Zinc oxide surface functionalization and related effects on corrosion resistance of titanium implants

Abstract

Important clinical concerns in orthopedics and dental implantology are associated with a significant release of titanium (Ti) metal ions and debris due to the low corrosion resistance of this material. Chemical modifications on Ti surfaces have been performed in order to minimize effects of corrosion. In this contribution, zinc oxide (ZnO) thin films were deposited onto Ti surfaces and functionalized with four different organic bifunctional molecules in order to increase the corrosion resistance. SEM and XPS indicated the formation of nanostructured ZnO thin film with hydroxyl groups available for covalent functionalization. The adhesion mechanism analyzed by XPS suggest that the attachment on ZnO occurs by carboxylic acid, silane, thiol and hydroxyl groups for 4aminophenylpropionic acid (APPA), 3-aminopropyltrimetoxysilane (APTMS), 3-mercaptopropionic acid (MPA), and polyethylene glycol (PEG) molecules. Electrochemical analysis for the functionalized ZnO specimens with APPA showed noble open circuit potentials (−0.2 V) and significant decrease in the corrosion current density (5.3 × 10 −7 A/cm 2) when compared to the values obtained for pristine Ti (−0.56 V and 2.3 × 10 −6 A/cm 2), indicating a promising material for applications in biomedical fields.

Chemical functionalization of the ZnO monolayer: structural and electronic properties

“…27 In addition, the surface functionalization of ZnO nanoakes with thiourea can enhance their sensitivity and selectivity, and the ZnO nanoakes exhibit gas sensing characteristics, which pave the way for the realization of highly sensitive and selective ber optic sensors. 28 Trino et al 29 found that the functionalization of ZnO with four different organic bifunctional molecules not only could increase the corrosion resistance in ZnO, but could also lead to different wettabilities and surface energy behaviors.…”

Physicochemical, osteogenic and corrosion properties of bio-functionalized ZnO thin films: Potential material for biomedical applications

“…Commercial pure titanium grade 4 (Ti cp4 (ACNIS, Brazil)) discs, with a diameter of 12.7 mm and 3 mm of thickness, were prepared and coated with ZnO based in our previous work [10]. Briefly, the ZnO resin was synthesized by sol-gel method dissolving 72.05 g of citric acid in 200 mL of deionized water.…”

“…After the Ti discs were sandblasted and etched with Piranha solution (a mixture of 7:3 (v/v) 98% H 2 SO 4 and 30% H 2 O 2 ) the diluted ZnO solution was deposited by spin coating technique (2000 rpm during 60 s) [10]. Then, the ZnO surface was functionalized with two different bifunctional molecules 3-mercaptopropionic acid (MPA) and 3-4 aminophenyl propionic acid (APPA) by immersion method [10]. The 2 mM APPA solution was prepared in ethanol absolute by stirring until complete dissolution.…”

“…The 2 mM APPA solution was prepared in ethanol absolute by stirring until complete dissolution. Then it was heated to 40°C and the samples were immersed for 5 min [10]. An aqueous MPA solution (1 mM) was prepared by adjusting the pH to 3 with HCl.…”

“…An aqueous MPA solution (1 mM) was prepared by adjusting the pH to 3 with HCl. Then, the samples were immersed for 10 min in the MPA solution [10]. After the deposition of the organic molecules, all samples were dried in ambient conditions and kept in a desiccator until use.…”