Nanoparticle Cellular Uptake Measurement
Quantification of nanoparticle uptake into cells is a crucial issue for the application of novel nanomedicines and assessment of nanoparticle potential toxicity. Besides, it is also important to quantify the internalised amount. Because the internalised amount, instead of the applied dose, is commonly responsible for the biological action of nanoparticles. Previous studies have pointed that the uptake of nanoparticles into cells is usually related to endocytotic processes, which depend primarily on the properties of nanoparticles, such as the size, shape, and surface characteristics. And these properties can be modified by the nanoparticle preparation method in terms of the requirements of their application as well as the drugs' physicochemical characteristics. Creative Biogene is your reliable and professional partner in the field of mRNA delivery system development. We are able to offer nanoparticle cellular uptake measurement service to quantify nanoparticles in biological matrices and explore their interactions with organisms or cells.
Common uptake pathways that ultimately determine nanoparticle fate within a cell. (Mitchell, M. J., et al., 2020).
The available methods for nanoparticle uptake determination
The life-cycle of nanoparticles inside organisms or cells can be explored via quantifying the internalised dose and observing the uptake process over time. At present, according to the detected objects, the methods for determination of nanoparticle uptake can be divided into three main categories. Here we have made a brief introduction to these methods.
Taking advantage of the distinguishable chemical compositions
These methods take advantage of the distinguishable chemical compositions of nanoparticles, including ICP based techniques and Particle-Induced X-ray Emission (PIXE). ICP based techniques are usually used for quantification of nanoparticles in populations of cells. The method can determine the total amount of a given element, but not soluble nanoparticles, fragments of nanoparticles, and released ions. However, the sample is destroyed during the measurement, hindering further analysis. As one of non-destructive elemental analysis methods, PIXE can determine the total elemental amount without damaging the sample and is available to measure nanoparticle accumulation in individual cells.
Taking advantage of specific intrinsic properties
These kinds of methods take advantage of specific intrinsic properties of the nanomaterial, such as intrinsic luminescence, surface plasmon resonance, and other optical properties. According to the specific intrinsic properties, the appropriate detection techniques are exploited. For instance, carbon nanotubes have a characteristic Raman signal, which can be easily distinguished from the cell background. Therefore, the level of Raman signal detected can be used as a basis for analysis of nanomaterials inside cells. These methods are useful to confirm nanoparticle uptake, but not allow quantification of the internalised amount directly.
Taking advantage of additional labelling
The method is available for these nanoparticles, which have no specific intrinsic properties and are more difficult to distinguish from the cell background. Labelling provides more possibilities to quantify and study nanoparticles in biological matrices. The most common used forms of labelling include fluorescence labelling, radioactive isotope, and stable isotope. To ensure better determination of nanoparticles and keep the original surface unaltered, different strategies for labelling are available, such as internal labelling. The addition of labels can be applied in a majority of nanoparticles, including polymeric nanoparticles, carbon-based nanoparticles, lipid-based nanovectors, protein-based nanoparticles.
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In addition to physical and chemical characterization of nanoparticles, their biological responses also need to be measured in animal cell culture before start in vivo administration. To determine nanoparticle uptake study by the cells, we adopt confocal microscopy and flow cytometry. These methods are based on nanoparticles labelling with a fluorescent marker. Confocal microscopy is applied to helps to ascertain the nanocarriers localization inside the cells. Flow cytometry can be applied to determine uptake kinetics, saturates or competing processes, the response of the cells to the nanoparticles, and the absorption of nanoparticles by cells at different phases of the cell cycle. The method is commonly used, which can quantify nanoparticle uptake in both single cells and populations of cells in a short time.
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- Salvati, A., et al. (2018). "Quantitative measurement of nanoparticle uptake by flow cytometry illustrated by an interlaboratory comparison of the uptake of labelled polystyrene nanoparticles." NanoImpact, 9, 42-50.
- Mitchell, M. J., et al. (2020). "Engineering precision nanoparticles for drug delivery." Nature Reviews Drug Discovery, 1-24.