Development of functionalized superparamagnetic iron oxide nanoparticles for interaction with human cancer cells
Original entry by A.J. Kumar, APPHY 225 Fall 2009
A. Petri-Finka, M. Chastellaina, L. Juillerat-Jeanneretb, A. Ferraria, H. Hofmann. Biomaterials 26 (2005) 2685–2694
Melanoma; Human; Iron oxide nanoparticles; Particle size-cell uptake; PVA
The authors set out to develop, characterize, and optimize super-paramagnetic iron oxide nanoparticles (SPIONs) in such a way that they can be internalized by human cancer cells. Such SPIONs can potentially be used both in cancer diagnostics and therapeutics. Examples include: novel MRI technology, drug delivery, and cell separation. The SPIONs alone though will aggregate and will not interact with cells normally so their surface must be coated with polymer and functionalized, both to create a stable colloidal suspension and also to allow the SPIONs to interact with the cells. The authors cite iron oxides as a good material because of low toxicity levels. However recent studies may challenge this (see Iron oxide nanoparticles).
To coat the SPIONs, the authors used polyvinyl alcohol (PVA) and several similar derivatives (carboxylate functionalized PVA, thiol-functionalized PVA, amino-functionalized PVA). Human melanoma cells were then exposed to various concentrations of the particles under controlled conditions before being evaluated for the iron content of the cells. The iron content after the exposure was used as a measure of the uptake capacity of the cell for the various particles. They found that the cells were only able to uptake a sizeable amount of the amino-SPIONs.
The authors then go on to optimize various other tunable parameters, such as the polymer/iron mass ratio. Reducing the polymer coating too much though leads to a limit in the uptake that is potentially due to the colloidal stability limit. With a thin polymer coat, the SPIONs will begin to aggregate at a lower concentration and once aggregated, cannot be taken into the cell. In conclusion, the authors find that it is possible to create a functionalized SPION (namely the amino-SPION) that can be taken into a human cancer cell.
Soft Matter Connection
This is an interesting example of how soft-matter brings together physics, chemistry, and biology in practical applications. The SPIONs are useful for their magnetic properties, but they are made stable by a polymer coating. They are made biologically relevant by the additional functionalization of the polymer. For these to be used effectively and safely in a medical setting, experts from all these fields need to work together to make sure the relevant parameters are all accounted for.