Rapid Analysis of Cell-Nanoparticle Interactions using Single-Cell Raman Trapping Microscopy. 
Iron oxide nanoparticles have been used in preclinical studies to label stem cells for non-invasive tracking and homing.  The search continues for novel particle candidates that are suitable for clinical applications.  Since standard analyses to investigate cell-particle interactions and safety are labor-intensive, an efficient procedure is required to guide future particle development and to exclude adverse health effects.  The application of combined Raman trapping microscopy with fluidic chips is reported for the analysis of single cells labeled with different types of aminated iron oxide particles.  Multivariate data analysis revealed Raman signal differences that could be clearly assigned to cell-particle interactions and cytotoxicity, respectively.  A validation dataset verified that more than 95 % of the spectra were correctly classified.  Thus, our approach enables rapid discrimination of non-hazardous from cytotoxic nanoparticles as a prerequisite for safe clinical applications.