Name: real-time monitoring of ligand-receptor interactions with fluorescence resonance energy transfer
Uploaded: 2012-08-20T12:00:00
Description: Watch this Scientific Journal Video about Real-time Monitoring of Ligand-receptor Interactions with Fluorescence Resonance Energy Transfer at JoVE.com

Financial support for this work was provided through the National Science Foundation, National Institute of Health (NIH), Materials Technology Center (MTC) and ORDA at SIUC. We thank NSF for a grant (CHE-0959568) for the purchase of an FE-SEM. We would like to thank Prof. Matthew McCarroll for helpful discussions. Julia Reyes will like to thank COLCIENCIAS, Colombian Agency and Universidad Pedagogica y Tecnologica de Colombia for her scholarship and financial support.

A. Synthesis and Characterization of PDA Liposomes4,5,6
Note 1: Protect the PDA solution from light using aluminum foil wrapping on every container throughout all the experimental steps.
Note 2: Two different sets of liposome solution (B and C) were prepared following procedure A (Synthesis and characterization of PDA liposomes).
1. Synthesis of N-hydroxysuccinimide Diacteylene (NHS-PCDA)
<ol>
 <li>To prepare liposomes, an essen...

<ol>
	<li>Lakowicz, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Principles of Fluorescence Spectroscopy. , (1999).</li><li>Charych, D. H., Nagy, J. O., Spevak, W., Bednarski, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+Colorimetric+Detection+of+a+Receptor-Ligand+Interaction+by+a+Polymerized+Bilayer+Assembly.">Direct Colorimetric Detection of a Receptor-Ligand Interaction by a Polymerized Bilayer Assembly.</a> Science. 261, 585-588 (1993).</li><li>Yoon, B., Lee, S., Kim, J. -. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+Conceptual+and+Technological+Advances+in+Polydiacetylene-based+Supramolecular+Chemosensors.">Recent Conceptual and Technological Advances in Polydiacetylene-based Supramolecular Chemosensors.</a> Chem. Soc. Rev. 38, 1958-1968 (2009).</li><li>Xuelian, L. i., Kohli, P. u. n. i. t. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigating+Molecular+Interactions+in+Biosensors+Based+on+Fluorescence+Resonance+Energy+Transfer.">Investigating Molecular Interactions in Biosensors Based on Fluorescence Resonance Energy Transfer.</a> J. Phys. Chem. C. 114, 6255-6264 (2010).</li><li>Li, X., Matthews, S., Kohli, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+Resonance+Energy+Transfer+in+Polydiacetylene+Liposomes.">Fluorescence Resonance Energy Transfer in Polydiacetylene Liposomes.</a> J. Phys. Chem. B. 112, 13263-13272 (2008).</li><li>Li, X., McCarroll, M., Kohli, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulating+Fluorescence+Resonance+Energy+Transfer+in+Conjugated+Liposomes.">Modulating Fluorescence Resonance Energy Transfer in Conjugated Liposomes.</a> Langmuir. 22, (2006).</li><li>New, R. R. C., New, R. R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Liposomes: A Practical Approach. , 33-104 (1990).</li><li>Chen, X., Lee, J., Jou, M. J., Kim, J. -. M., Yoon, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colorimetric+and+Fluorometric+Detection+of+Cationic+Surfactants+Based+on+Conjugated+Polydiacetylene+Supramolecules.">Colorimetric and Fluorometric Detection of Cationic Surfactants Based on Conjugated Polydiacetylene Supramolecules.</a> Chem. Commun. , 3434-3436 (2009).</li><li>Yarimaga, O., Im, M., Choi, Y. -. K., Kim, T. W., Jung, Y. K., Park, H. G., Lee, S., Kim, J. -. 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+Color+Display+System+Based+on+Thermochromic+Conjugated+Polydiacetylene.">A Color Display System Based on Thermochromic Conjugated Polydiacetylene.</a> Macromolecular Research. 18, 404-407 (2010).</li></ol>

We have performed selective binding of lysine residue of protein on liposome surface using NHS-amine reaction. This FRET based method is capable of doing Real-time monitoring of biotin-streptavidin binding and protein (BSA) binding to the liposome surface. Similar procedure can be applied to study the binding dynamics of various protein interactions with their selective receptors. There is flexibility in choosing fluorophores that will provide changes in the J values depending upon the spectral characteristics o...

<table border="1">
	 <tbody>
 <tr>
 <td>Name of reagent</td>
 <td>Company</td>
 <td>Catalogue number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>10,12-pentacosadiynoic acid (PCDA)</td>
 <td>GFS chemicals</td>
 <td>3261</td>
 <td>Light sensitive</td>
 </tr>
 <tr>
 <td>N-hydroxysuccinimide (NHS)</td>
 <td>Acros organics</td>
 <td>157270250</td>
 <td>Moisture sensitive</td>
 </tr>
 <tr>
 <td>1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide hydrochloride (EDC)</td>
 <td>Chem-impex International</td>
 <td>00050</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)</td>
 <td>Avanti Polar lipids</td>
 <td>850345P</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Rhodamine-tagged Bovine Serum Albumin (BSA-Rh)</td>
 <td>Sigma Aldrich</td>
 <td>A4537</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>(1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(biotinyl)(biotin-DOPE)</td>
 <td>Avanti Polar lipids</td>
 <td>870282</td>
 <td>&nbsp;</td>
 </tr>
	 </tbody>
 </table>

real-time monitoring of ligand-receptor interactions with fluorescence resonance energy transfer

FRET is a process whereby energy is non-radiatively transferred from an excited donor molecule to a ground-state acceptor molecule through long-range dipole-dipole interactions1. In the present sensing assay, we utilize an interesting property of PDA: blue-shift in the UV-Vis electronic absorption spectrum of PDA (Figure 1) after an analyte interacts with receptors attached to PDA2,3,4,7. This shift in the PDA absorption spectrum provides changes in the spectral overlap (J) between PDA (acceptor) and rhodamine (donor) that leads to changes in the FRET efficiency. Thus, the interactions between analyte (ligand) and receptors are detected through FRET between donor fluorophores and PDA. In particular, we show the sensing of a model protein molecule streptavidin. We also demonstrate the covalent-binding of bovine serum albumin (BSA) to the liposome surface with FRET mechanism. These interactions between the bilayer liposomes and protein molecules can be sensed in real-time. The proposed method is a general method for sensing small chemical and large biochemical molecules. Since fluorescence is intrinsically more sensitive than colorimetry, the detection limit of the assay can be in sub-nanomolar range or lower8. Further, PDA can act as a universal acceptor in FRET, which means that multiple sensors can be developed with PDA (acceptor) functionalized with donors and different receptors attached on the surface of PDA liposomes.

Watch this Scientific Journal Video about Real-time Monitoring of Ligand-receptor Interactions with Fluorescence Resonance Energy Transfer at JoVE.com

Real-time Monitoring of Ligand-receptor Interactions with Fluorescence Resonance Energy Transfer

We demonstrate FRET between conjugated polymer polydiacetylene (PDA) and fluorophore attached to the surface of PDA liposomes for the sensing of biomolecules. PDA liposomes also contained receptor molecules on their surfaces for biomolecules to be used as probes. Ligand-receptor interactions lead to changes in the FRET efficiency between the fluorophore and PDA which is the basis of the sensing mechanism.

FRET is a process  whereby energy is non-radiatively transferred from an excited donor molecule to  a ground-state acceptor molecule through long-range ...

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