The invention belongs to the technical field of fine chemicals and relates to a naphthalimide fluorochrome and its preparation and application. According to the invention, the naphthalimide fluorochrome is a
fluorescence molecular probe which is designed and synthesized by PET mechanism and used in detecting environmental
viscosity changes and can be used to carrying out two-
photon ratio imaging and lifetime imaging on
viscosity changes in cells. The naphthalimide fluorochrome provided by the invention has advantages of simple synthesis, mild synthesis condition, good photostability and the like, and is not sensitive to pH, polarity and biomacromolecules. Thus, the naphthalimide fluorochrome can be used to detect
viscosity distribution in cells. In addition, it is reflected through two-
photon ratio imaging that viscosity in a
lysosome is the largest in a
cell.
Fluorescence ratio detection can overcome errors caused by only being dependent on
fluorescence intensity changes. On the other hand, through medical stimulation
on cells, viscosity changes in cells can be detected. Through
fluorescence lifetime, values of viscosity changes can be reflected more visually. The naphthalimide fluorochrome has wide application value in the field of
biology and environment.