Three-Dimensional pH Microprobing with an Optically-Manipulated Fluorescent Particle

Abstract

Abstract A novel pH microprobe has been developed, which makes it possible to measure inhomogeneous pH distributions with submicrometer three-dimensional resolution. A polyacrylamide particle incorporated with pH-sensitive fluorescein-acrylamide is manipulated with a laser trapping technique. It is demonstrated that the local pH in a water/glass interface is different from that of bulk water.