| AVS 60th International Symposium and Exhibition | |
| Nanoparticle-Liquid Interfaces Focus Topic | Thursday Sessions |
| Session NL+AS+BI-ThA |
| Session: | Nanoparticles with Proteins and Cells: Modelling and Measurement |
| Presenter: | D.Y. Petrovykh, International Iberian Nanotechnology Laboratory, Portugal |
| Authors: | C. Sousa, University of Minho, Portugal D. Sequeira, University of Minho, Portugal P.M. Martins, University of Minho, Portugal Y.V. Kolen’ko, International Iberian Nanotechnology Laboratory, Portugal S. Lanceros-Méndez, University of Minho, Portugal D.Y. Petrovykh, International Iberian Nanotechnology Laboratory, Portugal |
| Correspondent: | Click to Email |
The primary analytical challenge in characterizing bacterial cells loaded with nanoparticles (NPs) is that the various methods that are traditionally used to measure cells or NPs separately are not readily applied to the mixed samples. These complex samples may contain, for example, a mixture of free NPs, NP-loaded cells, and cells without NPs, while the relative concentrations of NPs and cells or the average number of NPs loaded in one cell is not always known or readily established. Accordingly, methods for separating the different sample components have to be developed and validated before the component of interest (NP-loaded cells in most cases) can be characterized. The final challenge is determining the localization of NPs in and around the cells, as for some applications in sensing and nanomedicine NPs bound to cells externally can be the goal, whereas for exploiting physical properties of NPs, e.g., to induce hyperthermia, maximizing the internalization of NPs by cells can be advantageous.
Our approach to investigating these complex analytical challenges is based on using model systems that are amendable to quantitative characterization by complementary methods, both separately and when mixed as indicated above. Specifically, we are using Staphyloccus aureus as model bacterial cells, in part because the typical 500 nm diameter of S. aureus cells is within the size range of NP aggregates or large NPs, therefore, the same microscopy and spectroscopy methods can be applied to both components of mixed cell-NP samples. We use gold NPs as the primary model NPs because the strong plasmon peak enables their characterization in solution, while the high density and atomic number of gold can be helpful during separation and for characterization by electron microscopy and spectroscopy. Superparamagnetic iron-oxide NPs with different organic shells are used as a second type of model NPs. We will describe the use of multiple complementary microscopy and spectroscopy techniques for developing, validating, and quantifying protocols for cell-NP separation and for characterization of cell loading by NPs.