Crystallographic features and cleavage nanomorphology of chlinochlore : Specific applications
Valdré, Giovanni (Universitá di Bologna. Dipartimento di Scienze della Terra e Geologico-Ambientali)
Malferrari, Daniele (Universitá di Modena e Reggio Emilia. Dipartimento di Scienze della Terra)
Brigatti, Maria Franca (Universitá di Modena e Reggio Emilia. Dipartimento di Scienze della Terra)

Data:	2009
Resum:	Natural and synthetic micas have been used widely as substrates to study biological systems; but, as in the case of negatively charged DNA, anionic charge repulsion may render micas a less than ideal templating surface for many biological systems. The purpose of this study was to investigate the potential for the chlorite clinoclore, which contains a positively charged interlayer octahedral sheet, to serve as a substrate for DNA adsorption. The relationships between clinochlore cleavage characteristics, in terms of nano-morphology, and surface potential are investigated, as are its average crystal chemistry and topology. That the structural features of clinochlore can be used successfully to condense, order, and self assemble complex biomolecules, such as DNA is also proven. A natural IIb-4 clinochlore [C1 symmetry, unit-cell parameters a = 0. 53301(4); b = 0. 92511(6); c = 1. 4348(1) (nm); α = 90. 420(3); β = 97. 509(3); γ = 89. 996(4) (°)] with chemical composition (MgFe TiAlCr ) Mg (Si Al Fe )O(OHF) was selected. The octahedral sites of the silicate layer (<M(1)-O> = 0. 2080 nmand < M(2)-O> = 0. 2081 nm) are equal and occupied by Mg, whereas the octahedral sites in the interlayer M(3) and M(4) (<M(3)-O> = 0. 2088 nmand <M(4)-O> = 0. 1939 nm) show different sizes and are mostly completely occupied by divalent (Mg and Fe) and trivalent (Al) cations, respectively. The clinochlore cleaved surface is present in two forms: (1) the stripe type (0. 40 nm in height, up to several micrometers long and ranging from some nanometers to a few microns in lateral size); and (2) the triangular type (0. 40 nmin height). Both features may result either frominterlayer sheets whose cleavage weak directions are related to the different M(3) and M(4) site occupancy, or fromweak interlayer bonding along specific directions to the 2:1 layer underneath. The cleaved surface, particularly at the cleaved edges, presents high DNA affinity, which is directly related to an average positive surface and ledge potential.
Nota:	Altres ajuts: MIUR/PRIN-2006
Drets:	Aquest material està protegit per drets d'autor i/o drets afins. Podeu utilitzar aquest material en funció del que permet la legislació de drets d'autor i drets afins d'aplicació al vostre cas. Per a d'altres usos heu d'obtenir permís del(s) titular(s) de drets.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	AFM ; Clinochlore ; Crystal structure ; Surface applications ; XAS
Publicat a:	Clays and Clay Minerals, Vol. 57, Núm. 2 (2009) , p. 183-193, ISSN 1552-8367

DOI: 10.1346/CCMN.2009.0570205

11 p, 1.1 MB  Accés restringit a la UAB

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