BR-102024018221-A2 - Chitosan composite coating? Zinc oxide, applied to the surface of a NiTi alloy.

Abstract

The present invention relates to a chitosan-zinc oxide composite coating, applied to the surface of a NiTi alloy, providing corrosion resistance in a physiological environment, obtained through electrophoretic deposition under different experimental conditions of potential and pH of the electrolytic solution. The application areas of this material are broad, thanks to the properties of the metals involved combined with chitosan, including application in the production of biomedical devices for use in medicine, such as stents, plates, pins and wires used in orthodontic and orthopedic appliances.

Inventors

• JOSÉ ANDERSON MACHADO OLIVEIRA
• THALES GOMES ARAUJO
• ANA REGINA NASCIMENTO CAMPOS
• RENATO ALEXANDRE COSTA DE SANTANA
• ARTHUR FILGUEIRA DE ALMEIDA
• JOSIANE DANTAS COSTA
• JADSON DE FARIAS SILVA

Assignees

• Universidade Federal De Campina Grande - Pb

Dates

Publication Date

20260317

Application Date

20240904

Claims (4)

1. 1. A chitosan-zinc oxide composite coating, characterized by being applied to the surface of a NiTi alloy, conferring corrosion resistance in a physiological environment, obtained through electrophoretic deposition under the following experimental conditions: a) pH of the electrolytic solution adjusted to 4.5 or 5.5; b) Applied electrical potential of 5, 7.5 or 10 V; c) Temperature of 25 ± 2 °C; d) Deposition time of 10 minutes.
2. 2. Process for preparing the electrolytic solution for the deposition of the chitosan-zinc oxide composite coating, characterized by comprising: a) Dissolving 0.5 g/l of chitosan, 75% deacetylated, in a solution of acetic acid (1%) with magnetic stirring for 24 hours; b) Adding 1 g/l of zinc oxide (ZnO) to the chitosan solution, with magnetic stirring for 1 hour; c) Adjusting the pH of the electrolytic solution using a solution of NaOH (1 M).
3. 3. Electrophoretic deposition process of a chitosan-zinc oxide composite coating on a NiTi alloy, characterized by the use of an electrolytic solution prepared according to Claim 2, under the pH, electrical potential, temperature and time conditions specified in Claim 1.
4. 4. Product obtained, characterized by a chitosan-zinc oxide composite coating applied over a NiTi alloy, according to the process described in Claims 1 and 3, conferring to the final product resistance to corrosion in a physiological medium, such as Ringer's solution.

Description

FIELD OF THE INVENTION [001] The present invention relates to a metallic alloy coated with a biopolymeric material, and more specifically to a chitosan-zinc oxide composite coating, applied to the surface of a NiTi alloy, conferring corrosion resistance in a physiological environment, obtained through electrophoretic deposition under different experimental conditions of potential and pH of the electrolytic solution. The application areas of this material are broad, thanks to the properties of the metals involved combined with chitosan, including application in the production of biomedical devices for use in medicine, such as stents, plates, pins and wires applied in orthodontic and orthopedic appliances. BACKGROUND OF THE INVENTION [002] The use of composite coatings to functionalize the surface of NiTi shape memory alloy (Nitinol) is a commonly used practice to improve the biocompatibility of the system. However, local inflammation caused by the release of Ni2+ ions can cause implant failure in allergic individuals. Therefore, a commonly adopted strategy to avoid this problem is based on functionalizing the surface of the NiTi alloy with heat treatments or by applying protective coatings. Among the coatings used, polymeric coatings stand out due to their ease of application combined with the intrinsic biocompatibility presented by some polymers, for example, natural polymers such as polysaccharides, proteins, and polyphenols. An example is chitosan, a natural polymer that can be applied to functionalize the surface of the NiTi alloy with organic and/or inorganic materials. [003] In the literature, there are works that describe the application of chitosan and zinc oxide coatings on the surface of NiTi alloy. However, no study to date has used the same combinations of experimental conditions employed in our technology. Furthermore, no patents were found that describe this process for obtaining the technology. [004] Some of the only records found in the patent literature regarding metal alloys are described below. [005] Document CN211884921, entitled “Nickel-titanium alloy push wire with hydrophilic coating” describes a push wire made of nickel-titanium alloy with a hydrophilic coating, consisting of three layers: a base layer, a coupling layer and a hydrophilic polyvinylpyrrolidone layer, with the total coating thickness controlled between 0.005 and 0.008 mm. The coating on the metal wire offers a more efficient solution compared to conventional coating methods. [006] Document WO2020/138670, entitled “Stent containing biodegradable polymer and Nitinol, and corresponding manufacturing method”. The invention relates to a stent composed of a biodegradable polymer and Nitinol, and to a manufacturing method where a zigzag-shaped Nitinol ring is formed and positioned at regular intervals. The stent is used in a blood vessel, where the biodegradable polymer is absorbed by the vessel, thus significantly reducing vessel irritation. [007] Document US8734911, entitled “Nanocoupling for improved adhesion of polymer coatings to metallic substrates”. This patent addresses the improvement of polymer adhesion to metallic substrates, including Nitinol, through a nanocoupling process, which improves the durability and biocompatibility of the polymeric coating. [008] Document EP3775317, entitled “Polymer coatings for shape memory alloys for use in percutaneous cardiac pumps”. The technology refers to a Nitinol alloy coated with a highly flexible and fluid-unpredictable polymeric material, having enhanced adhesion and performance properties on the metallic mesh surface, thus improving the overall performance of the percutaneous cardiac pump. [009] Document CN112301395, entitled “Method for preparing a nickel-titanium alloy fixed with a ceramic and polymer composite membrane”. The invention describes a method for preparing a nickel-titanium alloy fixed with a composite film of Ti(C,N)TiO2 ceramic and a polypyrrole-chitosan polymer. [010] Document CN110144593, entitled “Fluorine-containing nanopolymer-modified nickel-titanium alloy material with superhydrophobic and oleophobic properties and method of preparation thereof”. The invention relates to a fluorine-containing nanometer-modified nickel-titanium alloy material with superhydrophobic and oleophobic performances. The composite-coated nickel-titanium alloy material achieves unique advantages in the preparation of implantable medical devices and can effectively inhibit endangial hyperplasia to prevent vascular restenosis and inhibit bacterial colonization and growth. [011] Analyzing the documents presented and based on the applications involved, to date no documents have been found that are innovative in the product and process of a Nickel-Titanium alloy coated with chitosan-zinc oxide composite, resistant to corrosion in physiological environment. OBJECTIVE OF THE INVENTION [012] The objective of the present invention relates to a chitosan-zinc oxide composite coating, applie