Semiconductor nanoparticles for biomedical applications have been researched for some time now. Not only are they millionths of a millimeter in size, they also offer great potential for cancer diagnostics and therapy, so-called theranostics. They enter cells, are activated by ultrasonic radiation and destroy the cells using the generated vibration.
Until now, the use of many semiconductor nanoparticles in the human body has failed due to their high toxicity. Yet this is different when it comes to silicon nanoparticles, says Dr. Vladimir Sivakov, Head of the Semiconductor Nanostructures Work Group at the Leibniz Institute of Photonic Technology (German: Leibniz-Institut für Photonische Technologien) in Jena.
Dr. Sivakov, what exactly are silicon nanoparticles?
Dr. Vladimir Sivakiv
:Silicon is the second most abundant material in the earth’s crust. It is, therefore, available in nearly unlimited quantities. Thanks to special top-down or bottom-up processes, it is possible to produce silicon at the nanometer scale. The properties of such nanoscale objects differ in part significantly from the properties of the bulk material. We are able to produce highly porous silicon nanoparticles well under 100 nanometers in size with the processes we use. In addition, the thus produced silicon nanostructures emit orange-red light when they are irradiated with suitable wavelengths. This phenomenon called photoluminescence combined with the large surface area of the porous silicon nanoparticles makes them interesting as contrast agents but also as delivery vehicles for various therapeutic agents for cancer therapy.
Why is silicon so well suited for medicine? Is it possible to detect or rather treat every type of cancer with it?
: Silicon is a material that has a non-toxic effect on the human body. Another significant advantage is the fact that compared to metallic or oxidic particles like gold or iron oxide, silicon is gradually broken down by the human body into silicic acid and can, therefore, be excreted without any problems after diagnostics and therapy have been completed. Unlike metallic nanoparticles which remain in the body and can cause further discomfort.
In principle, it is possible to diagnose and also treat any type of cancer with these particles. However, we are still in the early stages of our research in this case. Yet it is possible to equip silicon nanoparticles with a cancer-specific antigen on the surface. In doing so, the particles primarily accumulate in those regions of the body that are affected by cancer. This selectivity is just one of the many challenges we want to rise up to.