Gold is one of the few metals that is not rejected by our body. Gold nanoparticles (AuNPs) thus provide non-toxic routes to drug and gene delivery applications. With these systems, the Gold core imparts stability to the manufactured assembly, while the thin monolayer allows smart tuning of surface properties such as charge, optical properties and hydrophobicity. Yet another additional attractive feature of AuNPs is their interaction with thiols; providing an effective and selective means of controlled intracellular release.
Generally metal nanoparticles stabilized by an increasingly varied and diverse range of molecules are now creating a new bread of materials different from both conventional bulk materials and atoms. The stabilizers play a crucial role in not only protecting the metal nanoparticles but also controlling its function.
Researchers at the University of Trieste, The University of Bologna, both in Italy and The University of Groningen in the Netherlands have successfully synthesized for the first time a gold water soluble nanoparticle, protected by a thin layer of fluorinated amphiphillic thiols.
[Gentilini et al., J. Am. Chem. Soc., ASAP 10.1021/ja8058364] state that with the ease of adding other thiolates in the thin layer and the strong hydrophobicity of the perfluorinated region, this particular class of nanoparticles may become excellent examples of multicompartment nanoparticles, with the capacity to store and release active particles.
In the research by Gentilini et al., the thiols were devised to form a perfluorinated area close to the gold surface and to have a hydrophilic portion in contact with the bulk solvent to impart solubility in water. Au NPs with core diameters ranging from 1.6 to 2.9 nm, depending on the reaction conditions, were obtained.
Specifically tuned nanoparticles can be obtained by varying the thiol used, the researchers were able to form gold nanoparticles soluble in water or solvents by simply varying the structure of the thiol added.
The immerging features of biocompatible water-soluble gold nanoparticles and the properties of polymers or aggregates of perfluorinated amphiphiles will open the way to new biomedical applications, for example, in the field of antioxidant carriers or in the development of multicompartment nanoparticles with the capacity to store and release active molecules.
To summarise the researchers of this work have succeeded in synthesizing the first example of water-soluble gold nanoparticles protected by a monolayer of fluorinated amphiphilic thiols The solubility properties of the nanoparticles in connection with the intrinsic features of perfluorinated amphiphiles opens the way to possible applications in the medical field such as antioxidant carriers. The enormous potential of these new nanostructures is currently under active investigation in the laboratories.