Fabrication of TIO 2 nanotube arrays by progressive anodization of ti thin film on insulated substrates

Abstract

In one aspect, the disclosure relates to a method for producing TiO2 nanotubes on a nonconductive substrate such as, for example, zirconia, and medical implants such as joint or bone replacements, dental implants, and the like, comprising the same. In another aspect, the length of the TiO2 nanotubes can be customized based on anodization parameters. Also disclosed herein is a customized anodization device for performing the disclosed methods.

Description

ATTORNEY DOCKET NO. T19511W0001 (222112-2520)FABRICATION OF TIO2NANOTUBE ARRAYS BY PROGRESSIVE ANODIZATION OF Tl THIN FILM ON INSULATED SUBSTRATESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Ser. No. 63 / 690,901 , filed September 5, 2024, which is incorporated herein by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This invention was made with government support under Grant No. DE025001 awarded by the National Institutes of Health. The government has certain rights in the invention.BACKGROUND

[0003] The exploration of anodization of valve metals, particularly titanium, has emerged as a fascinating area of research with versatile applications in various scientific domains. These anodized materials, characterized by highly uniform and regular porous structures, serve as templates for creating materials with well-defined geometries. TiO2nanotubes, produced through anodization, have garnered significant importance due to their diverse applications. TiO2nanotubes possess desirable properties such as chemical and thermal stability, catalytic activity, high refractive index, and biocompatibility, making them suitable for applications in electronics, electrochromic devices, gas sensors, biomedical devices, solar cells, and photocatalysis.

[0004] The generation of TiO2nanotubes and the preference for anodization as the method of choice offer an intriguing exploration into controlled nanostructuring. Anodization stands out as a versatile and reliable approach for growing TiO2nanotubes, providing distinct advantages in terms of precision and tunability. Through this process, titanium can be anodized either in bulk or as a thin film, with each approach offering unique possibilities. Anodizing titanium in bulk allows for the detachment of the titania layer from the residual titanium metal, serving as a versatile template for diverse applications. The flexibility of anodization parameters, such as voltage, temperature, and solution composition, facilitates the creation of a wide range of tunable morphologies within the resulting nanoporous titania, notably including nanotubes. The capability to control crucial aspects like tube diameter is a notable advantage, with achievable pore diameters ranging from approximately 10 nm to 350 nm. Moreover, this method provides the opportunity to fabricate various exotic titanium oxide structures by adjusting the anodization conditions, including nanopillars, nanowires, multilayered structures,ATTORNEY DOCKET NO. T19511W0001 (222112-2520) and bamboo nanotubes. The inherent versatility and controllability of anodization make it a preferred method for the precise growth of TiO2nanotubes with diverse morphologies.

[0005] One of the most promising applications of TiO2nanotube surfaces lies in their use for antibacterial dental implant coatings, providing a textured surface that enhances antibacterial properties. While titanium remains the most common material for dental implants, the rise of non-metallic materials like zirconium dioxide (zirconia) offers distinct advantages, particularly for patients with metal sensitivities. Zirconia’s non-metallic composition ensures biocompatibility, reducing the risk of allergic reactions. Additionally, zirconia implants provide superior aesthetic benefits, closely resembling the natural appearance of teeth and blending seamlessly with the surrounding tissue. This makes them particularly suitable for patients with thin gingival biotypes, as they are less likely to be visible through the gum line. The innovative combination of TiO2nanotube coating on zirconia dental implants holds promise for an all- encompassing material choice for dental implants.

[0006] Clinical and animal studies have also shown that zirconia implants exhibit comparable or even superior osseointegration and antibacterial properties compared to titanium implants. These features contribute to better prevention of peri-implantitis, enhanced bone healing, and increased long-term implant stability. It has been demonstrated in vivo that zirconia implants with modified surfaces achieve osseointegration on parwith titanium implants. It has also been shown that titanium implants coated with zirconia resulted in a significantly higher boneimplant contact percentage compared to pure titanium implants. Furthermore, it was found that soft tissues around titanium implants exhibited a stronger inflammatory response to experimental plaque ac-cumulation, with elevated levels of IL- 1 p, IL-6, and TNF-a, compared to zirconia implants, highlighting zirconia’s superior antibacterial properties.

[0007] The uniformity and the diameter of the nanotubes on the surface of dental implants significantly impact their antibacterial properties. The typical TiO2anodization process starts from fully submerging the Ti thin film into a fluorine-based electrolyte. When an anodization voltage is applied to the thin film on an insulated substrate, a fully anodized region forms at the surface of the electrolyte since the higher current density closer to the surface completely anodizes the Ti thin film, blocking the current and preventing further anodization of the rest of the sample. This results in a discontinuation of nanotubes on the sample surface with low uniformity and limited diameters. The anodization of Ti thin film deposited on glass substrates has previously been demonstrated, but only nanotube diameters of less than 100 nm were achieved. Therefore, it would be desirable to develop a specialized method to anodize Ti thin film deposited on non-conductive substrates. It would further be desirable if nanotube diameters and other properties could be optimized and / or customized depending on desiredATTORNEY DOCKET NO. T19511W0001 (222112-2520) end use and other factors. These needs and other needs are satisfied by the present disclosure.SUMMARY

[0008] In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, the disclosure, in one aspect, relates to a method for producing TiO2nanotubes on a nonconductive substrate such as, for example, zirconia, and medical implants such as joint or bone replacements, dental implants, and the like, comprising the same. In another aspect, the length of the TiO2nanotubes can be customized based on anodization parameters. Also disclosed herein is a customized anodization device for performing the disclosed methods.

[0009] Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. In addition, all optional and preferred features and modifications of the described embodiments are usable in all aspects of the disclosure taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

[0011] FIG. 1 shows an illustration of a customized anodization tool configuration useful herein.

[0012] FIG. 2 shows a schematic of the disclosed anodization process of Ti thin film deposited on a glass substrate.

[0013] FIGs. 3A-3D show photographs of Ti thin film on a glass substrate under various anodization conditions. (FIG. 3A) The sample before anodization. (FIG. 3B) Fixed anode where disrupted Ti continuity leads to incomplete nanotube formation. (FIG. 3C) Progressive anodization with excessive anode speed results in shallow nanotubes nearthe interface. (FIG.ATTORNEY DOCKET NO. T19511W0001 (222112-2520)3D) Optimized progressive anodization where the anode speed matches the anodization rate, producing a uniform nanotube array with full anodization.

[0014] FIGs. 4A-4D show surface morphology of Ti thin film with the deposition rate of (FIG. 4A) 0.5 A / s and (FIG. 4B) 3 A / s and the nanotube formation after anodization process on Ti thin film with the deposition rate of (FIG. 4C) 0.5 A / s and (FIG. 4D) 3 A / s.

[0015] FIGs. 5A-5D show surface morphology of anodized TiO2nanotubes with NH4F concentration of 0.5% and voltage of (FIG. 5A) 30 V, (FIG. 5B) 50 V, (FIG. 5C) 70 V, and (FIG. 5D) 90 V.

[0016] FIGs. 6A-6D show surface morphology of anodized TiO2nanotubes with NH4F concentration of (FIG. 6A) 0.5%, (FIG. 6B) 1%, (FIG. 6C) 2%, and (FIG. 6D) 3% and voltage of 90 V.

[0017] FIGs. 7A-7B show surface morphology of anodized TiO2nanotubes (FIG. 7A) before and (FIG. 7B) after soaking in 3% NH4F for 30 min.

[0018] Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.DETAILED DESCRIPTION

[0019] In one aspect, disclosed herein a method for producing TiO2nanotubes on a nonconductive substrate such as, for example, zirconia or glass. In one aspect, the model elucidating the theory behind the formation of anodized TiO2nanotube arrays posits that Ti anodization results from the interplay between electrochemical oxide formation and chemical dissolution of the oxide by fluoride ions. In another aspect, anodization requires placing the Ti material in a conductive analyte alongside a counter electrode. In a further aspect, in the absence of fluoride ions (F~), a thin barrier metal oxide is first produced on the metal surface through the reaction:Ti + 2H2O -> TiO2+ 4H++ 4e- (1)

[0020] In another aspect, this reaction can be augmented by applying an electric field, facilitating ion transport (O2-and Ti4+ions) through the growing oxide. However, as the oxide layer thickens during anodization, the electric field across the film diminishes, constraining the oxidation process and causing a decrease in the oxidation current. Further in this aspect, atATTORNEY DOCKET NO. T19511W0001 (222112-2520) the oxide / electrolyte interface, Ti4+ions are not rendered soluble by complexation, leading to the precipitation of a loose and porous hydroxide layer (Ti(OH)xOy) that hinders further diffusion. In the presence of fluoride ions, two effects alter the scenario.

[0021] (i) Direct complexation with transported cations at the oxide electrolyte interface, preventing Ti(OH)xOy precipitation:Ti4++ 6F- [TiFs]2(2)

[0022] (ii) Reaction with the oxide to form water-soluble [TiFe]2-complexes, leading to dissolution and breakdown of the barrier layer:TiO2+ 6F- + 4H+-> [TiF6]2- + 2H2O2(3)

[0023] In a further aspect, this leads to continuous etching, resulting in an initial increase in current. In one aspect, over time, the rate of titanium oxide growth, assisted by the electric field, equals the rate of dissolution by fluoride ions, leading to a constant barrier layer thickness. In another aspect, the current eventually decreases due to factors such as a reduction in the diffusion of fluoride-containing species into and out of the tubes, or when the conductivity of the whole thin film is no longer high enough to support the current itself.

[0024] Herein is disclosed a progressive anodization technique designed to fabricate TiO2nanotube arrays on non-conductive substrates, such as glass and zirconia, which has been a longstanding challenge in the field. In a further aspect, while previous research has successfully demonstrated anodization on conductive substrates such as titanium and ITO- coated glass, achieving uniform nanotube growth on insulating materials has remained problematic due to the discontinuity in the conductive Ti layer. In an aspect, herein is described the implementation of a motorized vertical moving anode that enables controlled submersion of the sample into the electrolyte, ensuring uniform anodization and preventing early termination of the reaction. In a further aspect, this progressive anodization approach eliminates the common issue of inhomogeneous nanotube formation observed in past studies and allows for precise control over nanotube diameter and uniformity. In one aspect, described herein is a comprehensive analysis of the effects of Ti deposition rate, anodization voltage, NH4F concentration, and post-etching conditions, which are critical parameters for optimizing nanotube morphology and have not been previously systematically studied together.Method for Fabricating TiO2Nanotubes on a Substrate

[0025] In one aspect, disclosed herein is a method for fabricating TiO2nanotubes on a substrate comprising a Ti thin film, the method including at least the steps of:ATTORNEY DOCKET NO. T19511W0001 (222112-2520)(a) contacting at least a portion of the substrate with an anodization bath, wherein the anodization bath comprises a cathode electrically connected to the substrate and an electrolyte;(b) subjecting the anodization bath to an anodization voltage; and(c) vertically lowering the substrate in the anodization bath; wherein contact between the anodization bath and the substrate in the presence of the anodization voltage produces the TiC>2 nanotubes.

[0026] In a further aspect, a “portion” as used herein refers to an amount of surface area of the substrate equal to 1% of the total surface area of the substrate, up to 100% of the total surface area of the substrate. Other values between 1 % and 100% are also contemplated and should be considered disclosed. It is to be understood that some part of the substrate must be inContact with the anodization bath in order for anodization to occur, and that as the substrate is vertically lowered into the anodization bath, greater and greater portions of the surface area of the substrate will be exposed to the anodization bath.

[0027] In one aspect, the substrate further includes a base material, wherein the base material is nonconductive. Exemplary base materials include, but are not limited to, glass and zirconia.

[0028] In one aspect, the cathode can be or include graphite. In another aspect, the Ti film deposition rate during anodization is from about 0.5 A / s to about 3 A / s, or from about 0.5 A / s to about 2 A / s, about 1 A / s to about 2 A / s, or can be about 0.5, 1 , 1.5, 2, 2.5, or about 3 A / s, or a combination of any of the foregoing values, or a range encompassing any of the foregoing values..

[0029] In an aspect, the electrolyte can be aqueous NH4F. In another aspect, the aqueous NH4F has a concentration of from about 0.5% (v / v) to about 3% (v / v) in water, or from about 0.5% to about 2% (v / v), about 0.5% to about 1 % (v / v), from about 1 .5% to about 3% (v / v), or of about 0.5, 1 , 1.5, 2, 2.5, or 3% (v / v), or a combination of any of the foregoing values, or a range encompassing any of the foregoing values.

[0030] In still another aspect, anodization voltage can be from about 30 V to about 90 V, from about 30 V to about 45 V, from about 45 V to about 90 V, from about 35 V to about 80 V, or can be about 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or about 90 V, or a combination of any of the foregoing values, or a range encompassing any of the foregoing values.

[0031] In another aspect, the method further includes soaking the TiO2nanotubes and substrate in aqueous NH4F. In one aspect, the soaking is performed in 3% aqueous (v / v) NH4F, although other concentrations are contemplated and should be considered disclosed.ATTORNEY DOCKET NO. T19511W0001 (222112-2520)In another aspect, soaking is conducted for about 30 min. In still another aspect, soaking is performed before step (a) or after step (c).Anodized Substrates and Articles

[0032] In one aspect, disclosed herein is an anodized substrate including TiO2nanotubes produced by the disclosed method. Also disclosed herein are articles including the anodized substrate. In one aspect, the TiO2nanotubes have a diameter of from about 10 nm to about 120 nm, or of from about 50 nm to about 120 nm, or about 75 nm to about 100 nm, or of about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 105, 110, 115, or about 120 nm, or a combination of any of the foregoing values, or a range encompassing any of the foregoing values. In another aspect, length of the nanotubes can be customized based on anodization parameters as described further herein in the Examples.

[0033] In one aspect, the article can be a medical implant, including, but not limited to, a dental implant. In another aspect, the dental implant can be a crown, a post for restoring endodontically treated teeth, a tooth veneer, a partial denture, a palatal obturator, a removable metal framework for dentures, implant-supported bars for denture retention, a removable denture attachment, an orthodontic appliance, or a combination thereof.Anodization Device

[0034] In one aspect, and referring to FIG. 1 , disclosed herein is an anodization device including at least the following:(a) an electrochemical reactor chamber 104 that holds an electrolyte;(b) a cathode 102, wherein the cathode is at least partially immersed in the electrolyte in the electrochemical reactor chamber;(c) an anode 100; and(d) a connection shaft 108; wherein the cathode and the anode are electrically linked to a first power supply; wherein the anode is physically attached to the connection shaft via a motorized arm 106; wherein the connection shaft is electrically connected to a motor electrically linked to a second power supply; wherein the motor is configured to vertically move the connection shaft and anode to immerse the anode in the electrolyte.ATTORNEY DOCKET NO. T19511W0001 (222112-2520)

[0035] In an aspect, vertical motion is accomplished by the motorized arm in the direction indicated by the arrow A. In one aspect, electrochemical reactor chamber is cylindrical, although other shapes are contemplated and should be considered disclosed. In another aspect, the cathode can be made from graphite or another suitable material. In any of these aspects, the anode can be a titanium thin film deposited on a nonconductive substrate, such as, for example, glass or zirconia. In another aspect, the first power supply can be a DC power supply. In still another aspect, the electrolyte can be aqueous NH4F.

[0036] Many modifications and other embodiments disclosed herein will come to mind to one skilled in the art to which the disclosed compositions and methods pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the disclosures are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.

[0037] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0038] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present disclosure.

[0039] Any recited method can be carried out in the order of events recited or in any other order that is logically possible. That is, unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

[0040] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing dateATTORNEY DOCKET NO. T19511W0001 (222112-2520) of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided herein can be different from the actual publication dates, which can require independent confirmation.

[0041] While aspects of the present disclosure can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present disclosure can be described and claimed in any statutory class.

[0042] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed compositions and methods belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0043] Prior to describing the various aspects of the present disclosure, the following definitions are provided and should be used unless otherwise indicated. Additional terms may be defined elsewhere in the present disclosure.Definitions

[0044] As used herein, “comprising” is to be interpreted as specifying the presence of the stated features, integers, steps, or components as referred to, but does not preclude the presence or addition of one or more features, integers, steps, or components, or groups thereof. Moreover, each of the terms “by,” “comprising,” “comprises,” “comprised of,” “including,” “includes,” “included,” “involving,” “involves,” “involved,” and “such as” are used in their open, non-limiting sense and may be used interchangeably. Further, the term “comprising” is intended to include examples and aspects encompassed by the terms “consisting essentially of’ and “consisting of.” Similarly, the term “consisting essentially of’ is intended to include examples encompassed by the term “consisting of.

[0045] As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a pore diameter,” “a non-conductive substrate,” or “an anodization voltage,” includes, but is not limited to, mixtures, combinations, or series of two or more such pore diameters, non-conductive substrates, or anodization voltages, and the like.ATTORNEY DOCKET NO. T19511W0001 (222112-2520)

[0046] It should be noted that ratios, concentrations, amounts, and other numerical data can be expressed herein in a range format. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms a further aspect. For example, if the value “about 10” is disclosed, then “10” is also disclosed.

[0047] When a range is expressed, a further aspect includes from the one particular value and / or to the other particular value. For example, where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure, e.g. the phrase “xto y” includes the range from ‘x’ to ‘y’ as well as the range greater than x’ and less than ‘y’. The range can also be expressed as an upper limit, e.g. ‘about x, y, z, or less’ and should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of ‘less than x’, less than y’, and ‘less than z’. Likewise, the phrase ‘about x, y, z, or greater’ should be interpreted to include the specific ranges of ‘about x,’ about y , ’ and ‘about z’ as well as the ranges of ‘greater than x,’ greater than y , ’ and ‘greater than z.’ In addition, the phrase “about ‘x’ to ‘y’”, where ‘x’ and ‘y’ are numerical values, includes “about x’ to about ‘y’”.

[0048] It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of “about 0.1% to 5%” should be interpreted to include not only the explicitly recited values of about 0.1 % to about 5%, but also include individual values (e.g., about 1 %, about 2%, about 3%, and about 4%) and the sub-ranges (e.g., about 0.5% to about 1.1 %; about 5% to about 2.4%; about 0.5% to about 3.2%, and about 0.5% to about 4.4%, and other possible sub-ranges) within the indicated range.

[0049] As used herein, the terms “about,” “approximate,” “at or about,” and “substantially” mean that the amount or value in question can be the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflectingATTORNEY DOCKET NO. T19511W0001 (222112-2520) tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art such that equivalent results or effects are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonably determined. In such cases, it is generally understood, as used herein, that “about” and “at or about” mean the nominal value indicated ±10% variation unless otherwise indicated or inferred. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about,” “approximate,” or “at or about” whether or not expressly stated to be such. It is understood that where “about,” “approximate,” or “at or about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0050] As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0051] Unless otherwise specified, temperatures referred to herein are based on atmospheric pressure (i.e., one atmosphere).

[0052] Now having described the aspects of the present disclosure, in general, the following Examples describe some additional aspects of the present disclosure. While aspects of the present disclosure are described in connection with the following examples and the corresponding text and figures, there is no intent to limit aspects of the present disclosure to this description. On the contrary, the intent is to cover all alternatives, modifications, and equivalents included within the spirit and scope of the present disclosure.ASPECTS

[0053] The present disclosure can be described in accordance with the following numbered aspects, which should not be confused with the claims.

[0054] Aspect 1 . A method for fabricating TiO2nanotubes on a substrate comprising a Ti thin film, the method comprising:(a) contacting at least a portion of the substrate with an anodization bath, wherein the anodization bath comprises a cathode electrically connected to the substrate and an electrolyte;(b) subjecting the anodization bath to an anodization voltage; and(c) vertically lowering the substrate in the anodization bath; wherein contact between the anodization bath and the substrate in the presence of the anodization voltage produces the TiO2nanotubes.ATTORNEY DOCKET NO. T19511W0001 (222112-2520)

[0055] Aspect 2. The method of aspect 1 , wherein the substrate further comprises a base material, wherein the base material is nonconductive.

[0056] Aspect 3. The method of aspect 2, wherein the base material comprises glass or zirconia.

[0057] Aspect 4. The method of any one of aspects 1-3, wherein the cathode comprises graphite.

[0058] Aspect 5. The method of any one of aspects 1-4, wherein a Ti film deposition rate during anodization is from about 0.5 A / s to about 3 A / s.

[0059] Aspect 6. The method of any one of aspects 1-5, wherein the electrolyte comprises aqueous NH4F.

[0060] Aspect 7. The method of aspect 6, wherein the aqueous NH4F has a concentration of from about 0.5% (v / v) to about 3% (v / v) in water.

[0061] Aspect 8. The method of any one of aspects 1-7, wherein the anodization voltage is from about 30 V to about 90 V.

[0062] Aspect 9. The method of any one of aspects 1-8, further comprising soaking the TiO2nanotubes and substrate in aqueous NH4F.

[0063] Aspect 10. The method of aspect 9, wherein the soaking is performed in 3% aqueous (v / v) NH4F.

[0064] Aspect 11 . The method of aspect 9 or 10, wherein soaking is conducted for about 30 min.

[0065] Aspect 12. The method of any one of aspects 9-11 , wherein soaking is performed before step (a).

[0066] Aspect 13. The method of any one of aspects 9-11 , wherein soaking is performed after step (c).

[0067] Aspect 14. An anodized substrate comprising TiO2nanotubes produced by the method of any one of aspects 1-13.

[0068] Aspect 15. An article comprising the anodized substrate of aspect 14.

[0069] Aspect 16. The article of aspect 15, wherein the TiO2nanotubes have a diameter of from about 10 nm to about 120 nm.

[0070] Aspect 17. The article of aspect 15 or 16, wherein the article comprises a medical implant.ATTORNEY DOCKET NO. T19511W0001 (222112-2520)

[0071] Aspect 18. The article of aspect 17, wherein the medical implant comprises a dental implant.

[0072] Aspect 19. The article of aspect 18, wherein the dental implant comprises crown, a post for restoring endodontically treated teeth, a tooth veneer, a partial denture, a palatal obturator, a removable metal framework for dentures, implant-supported bars for denture retention, a removable denture attachment, an orthodontic appliance, or a combination thereof.

[0073] Aspect 20. An anodization device comprising:(a) an electrochemical reactor chamber comprising an electrolyte;(b) a cathode, wherein the cathode is at least partially immersed in the electrolyte in the electrochemical reactor chamber;(c) an anode; and(d) a connection shaft; wherein the cathode and the anode are electrically linked to a first power supply; wherein the anode is physically attached to the connection shaft via a motorized arm; wherein the connection shaft is electrically connected to a motor electrically linked to a second power supply; wherein the motor is configured to vertically move the connection shaft and anode to immerse the anode in the electrolyte.

[0074] Aspect 21. The anodization device of aspect 20, wherein the electrochemical reactor chamber is cylindrical.

[0075] Aspect 22. The anodization device of aspect 20 or 21 , wherein the cathode comprises graphite.

[0076] Aspect 23. The anodization device of any one of aspects 20-22, wherein the anode comprises a titanium thin film deposited on a nonconductive substrate.

[0077] Aspect 24. The anodization device of aspect 23, wherein the nonconductive substrate comprises glass or zirconia.

[0078] Aspect 25. The anodization device of any one of aspects 20-24, wherein the first power supply comprises a DC power supply.

[0079] Aspect 26. The anodization device of any one of aspects 20-25, wherein the electrolyte comprises aqueous NH4F.ATTORNEY DOCKET NO. T19511W0001 (222112-2520)EXAMPLES

[0080] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and / or methods claimed herein are made and evaluated, and are intended to be purely exemplary of the disclosure and are not intended to limit the scope of what the inventors regard as their disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric.Example 1 : Materials and Methods

[0081] The titanium thin film employed in this study was prepared through electron beam evaporation. Using a high-purity titanium target, a 300 pm layer of titanium was deposited onto glass substrates, employing two different beam powers and the resulting deposition rates of 0.5 A / s and 3 A / s. These rates were selected to investigate their impact on grain size and the resulting nanotube morphology. Experiments were conducted on microscope glass slides (Thermo Fisher Scientific, Waltham, MA, USA) due to their insulating properties, which simulate the characteristics of zirconia dental implants. Standard cleaning protocols with acetone (Thermo Fisher Scientific, Waltham, MA, USA), IPA (Thermo Fisher Scientific, Waltham, MA, USA), and nitrogen (Airgas, Radnor, PA, USA) ensured surface consistency. Anodization was conducted in a 95 wt% ethylene glycol (Sigma-Aldrich, St. Louis, MO, USA) solution containing varying concentrations (0.5%, 1 %, 2%, and 3%) of ammonium fluoride (NH4F) (Sigma-Aldrich, St. Louis, MO, USA), with distilled water constituting the remaining composition. Given the non-conductive nature of the glass substrate, a specially designed anodization device, illustrated in FIG. 1 , was utilized to ensure a consistent and uniform anodization process across the entire sample surface. The device featured a cylindrical electrochemical reactor chamber incorporating a graphite cathode and a vertically motorized anode connected to the as-deposited Ti-on-glass sample. Both electrodes were linked to a 30 to 90 DC power supply (Keysight, Santa Rosa, CA, USA). The mobile anode was connected to a 3D printed connection shaft affixed to a high torque, low rpm motor powered by an additional power supply, where the vertical moving speed of the anode sample can be precisely controlled. This mechanism regulated the speed at which the sample was gradually immersed into the electrolyte.Example 2: Results and DiscussionATTORNEY DOCKET NO. T19511W0001 (222112-2520)

[0082] The schematic diagram of the anodization process and mechanism in this work is depicted in FIG. 2. In the early stages of anodization, Equation (1) results in the formation of a thin oxide layer on the titanium sheet, causing a rapid reduction in current density due to its poor electrical conductivity. Under sufficient applied voltage, electric field-assisted reduction occurs at the TiC>2 / Ti interface with Equations (2) and (3), resulting in the etching of the TiC>2. Oxygen ions (O2-) transport from the solution to the oxide layer, while titanium ions (Ti4+) move from the titanium to the oxide / solution interface, dissolving into the solution. This process leads to a continuous increase in the depth of the porous structure, causing the formation of an ordered nanotube array vertically oriented to the substrate. Chemical dissolution of the TiO2with Equation (3) simultaneously reduces the thickness of the nanotube wall, increasing the diameter of the nanotubes. The length of TiO2nanotube arrays continues to increase until the bottom of the tubes touches the non-conductive glass substrate, where the discontinuation of the conductive Ti layer ceases the current-driven reactions.

[0083] The effect of utilizing the customized anodization tool with controllable anode submerging speed on sample surface uniformity is shown in FIGs. 3A-3D. A sample consisting of Ti thin film deposited on a glass substrate, as depicted in FIG. 3A, underwent the traditional anodization process with a fixed anode, fully submerged in the NH4F electrolyte before applying voltage. The resulting appearance in FIG. 3B shows a band of transparent nanotube region formed at the surface of the electrolyte due to the higher current density closer to the wire connection. This disrupted the continuity of the conductive Ti layer, preventing further anodization and leaving the rest of the sample with incomplete nanotube growth. To address this issue, the anode placement was changed from a fixed position to one that moves vertically at a controllable speed, allowing anodization to progress from the edge of the sample upward as local nanotubes grow to their full length. A sample anodized with this new mechanism using the customized tool is shown in FIG. 3C. The dashed line indicates the final surface level of the electrolyte at the end of the anodization process, where the speed of the moving arm exceeded the anodization rate. This mismatch resulted in shallower nanotube depths near the air-electrolyte interface due to insufficient submerging time. Finally, FIG. 3D demonstrates the optimized result, where the speed of the sample submerging aligned precisely with the anodization rate. This produced a uniform nanotube array surface morphology, as evidenced by the transparent and consistent appearance across the entire region under the electrolyte. The success of the fully anodized nanotube surface with excellent uniformity highlights the effectiveness of the improved progressive anodization mechanism.

[0084] The correlation between the deposition rate in electron beam evaporation and the resulting grain size and surface roughness of the metal thin film has been robustly established.ATTORNEY DOCKET NO. T19511W0001 (222112-2520)Lower deposition rates produced smaller, uniform grains, conducive to dense nanotube formation, while higher rates resulted in larger grains, limiting uniformity. FIGs. 4A-4D illustrate the comparison between titanium thin films deposited via electron beam at two distinct rates, namely 0.5 A / s and 3 A / s, and their corresponding anodized nanotube surface morphologies in SEM images. All the other anodization conditions, such as sample size, anode moving speed, NH4F concentration, and applied voltage, remained constant. At the slower deposition rate of 0.5 A / s, the grain size was approximately 10 nm in diameter and exhibited an even dispersion in size. Conversely, the higher deposition rate of 3 A / s resulted in an increased grain size of the titanium thin film to around 100 nm on average, accompanied by greater variation in grain sizes. Along the grain boundaries, the sharper morphology of the metal surface induces faster rates for the anodization reactions due to the larger specific surface area, defining the starting locations for the growth of the nanotubes. The thin film with the higher deposition rate, composed of larger chunks, experienced limitations in the formation of well-aligned nanotubes with larger diameters since the total grain boundary length per area is short. In contrast, the titanium thin film with a smaller deposition rate and corresponding grain size demonstrated denser and longer grain boundaries, resulting in more concentrated and uniform nanotube arrays after the anodization. In summary, the grain size significantly influenced nanotube uniformity. Films deposited at 0.5 A / s yielded finer grains with increased grain boundary density, promoting uniform nanotube arrays. Conversely, films deposited at 3 A / s had coarser grains, resulting in less uniform nanotube distribution due to reduced nucleation sites.

[0085] To explore the impact of anodization voltage on the diameter and surface characteristics of the nanotube array, four distinct voltages — 30, 50, 70, and 90 volts — were employed for anodizing titanium thin films on glass substrates. The titanium deposition rate was maintained at 0.5 A / s, a rate previously determined to be optimal. Anode movement speed and NH4F electrolyte concentration were held constant at 0.5 mm / min and 1 wt%. The resulting SEM images in FIGs. 5A-5D depict a positive correlation between nanotube density / size and anodization voltage due to the enhancement of both the oxidation and etching rate. Additionally, higher voltages led to increased circularity, indicating more matured anodization reactions with elevated current densities. Investigation of higher voltages than 90 V was also performed but the heat and bubble generated during the anodization peeled off the nanotube layers from the substrate.

[0086] The influence of NH4F electrolyte concentrations on nanotube array surface morphology was also explored in FIGs. 6A-6D. Four concentrations, 0.5, 1 , 2, and 3 wt% were investigated, each yielding nanotube inner diameters of 50, 80, 100, and 120 nm. Similarly toATTORNEY DOCKET NO. T19511W0001 (222112-2520) the effect of different voltages, nanotube size exhibited a positive correlation with NH4F concentrations, attributed to accelerated etching and dissolution of the TiO2barrier layer. Higher electrolyte concentrations also lead to thinner side walls of the nanotubes since the etching part of the reactions dominated more. The same phenomenon could also be observed when the sample with anodized TiO2nanotubes was soaked in 3% NH4F electrolyte again for 30 min without applying voltage. As shown in FIGs. 7A-7B, the size of the nanotubes increased 100% due to the continuing etching of the reactions coupled with the absence of electric-field-driven oxidation.

[0087] The comprehensive overview of the experimental findings and comparison with literature numbers are presented as tables. Table 1 organizes the detailed results of nanotube formation under various process conditions, such as deposition rates, anodization voltages, NH4F concentrations, and post-soaking treatments. This highlights the significant influence of each parameter on the size and uniformity of the nanotubes, demonstrating the effectiveness of the optimized progressive anodization method. The formation of TiO2nanotubes during anodization is governed by the delicate balance between electrochemical oxide formation and chemical dissolution. This simultaneous growth and dissolution creates a porous structure. The balance between these reactions ensures uniform nanotube growth. Deviations, such as excessive dissolution or insufficient oxide formation, disrupt the process and lead to irregular morphologies. These mechanisms are critical for optimizing the anodization process, especially for achieving uniform nanotube arrays on non-conductive substrates like glass or zirconia. Table 2 further underscores the novelty of this study by contrasting this study with those of previous works. Notably, the optimized approach in this study achieves larger nanotube sizes with superior uniformity on non-conductive substrates compared to earlier methods. This advancement addresses the longstanding challenge of achieving high-quality nanotubes on insulating substrates, which expands their applicability to diverse fields such as biomedical devices and sensors.ATTORNEY DOCKET NO. T19511W0001 (222112-2520)Conclusions

[0088] The fabrication of TiO2nanotubes through the anodization of Ti thin films on insulated substrates offers a versatile and controlled nanostructuring approach. The anodization process, governed by the interplay of electrochemical oxide formation and chemical dissolution, enables the precise growth of TiO2nanotubes with diverse morphologies. By employing a specially designed anodization tool, the study ensured consistency and uniformity in the anodization process of thin films deposited on non-conductive glass substrates. This work revealed that slower Ti deposition rates, higher anodization voltages, and higher NH4F concentrations, combined with post-etching treatments, result in more uniform and mature nanotubes with larger diameters. Compared to previous methods with conductive substrates, the optimized approach demonstrated the ability to fabricate larger and more uniform nanotubes on non-conductive substrates, addressing a key challenge in the field. The findings of this study open new possibilities for the application of TiO2nanotube arrays on non- conductive substrates, particularly in biomedical and electronic fields. One of the most promising applications is the enhancement of zirconia-based dental implants. By integrating TiO2nanotubes onto zirconia surfaces, it is possible to improve implant osseointegration and antibacterial properties, reducing the risk of peri-implantitis and enhancing long-term implant stability. Additionally, the uniform nanotube arrays achieved through progressive anodization could be utilized in biosensors for real-time diagnostics, where enhanced surface area and charge transport properties are crucial for improved sensitivity and performance. Beyond biomedical applications, the methodology developed in this research can be extended to energy-related technologies. TiO2nanotube arrays are widely recognized for their photocatalytic properties, and their fabrication on non-conductive substrates could lead to advancements in self-cleaning coatings, water purification systems, and high-efficiency dye- sensitized solar cells. The ability to precisely control nanotube dimensions through theATTORNEY DOCKET NO. T19511W0001 (222112-2520) optimized anodization process also presents opportunities for developing next-generation nanostructured electrodes in energy storage devices, such as lithium-ion batteries and supercapacitors. Future research will focus on expanding the applicability of this technique to other insulating materials, optimizing nanotube surface functionalization for specific applications, and integrating real-time monitoring mechanisms to further refine the anodization process. Additionally, investigations into the long-term stability and mechanical properties of nanotube-coated zirconia implants will be conducted to validate their suitability for clinical applications.

[0089] It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.REFERENCES1. Abdellatif, S.; et al. Refractive Index and Scattering of Porous TiO2 Films. Microporous Mesoporous Mater. 2018, 264, 84-91.2. Albu, S.P.; et al. Influence of Anodization Parameters on the Expansion Factor of TiO2 Nanotubes. Electrochim. Acta 2013, 91 , 90-95.3. Apratim, A.; et al. Zirconia in Dental Implantology: A Review. J. Int. Soc. Prev. Community Dent. 2015, 5, 147-156.4. Arshi, N. et al. 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Claims

ATTORNEY DOCKET NO. T19511W0001 (222112-2520)CLAIMSWhat is claimed is:

1. A method for fabricating TiO2 nanotubes on a substrate comprising a Ti thin film, the method comprising:(a) contacting at least a portion of the substrate with an anodization bath, wherein the anodization bath comprises a cathode electrically connected to the substrate and an electrolyte;(b) subjecting the anodization bath to an anodization voltage; and(c) vertically lowering the substrate in the anodization bath; wherein contact between the anodization bath and the substrate in the presence of the anodization voltage produces the TiC>2 nanotubes.

2. The method of claim 1, wherein the substrate further comprises a base material, wherein the base material is nonconductive.

3. The method of claim 2, wherein the base material comprises glass or zirconia.

4. The method of claim 1 , wherein the cathode comprises graphite.

5. The method of claim 1 , wherein a Ti film deposition rate during anodization is from about 0.5A / s to about 3 A / s.

6. The method of claim 1 , wherein the electrolyte comprises aqueous NH4F.

7. The method of claim 6, wherein the aqueous NH4F has a concentration of from about 0.5%(v / v) to about 3% (v / v) in water.

8. The method of claim 1 , wherein the anodization voltage is from about 30 V to about 90 V.

9. The method of claim 1 , further comprising soaking the TiO2nanotubes and substrate in aqueous NH4F.

10. The method of claim 9, wherein the soaking is performed in 3% aqueous (v / v) NH4F.

11. The method of claim 9, wherein soaking is conducted for about 30 min.

12. The method of claim 9, wherein soaking is performed before step (a).

13. The method of claim 9, wherein soaking is performed after step (c).ATTORNEY DOCKET NO. T19511W0001 (222112-2520)14. An anodized substrate comprising TiC>2 nanotubes produced by the method of any one of claims 1-13.

15. An article comprising the anodized substrate of claim 14.

16. The article of claim 15, wherein the TiC>2 nanotubes have a diameter of from about 10 nm to about 120 nm.

17. The article of claim 15, wherein the article comprises a medical implant.

18. The article of claim 17, wherein the medical implant comprises a dental implant.

19. The article of claim 18, wherein the dental implant comprises crown, a post for restoring endodontically treated teeth, a tooth veneer, a partial denture, a palatal obturator, a removable metal framework for dentures, implant-supported bars for denture retention, a removable denture attachment, an orthodontic appliance, or a combination thereof.

20. An anodization device comprising:(a) an electrochemical reactor chamber comprising an electrolyte;(b) a cathode, wherein the cathode is at least partially immersed in the electrolyte in the electrochemical reactor chamber;(c) an anode; and(d) a connection shaft; wherein the cathode and the anode are electrically linked to a first power supply; wherein the anode is physically attached to the connection shaft via a motorized arm; wherein the connection shaft is electrically connected to a motor electrically linked to a second power supply; wherein the motor is configured to vertically move the connection shaft and anode to immerse the anode in the electrolyte.

21. The anodization device of claim 20, wherein the electrochemical reactor chamber is cylindrical.

22. The anodization device of claim 20, wherein the cathode comprises graphite.

23. The anodization device of claim 20, wherein the anode comprises a titanium thin film deposited on a nonconductive substrate.ATTORNEY DOCKET NO. T19511W0001 (222112-2520)24. The anodization device of claim 23, wherein the nonconductive substrate comprises glass or zirconia.

25. The anodization device of claim 20, wherein the first power supply comprises a DC power supply.

26. The anodization device of claim 20, wherein the electrolyte comprises aqueous NH4F.

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