Silicon to transport drugs in the human body: a novel drug delivery method under development

Several Finnish universities have joined forces to develop an innovative drug delivery method that utilises silicon to transport drugs in the human body. Among other advances, the project has been able to sustain the effect of peptides controlling appetite, which may facilitate the use of nanotechnology for dieting purposes. The research is being carried out as part of the Academy of Finland's Research Programme on Nanoscience (FinNano).

Different types of drug molecules can be bound to the porous structure of silicon, thereby making it possible to alter their properties and control their behaviour within the body.

Porous silicon can be produced as both micro- and nanoparticles, which facilitates the introduction of the material through different dosing routes - orally, as injections or subcutaneous applications. Furthermore, biodegradable nanoparticles can be used for drug targeting.

Silicon is more familiar as a raw material used in computer microprocessors. In nanomedicine applications, the wafers are equipped with nano-sized pores instead of processors. The pores are slightly larger than the drug molecules loaded in them. The porous surfaces of the silicon particles, created through a process called electrochemical etching, are modified to be chemically suitable regarding the molecules to be loaded in the pores and the application. The drug is loaded by immersing the particles in a suitable drug solution, whereby sensitive substances, such as peptides and proteins, can also be easily loaded into the pores effectively.

The biopharmaceutical properties of the drug in the pores are different from those of the original drug. The rate of release for pore-bound drugs can be changed in a controlled manner by selecting the proper pore size and surface chemical properties in relation to the size and chemical properties of the drug molecule.

The drug can be rapidly released and dissolved from the pores, in cases where we are looking to improve the solubility properties of specific low-soluble drugs. The release of the drug can also be delayed, if the aim is to sustain the therapeutic effect. Porous particles can be targeted to specific tissues in the body by attaching targeting molecules to their surface, whereby a significant amount of the drug loaded in the pores accompanies the particles to the effect site. This would increase, for example, the effectiveness of cancer treatments and reduce side-effects.

Nanoporous silicon is applicable as an adjuvant component for both traditional drugs and for peptides, proteins and genetic drugs. The development of silicon as an adjuvant material for medicinal products is based on interdisciplinary research in which physicists, pharmacists, physicians, biotechnologists, chemists, and experts in the material sciences work in cooperation within a broad national research network. The network includes groups from the universities of Kuopio, Turku, Helsinki and Oulu as well as from Lappeenranta University of Technology.