail the systemic administration of a porphyrin to a cancer patient, the accumulation of the drug in the tumor, and the localized exposure of the tumor to a laser light of a specific wavelength or ultrasound. The exposure to laser light or ultrasound leads to the generation of reactive oxygen species by the porphyrin and subsequent cell death4,5. In photodynamic diagnosis (PDD), porphyrin fluorescence is used to distinguish cancer cells from normal cells6. In this context, protoporphyrin IX, a natural fluorescent porphyrin that accumulates in tumors upon the systemic or local injection of its precursor, 5-aminolevulinic acid (5-ALA), is used to identify gastrointestinal stromal tumors, bladder cancer, and brain cancer7,8. More recently, 5-ALA treatment was explored as an approach to detect minimal residual disease in multiple myeloma9. Our laboratory has been using the tetraaryl porphyrin TCPP (5,10,15,20-tetrakis-(4-carboxyphenyl)-21,23H-porphine) for its ability to selectively stain lung cancer cells and cancer-associated cells in human sputum samples, which is a property that has been exploited in slide-based and flow cytometric diagnostic assays10.
Some porphyrins are bifunctional in that they can be used as therapeutic and diagnostic agents2,11. In biomedical research, such bifunctional porphyrins are used to evaluate how their ability to selectively target and kill cancer cells is a function of their structure as well as how it is affected by the presence of other compounds12,13,14,15,16. Both the cellular uptake of porphyrins and their cytotoxicity can be measured on a flow cytometric platform in a high-throughput manner. The absorption and emission spectra of fluorescent porphyrins are complex, but most flow cytometric platforms are equipped to correctly identify them. The absorption spectrum of fluorescent porphyrins is characterized by a strong absorption band in the 380-500 nm range, known as the Soret band. Two to four weaker absorption bands are generally observed in the 500-750 nm range (Q bands)17. A blue&#160;488 nm laser, present in most flow cytometers, or a violet laser (405 nm) can generate light of the appropriate wavelength to excite porphyrins. The emission spectra of porphyrins typically display peaks in the 600-800 nm range18, which results in very little spectral overlap with fluorescein isothiocyanate or phycoerythrin (PE) fluorophores but considerable overlap with other often-used fluorophores, such as allophycocyanin (APC), as well as tandem fluorophores, such as PE-Cy5 and others. Therefore, when using porphyrins in multi-color flow cytometry assays, single-fluorophore controls are essential to adequately correct the spillover of fluorescence in channels other than the one designated to measure the porphyrin&#39;s fluorescence.
Ideally, the single-fluorophore controls used to calculate the spillover matrix for a panel of fluorophores (also called &#34;compensation controls&#34;) should consist of the same cell type(s) as the sample. However, using the sample for this purpose is not optimal if there is very little sample to begin with or if the target population within the sample is very small&#160;(for example, if one wants to look at minimal residual disease or cancer cells at the early stages of the disease). A useful alternative to cells is beads coupled with the same fluorophore that is used to analyze the sample. Many such beads are commercially available; these beads are either prelabeled with the desired fluorophore (prelabeled fluorophore-specific beads)19,20, or a fluorescently labeled antibody can be attached to them (antibody capture beads)20,21. While commercial compensation beads are available for many fluorophores, such beads are unavailable for porphyrins, despite their increasing use in basic and clinical research.
In addition to sample preservation and appropriately sized positive versus negative populations, the other advantages of using beads as compensation controls are the ease of preparation, low background fluorescence, and excellent stability over time22. The potential disadvantage of using beads as a compensation control is that the emission spectrum of the fluorescent antibody captured on beads may differ from that of the same antibody used to label the cells. This may be of specific importance when using a spectral flow cytometer20. Therefore, the development of beads as a compensation control needs to be performed on the flow cytometer that will be used for the assay for which the beads are developed. Moreover, the development of the beads needs to include a comparison with cells labeled with the same fluorescent staining reagent.
Here, we describe the preparation of TCPP amine-functionalized polystyrene compensation beads, whose median fluorescence intensity in the detection channel was comparable to that of TCPP-labeled cells in sputum, and their use as compensation controls for flow cytometry. The autofluorescence of equivalent, non-functionalized beads was sufficiently low for their use as negative fluorescence compensation controls. In addition, these beads demonstrated stability in storage for nearly 1 year.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Amber plastic vials, 2 mL, U- bottom, polypropylene</td>
			<td>Research Products International&#160;&#160;</td>
			<td>ZC1028-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Amine-funtionalized polystyrene divinylbenzene crosslinked (PS/DVB) beads, 10.6 &#956;m diameter, 2.5% w/v aqueous suspension, 3.82 x 107 beads/mL, 7.11 x 1011 amine groups/ bead</td>
			<td>Spherotech</td>
			<td>APX-100-10</td>
			<td>Diameter spec. 8.0-12.9 um, suspension 2.5% w/v 3.82 x 107 beads/mL, 7.11 x 1011 amine groups/ bead</td>
		</tr>
		<tr>
			<td>Conical tubes, 50 mL, Falcon</td>
			<td>Fisher Scientific</td>
			<td>14-432-22</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td></td>
			<td></td>
			<td>with appropriate rotor</td>
		</tr>
		<tr>
			<td>Disposable polystyrene bottle with cap, 150 mL</td>
			<td>Fisher Scientific</td>
			<td>09-761-140</td>
			<td></td>
		</tr>
		<tr>
			<td>EDC (N- (3- dimethylaminopropyl)- N&#39;- ethylcarbodiimide hydrochloride), &#8805;98%</td>
			<td>Sigma</td>
			<td>03450-1G</td>
			<td>CAS No:&#160; 25952-53-8</td>
		</tr>
		<tr>
			<td>FlowJo Single Cell Analysis Software (v10.6.1)</td>
			<td>BD</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glass coverslips, 22 x 22 mm</td>
			<td>Fisher Scientific</td>
			<td>12-540-BP</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass fiber syringe filters (Finneran, 5 &#181;m, 13 mm diameter)</td>
			<td>Thomas Scientific</td>
			<td>1190M60</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass microscope slides, 275 x 75 x 1 mm</td>
			<td>Fisher Scientific</td>
			<td>12-550-143</td>
			<td></td>
		</tr>
		<tr>
			<td>Hanks Balanced Salt Solution (HBSS)</td>
			<td>Fisher Scientific</td>
			<td>14-175-095</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropanol, ACS grade</td>
			<td>Fisher Scientific</td>
			<td>AC423830010</td>
			<td></td>
		</tr>
		<tr>
			<td>Mechanical pipette, 1 channel, 100-1000 uL with tips</td>
			<td>Eppendorf</td>
			<td>3123000918</td>
			<td></td>
		</tr>
		<tr>
			<td>MES (22- (N- mopholino)- N&#39;- ethanesulfonic acid, hemisodium salt</td>
			<td>Sigma</td>
			<td>M0164</td>
			<td>CAS No:&#160; 117961-21-4</td>
		</tr>
		<tr>
			<td>Navios EX flow cytometer</td>
			<td>Beckman Coulter</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Olympus BX-40 microscope with DP73 camera and 40X objective with cellSens software</td>
			<td>Olympus</td>
			<td></td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Pasteur pipettes, glass, 5.75&#34;</td>
			<td>Fisher Scientific</td>
			<td>13-678-6B</td>
			<td></td>
		</tr>
		<tr>
			<td>pH meter (UB 10 Ultra Basic)</td>
			<td>Denver Instruments</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette controller (Drummond)</td>
			<td>Pipete.com</td>
			<td>DP101</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic Syringe, 5 mL</td>
			<td>Fisher Scientific</td>
			<td>14955452</td>
			<td></td>
		</tr>
		<tr>
			<td>Polystyrene Particles (non-functionalized), SPHERO,&#160; 2.5% w/v, 8.0-12.9 &#181;m</td>
			<td>Spherotech</td>
			<td>PP-100-10&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Polypropylene tubes, 15mL, conical</td>
			<td>Fisher Scientific</td>
			<td>14-959-53A</td>
			<td></td>
		</tr>
		<tr>
			<td>Polystyrene tubes, round bottom&#160;</td>
			<td>Fisher Scientific</td>
			<td>14-959-2A</td>
			<td></td>
		</tr>
		<tr>
			<td>Rainbow Beads (Spherotech URCP-50-2K)</td>
			<td>Fisher Scientific</td>
			<td>NC9207381</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological pipettes, disposable - 10 mL</td>
			<td>Fisher Scientific</td>
			<td>07-200-574</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological pipettes, disposable - 25 mL</td>
			<td>Fisher Scientific</td>
			<td>07-200-576</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium bicarbonate (NaHCO3)</td>
			<td>Sigma</td>
			<td>S6014</td>
			<td>CAS No:&#160; 144-55-8</td>
		</tr>
		<tr>
			<td>TCPP (meso-tetra(4-carboxyphenyl)porphine)&#160; Frontier Scientific&#160;</td>
			<td>Fisher Scientific</td>
			<td>50-393-68</td>
			<td>CAS No:&#160; 14609-54-2</td>
		</tr>
		<tr>
			<td>Tecan Spark Plate Reader (or similar)</td>
			<td>Tecan Life Sciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tube revolver/rotator</td>
			<td>Thermo Fisher</td>
			<td>88881001</td>
			<td></td>
		</tr>
		<tr>
			<td>Vortex mixer</td>
			<td>Fisher Scientific</td>
			<td>2215365</td>
			<td></td>
		</tr>
	</tbody>
</table>

porphyrin-modified beads for use as compensation controls in flow cytometry

Flow cytometry can rapidly characterize and quantify diverse cell populations based on fluorescence measurements. The cells are first stained with one or more fluorescent reagents, each functionalized with a different fluorescent molecule (fluorophore) that binds to cells selectively based on their phenotypic characteristics, such as cell surface antigen expression. The intensity of fluorescence from each reagent bound to cells can be measured on the flow cytometer using channels that detect a specified range of wavelengths. When multiple fluorophores are used, the light from individual fluorophores often spills over into undesired detection channels, which requires a correction to the fluorescence intensity data in a process called compensation. 
Compensation control particles, typically polymer beads bound to a single fluorophore, are needed for each fluorophore used in a cell labeling experiment. Data from compensation particles from the flow cytometer are used to apply a correction to the fluorescence intensity measurements. This protocol describes the preparation and purification of polystyrene compensation beads covalently functionalized with the fluorescent reagent meso-tetra(4-carboxyphenyl) porphine (TCPP) and their application in flow cytometry compensation. In this work, amine-functionalized polystyrene beads were treated with TCPP and the amide coupling reagent EDC (N-(3-dimethylaminopropyl)-N&#8242;-ethylcarbodiimide hydrochloride) at pH 6 and at room temperature for 16 h with agitation. The TCPP beads were isolated by centrifugation and resuspended in a pH 7 buffer for storage. TCPP-related particulates were observed as a byproduct. The number of these particulates could be reduced using an optional filtration protocol. The resultant TCPP beads were successfully used on a flow cytometer for compensation in experiments with human sputum cells labeled with multiple fluorophores. The TCPP beads proved stable following storage in a refrigerator for 300 days.

Author Spotlight: Porphyrin-Modified Beads for Use as Compensation Controls in Flow Cytometry  

Porphyrin-Modified Beads for Use as Compensation Controls in Flow Cytometry

This protocol for the TCPP labeling of beads is relatively fast and efficient. Figure 1 shows a representative outcome of the TCPP bead-labeling process as determined by flow cytometry. Figure 1A shows the standardized profile of Rainbow beads, as detected in the appropriate channel for detecting TCPP. These beads serve as a QC for the standardization of the laser voltages for the detection of TCPP by the flow cytometer. Figure 1B s...

Watch this Scientific Journal Video about Porphyrin-Modified Beads for Use as Compensation Controls in Flow Cytometry at JoVE.com

The protocol describes how porphyrin-based compensation beads for flow cytometry are prepared by the reaction of amine-functionalized polystyrene beads with the porphyrin TCPP and the amide coupling reagent EDC. A filtration procedure is used to reduce the particulate byproducts.

Flow cytometry can rapidly characterize and quantify diverse cell populations based on fluorescence measurements. The cells are first stained with one or ...