Polyelectrolyte Multilayer Deposition on Nickel Modified with Self-Assembled Monolayers of Organophosphonic Acids for Biomaterials: Electrochemical and Spectroscopic Evaluation

Abstract

Layer-by-layer assembly of polyelectrolytes is an efficient method for the formation of functional thin films with the prospect of biomedical applications. Polyethyleneimine (PEI) is commonly used as an adhesion promoter but has been shown to be potentially cytotoxic and therefore could not be suitable for biomedical applications besides providing no or little corrosion protection to the underlying substrate. In the present work, we report on the use of a self-assembled phosphonic acid monolayer as a corrosion inhibitor and adhesion promoter for polyelectrolyte multilayer (PEM) formation on nickel substrates. The interest in using a phosphonic acid monolayer as an adhesion promoter for the deposition of polyelectrolyte multilayers lies in the robust grafting of the PEM adhesion promoter to the modified surface and the corrosion inhibition provided by this monolayer. This protection is crucial when considering the biodegradability of many polyelectrolytes used for biomedical applications. Nickel surfaces have thus been modified with an 11-methylundecanoatephosphonic acid monolayer. This monolayer has been shown to significantly improve the nickel corrosion resistance. Hydrolysis of the ester terminal function of this monolayer allowed the formation of negative charges on the modified nickel surfaces and therefore the successive deposition of chitosan and alginate layers.

Electroassisted Functionalization of Nitinol Surface, a Powerful Strategy for Polymer Coating through Controlled Radical Surface Initiation

“…Interestingly, many groups have reported preparation of SAMs on metals (e.g., gold, − steel, , titanium, ,− nickel, − iron, , or aluminium − ) and alloy surfaces (e.g., of Phynox, NiTi, − or some aluminum alloys − ) through a basic approach consisting of immersing the metal into a reactive solution of surfactants. Moreover, the elaboration of SAMs is a very convenient approach to introduce initiating functionalities with the purpose of promoting polymerization from the metal surfaces.…”

“…Moreover, the elaboration of SAMs is a very convenient approach to introduce initiating functionalities with the purpose of promoting polymerization from the metal surfaces. Among the various usable surfactants, phosphonic acid derivatives have been shown to robustly graft on metal oxide surfaces through hydrolysis-resistant M–O–P bonds. ,,− The formed layer constitutes an additional protection of the metal against its environment. ,,− Moreover, it enables the functionalization of its surface that can be harnessed for postpolymerization purposes, as the introduction of a functional polymer layer by a “grafting-from” approach. To be successful, this particular point implies therefore the introduction of selective functional moieties that allow the initiation of a chain growth process from the surface.…”

Electrografting of mixed organophosphonic monolayers for SI-ATRP of 2-methacryloyloxyethyl phosphorylcholine

“…[28][29][30][31][32] They constitute a strong reinforcement of the metal surface in aggressive environments. [33][34][35][36][37] To confer to the surface additional properties for applications, e.g., antifouling, 38,39 lubrication, 40,41 cell culture 42,43 or even cell differentiation, 44 appropriate polymer coatings are also used. One way to generate theses polymers is the surface-initiated controlled radical polymerization (SI-ATRP) which leads to the growth of polymer brushes with a good level of control over chain length, grafting density, and molecular architecture.…”

A Comparative Study of the Electro-Assisted Grafting of Mono- and Bi-Phosphonic Acids on Nitinol

“…This last process is an attractive way to modify interfacial properties of NiTi, mainly by providing new physico-chemical surface properties such as wettability, protein adsorption resistance, biocompatibility, and/or bioactivity, and possibly reinforce their corrosion resistance. Among the various surface modifiers, organophosphonic acid derivatives robustly graft on metal oxide surfaces through hydrolysis resistant M-O-P bonds [29][30][31][32][33], thereby contributing to a strong reinforcement of the Surfaces 2019, 2 521 metal surface against aggressive environments [32,[34][35][36][37]. A common way to form such SAMs, referred to as conventional grafting (CG), is by direct immersion of the substrate in the organophosphonic solutions at different temperatures.…”