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Conference: Bucharest University Faculty of Physics 2006 Meeting

Section: Solid State Physics and Materials Science

Title:

Preparations and AFM analysis of functionalized surfaces for binding proteins

Authors:

M. Alderighi(1), Marlena Filimon(2), V. Ierardi1 , R. Solaro(1)

Affiliation:

(1) Department of Physics, University of Pisa, Pisa, Italy

(2) Faculty of Physics, University of Bucharest, Bucharest-Magurele, Romania

E-mail

marlena.filimon@fizica.net

Keywords:

Atomic force microscopy, HSA and APTES

Abstract:

The design of biocompatible synthetic surfaces is an important issue for medical applications. Surface modification techniques provide good approaches to control the interactions between living systems and implanted materials by modifying the surface characteristics. The aim of our work is study a particular biocompatibility system: we have used chemical deposition of proteins (HSA-human serum albumin) over a silicon surface functionalized with a SAM (self-assemble monolayer). Sample preparation involved two steps: first the silicon surface was prepared with multiple chemical treatments (degrease with sulphuric acid and hydrogen peroxide 3:1, boiling solutions of dichloromethane, methanol and acetone) and activated in boiling water for 48h. Moreover the SAM formation was performed putting the silicon in a toluene diluted solution of APTES (3-aminopropyl-triethoxysilan) under nitrogen atmosphere. Wettability changes were investigated with qualitative measurements of contact angle: it was observed significant difference between untreated silicon, and APTES functionalized silicon. The second step involved the functionalization of the surface with the protein: this was achieved by putting the silicon surface in aqueous solution of human serum albumin (HSA) with a concentration 7×10-4 M. All these steps are made in order to prepare and functionalize the surface, which was investigated with AFM technique later. In fact, the microscope was used first in force curve mode for check if the SAM was effectively bonded to the surface, and after to imagine the protein bonded over the silicon sample. Both contact mode and tapping mode were performed during our analysis.