Raman Microscopy for Noninvasive Imaging of Pharmaceutical Nanocarriers: Intracellular Distribution of Cationic Liposomes of Different Composition

Abstract

Nanotechnology is playing an increasing role in targeted drug delivery into pathological tissues. Drug-loaded pharmaceutical nanocarriers can be delivered into diseased sites by passive targeting (spontaneous accumulation of nanocarriers in the areas with affected vasculature) or by active targeting (via site-specific ligands attached to the surface of drug-loaded nanocarriers). Subsequent level of targeting requires cellular internalization of nanocarriers and their specific association with certain individual cell organelles. The control over intracellular distribution of pharmaceutical nanocarriers requires effective and non-invasive methods of their visualization inside cells. In an attempt to enhance cellular internalization of pharmaceutical nanocarriers and their association with mitochondria specifically, we have prepared three types of cationic liposomes and investigated their intracellular distribution. The analysis was performed using Raman microspectroscopy in combination with optical microscopy, in order to provide morphological information as well as biochemical signatures of the sample. It was demonstrated that the Raman microscopy allows to evaluate the extent of mitochondrial association depending on the liposome composition.

Types of cell death and apoptotic stages in Chinese Hamster Ovary cells distinguished by Raman spectroscopy

“…Raman spectroscopy can be combined with confocal microscopy to yield Raman microscopy, a chemical imaging modality that enables subcellular spatial resolution of biomolecules without the use of endogenous labels or exogenous stains. Raman microscopy is being increasingly used to study the biochemical state of cells and tissues such as for the identification of cancerous cells (Huser & Chan, ), assessing differentiation status of stem cells (Schie & Huser, ), and studying the intracellular localization of drugs (Chernenko et al, ). Combined with confocal microscopy, it enables this subcellular localization of biomolecules.…”

Cell Growth Measurement

“…Based on the difference in monochromatic light with vibrational modes, Raman spectroscopy can be used for qualitative and quantitative measures of the changes in biochemical composition. For example, Raman spectroscopy was used as a noninvasive method to distinguish cells at different stages in the cell cycle [90]; to identify living cells from dead cells [91][92][93][94][95]; to image cellular organelles [96]; to track drug distribution [97] and metabolism [91]; to monitor cell apoptosis [94], death, and cytotoxicity [92,95]; and to study cell responses to external stimuli [97][98][99][100][101]. However, the analysis of Raman results requires expertise in identifying the spectroscopic fingerprint of a substance.…”

Spectral pre and post processing for infrared and Raman spectroscopy of biological tissues and cells

“…Recently, VCA has seen a number of applications in hyperspectral imaging using both IR and Raman spectroscopy, with applications including Raman histopathological imaging and also cellular studies including nano-bio interactions [88] Importantly, while this method can be used quite readily to reconstruct biochemical regions in the cell, like all methods it may be prone to error. Firstly, as highlighted by Chernenko et al [88], endmember spectra may contain mixtures of different biochemical components and while this may be reflective of the actual nature of the sample, may lead to inaccuracies in interpretation.…”