New Ways of Imaging Uptake and Intracellular Fate of Liposomal Drug Carrier Systems inside Individual Cells, Based on Raman Microscopy

Abstract

Recent developments, combining Raman spectroscopy with optical microscopy, provide a new noninvasive technique to assess and image cellular processes. Of particular interest are the uptake mechanisms of various cytologically active compounds. In order to distinguish the species of interest from their cellular environment spectroscopically, compounds may be labeled with deuterium. Here, we apply Raman microspectroscopy to follow the uptake of liposomal drug carrier systems that have been introduced to deliver biologically active compounds to their site of action within human breast adenocarcinoma MCF-7 cells. The distribution patterns of liposomes and liposomes surfacemodified with a cell-penetrating peptide (TAT-peptide, TATp) have been imaged over time. The spectroscopic information obtained provides a clear evidence for variable rates, as well as different efficiencies of liposome uptake depending on their surface properties. Depending on the experimental setup, the technique may be applied to fixed or living cell organisms.

Chapter 10 Infrared and Raman Microscopy in Cell Biology

“…We demonstrate the use of this technique (Matthäus et al, 2008) to investigate the cellular uptake and intracellular fate of lipid-based nanoparticles known as liposomes (Fig. 12A).…”

“…Purified TATp was received from Tufts University Core Facility (Boston, MA). TATp peptide was coupled to TATp-PEG2 000 -PE using published methods (Matthäus et al, 2008). For preparing TATp-liposomes, TATp-PEG2 000 -PE was added to the lipid film.…”

“…Although very small deuterated regions can be detected early in an uptake experiment, aggregation or incorporation of the deuterated phospholipids into other membrane structures occurs, resulting in contiguous regions of high deuterium content. To ascertain that the liposomes are observed within the cytoplasm and not just adsorbed on the cell surface, a depth profile in the xz-direction was collected (Matthäus et al, 2008) which indicated that the deuterated liposomes penetrate the cell body. The spectral appearances of the C-D stretching region, with respect to band shapes and peak positions, did not change significantly upon uptake, indicating that the lipid side chains did not undergo substantial conformational changes.…”

High throughput toxicity screening and intracellular detection of nanomaterials

“…Label‐free imaging of cell organelles,42, 43 uptake and intracellular fate of drug carriers44, 45, 46 and NMs inside individual cells32, 47, 48 have been studied.…”

Design and first applications of a flexible Raman micro-spectroscopic system for biological imaging

“…Not only biological tissues [27] and body fluids [18] can be examined by Raman spectroscopy, but even individual living cells [17,32,42]. This is a large research field with a host of promising applications, such as observation of cell metabolism, growth and aging, study of drug resistance or drug uptake [35], chemical mapping of cells [22,36], identification of cell in a mixed population, and many others. This could guide us to the understanding of changes within an individual cell that could lead to a disease development, because many diseases begin at the cellular level.…”