Label-Free Nanoparticle Imaging in Cells with Hyperspectral Microscopy

Blog Post

Post publication date:

Monday, September 5, 2022

CytoViva's enhanced darkfield hyperspectral microscopy enables optical observation and spectral characterization of nanoparticle samples as they interact with cells or tissue. No fluorescent labeling or other alteration of the sample is required with the CytoViva system.

Traditional confocal fluorescence and electron microscopy require either the addition of fluorescent labels or other sample alterations for the observation of nanomaterials in cells and tissue. These alterations can significantly increase the complexity of the experiment, create sample artifacts or limit specificity. In addition, neither technique can provide for discreet sample chemistry analysis, such as the detection of a drug load added to a nanoparticle.

CytoViva's enhanced darkfield hyperspectral microscopy was specifically designed to overcome these issues. The enhanced darkfield microscope optics create a very high signal-to-noise ratio optical image of the label-free samples. This optical image enables metal nanoparticles as small as 10nm-20nm to be clearly observed. More importantly, it also allows imaging of nanoparticle interaction with detailed cellular structures such as the nuclear membrane, without any fluorescent labeling.

When these samples are captured as a hyperspectral image, each nanoscale image pixel contains the visible near-infrared (VNIR) spectral response. This spectral data can be queried using custom spectral analysis software. This software allows for highly accurate development of spectral libraries from unique sample elements, such as the nanoparticles in the cells. In addition, the system can be used to identify discreet chemistry, such as a drug load or targeting protein added to the nanomaterials.

Figure 2 - Zoomed Image of AuNPs in Cells

Figure 3 - Mapping of AuNPs (in red) in Cells

Figure 4 - Example spectrum of AuNPs (red) and Cells (white)

In the images shown above, label-free gold nanoparticles (AuNPs) with a cell-targeting protein were incubated in unstained cell culture. Figure 1 is a hyperspectral image of the cells incubated with AuNPs. Figure 2 is a zoomed-in image showing a cell with internalized AuNPs. Using the spectral analysis software, a reference spectral library for AuNPs was created. See an example spectrum in Figure 4. The spectral library was compared against a negative control cell sample to ensure that only AuNPs are contained in the library. This AuNP spectral library was then used in a spectral mapping algorithm to map all pixels in red containing the AuNP spectrum (Figure 3).

To understand how your nanomaterials can be observed in a wide range of environments without fluorescent labeling or other alteration of the sample, contact us at info@schaefer-tec.it. We would be pleased to learn more about your current research and can schedule test imaging of your samples if appropriate.