Raman Micro-spectral Imaging of Cells and Intracellular Drug Delivery Using Nanocarrier Systems

Abstract

Raman spectroscopy in combination with optical microscopy provides a new non-invasive method to examine and image cellular processes. Based on the spectral parameters of a cell’s components it is possible to image cellular organelles, such as the nucleus, chromatin, mitochondria, or lipid bodies, at the resolution of conventional microscopy. Several multivariate or spectral de-mixing algorithms, for example, hierarchical cluster analysis or orthogonal subspace projection, may be used to reconstruct an image of a cell. The non-invasive character of the technique as well as the associated chemical information may offer advantages over other imaging techniques such as fluorescence microscopy. Currently of particular interest are the uptake and intracellular fate of various pharmaceutical nanocarriers, which are widely used for drug delivery purposes, including intracellular drug and gene delivery. We have imaged the uptake and distribution patterns of several carrier systems over time. In order to distinguish the species of interest from their cellular environment spectroscopically, the carrier particles or the drug load itself may be labeled with deuterium. The first part of the chapter will briefly introduce the concept of Raman imaging in combination with multivariate data analysis on some simple cell models, after which the results of the uptake studies are discussed.