Researchers in Japan have developed a new method for determining the presence of a number of proteins in cells and tissues using magnetic resonance imaging (MRI). The technique is based on the use of nanoclusters with grafted to the surface of fluorinated marks, which appear in the MRI in the presence of certain proteins, but remain invisible in their absence.

MRI signal is visible only in the presence of a target protein. (Figure from Nature Chem., 2009, 1, 557)

Method for determination of specific protein markers in tissues and cells may be useful for medical diagnostics and scientific research. This could apply the usual "proton" method of MRI (in the event that a suitable contrast agent may be contacted with the protein). To implement such an approach requires design containing contrast agent (usually - derivatives of gadolinium) antibodies to the protein. Unfortunately, the large water content in biological material provides a strong background and difficult to obtain a strong and clear signal.

¹⁹F provides a good signal to an MRI, which do not interfere with obtaining background noise, but the literature describes only a small number of systems that would introduce fluorinated tag for MRI in proteins. The research team ITAR Hamachi (Itaru Hamachi) of Kyoto University has developed a fluorine-containing tag, which does not appear in the MRI in the absence of the protein target and is manifested in his sample consists of a hydrophobic chain with one end of which is linked hydrophilic fluorine containing group and the other - ligand that is specific to the target protein. Amphiphilic nature of the samples leads to what is happening in the water of the spontaneous organization of nanoparticles, fluorinated fragment which "buried" inside the particle. In this state, the sample can give only a weak signal MRI. When contacting the sample with the protein ligand binds to the protein, the nanoparticle is divided into its constituent components, giving a clear signal in MRI. This approach allows us to "incorporate" MRI signal only in the presence of specific proteins in a sample.

Source: Nature Chem., 2009, 1, 557; DOI: 10.1038/NCHEM.365