Recently, the synthesis of Janus particles has created great interest in the scientific field. These particles received its name in allusion to the double-faced Roman god Janus; for this reason the particles with two chemically or physically different surfaces, receive the name of Janus particles.
Synthesized particles with different properties present new opportunities for many applications in the nanotechnology and biotechnology fields. Most of the synthesis of Janus particles consists of Au-Ag, Au-PS and Ag-PS. When these materials are irradiated by an external light beam, the region in the UV spectrum, of maximum absorption, change.This is the main reason in selecting materials. Factors changing this maximum absorbance include shape, size, space between particles, surroundings effects, among others.
These manipulations, which can restrict where nanoparticles will have its maximum absorbance in the spectrum, allow us to move the nanoparticles in a direction faster or slower with the ability to bring one or two substances attached to their surfaces.It also enables the nanoparticles to be irradiated by a light beam through the human skin without any effect (either to cure malignant cancer cells by burning or for internal surgery).
But, how can this be possible? Like said in the beginning, Janus particles have the advantage of have two properties where can stick two different molecules at the same time and transport them throught low viscosity enviroment to a specific location.
Cancer treatment and internal surgery could be done with nanoparticles, because with the appropriated size, surroundings conditions and dielectric core (polystyrene) it is possible to shift the maximum absorbance of the Janus particles to the NIR region (does not affect human or animal skin).
Janus particles have a promising future ahead for the biotechnology and engineering fields in general. Progress is increasing and soon there will be small vehicles making possible work in places where human have never reached.
Ken-Tye Yong, Yudhisthira Sahoo, Mark T. Swihart, Paras N. Prasad; Synthesis and plasmonic properties of silver and gold nanoshells on polystyrene cores of different size and of gold-silver core-shell nanostructures; Science Direct: Physicochem Eng Aspects 290 (2006) 89-105
Perro, A.; Reculussa, S.; Pereira, F.; et al. Towards large amounts of Janus nanoparticles through a protection deprotection route. ChemComm, 2005, 5542-5543.
Lassiter, JB; Aizpurua, J; Hernández, LI; Brandl, DW; Romero, I; Lal, S; Hafner, JH; Nordlander, P; and Halas, NJ. Close Encounters Between Two Nanoshells. Nano Letters, 2008, Vol. 8, No. 4; pp 1212-1218.