IJUP08 - Universidade do Porto

Investigation of the Interactions between Phospholipids and Gold
Nanoparticles at Air/water Interface
C. Carreira, F. Silva and C. Pereira
CIQ-L4, Chemistry Department, Faculty of Sciences, University of Porto, R. do Campo Alegre,
687, 4169-007 Porto Portugal.
This study aims to explore the interaction between gold oleylamine modified nanoparticles
and phospholipids using monolayers at the air / water interface and how the pH of the
subfase influence these interaction. This study can provide insights on the importance of
the charge and hydrophilic character of gold nanoparticles on their interaction with model
membranes.
The combined information from the surface pressure and surface potential isotherms
allowed the analysis of the molecular properties of the films.
Langmuir films were prepared at the air/water interface using a standard LB trough (KSV
mini trough) and the surface potential was measured using the vibrating plate method. The
films were prepared spreading 1,3 mg/mL chloroform solution of DPPC on a subphase
containing a 30 µL nanoparticles solution. The nanoparticles solution was obtained by
dilution of a stock solution with different buffers, and kept at 20 ºC. The monolayer was
compressed at the speed of 10 mm/min.
The gold oleyl amine functionalized nanoparticles were prepared accordingly to the
literature [1].
Figure 1 shows the pressure-area isotherms for the mixed gold nanoparticles and DPPC
monolayers, at different pH.
Surface Pressure/ mNm -1
50
45
40
35
30
25
20
15
10
5
0
30 50 70 90 110 130 150
Mma / Å 2 molecule -1
pH:
8.78
6.91
2.32
4.87
12.29
Fig. 1 – Surface pressure isotherm for interaction between gold oleyl amine modified nanoparticles
and DPPC at different pH
A decrease of the subphase pH leads to an expansion of the gold nanoparticles/DPPC
monolayer. Further results will be presented and discussed.
References:
[1] Aslam, M., Fu, L., Su, M., Vijayamohanan, K., Dravid, V.P. (2004) J. Mater. Chem., 14, 1795
188