Protein-Nanoparticle Interactions

The bare iron oxides are often negatively charged in water due to absorption of OH- groups on the surface of SPION. Surface charges give rise to an electric field and this will attract counter ions. The layer of surface charges and counter ions make up the electric double layer. The attraction of the electric field is decreased for the coated nanoparticles due to a reduction in amount of the surface charge. During the interaction of SPION to Dulbecco’s Modified Eagle’s Medium (DMEM) which contains many sources of proteins in Fetal Bovine Serum (FBS), the dynamic layer of protein (and other bio-molecules) adsorbs to nanoparticles surfaces immediately. As a result, the composition of the DMEM medium can be changed, owing to the attraction of proteins in the diffuse layer of magnetic nanoparticles. Our group showed that a more reliable way of identifying cytotoxicity for in vitro assessments is to use particles with saturated surfaces via interactions with DMEM before usage. By using nanoparticles whose surface had been passivated, the changes in the composition of cell medium would be minimal.

The goal of our research is to define the rates of association and dissociation of proteins, which are vary quite considerably with protein and characteristic of the particle such as shape and purity. Multi-protein absorbance is detected via the second derivative curves at the wavelength range of 250-300 nm for the uncoated and coated nanoparticles (See the below Figure). The affinity of proteins to the surface of SPION is related to the surface properties of SPION, i.e. the extend of hydrophilicity, which would be the basis of cell–nanoparticle interactions.

• Morteza Mahmoudi, Abdolreza Simchi, Mohammad Imani, Mohammad A. Shokrgozar, Abbas S. Milani, Urs Hafeli, Pieter Stroeve, "A new approach for the in vitro identification of the cytotoxicity of superparamagnetic iron oxide nanoparticles", Colloids and Surfaces B: Biointerfaces, 2010, 75, 300-309. Impact Factor = "2.600"
• Morteza Mahmoudi, Abdolreza Simchi, Mohammad Imani, "Cytotoxicity of Bare and Polyvinyl Alcohol Coated Superparamagnetic Iron Oxide Nanoparticles", The Journal of Physical Chemistry C, 2009, 113 (22), 9573–9580. Impact Factor = "4.224"
• Morteza Mahmoudi, Abdolreza Simchi, Mohammad Imani, Abbas S. Milani, Pieter Stroeve, "Biocompatibility and toxicity of bare and poly (ethylene glycol)-co-fumarate coated superparamagnetic iron oxide nanoparticles; introducing new toxicity procedure", Nanotechnology, 2009, 20 (22), 225104. Impact Factor = "3.137"