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The understanding of the interaction of nanoparticles with cell membranes and the penetration of these nanoobjects through cell wall is highly required for their biomedical application. In this work were aimed at the study of the interaction of gold nanoparticles with model phospholipid membranes prepared at the air/water interface in a Langmuir trough. Spherical (10 and 15 nm mean diameter) and rod-like gold (aspect ratio: 2.8) nanoparticles were synthesized and biofunctionalized with L-cysteine and L-glutathione. The gold nanoparticles were characterized by TEM images and UV-Vis absorbance measurements. The interaction of the biofunctionalized gold nanoparticles with the model monolayer membrane was studied by surface pressure versus surface area compressional isotherms and by the measurement of the change in surface pressure of a preformed model membrane. The effect of the initial surface pressure of the preformed membrane was evaluated to determine the maximum insertion pressure and synergy. We have found that the driving forces of the bioconjugated Au nanoparticle (NP) or Au nanorod (NR) penetration into the monolayer membrane is mostly determined by electrostatic interaction and orientational van der Waals forces. Monolayer films were transferred with Langmuir-Blodgett technique onto solid substrates and the nanoparticles were visualized with AFM technique.

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Abstract. Ultrathin gold nanofilms (≈ 50 nm) are suitable for detection of adsorbed molecules at solidliquid interface of various sizes due to their surface plasmon resonance (SPR) properties. This SPR technique makes it possible to study the surface adsorption in nanomol range amount on gold surfaces of a maximum of one mm 2 and to determine the adsorbed amount as a function of equilibrium concentration. Adsorption of L-cysteine, L-glutathione, ibuprofen and dopamine on the gold surface was examined. Moreover, the binding capability of ibuprofen and dopamine molecules on the gold surface functionalized by L-cysteine and L-glutathione was studied as well. Adsorption isotherms were recorded using the flow measuring technique, which allows determination of the amount of adsorbed material even in the nmol/cm 2 order of magnitude, the cross sectional areas of adsorbed molecules. The adsorption enthalpies (isosteric heat of adsorption) were determined from adsorption isotherms at different temperatures. The surface orientations of the studied molecules were analyzed by MarvinSketch program. (doi: 10.5562/cca2343)

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