In situ single cell monitoring by isocyanide-functionalized Ag and Au nanoprobe-based Raman spectroscopy.

The development of effective cellular imaging requires a specific labeling method for targeting, tracking, and monitoring cellular/molecular events in the living organism. For this purpose, we studied the cellular uptake of isocyanide functionalized silver and gold nanoparticles by surface enhanced Raman scattering (SERS). Inside a single mammalian cell, we could monitor the intracellular behavior of such nanoparticles by measuring the SERS spectra. The NC stretching band appeared clearly at approximately 2,100 cm-1 in the well-isolated spectral region from many organic constituents between 300 and 1,700 or 2,800 and 3,600 cm-1. The SERS marker band at approximately 2,100 cm-1 could be used to judge the location of the isocyanide-functionalized nanoparticles inside the cell without much spectral interference from other cellular constituents. Our results demonstrate that isocyanide-modified silver or gold nanoparticle-based SERS may have high potential for monitoring and imaging the biological processes at the single cell level.