STRUCTURAL INVESTIGATION OF MONOLAYERS COMPOSED BY LIPIDS AND AMPHIPHILIC PEPTIDES IN THE PRESENCE OF GLYPHOSATE PESTICIDE VIA LANGMUIR-BLODGETT

In recent decades the use of pesticides in agronomy has increased with a proposal to control agricultural pests. Therefore, developing new platforms capable of detecting the presence of these compounds in food and water is essential. In this study, we propose the structural study of monolayers composed of phosphatidylcholine (PC) doped with a new lipopeptide (LP) able to detect the presence of glyphosate, N-(phosphonomethyl) glycine (PNG). This biomolecule contains in the hydrophilic part the amino acids L-serine (S), L-proline (P), L-arginine (R), L-tryptophan (W), and L-glycine (G), covalently linked to a hydrophobic part formed by a long aliphatic chain. Different molar ratios were used between LP and PC (LP/PC) from 0.05≥R≥1. For each monolayer, we vary the PNG concentration in the range of 1 to 15 uM. The Increasing the amount of LP in the lipid monolayer, we observed the reduction of the mean molecular area and the decrease of maximum pressure (Figure 1A). The isotherm remains constant when adding the PNG in the water subphase for the LP/PC =0.05 (Figure 1C). However, for the monolayer LP/PC =1.0, increasing the PNG concentration, the maximum pressure decreases until it reaches a value around 23mN/m (Figure 1B and 1C). These results suggest that we can determine the percentage of LP needed in the monolayer to detect a minimum concentration of PNG in a water solution.