Label-Free Raman Spectral Imaging of Intracellular Delivery and Degradation of Polymeric Nanoparticle Systems

Abstract

Novel optical imaging methods, such as Raman microspectroscopy, have been gaining recognition in their ability to obtain noninvasively the distribution of biochemical components of a sample. Raman spectroscopy in combination with optical microscopy provides a label-free method to assess and image cellular processes, without the use of extrinsic fluorescent dyes. The submicrometer resolution of the confocal Raman instrumentation allows us to image cellular organelles on the scale of conventional microscopy. We used the technique to monitor subcellular degradation patterns of two biodegradable nanocarrier systems-poly(epsilon-caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA). Our results suggest that both drug-delivery systems eventually are incorporated into Golgi-associated vesicles of late endosomes. These processes were monitored via the decrease of the molecule-characteristic peaks of PCL and PLGA. As the catabolic pathways proceed, shifts and variations in peak intensities and intensity ratios in the rendered Raman spectra unequivocally delineate their degradation patterns.

Molecular pathology via IR and Raman spectral imaging

“…Yet, the most important application of this technology is to monitor transport processes into cells [100,101], for example, the uptake of drug-loaded nanoparticles. Here, the inherent chemical differences between the cytoplasm and the nanoparticle provide the imaging contrast.…”

Controlling and Monitoring Intracellular Delivery of Anticancer Polymer Nanomedicines

“…[216] Chernenko et al used Raman spectroscopy to study the subcellular degradation of PCL and poly(l-lactide-co-glycolide) (PLGA) nanoparticles ( Figure 3A). [217] Comparison of polymer and cell associated signals and the use of a mathematical algorithm allowed the reconstruction of pseudocolor images. Figure 3B shows results of examples carried out with fixed Hela cells which were incubated with PCL and PLGA nanoparticles for 7 and 2 h, respectively.…”

“…Adapted with permission. [217] Copyright 2009, American Chemical Society. behavior of nontargeted and EGFR-targeted PEG-PLGA/ PCL blend nanoparticles in SKOV-3 human ovarian adenocarcinoma cells.…”

Advanced Optical Imaging of Endocytosis

“…Chernenko and colleagues applied hyperspectral confocal Raman microscopy to noninvasively query the distribution of cellular organelles relative to two biodegradable polymeric nanoparticle delivery systems (Chernenko, et al, 2009). It is very important to characterize the biocompatibility, cellular uptake and intracellular trafficking of these and other nanoparticle vehicles for drug delivery.…”