engleski

Self-assembled monolayers of phosphonic acids on Nitinol: The effect of terminal functional groups

Nitinol, nickel-titanium alloy derives its attractiveness from unique properties like shape memory effect and superelasticity. Owing to these desirable mechanical properties and good chemical stability, Nitinol is a popular material with a widespread use in biochemical engineering with application in medicine for manufacturing cardiovascular and orthodontic implants. In this work, to prevent the unwanted release of toxic/allergenic nickel ions, Nitinol surface was modified by biocompatible phosphonic acid self-assembled monolayers (SAMs) that form an effective interface between the human body and the implant surface. In order to determine the influence of the terminal functional group of SAM on the corrosion behavior, dodecyl-phosphonic acid SAMs with different terminal functional groups (-OH and –CH3) were prepared on Nitinol. The corrosion resistivity and biocompatibility of Nitinol modified by phosphonic acid SAMs in simulated body fluid (Hank’s solution) were studied using electrochemical ac and dc methods. Surface characterizations of unmodified and modified surfaces of Nitinol were done by goniometry and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). The obtained results have revealed that both phosphonic acid molecules show bidentate bonding on Nitinol surface, but SAM with hydrophilic terminal group provides better corrosion resistance in comparison to SAM with hydrophobic terminal group.

Nitinol ; Self-assembled monolayers (SAMs) ; Bonding of phosphonic acids SAMs ; Terminal functional group ; Electrochemical and surface-analytical methods

nije evidentirano