Generally, most of the developed fluorescent probes exhibit emission changes in a target specific manner with various mechanism such as photo induced electron transfer (PET), aggregation induced emission (AIE), and fluorescent resonance energy transfer (FRET). Excited-state intramolecular proton transfer (ESIPT) is recently attracting the attention of scientists because it shows a remarkably large stokes shift to solve the problems caused by self-absorption1-2. We have synthesized a new type of thiophene bearing ESIPT fluorescent probes (TEPs). The ESIPT probes clearly showed dual emission behavior in response to solvent polarity. Moreover, it showed pH responsive absorption and fluorescence emission changes in aqueous phase. Among them, dithiophene-bearing ESIPT probe (2) exhibited turn-on fluorescence emission as increasing pH above physiological condition. Finally, we have demonstrated response of the application of dithiophene-bearing ESIPT probe (2) on biological specimen. We have successfully visualized the mitochondrial compartment and specific bacteria owing to the higher pH. Detailed aspect of this system will be discussed in this symposium