For the mitochondria co-localisation study, NIH-3T3 cells were co-stained and incubated for 30 mins at 37 °C inside the cell culture incubator (5% CO2). The culture media containing Mito Tracker Green (MTG), a commercial mitochondria-specific dye (300 nM) and Mito-pH2 (500 nM). After washing two times with PBS, the fluorescence images were recorded respectively with band path 580-620 nm upon excitation at 561 nm (Mito-pH2 dye) and band path 500-520 nm upon excitation at 488 nm (MTG). Pearson's correlation coefficient (PCC) was calculated using the JACoP plugin of ImageJ.