Intracellular pH Sensors Based on Surface-Enhanced Raman Scattering

Abstract
We present the development of nanoscale pH sensors based on functionalized silver nanoparticles and surface-enhanced Raman scattering (SERS). The SERS spectrum from individual silver nanoparticle (50−80 nm in diameter) clusters functionalized with 4-mercaptobenzoic acid shows a characteristic response to the pH of the surrounding solution and is sensitive to pH changes in the range of 6−8. Measurements from nanoparticles incorporated in living Chinese hamster ovary cells demonstrate that the nanoparticle sensors retain their robust signal and sensitivity to pH when incorporated into a cell.