Characterization of LBL films containing Pheophytin-b
Gisele E. Nunes Pauli; Felipe B. Araruna; José Roberto S. A. Leite; Carla Eiras; Otemberg Souza Chaves; Severino Gonçalves Brito Filho; Maria de Fátima Vanderlei Souza; Ivan H. Bechtold;
The self-assembled layer-by-layer (LbL) technique is a method based on alternate adsorption of oppositely charged polyelectrolytes, through electrostatic interactions, leading to well organized films with a precise control of the film thickness [1]. Due to its versatility and simplicity, it has been explored for a wide variety of systems including those containing azodyes [2, 3], biological systems [4], etc. Pheophytin-b is a compound derived from chlorophyll, with nanobiomedical properties that have been studied for use in Photodynamic Therapy [5].
In this work we produce LbL films with pheophytin-b (isolated from the plant Turnera subulata, and the biological material collected Campus UFPB/ Paraiba), together with a cationic polymer poly(allylamine hydrochloride) (PAH). The multilayer formation was investigated via UV–Vis spectroscopy by monitoring the 410 nm absorption band associated to pheo-b, where distinct molecular interactions between the materials were verified. The morphology of the films was analyzed by atomic force microscopy (AFM). The electrochemical properties through redox behavior of pheo-b were studied with cyclic voltammetry. The produced films were applied as sensors for hydrogen peroxide detection. In terms of sensing, PAH/pheo-b films exhibited promising results.
Keywords: Pheophytin-b, Layer-by-Layer (LBL) technique, Biosensors.
[1] G. Decher, Science 277, 1232, (1997).
[2] V. Zucolotto, P. J. Strack, F. R. Santos, D. T. Balogh, C. J. L. Constantino, C. R. Mendonça and O. N. Oliveira, Thin Solid Films, 453, 110, ( 2004).
[3] Nunes, G.E.; Sehnem, A.L.; and Bechtold, I.H. Liquid Crystals,Vol. 39, No. 2, p.205, 2012.
[4] Crespilho, F. N.; Zucolotto, V.; Siqueira Jr., J. R.; Constantino, C. J. L.; Nart, F. C.; Oliveira Jr., O. N. Environ. Sci. Techol., 39, 5385, 2005.
[5] Ribeiro, J. N.; Jorge, R. A.; Silva, A. R.; Flores, A. V.; Ronchi1, L. M.; Tedesco, A. C. Ecl. QuÃm.,Vol. 32, No. 1: p.7, 2007.