Researchers from Abo Akademi University and the University of Turku in Finland
have discovered that the stability of functionalised nanoparticles is crucially
dependent on all functional groups present on the surface. Using the sensitive
nanoscale particle sizing and zeta potential measurement capabilities of a Zetasizer
Nano from Malvern Instruments,
they showed that poly(ethylene imine) (PEI) functionalised silica particles
made promising candidates for bioapplications. This research has now led to
the development of a selective nanoparticulate system for cancer cell targeting.
One of the key aims in biomedical science is to develop applications that can
target and deliver drug to specific cell populations. Porous, non-toxic silica
based structures have potential as biocompatible vehicles for intracellular
delivery of an active ingredient. However, any modification to the original
particle structure, such as the addition of an imaging agent, surface coating
or a targeting agent, changes both its size and surface charge. This leads to
changes in the stability of the particulate system.
Using both particle sizing using dynamic light scattering (DLS) and zeta potential
measurements with a Zetasizer Nano, the Finnish research team showed both direct
and indirect effects on the suspension stability of functionalised silica particles
as a result of surface modification. These results were published in the Journal
of Nanomaterials in 2008. The team then went on, publishing results in ACS Nano
in 2009 that used similar techniques to develop a multifunctional nanodevice
for cancer therapy that demonstrated remarkably good cell specificity.
The size, stability and cell specificity of functionalised nanoparticles for
targeted drug delivery is crucially dependent on each surface modification as
well as the overall surface charge. Besides the fact that surface charge along
with particle size are directly decisive for a nanoparticles’ biodistribution,
other highly critical factors, such as cytotoxicity and the efficiency of cellular
uptake, are associated with nanoparticle size. While the technique of dynamic
light scattering (DLS) is ideally suited for the determination of particle size,
zeta potential measurements indicate the repulsive force that is present and
can be used to predict the long-term stability of the product. By enabling both
types of measurements, with the sensitivity and resolution required to define
nanoscale changes, Malvern’s Zetasizer is the ideal solution for biomedical
scientists.