UC Irvine

Tumor heterogeneity means the ecosystem of tumor contains variety of cell types, which makes cancer cells hard to detect and increases the difficulty of cancer treatment. Fluorescent probes can provide the molecular information that is critical for diagnosis. The range of fluorescence emission within the visible spectrum allows for multiple target labels. However, a limited range of fluorescence probes have been synthesized and are available for use. Therefore, expanding the number of probes becomes an urgent task. Fluorescence lifetime imaging microscopy (FLIM) can identify fluorescent species based solely on the fluorescence lifetime. The phasor approach to FLIM graphically depict lifetime distributions on a pixel-by-pixel basis. So, the phasor approach to FLIM could be an effective tool in helping to boost the number of detection channels if a library of lifetime probes could be constructed. In addition, the tunability of fluorescent lifetimes can be graphically represented on the phasor plot by determining the fractional contribution of two fluorescent probes. Thus, the main idea of this study is to construct libraries of probes with unique fluorescent lifetimes that will increase the detection capacity of fluorescence imaging. In this study, new fluorescent probes were made by encapsulating different fluorescent species inside the silica nanoparticles through reverse microemulsion methods. Three kinds of lifetime probe mixtures have been synthesized by encapsulating different types of quantum dots, both quantum dots and dark quencher dyes, and quantum dots and fluorescent dyes inside the silica nanoparticles. By changing the amount of fluorescent species, tunable fluorescent lifetime can be achieved. The first fluorescent lifetime libraries have been constructed by synthesizing the probes with different fluorescent species and then selecting the ideal lifetimes. The construction and expansion of fluorescent lifetime probe libraries provides a possibility of simultaneously detecting multiple targeted cell types.