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Hydrosomes: femtoliter containers for fluorescence spectroscopy studies

Jofre, Ana M. and Tang, Jianyong and Greene, Mark E. and Lowman, Geoffrey M. and Hodas, Nathan and Kishore, Rani and Helmerson, Kristian and Goldner, Lori S. (2007) Hydrosomes: femtoliter containers for fluorescence spectroscopy studies. In: Optical Trapping and Optical Micromanipulation IV. Proceedings of SPIE. No.6644. Society of Photo-Optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 66440E. ISBN 9780819467928.

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We report on improvements and innovations in the use of hydrosomes to encapsulate and study single molecules. Hydrosomes are optically-trappable aqueous nanodroplets. The droplets are suspended in a fluorocarbon medium that is immiscible with water and has an index of refraction lower than water, so hydrosomes are stable and optically trapped by a focused laser beam (optical tweezers). Using optical tweezers, we hold the hydrosomes within a confocal observation volume and interrogate the encapsulated molecule by fluorescence excitation. This method allows for long observation times of a molecule without the need for surface immobilization or liposome encapsulation. We have developed a new way for creating hydrosomes on demand by inertially launching them into the fluorocarbon matrix using a piezo-activated micropipette. Time-resolved fluorescence anisotropy studies are carried out to characterize the effects of the hydrosome interface boundary on biological molecules and to determine whether molecules encapsulated within hydrosomes diffuse freely throughout the available volume. We measured the fluorescence anisotropy decay of 20mer DNA duplexes, and enhanced green fluorescent protein (GFP). We conclude that the molecules rotate freely inside the nanodroplets and do not stick or aggregate at the boundary.

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Additional Information:© 2007 Society of Photo-Optical Instrumentation Engineers (SPIE). We acknowledge funding from the Office of Naval Research (ONR), the National Research Council (NRC), and the NIST Physics Laboratory. The FC-70 used in this work was a generous gift from 3M. We thank Joseph Reiner, Kimberly Briggman, John Denker, and Jeeseong Hwang for helpful discussions. We also thank Joseph Reiner for the schematic diagram of the apparatus shown in Figure 1. Certain commercial equipment, instruments, or materials are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.
Funding AgencyGrant Number
Office of Naval Research (ONR)UNSPECIFIED
National Research CouncilUNSPECIFIED
National Institute of Standards and Technology (NIST)UNSPECIFIED
Subject Keywords:nanocontainers, nanodroplets, optical trapping, single molecule, anisotropy, fluorescence spectroscopy, nanochemistry, microreactors
Series Name:Proceedings of SPIE
Issue or Number:6644
Record Number:CaltechAUTHORS:20191106-114240209
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Official Citation:Ana M. Jofre, Jianyong Tang, Mark E. Greene, Geoffrey M. Lowman, Nathan Hodas, Rani Kishore, Kristian Helmerson, and Lori S. Goldner "Hydrosomes: femtoliter containers for fluorescence spectroscopy studies", Proc. SPIE 6644, Optical Trapping and Optical Micromanipulation IV, 66440E (5 September 2007);
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99695
Deposited By: Tony Diaz
Deposited On:06 Nov 2019 20:01
Last Modified:16 Nov 2021 17:48

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