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 polyethyleneimine (PEI) functionalised silica particles made promising candidates for bioapplications. This study has 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 a 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 particle sizing employing dynamic light scattering (DLS) and zeta potential measurements with a Zetasizer Nano, the 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 first published in the Journal of Nanomaterials. The team then published further results in ACS Nano, using similar techniques to develop a multifunctional nanodevice for cancer therapy that demonstrated good cell specificity.
According to Malvern Instruments, 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. While DLS is suitable for determining 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 allowing both types of measurements, with the sensitivity and resolution required to define nanoscale changes, the Zetasizer is said to be the ideal solution for biomedical scientists.