Tuning the interface of nanoparticles with biological environments
Wolfgang J. Parak1,2*
1
Fachbereich Physik, Philipps-Universität Marburg, Renthof 7, 35037 Marburg, Germany
2
CIC Biomagune, Paseo Miramón 182, 20009 San Sebastian, Spain
Investigations of the interaction of functionalized inorganic colloidal nanoparticles with mammalian
cells are now performed within the context of nanotechnology since two second decades, and even
some earlier examples exist. We will highlight some generally-accepted concepts about this research.
While details of these complex interactions strongly depend, amongst others, upon the specific
properties of the nanoparticles used, cell type, and their environmental conditions, a number of
fundamental principles exist, which are outlined in this review. We will correlate interaction of the
nanoparticles with cells with the physicochemical properties of the nanoparticles, in particular with
their surface chemistry. The problem of entanglement of different physicochemical properties will be
discussed. A special focus will be given on potential cytotoxicity associated with nanoparticle uptake
by cells.
Colloidal particles with fluorescence read-out are commonly used as sensors for the quantitative
detection of ions. Regardless the sensing mechanism the particles act as carriers. Surface chemistry
of the particles thus determines their interaction with cells, in particular pathway of uptake,
intracellular location, as toxicity. Different surface chemistry for particle functionalization will be
compared, which can be applied to different particle geometries such as spheres, rods, etc. It also
will be explained how surface chemistry can interfere with read-out. Besides delivery and
intracellular location of particle-based fluorophores also other experimental difficulties such as
crosstalk of the fluorescence read-out with pH, and spectral overlap of the emission spectra of
different fluorophores will be discussed.