Resumo

RIVAS, Carlos F; NUNEZ, Oswaldo; LONGORIA, Francisco  e  GONZALEZ, Lucy. Langmuir and freundlich isotherms as model for the adsorption of nucleic acid components on WO₃. Saber [online]. 2014, vol.26, n.1, pp.43-49. ISSN 1315-0162.

In this paper, we studied the effect of pH (3-10) in the adsorption of nucleic acid constituents; nucleobases, nucleosides and nucleotides, on tungsten trioxide (WO₃). Isotherms of Langmuir and Freundlich were used to describe adsorption processes. It was noted that neutral pH favors the adsorption of nucleic acid components. The adsorption date suggests that there is a considerable difference in the binding capacity of the nucleobases and their derivatives on WO₃, which depends on the molecular architecture of the adsorbed species. It was found that adsorption of biomolecules onto the catalyst has following sequence: Nucleotide > Nucleoside > Nucleobase. The highest values of the maximum adsorption capacity (X_m) were obtained for nucleotides, finding that at pH 7 the CMP'5 (X_m = 64.94 mg/L) > UMP'5 (X_m = 54.64 mg/L) GMP'5 (X_m = 54.35 mg/L) > AMP'5 (X_m = 45.05 mg/L). Freundlich constants (K_F) ranged between 4 and 7. For all pH, nucleosides and nucleotides have values of n (constant of adsorption intensity) close to unity, indicating that the active sites of catalyst are energetically equivalent, except the AMP'5 at pH 7 (n = 2.16). The neutral pH is optimum to chemically modify the surface of the WO₃.

Palavras-chave : Nucleotide; nucleoside; nitrogenous base; biomolecules.

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