Funcionalização de pontas por PECVD e aplicações em nanobiossensores via espectroscopia de força química

Abstract

This work studies the modification of the silicon substrate basead on the deposition of silicon nitride and ethylenediamine (EDA) and specific interaction (covalent single and multiple) between the NH2 functional group present in the EDA and glutaraldehyde crosslinking agents. Fourier transform infrared spectroscopy (FTIR) and X-Ray Photoelectron Spectroscopy (XPS), was used to evaluating the changes in organic compounds on the surface. Therewithal Atomic force microscopy was used in order to estimate topography variations after each step of functionalization. In the surface functionalization steps we observed that glutaraldehyde makes covalent bond with ethylenediamine and the interactions between the functionalized surface macromolecules are strongly interconnected. For estimating the interactions between the macromolecules on functionalized surface, were applied the force curves through of theory freely jointed chain models which made it possible study the behavior of macromolecule in different strengths and reaction times. In order to assess as occurs the connections of macromolecules between themselves and the environment are used mathematical models of the wormlike chain (WLC) that describes the strength of mechanical stresses well as loading rate model it is based on the Gibbs free energy. One result of shown that the variation of force and time increase the Persistence Length (CP) between biotin-avidin and it proves that this entire dynamics depends of interaction time between the AFM tip and the macromolecule is fundamental in the biosensor.