Abstract 4304: Evaluation of different near-infrared fluorescent dyes
Authors: Lambros Maria P. , Sanchez Antonio , Desai Surbhi , Kondapalli Labanya 
Published: May 2015

Abstract
Purpose.
The purpose of this work is to evaluate different near infrared (NIR) fluorescent dyes in terms of tissue penetration and intensity. Fluorescent dyes active in the NIR region are of great interest in cancer targeting and imaging. The advantages of NIR dyes include minimal auto-fluorescence from biological samples, high tissue penetration depth and reduced light scattering.
Materials and Methods.
Different NIR fluorescent dyes, Dylight 755-4xPEG, Dylight 800, Dylight 747B4, Dylight 776B4, Dylight 776B2, Dylight 755 and Dylight 747B1 were conjugated to phospholipids (Thermo Scientific, Rockford, IL). Each of the fluorescent dyes was separately encapsulated in a liposome and an emulsion formulation. All of the fluorescent dye liposome and emulsion formulations were placed at the bottom of 12 well-plates and the fluorescence of each formulation was measured when the surface of each formulation was uncovered and when the surface of each formulation was covered with different thickness of matrigel inserts. Furthermore, the penetration intensity of the fluorescence of each formulation was evaluated after each formulation was injected in different depths of chicken tissue. The UVP iBox Scientia imaging system (UVP, LLC, Upland, CA) was used to measure the fluorescence of the different formulations.
Results.
Fluorescence from uncovered formulations: Dyes encapsulated in emulsions showed higher fluorescence than those encapsulated in liposomes. Dylight 747B4 showed the highest fluorescence of all the dyes encapsulated in liposomes. In emulsion formulations, Dylight 755-4xPEG, Dylight 800, Dylight 747B4, Dylight 755 and Dylight 747B1 showed higher fluorescence than Dylight 776B4 and Dylight 776B2.
Fluorescence from formulations covered with different thickness of matrigel inserts: Dyes encapsulated in liposomes showed decreasing fluorescence with increasing thickness of matrigel inserts. Dyes encapsulated in emulsions showed high fluorescence intensity and their intensity was not affected by the thickness of the matrigel inserts.
Fluorescence from formulations injected in different tissue depths: Of all the dyes encapsulated in liposomes and injected at 2 inches of tissue depth, only the Dylight 747B4 showed measurable fluorescence intensity. All the dyes encapsulated in emulsions and injected at 2 or 4 inches of tissue depth showed fluorescence, however the dyes injected at 4 inches depth showed light-scattering.
Conclusions.
The carrier which encapsulates the dye significantly affects the fluorescence of the dye. In these experiments, emulsion formulations showed more intense fluorescence than liposome formulations of the same dyes. Of all the fluorescent dyes evaluated, Dylight 747B4 encapsulated in emulsions has the highest and fluorescence intensity and tissue penetration.
Citation Format: Maria P. Lambros, Antonio Sanchez, Surbhi Desai, Labanya Kondapalli. Evaluation of different near-infrared fluorescent dyes. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4304. doi:10.1158/1538-7445.AM2014-4304