Fabrication of Phytic Acid Sensor Based on Mixed Phytase-Lipid Langmuir-Blodgett Films

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• 作者：Luciano Caseli ; Marli L. Moraes ; Valtencir Zucolotto ; Marystela Ferreira ; Thatyane M. Nobre ; Maria Elisabete D. Zaniquelli ; Ubirajara P. Rodrigues Filho ; Osvaldo N. Oliveira ; Jr.
• 刊名：Langmuir
• 出版年：2006
• 出版时间：September 26, 2006
• 年：2006
• 卷：22
• 期：20
• 页码：8501 - 8508
• 全文大小：183K
• 年卷期：v.22,no.20(September 26, 2006)
• ISSN：1520-5827

文摘

This paper reports the surface activity of phytase at the air-water interface, its interaction with lipid monolayers,and the construction of a new phytic acid biosensor on the basis of the Langmuir-Blodgett (LB) technique. Phytasewas inserted in the subphase solution of dipalmitoylphosphatidylglycerol (DPPG) Langmuir monolayers, and itsincorporation to the air-water interface was monitored with surface pressure measurements. Phytase was able toincorporate into DPPG monolayers even at high surface pressures, ca. 30 mN/m, under controlled ionic strength, pH,and temperature. Mixed Langmuir monolayers of phytase and DPPG were characterized by surface pressure-areaand surface potential-area isotherms, and the presence of the enzyme provided an expansion in the monolayers (whencompared to the pure lipid at the interface). The enzyme incorporation also led to significant changes in the equilibriumsurface compressibility (in-plane elasticity), especially in liquid-expanded and liquid-condensed regions. The dynamicsurface elasticity for phytase-containing interfaces was investigated using harmonic oscillation and axisymmetric dropshape analysis. The insertion of the enzyme at DPPG monolayers caused an increase in the dynamic surface elasticityat 30 mN m^-1, indicating a strong interaction between the enzyme and lipid molecules at a high-surface packing.Langmuir-Blodgett (LB) films containing 35 layers of mixed phytase-DPPG were characterized by ultraviolet-visible and fluorescence spectroscopy and crystal quartz microbalance nanogravimetry. The ability in detecting phyticacid was studied with voltammetric measurements.