“…The pH conditions in vivo differ significantly because of the differences in compositions and microenvironment of organs and tissues. Generally, the pH values are around 7.0–7.4 in normal blood and tissues 159 , 4–6 in intracellular lysosomal/endosomal organelles 160 , and 6–8 in the lesions ( e.g. , tumor microenvironment) 161 .…”