Interaction of biofunctionalized gold nanoparticles with model lipid membranes

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(1)Interaction of biofunctionalized gold nanoparticles with model lipid membranes N. 1Supramolecular. 2Department. 1 Ábrahám ,. E.. 1 Csapó ,. I.. 1,2 Dékány. and Nanostructured Materials Research Group of The Hungarian Academy of Sciences, H-6720, Szeged, Aradi vt. 1., Hungary. of Medical Chemistry, University of Szeged, Dóm Square 8, Szeged H-6725, Hungary. Introduction The study of the interaction of different molecules or nanoparticles with the cell membrane is a key factor when developing new biocompatible systems for diagnostic or therapeutic applications. The aim of our work was to syntheize and functionalize gold nanoparticles and study the interaction with a model phospholipid membrane. Langmuir monolayers at the air/water interface were prepared as model membranes. These floating monolayers are simple and practical models for biological membranes since many parameters can be tuned easily (composition, density of molecules in the membrane, composition of the subphase, etc.).. Gold nanoparticles. Study of the interaction. Gold nanoparticles were prepared by the widely used Turkevich method [1,2].. The interaction between functionalized Au NPs and the Langmuir mnlayer membrane was followed by the change in the surface pressure of the floating film.. 35. 1,0 10,21 ± 0,93 nm. absorbance. 25. number, %. 518 nm. 0,8. 20 15 10. 5. 0,4 0,2. 5. 4. Fig. 4. Change in surface pressure due to interaction of Au-cys NPs with the monolayer membrane.. DPPC membrán. DPPC. 0,6. , mN/m. 30. Asolectin asolectin membrán. 3 2. 0 2. 4. 6. 8. 10. 12. 14. 16. 0,0 300. 18. 400. 500. 600. 700. 800. wavelength (nm). d, nm. 1. -O H2N. Fig. 3. UV-Vis absorbance spectra of Au NPs aqueous sol. Biofunctionalisation of Au NPs was realized with cysteine (cys) and gluthatione (gsh) around pH 7.4, which is characteristic for biological systems. Aggregation of the Au NPs can be avioded at this pH.. 10. 20. 30. 40. 50. S. 0, mN/m. cysteine (cys). HO. C. CH. O. C H2. H2 C. C. H N. O CH. O H2C. S. C. N H. S. H2 C. C O. CH2 CH C. S. H2N. Fig. 5. Change in surface pressure due to interaction of Au-gsh NPs with the monolayer membrane. NH2. Table 1. Characteristics of functionalized Au NPs. O. S. 0. O O-. 4. , mN/m. Fig. 2. Size distribution histogram of Au NPs. C. H2C. 0. Fig. 1. TEM image of Au NPs. CH. DPPC. 3. DPPC membrán. 2. Asolectin membrán. asolectin. OH. 1. S. 0. Au. Au-cys. Au-gsh. O. gluthatione (gsh). HO. C. CH. H2 C. NH2. DLS (nm). 11. ζ potential (mV). -52. 12 -61. O H2C C H2. C. N H. CH. S C O. H N. 0. O C H2. C. OH. 20. 30. 40. 50. 60. 70. 0, mN/m. 12 The increase in the surface pressure reveals the incorporation of the functionalized nanoparticles in the membrane.. -65. The floating monolayers with incorporated Au particles were transfered onto soild substrates and the particles were visualized by AFM images.. Model membrane systems Model membrane materials:. AFM image clearly shows the gold nanoparticles in the membrane.. - DPPC (dipalmytoil-phosphatidilcoline) - Asolectin (mixture of phospholipids and fatty acids) Langmuir trough Kibron MicroTroughS. 10. Au NPs. Subphases:. 7,9 nm. - ultrapure water - Au NPs sol (pH: 7.4). Membrane preparation:. Au NPs sol. Langmuir monolayer of the lipids was formed at the air/liquid interface.. 1 µm. Fig. 6. Visualization of Au-cys NPs in the solid supported monolayer membrane on AFM images.. Conclusions We have synthesized monodispersed, spherical gold nanoparticles which were biofunctionalized with cysteine and gluthatione. The interaction of the cysteine and gluthatione coated Au particles with lipid monolayers at the air/liquid interface as model membranes was studied. Surface pressure measurement results and AFM images reveal the successful penetration of metal nanoparticles into the model membrane.. References [1] J. Turkevich, Gold Bull. 3 (1985) 18. [2] A. Majzik, Colloids Surf B, 81 (2010) 235.. Acknowledgement The publication/presentation is supported by the European Union and co-funded by the European Social Fund, project number: TÁMOP-4.2.2/B-10/1-2010-0012..

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