Tailored surface functionalization of inorganic nanoparticles for controlled protein adsorption and cellular uptake
Final Report Abstract
To target cells with nanoparticles, for example for programmed drug delivery and release, a wellknown behavior of nanoparticles in biological environments is essential. The stability and integrity of the nanoparticles are critical parameters: If the particles dissolve too early or in the wrong place, this will have serious consequences, e.g., when drugs are release uncontrolled. However, the integrity of nanoparticles is not always easy to detect. In particular, in situ, directly in a cell or in a protein rich serum, this is often not possible or involves complex procedures. In this project, a new method was developed to directly measure the integrity of silica and polymer-based nanoparticles in situ and inreal-time by fluorescence measurements. During initial fluorescence-labeling experiments, we found that the molecule Thioflavin T has the property to response towards the integrity of the nanoparticles: If one incorporates Thioflavin T in the particles, its fluorescence is strongly influenced by the structure of the nanomaterial surrounding the molecule. The fluorescence spectrum shifts and fluorescence yields strongly decrease, when structural changes of the nanomaterial occur such as when the particle degrades. The effect is much stronger than observed with conventional fluorescent labels due to a rotation within the Thioflavin T molecule that results in particular relaxation after excitation at specific wavelengths and as function of the mechanical properties of the nanoparticle matrix. This enabled a highly sensitive and simple detection of the integrity of different nanoparticles in biological media, during cellular uptake, and during intracellular processing by fluorescence spectroscopy and fluorescence microscopy. It was found that the silica nanoparticles after cellular uptake and processing into lysosomes were much more stable than in the cell medium before recording. Subsequently, we grafted a controlled protein corona onto such nanoparticles, consisting of tailored composition of transferrin and epidermal growth factor to selectively stimulate certain cellular receptors that are overexpressed in cancer cells. It was investigated how the bifunctional protein layer is biologically recognized using monoclonal antibodies and by observing cellular uptake via the respective transferrin and epidermal growth factor receptors. It turned out that after optimized synthesis both ligands are recognized and cells can be stimulated to uptake the particles in tailored fashion. The bifunctionality allows furthermore, generating two specific biological responses with only one nanoparticle. The results are highly advantageous for the detailed in situ examination of the fate of nanoparticles in biological environments and to program cellular uptake by multifunctional, specific functionalization and surface design.
Publications
- Labeling the Structural Integrity of Nanoparticles for Advanced In Situ Tracking in Bionanotechnology. ACS Nano 2016, 10, 4660–467
Meder, F.; Thomas, S.; Fitzpatrick, L.W.; Alahmari, A.; Wang, S.; Beirne, J.G.; Vaz, G.; Redmond, G.; Dawson, K.A.
(See online at https://doi.org/10.1021/acsnano.6b01001)
