Detection of PLGA-based nanoparticles at single cell level by Synchrotron Radiation FTIR Spectromicroscopy and correlation with X-Ray Fluorescence Microscopy
Poly-lactide-co-glycolide (PLGA) is one of the few polymers approved by the Food and Drug Administration (FDA) as carrier for drug administration in humans and, therefore, it is one of the most used materials in the formulation of polymeric nanoparticles (NPs) for therapeutic purposes. Since the cellular uptake of polymeric NPs is a highlight topic in the nanomedicine field, the development of techniques able to assure an incontrovertible evidence of NPs presence in the cells plays a key role for gaining understanding of their therapeutic potential.
On the strength of this premise, this paper aims to evaluate the application of the Synchrotron Radiation-based FTIR (SR-FTIR) spectromicroscopy and the Synchrotron Radiation X-Ray Fluorescence (SR-XRF) microscopy in the study of the in vitro interaction of PLGA NPs with cells. To reach this aim, we used PLGA NPs, sizing around 200 nm and loaded with superparamagnetic iron oxide nanoparticles (Fe3O4; size 10-15 nm) (PLGA-IO-NPs). After having exposed human mesothelial (MeT5A) cells to PLGA-IO-NPs (0.1 mg/ml), the cells were analyzed after fixation both by SR-FTIR spectromicroscopy and SR-XRF microscopy setups. SR-FTIR-SM enabled the detection of PLGA NPs at single cell level allowing the polymer detection inside the biological matrix by the characteristic band in the 1700\u20132000 cm 12 1 region. The precise PLGA IR-signature (1750 cm 12 1 centered pick) was clearly evident also within an area of high amide density. SR-XRF microscopy performed on the same cells investigated under SR-FTIR microscopy allowed to put in evidence the Fe presence in the cells and to emphasize the intracellular localization of the PLGA-IO-NPs. These findings suggest that SR-FTIR and SR-XRF techniques could be two valuable tools to follow the PLGA NPs fate in the in vitro studies on cell cultures
