TY - JOUR A1 - Kneipp, Janina A1 - Kneipp, H. A1 - Wittig, B. A1 - Kneipp, K. T1 - One- and Two-Photon Excited Optical pH Probing for Cells Using Surface-Enhanced Raman and Hyper-Raman Nanosensors JF - Nano letters N2 - We demonstrate spatially resolved probing and imaging of pH in live cells by mobile and biocompatible nanosensors using surface-enhanced Raman scattering (SERS) of 4-mercaptobenzoic acid (pMBA) on gold nanoaggregates. Moreover, we also show that this concept of pH nanosensors can be extended to two-photon excitation by using surface-enhanced hyper-Raman scattering (SEHRS). In addition to the advantages of two-photon excitation, the SEHRS sensor enables measurements over a wide pH range without the use of multiple probes. PY - 2008 DO - https://doi.org/10.1021/nl071418z SN - 1530-6984 SN - 1530-6992 VL - 7 IS - 9 SP - 2819 EP - 2823 PB - American Chemical Society CY - Washington, DC AN - OPUS4-18230 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -