Science China Physics, Mechanics and Astronomy

, Volume 54, Issue 12, pp 2225–2229 | Cite as

Observation of mitochondrial activity based on temporal and spatial pH variations measured by near-field fluorescent ratiometry

  • YongBo Li
  • Ryosuke Shionhara
  • Kentaro Iwami
  • Yoshihiro Ohta
  • Norihiro Umeda
Research Paper


A novel method combining dual wavelength fluorescent ratiometry with scanning near-field optical microscopy (SNOM) is proposed and developed to measure the concentration and distribution of protons in the vicinity of biological samples. This method involves immersing mitochondria in a pH-sensitive fluorescent dye solution instead of injecting the dye into the surface of the mitochondrial membrane. It uses a dual emission pH-sensitive dye and SNOM with a thermally pulled and metal-coated optical fiber probe to improve the spatial resolution. The time dependence of the fluorescence intensity ratio (FIR) under acid addition and the response of mitochondria to nutritional supplementation were studied by using this method. Activation of mitochondria and a distance-dependent delay in the FIR response were observed. The results confirmed that mitochondrial activity could be observed by using this method.


local pH pH measurement SNOM proton concentration mitochondrial membrane ATP synthesis 


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Copyright information

© Science China Press and Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • YongBo Li
    • 1
  • Ryosuke Shionhara
    • 1
  • Kentaro Iwami
    • 1
  • Yoshihiro Ohta
    • 2
  • Norihiro Umeda
    • 1
  1. 1.Department of Mechanical Systems EngineeringTokyo University of Agriculture and TechnologyTokyoJapan
  2. 2.Department of Biotechnology and Life ScienceTokyo University of Agriculture and TechnologyTokyoJapan

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