Enzymatic Modification of a Chemisorbed Lipid Monolayer

• Published in: Langmuir Vol. 12; no. 18; pp. 4411 - 4416
• Main Authors: Turner, David C, Peek, Brian M, Wertz, Thomas E, Archibald, Douglas D, Geer, Robert E, Gaber, Bruce Paul
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 04.09.1996
• Subjects: Biological and medical sciences; Biotechnology; Chemical industry. Chemical engineering; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects; Monolayer; Enzymatic treatment; Chemical modification; Enzyme; Phospholipid; Hydrolases; Structure modification; Esterases; Phosphoric diester hydrolases; Phospholipase C; Surface structure
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la951520o

The selectivity and specificity of enzymes may be exploited to create chemically complex surfaces which are difficult or impossible to achieve using classical synthetic chemistry. In this paper we discuss the preparation of a chemisorbed lipid film on a silicon wafer and explore the activity of free phospholipase C (PLC) on that film. A carboxylic acid derivative of the lipid dimyristoylphosphatidylcholine (DMPC) was attached to an amino-terminal silane (EDA) via amide bond formation to create an immobilized lipid layer (EDA−DMPC). Films were characterized using X-ray photoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS), atomic force microscopy (AFM), X-ray reflectivity, and ellipsometry. Following treatment with the enzyme phospholipase C (PLC), which catalyzes the cleavage of the lipid headgroup at the glycerol−phosphate ester bond, the lipid film was reanalyzed using the above techniques. Before analysis, nonspecifically adsorbed PLC was removed with a 25% trifluoroethanol rinse. XPS and SIMS results of the cleaned films show nearly complete removal of the phosphate from the lipid layer, indicating enzymatic activity of the PLC on the chemisorbed lipid layer.