Paper BI+SS+AS-TuM12
Application of CD and SRCD Techniques to the Study of Protein/Nanoparticle Complexes

Tuesday, October 30, 2012, 11:40 am, Room 23

Nanotechnology is having a large impact in very different scientific fields and the use of nanotechnology-based materials is not just limited to research laboratories, but has already been applied in several industrial sectors and into real products as disparate as medical diagnostic tools, drug delivery systems, cosmetics, and consumer products.

In particular, engineered nanoparticles (ENPs) are used in different applications such as cosmetics, food and medicine and currently more than 600 products containing nanomaterials are already on the market[1,2,3]. At the same time there is a growing public concern about the safety of ENPs since it has been demonstrated that those intended for industrial and medical applications could cause adverse effects in mammalians or aquatic organisms by specific mechanisms depending on their physical chemical properties[4]. However, the interaction of nanomaterials with complex matrices is far to be understood. In fact, although it is now increasingly accepted that the surface of nanoparticles in a biological environment is modified by the so called “protein corona”[5,6], the importance of the detailed structure of the adsorbed protein-solution interfaces is still not much addressed in the nanotoxicology literature[7] .

In this work, we report the use of Circular Dichroism (CD) and Synchrotron Radiation Circular Dichroism (SRCD) to detect changes in the secondary structure and stability of different classes of proteins interacting with nanoparticles. In particular, we show that by using the SRCD we can detect structural changes of proteins in the nanomolar concentration range when they form protein-nanoparticle complexes[8]. Furthermore, the adsorption of protein on NP modifies their melting point in a composition and size dependent manner, indicating once more that the protein corona formation is strongly depending on the nanoparticles physico-chemical properties. For instance, while the presence of Au NPs do not influence the thermal unfolding process of human serum albumin (HSA), a significant decrease of the HSA melting temperature (about 6ºC) is observed in presence of Ag NPs.

[1] R.A: Petros, J. M. DeSimone, Nature Rev., 9, (2010), 616.

[2] G.J. Noynek et al., Crit. Rev. Toxicol., 37, (2007), 251.

[3] N. Sozer, J.L. Kokini, Trends in Biotechnol., 27(2), (2009), 82.

[4] G. Obersdorter et al., Env. Health Persp. 113, (2005), 823

[5] I. Lynch, K. A. Dawson, Nanotoday, 3(1-2), (2008), 40

[6] M.P. Monopoli et al., J. Am. Chem Soc., 133, (2011), 2525

[7] P. Sabatino at al., J. Coll Interface Sci., 314, (2007), 389

[8] S. Laera et al., Nano Lett.11, (2011), 4480.