Process for the preparation of a suspension of nanosized synthetic zeolite materials, suspensions of nanosized synthetic zeolite materials obtained by said process and their uses in therapy and diagnosis

A method for the preparation of a colloidal aqueous suspension of stable zeolite single nanocrystals with monodisperse particle size distribution ranging from 5 to 200 nm, said stable zeolite single nanocrystals having a three-dimensional framework comprising silicon or silicon and aluminum, said framework comprising channels and cavities at least partially filled with at least one gas of O2 or CO2 and at least one cation C of Gd, Fe, Cu, or Ce in an amount ranging from about 0.1 to about 10 weight % with respect to the total mass of said nanocrystals, wherein said method comprises the following steps:

• 1) subjecting a colloidal suspension CS1 of at least one type of stable zeolite single nanocrystals with monodisperse particle size distribution ranging from about 5 to 200 nm, said stable zeolite single nanocrystals having a three-dimensional framework comprising at least one of silicon or aluminum, said framework comprising channels and cavities and alkali metal cations M, to an ion exchange of at least a part of the alkali metal cations M with at least one cation C of Fe, Gd, Cu, or Ce, to obtain a colloidal suspension in water CS2 of zeolite single nanocrystals having a three-dimensional framework comprising channels and cavities, and at least one cation C of Fe, Gd, Cu, or Ce in an amount ranging from 0.1 to 10 weight % with respect to the total mass of the zeolite single nanocrystals;
• wherein step 1) is carried out by adding to the colloidal suspension CS1, a solution containing at least one salt of a cation C of Fe, Gd, Cu, or Ce;
• 2) purifying the colloidal suspension CS2 of zeolite single nanocrystals obtained in step 1) with water until a pH ranging from 6.5 to 7.5 is reached;
• and
• 3) contacting the purified colloidal suspension of zeolite single nanocrystals obtained in step 2) with at least one gas of O2 or CO2.