Geology and Health

The main purpose of this paper aims at the characterisation of the surface potential of various layered minerals for the control of DNA, nucleotides and cells adsorption. A critical factor in the imaging of biomolecules and biomolecular processes is the nature of the substrate on which the biomolecule is adsorbed. In the past, the underlying assumption, derived from current models of biomolecules’ adsorption, is that the substrate surface plays a “passive” role in the process and functionalization is required before or during the deposition. Several techniques have been developed to tailor the adsorption of biomolecules according to different experimental requirements. These include the functionalization of the surface with self-assembled monolayers, the use of ligand-receptor complexes and the regulation of the buffer conditions. Our experiments showed clearly that the above assumption is not completely correct for layer silicates because very similar atomic flat crystals, as in the case of muscovite and biotite, presented very different affinity to DNA adsorption. Furthermore, it was found that chlorites have the ability to nanoconfine the deposition of DNA molecules on particular areas (brucite-like) of the surface. This effect became even more interesting when it was noted that some DNA strands could be stretched between two brucite areas. The stretching was shown to be produced by the anisotropy of the surface potential and therefore can be considered an active process induced by the surface. The molecules were also shown to be “suspended” between the two brucite areas with very small interactions with the underlying surface. The possibility to manipulate DNA molecules on a flat surface, as in the case of chlorite, has great potential, in biological, medical and health sciences, for example to exploit its use (and that of similar layer silicates) to study DNA-enzyme complexes, cellular behaviour and biochemical assays.