Glucagon-Secreting Alpha Cell Selective Two-Photon Fluorescent Probe TP-α: For Live Pancreatic Islet Imaging

Abstract

Two-photon (TP) microscopy has an advantage for live tissue imaging which allows a deeper tissue penetration up to 1 mm comparing to one-photon (OP) microscopy. While there are several OP fluorescence probes in use for pancreatic islet imaging, TP imaging of selective cells in live islet still remains a challenge. Herein, we report the discovery of first TP live pancreatic islet imaging probe; TP-α (Two Photon-alpha) which can selectively stain glucagon secreting alpha cells. Through fluorescent image based screening using three pancreatic cell lines, we discovered TP-α from a TP fluorescent dye library TPG (TP-Green). In vitro fluorescence test showed that TP-α have direct interaction and appear glucagon with a significant fluorescence increase, but not with insulin or other hormones/analytes. Finally, TP-α was successfully applied for 3D imaging of live islets by staining alpha cell directly. The newly developed TP-α can be a practical tool to evaluate and identify live alpha cells in terms of localization, distribution and availability in the intact islets.

Development of background-free tame fluorescent probes for intracellular live cell imaging

“…As the first step, we conducted phenotypic HTS to investigate cell permeability and nonspecific binding properties of the probes in a training set. We tested about 2,085 probes consisted of a wide range photophysical properties from numerous fluorophore cores such as BODIPY 12 13 14 15 , xanthone 16 17 , rosamine 18 , cyanine 19 20 and ACEMAN 21 . Their cellular influx and efflux profiles were examined in two types of mammalian cells, U-2 OS and CHO.…”

Opportunities for Persistent Luminescent Nanoparticles in Luminescence Imaging of Biological Systems and Photodynamic Therapy

“…NIR excitation has attracted much attention due to its deeper penetration in the biological tissues [ 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ]. Usually, the up-conversion (UC) phenomenon, followed by energy transfer, is used to induce persistent luminescence using NIR radiation [ 254 ].…”

“…Using the same analogy that the grass represents a cell, we will achieve what is shown in Figure 1 d. Because there is no continuous illumination, all the emission background is eliminated, and we can locate where the luminescent compound is located. Thus, the application of PeL materials eliminates the background emission and depth penetration problems, resulted from the excitation wavelengths in the UV-Vis, commonly used in luminescence imaging of biological systems [ 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ].…”

A Diversity‐Oriented Library of Fluorophore‐Modified Receptors Constructed from a Chemical Library of Synthetic Fluorophores

“…Therefore, a library of fluorophores with the CA group can be readily converted into the library of F‐Revs by using a cysteine‐modified Rev peptide (CRev) through selective reaction with the thiol group of cysteine. Four types of fluorophore scaffolds—CXCA, TPGCA, CORCA, and CyRCA, classified as derivatives of xanthone, acedan, coumarin, and cyanine, respectively—were selected for the construction of CA‐containing DOFLs (Scheme and Figures S2–S5). A library of fluorophores with the same scaffold would show similar fluorescence properties such as excitation and emission wavelengths, which is useful for simplifying the screening protocol.…”