Biodistribution and quantitation of metal oxide nanoparticle at the subcellular level using confocal Raman microscopy

Introduction Health impact of nanomaterials is getting more relevance, since they are increasingly finding applications in many industrial and biomedical fields. To evaluate the toxicological response of NMs, and in particular... [ view full abstract ]

Introduction

Health impact of nanomaterials is getting more relevance, since they are increasingly finding applications in many industrial and biomedical fields. To evaluate the toxicological response of NMs, and in particular of metal oxide nanoparticle (NPs), their quantification in biological matrixes and distribution pattern are essential. With current technologies locating and quantifying metal oxide NPs in cells and organs is still complicated, expansive and time consuming. Here we demonstrate that Confocal Raman Microscopy (CRM) – a non-invasive, non-destructive and label-free technique – can be used not only for the visualization and detection of NMs within biological systems, but also for their simultaneous quantification.

Methods

Nanostructured composite films containing cerium dioxide nanoparticles (CeO₂ NPs) have been fabricated exploiting the layer-by-layer (LbL) technique (Figure 1). We used such nano-composite films as standards to calibrate CRM device by using Ion Beam Microscopy (IBM) techniques as dosimetric reference tool.

Results

Nano-composite films with homogeneous distribution and controlled amounts of CeO₂ NPs have been built up and well characterized (Figure 1). A good correlation between the absolute amount of Ce, determined with IBM techniques, and the CRM response is obtained. The method has been validated with a biological matrix, by using the CRM for the simultaneous imaging, detection and quantification of CeO₂ NPs in lung tissue (Figure 2).

Discussion

CRM combines confocal optics features with the ability of Raman spectroscopy to determine the chemical composition of the materials. Consequently, it can be used for the 3D co-localization of metal oxide NPs with cell compartments. Results demonstrate that this novel approach can be further used for the simultaneous imaging and quantification of metal oxide NPs within biological systems. This label-free, non-destructive and fast approach overcomes the limitations of other technologies currently applied in nano-toxicology for NPs dosimetry.

Images

Figure 1: Nano-composite film of CeO₂ NPs on a silicon substrate: SEM and confocal Raman images overlapped.

Figure 2: Bright-field image and 3D Raman Image reconstruction of a macrophage in vicinity of alveola from lung tissue section.