Forming monolith nanostructures on implantable devices

Abstract

This disclosure relates to a method for forming a monolithic nanostructure on an implantable device, the method comprising: a. depositing a metal film onto the surface of the implantable device; b. heating the metal film for a period of time, such that the metal film transforms into a plurality of discrete nanoparticles, the plurality of nanoparticles thereby forming an etch mask on the surface of the implantable device; c. etching the implantable device such that the surface of the implantable device is etched through the etch mask, thereby forming a monolithic nanostructure on the surface of the implantable device; and d. (optionally) removing the etch mask, for example by immersion in an aqueous solution of aqua regia.

Description

[0001] This disclosure relates to a method for forming a monolithic nanostructure on a prosthetic device, and a prosthetic device including a surface having a monolithic nanostructure. Background of the Invention

[0003] An implant is a medical device used to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. Medical implants are artificial devices, unlike grafts, which are transplanted biomedical tissues. The surfaces of implants that come into contact with the body may be made of biomedical materials such as titanium, silicone, or apatite, depending on what is most practical. In some cases, implants may contain electronic devices, such as artificial pacemakers and cochlear implants.

[0004] Several types of medical implants exist, such as orthopedic implants, which are used to alleviate problems with the body's bones and joints. They are commonly used to treat fractures, osteoarthritis, scoliosis, spinal stenosis, and chronic pain. Examples include a wide variety of needles, rods, screws, and plates that anchor to the fractured bone as it heals.

[0005] Another example of implants is dental implants, which are dental prostheses used to integrate with the bone of the jaw or skull to support dental crowns, bridges, dentures, facial prostheses, or surgical components used as orthodontic anchors. Dental implants rely on a biological process called osseointegration, in which materials such as titanium bind tightly to bone formation.

[0006] The placement of dental implants typically involves positioning the implant to facilitate osseointegration. Osseointegration requires varying amounts of healing time before the dental prosthesis (usually a tooth, bridge, or denture) is attached to the implant or before the abutment that will hold the prosthesis in place.

[0007] Due to its biocompatibility and mechanical properties, the vast majority of dental implants are made of commercially available pure titanium. However, for general medical implants, especially dental implants, a significant challenge lies in bacterial infection and subsequent implant degradation.

[0008] In fact, it is estimated that 5% of all dental implants fail immediately after placement, and about half of dental implants become infected with bacteria. Therefore, a major challenge in implantology, especially dental implantology, is to improve osseointegration of the implant while preventing bacterial infection in order to achieve long-term implant success.

[0009] Methods for improving osseointegration or bacterial prevention of implants already exist, and they typically rely on mechanical, chemical, or physical methods such as plasma spraying, sandblasting, and acid etching. These methods generally depend on roughening the implant surface to increase the total surface area, thereby promoting cell migration and attachment to the implant, thus enhancing the osseointegration process.

[0010] For bacterial prevention on implant surfaces, a common approach is the use of zirconium, such as sandblasting titanium surfaces with zirconium oxide particles. This method has shown potential to reduce bacterial adhesion to implant surfaces, at least for certain bacterial species. However, because the surface of such implants contains multiple elements, long-term stability may be problematic, and there is a potential risk of further side effects. Summary of the Invention

[0011] The inventors have realized that implantable devices having surfaces containing monolithic nanostructures can lead to improved osseointegration and enhanced bacterial prevention.

[0012] Therefore, this disclosure relates in a first aspect to a method for forming monolithic nanostructures on implantable devices, the method comprising:

[0013] Depositing a metal film onto the surface of an implantable device;

[0014] The metal film is heated for a period of time, causing the metal film to transform into multiple nanoparticles, which in turn form an etching mask on the surface of the implantable device.

[0015] Etching an implantable device such that the surface of the implantable device is etched through an etching mask, thereby forming a monolithic nanostructure on the surface of the implantable device; and

[0016] (Optional) Remove the etched mask.

[0017] Implantable devices are used in many different areas of the body and can be used for various reasons, such as supporting healing or anchoring prostheses. The oral cavity is perhaps the most challenging environment for implantable devices because the oral microbiome can contain a wide variety of bacterial species. Microbial aggregates in the mouth can form a coating on teeth called plaque. However, if a dental implant is present in the mouth, the same bacteria can cause peri-implant diseases, including peri-implantitis (which usually does not involve bone loss) affecting the gingival tissue surrounding the implant; or peri-implantitis (which involves deterioration of the bone supporting the implant). While peri-implantitis is usually reversible, peri-implantitis requires surgical intervention. Therefore, the bacterial prophylactic properties of implantable devices, especially dental implants, are crucial for the long-term success of implantation.

[0018] Therefore, it is preferred that the nanostructures formed on the surface of the implantable device are configured for osseointegration and prevention of bacterial growth. In one embodiment of this disclosure, the nanostructures are thus configured to reduce bacteria commonly associated with peri-implantitis (e.g., P. Gingivalis, T. Denticola, and F. Nucleatum The adhesion of the nanostructure is facilitated. Preferably, the size of the integral nanostructure is smaller than the size of the bacteria. Therefore, it is preferable that the average size of the nanostructure is less than 0.5 μm.

[0019] In addition to forming nanostructures for improved osseointegration and bacterial prevention, this disclosure also allows for the formation of nanostructures on non-planar surfaces. This makes the methods disclosed herein highly suitable for forming nanostructures on implant surfaces, such as dental implant surfaces, which are typically non-planar. The methods disclosed herein do not rely on forming a thick oxide layer to treat the implant surface, a common step in prior art surface modification methods. In contrast, the methods disclosed herein can form monolithic nanostructures with advantageous properties (such as improved osseointegration and enhanced bacterial prevention, as disclosed elsewhere herein) in the absence of an oxide layer or only in the presence of a naturally formed oxide layer (i.e., a natural oxide layer, typically less than 10 nm thick).

[0020] Preferably, the deposited metal film uniformly covers the surface of the implantable device with a metal, such as gold, silver, aluminum, nickel, or a combination thereof. The deposited metal film typically has a thickness between 1 nm and 25 nm and can be deposited using any thin film deposition method, such as atomic layer deposition, electron beam deposition, or sputtering.

[0021] By heating, dehumidification of the metal film can occur during the heating step, causing the metal film to transform into multiple nanoparticles. This step may include or consist of rapid thermal annealing of the metal film, wherein the metal film is typically subjected to a temperature between approximately 70°C and 900°C for at least 1 minute, for example, at least 2 minutes.

[0022] The surface can be etched using any dry or wet etching process. Preferably, the surface of the implanted device is etched using an etching mask formed of nanoparticles. The properties of the nanostructure can be tuned by adjusting the properties of the nanoparticles or the etching step. The nanostructure can be adjusted, for example, in terms of shape, height, tip width (tip apex diameter), sidewall angle, spacing, apex diameter, surface density, and aspect ratio. For implants such as dental implants, these properties can be selected to improve osseointegration and bacterial prevention.

[0023] The properties of a nanostructure, determined by the configuration of nanoparticles, can include, for example, density, spacing, and tip width. The etching process can further determine several properties of the nanostructure. Etching processes can include wet etching or dry etching. The typical isotropic and anisotropic properties of these methods can influence the properties of the nanostructure.

[0024] Etching steps may include dry etching, in which the exposed surface of the implantable device is subjected to ion bombardment to remove a portion of the material from the exposed surface. Dry etching methods include inductively coupled plasma (ICP), reactive ion etching (RIE), and ion beam etching (IBE), and they are typically anisotropic. Alternatively, etching steps may include wet etching, in which the exposed surface of the implantable device is subjected to an etching solution. Typically, wet etching is isotropic; however, this may depend on the etching solution.

[0025] In certain embodiments of this disclosure, the etching mask may preferably be removed, for example, by immersing the etching mask in a suitable solution. The solution is preferably chosen to selectively etch the nanoparticles, and may be, for example, an aqueous solution of aqua regia for etching gold.

[0026] This disclosure further relates to an implantable device including a surface having a monolithic nanostructure for osseointegration and bacterial membrane prevention, which is formed by a method for forming a monolithic nanostructure on an implantable device as disclosed elsewhere herein.

[0027] This disclosure also relates to an implantable device comprising a surface having a monolithic nanostructure for osseointegration and bacterial membrane prevention, wherein said nanostructure is:

[0028] It is basically conical in shape, with the base in contact with the substrate; or

[0029] It is basically ridge-shaped, formed between several concave recesses on the surface.

[0030] Essentially, cone-shaped nanostructures are likely the result of anisotropic etching, typically dry etching. Similarly, ridge-shaped nanostructures are likely the result of isotropic etching, typically wet etching.

[0031] Brief description of the attached figures

[0032] Figure 1 A summary of a method for forming monolithic nanostructures according to one embodiment of the present disclosure is shown.

[0033] Figure 2 shows various types of nanoparticles formed by thermal deposition of a metal film according to one embodiment of the present disclosure.

[0034] Figure 3 A conical monolithic nanostructure according to one embodiment of the present disclosure is shown.

[0035] Figure 4 shows a ridge-shaped monolithic nanostructure formed between several substantially concave indentations on a surface according to one embodiment of the present disclosure.

[0036] Figure 5 shows an exemplary conical monolithic nanostructure produced according to one embodiment of the present disclosure.

[0037] Figure 6 A schematic diagram of a monolithic nanostructure according to one embodiment of the present disclosure is shown.

[0038] Figure 7 A schematic diagram of an etching step according to one embodiment of the present disclosure is shown.

[0039] Figure 8 The antimicrobial properties of a surface treated according to one embodiment of the present disclosure are shown. Invention Details

[0041] definition

[0042] As used herein, biocompatibility refers to the ability of a material, device, or part of a device to perform an appropriate host response in a particular application. As used herein, bacterial prevention refers to a reduction in bacterial adhesion and biofilm formation compared to unstructured surfaces, such as structured surfaces, like nanostructured surfaces. As used herein, an implantable device is a medical device manufactured to replace a missing biological structure, support a damaged biological structure or prosthesis, or enhance an existing biological structure. Surfaces of implantable devices that come into contact with the body may be made of biomedical materials such as titanium, silicone, or apatite, depending on the most practical material available.

[0043] As used herein, dental implants refer to dental prostheses used to integrate with the jawbone or skull to support dental implants such as crowns, bridges, dentures, facial prostheses, or as orthodontic anchors. A dental implant is an implantable device.

[0044] As used in this article, osseointegration refers to functional ankylosis, in which new bone is placed directly on the surface of the implant, and the implant exhibits mechanical stability (i.e., resistance to instability caused by mechanical agitation or shear forces).

[0045] As used in this article, vacuum refers to a pressure substantially below atmospheric pressure (760 Torr). As used in this article, medium vacuum refers to a pressure between 25 and 10... -3 The pressure between Torr. As used in this article, high vacuum refers to 10 -3 Up to 10 -9 Pressure between Torr.

[0046] In a first aspect, this disclosure relates to a method for forming nanostructures on an implantable device. The nanostructures are preferably monolithic, for example, formed from a single substrate material. Preferably, the method includes depositing a thin layer, such as a metal film, onto the surface of the implantable device. This surface may be a selected surface of the implantable device or a selected portion of a selected surface. Typically, this surface is used for functional fixation, such as for forming contact with new bone and / or gingival tissue. Deposition can be performed by physical or chemical thin film deposition to form a thin film, preferably a metal film. The thickness of the film can be in the nanometer range, for example, a few nanometers thick, preferably about 1 nanometer to about 50 nanometers thick. The method preferably further includes a heating step, wherein heat is applied to the film and / or surface, causing the film to transform into nanoparticles. The nanoparticles are preferably particles with an average size, for example, a diameter in the nanometer range. The heating step may include rapid heat treatment, such as rapid thermal annealing. Preferably, the surface of the implantable device is etched using an etching mask containing nanoparticles. The surface can thus be etched using the etching mask, thereby forming the nanostructure. The nanoparticles are preferably spaced apart such that the surface can be etched using the etching mask. Etching of implantable devices may include anisotropic and / or isotropic etching, or consist of both. Typically, wet etching results in isotropic etching, while dry etching results in anisotropic etching. Therefore, the final properties of the nanostructure are influenced by the choice of etching method. Anisotropic etching can produce conical nanostructures, while isotropic etching can produce ridge-like structures. Preferably, the nanostructure is formed in the surface of the implantable device, for example, in the negative space between nanostructures, where the etching step may have removed material from the implantable device. In certain embodiments of this disclosure, such as where at least some of the nanoparticles remain on the surface of the implantable device after the etching step, it may be preferable to remove the etching mask. The etching mask can be removed, for example, by immersion in a suitable solution, such as aqua regia. In other embodiments of this disclosure, such as where the nanoparticles are substantially or completely etched by the etching step, the step of removing the etching mask may not be preferred. Preferably, the nanostructure promotes osseointegration and antimicrobial activity.

[0047] Implant materials

[0048] In one embodiment of this disclosure, the material of the implantable device (e.g., the entire implantable device or the surface of the implantable device, preferably at least a portion forming the monolithic nanostructure of this disclosure) is biocompatible, corrosion-resistant, and / or crack-resistant. The material of the implantable device (e.g., the entire implantable device or the surface of the implantable device) may, for example, comprise or consist of metals or ceramics. The material of the implantable device may, for example, be titanium, zirconium, zirconium oxide (zirconia), or alloys thereof. Preferably, the alloy contains titanium in an amount sufficient to form titanium oxide on, for example, the surface, preferably more than 85% titanium. Alternatively, the material of the implantable device may be a polymer, such as polyethylene, for example, ultra-high molecular weight polyethylene (UHMWPE) or cross-linked polyethylene (XLPE). Pure titanium is generally a preferred material for implantable devices (e.g., dental implants) because of its excellent biocompatibility and mechanical properties. The biocompatibility of titanium implants is generally attributed to the formation of a stable oxide layer on their surface. The thickness of the natural oxide layer of titanium is typically less than 10 nm, for example, between 4 and 6 nm, and is therefore generally significantly different from chemically modified titanium surfaces, where the thickness of the oxide layer has been increased. Some existing processes may rely on forming an oxide layer of a certain thickness, such as at least 100 nm, to create a structure with desired properties, such as a trench with sidewalls having specific sidewall angles. In contrast, the method disclosed in this invention does not rely on the formation of a thick oxide layer, i.e., an oxide layer thicker than naturally formed oxides (typically less than 10 nm, more typically less than 20 nm). Various zirconia materials are known to those skilled in the art, for example, as described in the following literature: Apratim et al., J. Int. Soc. Prev.Community Dent. 2015 May-Jun; 5(3): 147–156.

[0049] Commercially pure titanium (cpTi) is classified into four grades, each with a different oxygen content. Grade 4 typically has the highest oxygen content (approximately 0.4%), while Grade 1 has the lowest (approximately 0.18%). The mechanical differences between the different grades of cpTi are primarily due to the presence of trace contaminants. Iron is added for corrosion resistance, aluminum is added to increase strength and reduce density, and vanadium acts as an aluminum scavenger to prevent corrosion. The hexagonal close-packed lattice of Ti is called α-Ti (α phase), while the body-centered cubic lattice is called the β phase. When heated above 883°C, the α phase transforms into the β phase. Similarly, polycrystalline zirconium exists in monoclinic, cubic, and tetragonal crystal forms. These phases can be stabilized by CaO, MgO, and Y₂O₃, which can result in multiphase partially stabilized zirconium oxide (PSZ). In a preferred embodiment of the invention, the material of the implantable device comprises or is composed of Grade 4 titanium and / or Grade 5 titanium.

[0050] Titanium possesses many properties that make it suitable for implantation devices, such as biocompatibility, high passivity, controlled thickness, rapid formation, ability to self-repair immediately after damage, resistance to chemical erosion, catalytic activity for a variety of chemical reactions, and bone-compatible elastic modulus.

[0051] Compared to pure titanium, titanium-zirconium alloys can exhibit improved mechanical properties, such as increased elongation and fatigue strength. A common titanium and zirconium alloy is Straumann Roxolid, which contains 13-17% zirconium.

[0052] In one embodiment of this disclosure, the implantable device is a dental implant. Therefore, the implantable device can be a dental prosthesis for osseointegration with the jawbone or skull to support a dental crown, bridge, denture, facial prosthesis, or a surgical component used as an orthodontic anchor. For example, an abutment can be attached to a dental implant to retain the dental prosthesis, for example in a single dental implant restoration. Alternatively, a dental implant can be used for implant-retained fixed bridges, where typically multiple dental implants are attached to the bone and support the bridge.

[0053] bacteria

[0054] Bacterial infection at the implantation site is a significant concern for successful implantation, and the oral cavity is arguably the most challenging environment for implantable devices due to the potentially vast array of bacterial species within the oral microbiome. Microbial aggregates in the mouth can form a coating on teeth called plaque. However, if a dental implant is present in the mouth, the same bacteria can cause peri-implant diseases, including peri-implantitis (which typically does not involve bone loss) affecting the gingival tissue surrounding the implant, or peri-implantitis (which involves deterioration of the bone supporting the implant). While peri-implantitis is usually reversible, peri-implantitis requires surgical intervention. Therefore, the bacterial prophylactic properties of implantable devices, particularly dental implants, are crucial for long-term implantation success.

[0055] Therefore, preferably, the nanostructures formed on the surface of the implantable device are configured to prevent bacterial growth, and preferably increase osseointegration while preventing bacterial growth. In one embodiment of the invention, the nanostructures are thus configured to reduce bacteria commonly associated with peri-implantitis (e.g., P. Gingivalis, T. Denticola and F. Nucleatum The adhesion of the nanostructures is facilitated. Preferably, the size of the monolithic nanostructures is smaller than the size of the bacteria. Therefore, it may be preferable that the average size, such as the average tip width, the average distance between nanostructures, and / or the average height of the nanostructures, is less than 0.5 μm. Table 1 shows the typical sizes of common bacteria associated with peri-implantitis.

[0056]

[0057] Table 1. Typical sizes of common bacteria associated with peri-implantitis.

[0058] The implantable device can be any type of implant, preferably one in which osseointegration and / or bacterial prevention are desired. The implantable device can be, for example, an orthopedic implant. In one embodiment of this disclosure, the implantable device is a hip prosthesis, a knee prosthesis, an atrauma nail, a knee implant, a lag screw, an aspinal cage, a glenoid implant, an ankle fusion implant, a foot / toe implant, a long bone osteotomy plate or bone implant, a sacroiliac joint implant, a cranial plate and / or an amaxillofacial plate, or a portion thereof.

[0059] The size of nanostructures

[0060] Nanostructures can be configured for bacterial lysis, where bacteria are exposed to a topography that generates sufficiently high local stress across the entire bacterial cell wall. Thus, nanostructures can be configured as contact points between bacterial cell walls on the surface of the nanostructure, these contact points being much smaller than the bacteria. Preferably, the contact points between the nanostructure and the bacteria are far enough apart to allow sufficiently high local stress for bacterial lysis. Therefore, it may be preferred that the tip diameter (also called tip width), for example, the tip of the nanostructure, or the tip width (tip diameter) is less than half the size of the bacteria, for example, less than half the longest dimension of the bacteria. Preferably, the tip width averages less than 0.25 μm, or the spacing, for example, the surface between the walls of the nanostructure, has an average dimension of less than 0.5 μm. For nanostructures according to a particular embodiment of this disclosure, the nanostructures may not be concentric; in this case, referring to the stress-induced surface as the tip width may be more accurate, where the tip width / tip diameter typically refers to the lowest tip width of a non-concentric nanostructure. While it is preferred that the tip width be less than half the longest dimension of the relevant bacteria, for example, the tip width is typically preferred to be less than 0.5 μm, the method of the present invention can achieve nanostructures with higher antibacterial properties by having smaller vertex diameters. Therefore, it is preferred that the tip width of the nanostructure be less than 0.5 μm, more preferably less than 50 nm, even more preferably less than 20 nm, even more preferably less than 10 nm, and most preferably less than 7 nm.

[0061] In one embodiment of the invention, the tip width of the nanostructure is less than 30 nm, more preferably less than 20 nm, even more preferably less than 10 nm, and most preferably less than 6 nm.

[0062] In embodiments of this disclosure, forming a nanostructure on a surface includes a deposition step, a heating step, an etching step, and preferably an etching mask removal step. Table 2 summarizes typical parameters of the method. Materials for the metal film include, for example, gold, silver, aluminum, and nickel.

[0063]

[0064] Table 2. Process parameters for nanoparticle formation

[0065] sediment

[0066] The material of the metal film is preferably selected such that nanoparticles can be formed on the surface when heat is applied, for example by rapid thermal annealing. In specific embodiments of this disclosure, the material of the metal film is selected such that it is at least partially etched in the etching step. In one embodiment of the invention, the material of the metal film is selected from gold, silver, aluminum, nickel, alloys thereof, or combinations thereof. Preferably, the metal film is deposited such that the surface of the implantable device is uniformly covered with a metal, such as gold, silver, aluminum, nickel, or combinations thereof. More preferably, the deposited metal film has a thickness in the nanometer range. Thicker metal films can form larger nanoparticles upon heating. Therefore, the thickness of the metal film is preferably between 1 nanometer and 50 nanometers, more preferably between 1 nanometer and 25 nanometers. Therefore, the metal film can be considered a thin film and can be deposited by a thin film deposition method. Therefore, the deposition includes or is composed of a method for generating and / or depositing a thin film coating on a substrate material, such as the surface of an implantable device.

[0067] Deposition can therefore include methods suitable for forming thin films, such as physical deposition, chemical deposition, and / or epitaxy. Physical deposition includes physical vapor deposition (PVD), in which a solid material is evaporated in a vacuum and deposited onto a substrate. Various physical vapor deposition methods exist, including, for example, evaporation methods such as electron beam evaporation, ion-assisted deposition, and thermal evaporation. Physical vapor deposition methods also include magnetron sputtering, which relies on the formation of a magnetically confined plasma near the surface of the target material, such as the surface of an implantable device; ion beam sputtering, which relies on an ion source to sputter the target material onto the substrate; and further includes pulsed laser deposition, which relies on laser pulses to evaporate the target material. Another type of thin film deposition is chemical deposition, in which a fluid precursor undergoes a chemical change on a solid surface, leaving a solid layer. Chemical deposition methods include atomic layer deposition (ALD), which relies on using a vapor precursor to deposit one conformal thin film at a time. Preferably, the deposition method allows for the deposition of metal films on planar and / or non-planar surfaces.

[0068] Deposition rate is generally not important to the final result. However, in certain situations, one may want more control over the deposition process. For example, in cases where the process is monitored in real time. For example, in these and other cases, a rate of 0.1... / s to 10 Between / s, more preferably 0.3 / s to 7 Between / s, the optimal value is approximately 1 Depositing metal at a rate of / s may be advantageous.

[0069] heating

[0070] The formation of nanostructures may include applying heat to a metal film, causing the film to transform into nanoparticles. The heating step may include rapid heat treatment of the metal film, such as rapid thermal annealing, or a process thereof. In one embodiment of the invention, the metal film is subjected to a temperature between about 70°C and 900°C, preferably between 300°C and 700°C. Preferably, the metal film is heated until it has transformed into nanoparticles, preferably completely. The metal film may be heated for at least 1 minute, for example, at least 2 minutes. Preferably, the metal film is heated for at least 1 minute, for example, at least 2 minutes.

[0071] Heating can dehumidify the metal film, causing it to transform into multiple nanoparticles. Therefore, the aggregation of the metal film can be driven by an increase in its surface energy during heating. When the surface energy of the metal film exceeds the sum of the surface energy of the implant and the interfacial energy between the two layers, the film may begin to aggregate, forming nanoparticles with minimal energy states and uniform contact angles.

[0072] Various conditions are suitable for applying heat to a metal film to transform it into nanoparticles. However, heating may preferably be carried out in an inert atmosphere, such as nitrogen, under certain conditions. Furthermore, in another embodiment of this disclosure, heating is carried out at below atmospheric pressure, preferably a medium vacuum or higher, more preferably a high vacuum or even higher. In a preferred embodiment of this disclosure, heat is applied, for example, rapid thermal annealing, at a pressure below 100 mTorr.

[0073] Nanoparticles

[0074] As discussed elsewhere herein, parameters such as the thickness of the metal film, heating conditions, and the materials of the metal film and surface affect the resulting properties and characteristics of the nanoparticles. The high tunability of the method disclosed in this invention allows for the formation of nanoparticles with specific desired properties. For example, in one embodiment of the invention, the density of the nanoparticles, i.e., the number per unit area, is between 1 and 2000 μm. -2 Between 1.7 and 1950 μm, more preferably between 1.7 and 1950 μm -2Between. The properties of the nanoparticles, such as size, density, and shape, are adjusted to allow the formation of an etch mask with desired properties. A preferred configuration of the etch mask is such that subsequent etching allows the formation of nanostructures that improve bone integration and bacterial prevention. For example, it is preferred that the nanoparticles are spaced sufficiently far apart that the etch solution can etch the surface through the etch mask. It should be noted that the nanoparticle pattern on the surface is often replicated as a pattern of nanostructures, possibly because the nanoparticles thus shield parts of the surface from etching. Typically, the material of the nanoparticles is the same as that of the metal film, but chemical processes may modify the material, such as oxidation during the conversion of the metal film into nanoparticles. The dimensional variability of the nanoparticles can be controlled by adjusting processing parameters, such as the duration of the heating step. In one embodiment of this disclosure, the nanoparticles have low dimensional variation, thereby allowing the formation of nanostructures with similar dimensions. The coefficient of variation for the nanoparticles is preferably less than 50%. As used herein, the coefficient of variation refers to the standard deviation divided by the mean. Therefore, the size of the nanoparticles on the surface, such as the diameter perpendicular to the surface, preferably the projected diameter, has a coefficient of less than 50%. In images acquired perpendicular to the surface, the diameter of the nanoparticles is preferably defined as the average of the maximum and minimum dimensions fitted by the ellipse. Therefore, the diameter of non-spherical nanoparticles can also be evaluated. In one embodiment of the invention, the average diameter of the nanoparticles is between 10 nm and 350 nm. Preferably, the d90 size value (diameter) of the nanoparticles is between 10 nm and 350 nm. As mentioned above, the average size of the nanoparticles depends on the thickness of the deposited metal film, as shown in the table below, which lists the average size and standard deviation measured after rapid thermal annealing of metal (gold) films on titanium surfaces of different thicknesses.

[0075]

[0076] Etching

[0077] In one embodiment of the invention, the etching step includes etching the surface using isotropic and / or anisotropic etching methods. Preferably, the surface of the implantable device is etched using, for example, an etching mask formed of nanoparticles to form a monolithic nanostructure. The configuration of the nanoparticles, combined with the configuration of the etching step, determines the configuration of the resulting nanostructure. The properties of the nanostructure can be adjusted by modifying the properties of the nanoparticles or the etching step. The nanostructure can be modified, for example, in terms of shape, height, tip width, sidewall angle, spacing, vertex diameter, surface density, and aspect ratio. For implants such as dental implants, these properties can be selected to maximize osseointegration and bacterial prevention of the implantable device.

[0078] In many embodiments of this disclosure, the etching characteristics of the etching method will have a significant impact on the resulting (monomaterial) nanostructures. Indeed, in specific embodiments of this disclosure, the etching step can be configured such that the etching mask (e.g., the nanoparticles of the etching mask) and the surface of the implantable device are etched differently, for example, with different orientations and / or etching rates. In specific embodiments of this disclosure, the etching step can be arranged such that the etching rate of the mask material (i.e., the material of the nanoparticles, such as gold) is lower than that of the material of the implantable device (e.g., the material of the surface of the implantable device, where the nanostructure will be formed), preferably at least in the lateral direction (i.e., parallel to the surface of the implantable device). This condition typically produces vertical columnar nanostructures.

[0079] In a preferred embodiment of the present invention, the etching rate of the mask material is 0.01-1 times that of the etching rate of the target material, more preferably 0.02-0.8 times that of the target material, and even more preferably 0.05-0.5 times that of the target material.

[0080] In one embodiment of the invention, the etching rate of the target material is about 100 nm / min, and the etching rate of the mask material is from 1 nm / min to 100 nm / min, more preferably from 5 nm / min to 50 nm / min, even more preferably from 10 nm / min to 50 nm / min, and most preferably from 20 nm / min to 40 nm / min.

[0081] In one embodiment of the invention, the etching rate of the target material is between 1 nm / min and 2000 nm / min, preferably between 20 nm / min and 200 nm / min.

[0082] To ensure high control over the etching process, it is generally desirable to select an etching rate that allows the nanostructure to form within 2-15 minutes, more preferably between 4-10 minutes. For example, for a nanostructure with a height of 200 nm, an etching rate of 20-50 nm / min may be preferred for high control over the etching step. Similarly, for a nanostructure with a height of 1000 nm, an etching rate of 100-200 nm / min may be preferred for high control over the etching step.

[0083] Properties determined by nanoparticles can include, for example, density, spacing, and tip width. Furthermore, the etching process can determine many properties of the nanostructure. Etching processes can include wet etching or dry etching. The typical isotropic and anisotropic properties of these methods can affect the properties of nanostructures on the surface of implantable devices.

[0084] In one embodiment of the invention, the etching step includes or consists of wet etching. The wet etching may include subjecting a portion of the surface to an etching solution. Wet etching is generally substantially anisotropic, for example, anisotropic. Some wet etchants etch crystalline materials at very different rates, depending on the exposed crystal facets. In single-crystal materials, this effect results in very high anisotropy. Preferably, an etching mask shields a portion of the surface from the etching solution to form nanostructures by etching. The etching solution may include or consist of hydrofluoric acid (HF) solution, nitric acid (HNO3) solution, ammonium hydroxide solution, hydrogen peroxide (H2O2) solution, or mixtures thereof, such as aqueous hydrofluoric acid and hydrogen peroxide solution. In a preferred embodiment, the etching solution includes hydrofluoric acid, nitric acid, and hydrogen peroxide. In another equally preferred embodiment of the invention, the etching solution includes hydrogen peroxide and ammonium hydroxide. Preferably, the etching solution is a buffer solution. Preferably, the etching solution is a solution capable of etching the material and / or nanoparticles of the implantable device surface. Preferably, the etching solution is selected to have a higher etching rate on the implantable device surface than on nanoparticles.

[0085] In one embodiment of the invention, the etching step includes or consists of dry etching. The dry etching may include bombarding the exposed surface of the implantable device with a reactive substance to remove a portion of the material from the exposed surface. Dry etching methods are generally substantially anisotropic, such as anisotropic, and include inductively coupled plasma (ICP), reactive ion etching (RIE), and ion beam etching (IBE). Dry etching may also be referred to as plasma etching and may include microwave plasma etching and hydrogen plasma etching. In one embodiment of the invention, the source gas is Cl2, Ar, CF4 / SF6, O2, or mixtures thereof. After etching, in certain embodiments, it is preferable to remove the etching mask. For example, by immersion in a solution that selectively etches the etching mask, such as aqua regia. However, removal of the etching mask may include any suitable method for removing the etching mask, such as nanoparticles. Removal of the etching mask can be performed by physical or chemical processes, such as dry etching or wet etching. Preferably, removal of the etching mask is selective for the etching of the etching mask. For example, using aqua regia can preferably etch gold nanoparticles onto other surfaces of the implantable device. Therefore, in one embodiment of the invention, the removal of the etch mask is accomplished by immersion in an etch solution, preferably a selective etch solution, such as aqua regia used for gold particles. This method is highly versatile because various properties of the final nanostructure can be adjusted, for example, by the thickness of the metal film, the material of the metal film, the heating conditions, the etch solution, and the etch time. Another solution that can be used to remove mask materials (e.g., nanoparticles) includes iodine-based solutions, such as KI:I₂:H₂O in a ratio of 100 g:25 g:500 ml.

[0086] In one embodiment of the invention, the sidewall angles of the nanostructures average between 18° and 90° (where 90° refers to vertical sidewalls). Therefore, the nanostructures can be conical, substantially cylindrical, and / or ridge-shaped. The sidewall angles can be largely determined by the configuration of the etching steps, such as processing parameters. A substantially cylindrical structure can be the result of a substantially anisotropic etching process, such as reactive ion etching. In such a process, the bombardment of accelerated ions can lead to directional etching of the substrate and / or nanoparticles, typically vertical or at least substantially vertical. The degree of etching of the nanoparticles can be reflected in the sidewall angles. For example, anisotropic etching processes configured to minimize the etching of nanoparticles typically result in sidewalls of substantially 90° for the formed nanostructures. On the other hand, anisotropic etching processes configured to substantially etch the nanoparticles result in sidewall angles of nanostructures that are typically substantially below 90°, for example, below 70°, or even below 50°, or even below 30°. Therefore, the degree of etching of the nanoparticles generally affects the sidewall angles of the nanostructures. In a preferred embodiment of the invention, the sidewall angle is between 18° and 90°, more preferably between 18° and 85°, and even more preferably between 25° and 75°, resulting in high antimicrobial properties of the formed nanostructure. Having relatively sharp nanostructure tips is generally important. Therefore, nanostructures with a 90° sidewall angle are generally less preferred. In contrast, nanostructures with sidewall angles below 90°, such as those between 18° and 85°, are preferred, for example, conical and / or ridge-shaped. The etching process can be configured to achieve the desired sidewall angle of the nanostructure, such as sidewall angles that provide optimized bacterial prevention and osseointegration properties for the implant surface. Furthermore, etching processes such as dry etching, such as RIE and ICP, are typically combinations of isotropic and anisotropic etching, such as combinations of physical and chemical etching. The etching of nanoparticles may be affected by the degree of chemical etching. A greater degree of chemical etching may also result in a greater degree of lateral etching of the nanoparticles. The lateral etching of the nanostructure can thus modify the etching mask so that a larger portion of the substrate is exposed by the etching mask. Nanoparticles that gradually decrease in size during the etching step can produce tapered nanostructures. Furthermore, the etching rate of the nanoparticles, such as the lateral etching rate relative to the surface of the implantable device, typically affects the sidewall angle of the nanostructure. A higher ratio between the etching rate of the implantable device surface and the etching rate of the nanoparticles during the etching step generally results in a higher sidewall angle for the nanostructure (i.e., high sidewall angles, such as 90°, where the nanoparticles remain substantially intact after etching, or where at least the coverage of the nanoparticles remains substantially intact after etching). Similarly, a lower ratio between the etching rate of the implantable device surface and the etching rate of the nanoparticles during the etching step generally results in a lower sidewall angle for the nanostructure.The etching rate of nanoparticles can be affected by the etching configuration and may include processing parameters such as gas source and chamber pressure.

[0087] Samples exposed to dry etching typically develop conical or columnar nanostructures. The dry etching process consists of two parts: physical etching (accelerated ion bombardment) and chemical etching (plasma of reactive gases in an etching chamber). Physical etching occurs in one direction and produces an anisotropic etching profile. Chemical etching operates in all directions and produces an isotropic etching profile. The final etching profile is a combination of both, such as... Figure 7 As shown and further described below.

[0088] When the overall etching rate to the mask material (e.g., nanoparticles) is low in the lateral direction, the size of the mask material does not decrease significantly during the process, resulting in columnar nanostructures of the target material. Conversely, when the overall etching rate to the mask material is high in the lateral direction, the size of the mask material decreases while the size of the exposed area increases. This results in tapered nanostructures of the target material. Tapered nanostructures are preferred for antimicrobial properties on implantable device surfaces.

[0089] The size of the etched nanostructure is determined by the size of the mask material (i.e., the size of the nanoparticles and the distance between them). The height of the etched nanostructure is determined by the applied etching time. Longer etching times result in increased structure height. Figure 3 An example SEM image of a dry-etched titanium nanostructure is shown.

[0090] Due to the isotropic etching profile of wet etching methods, wet-etched samples exhibit random shapes. The height of the etched structure is determined by the applied etching time. Similar to dry etching, the overall etching profile of a wet etching process is a combined effect of etching the mask material and the target material in both the lateral and vertical directions. Factors such as the type of etchant, the concentration of each etchant, the etching temperature, and the choice of mask material all affect the final etching profile. By changing these factors, nanostructures of different shapes can be formed, including ridged nanostructures (e.g., formed between several substantially recessed indentations) and conical nanostructures. Figure 4A Example SEM images of wet-etched titanium nanostructures with indentation shapes are shown. Figure 4 shows an example SEM image of a tapered wet-etched titanium nanostructure with a high aspect ratio. Figure 5B An example SEM image of a wet-etched titanium nanostructure with a low aspect ratio cone shape is shown.

[0091] Nanostructures

[0092] Nanostructures are preferably formed on the surface of implantable devices, such that they have an average orientation perpendicular to the surface. The density of nanostructures is typically similar to that of nanoparticles and can be as low as 1 μm. -2 Up to 2000μm -2 The average spacing between nanostructures is preferably less than the minimum size of bacteria associated with peri-implantitis. Therefore, in another embodiment of this disclosure, the average distance between two adjacent nanostructures, such as the average distance between the tips of two adjacent nanostructures, is between 10 nm and 300 nm. Furthermore, the height of the nanostructure, i.e., the distance from the surface plane perpendicular to the surface to the tip of the nanostructure, is preferably less than the size, such as the minimum size, of bacteria associated with peri-implantitis. Therefore, in another embodiment of the invention, the average height of the nanostructure is between 50 nm and 500 nm. In yet another embodiment of this disclosure, the average height of the nanostructure is between 10 nm and 500 nm, more preferably between 20 nm and 400 nm, even more preferably between 30 nm and 300 nm, and most preferably between 35 nm and 100 nm.

[0093] In another embodiment of this disclosure, the average aspect ratio of the nanostructure is between 0.14 and 50. As used herein, aspect ratio refers to the height of the nanostructure, such as the height from the base to the tip, divided by the width of the nanostructure, such as the width of the base of the nanostructure. The nanostructure can therefore be a high aspect ratio nanostructure. In another embodiment of this disclosure, the tip of the nanostructure has curvature, which can be described by the tip width (tip apex diameter). A tip width (tip apex diameter) between 10 nm and 350 nm may be preferred. In another embodiment of this disclosure, the tip width of the nanostructure is less than 0.5 μm. Therefore, it may be preferable that the tip width is less than the size of bacteria associated with peri-implantitis. The nanostructure can be substantially vertical, i.e., perpendicular to the surface, or the nanostructure can have an average sidewall angle of less than 90°. In one embodiment of the invention, the sidewall angle is between 18° and 90°. The nanostructure can therefore be substantially tapered, for example, extending from the surface of the implantable device.

[0094] In one embodiment of this disclosure, the base width of the nanostructure is less than 1 μm, more preferably less than 600 nm, even more preferably less than 400 nm, even more preferably less than 200 nm, still more preferably less than 10 nm, even more preferably less than 50 nm, and even more preferably less than 10 nm.

[0095] This disclosure further relates to an implantable device comprising a surface having a monolithic nanostructure for osseointegration and bacterial membrane prevention, which is formed by a method for forming a monolithic nanostructure as disclosed elsewhere herein.

[0096] This disclosure also relates to an implantable device comprising a surface having nanostructures for bone integration and bacterial membrane prevention. Preferably, the nanostructures are monolithic, for example, they are formed by removing material from the surface of the implantable device, and they are formed of the same material as the implantable device. The implantable device may have substantially tapered nanostructures extending from the surface of the implantable device. Preferably, the nanostructures extend substantially outward from the surface of the implantable device, for example, substantially perpendicular to the surface of the implantable device in contact with the nanostructures. Further preferably, the perimeter and / or width of the nanostructures decrease outward from the substrate, for example, the nanostructures have pointed ends. In another embodiment of this disclosure, the sidewalls of the nanostructures are substantially vertical sidewalls, for example, vertical. Thus, the nanostructures can also be substantially columnar. In another embodiment of the invention, the nanostructures are ridge-shaped. Preferably, the ridge-shaped nanostructures are formed between a plurality of substantially recessed indentations on the surface.

[0097] Nanostructures are preferably formed on the surface of implantable devices, such that they have an average orientation perpendicular to the surface. The density of nanostructures is typically similar to that of nanoparticles and can be as low as 1 μm. -2 Up to 2000μm -2 Within the range of [specific values]. Preferably, the average spacing between nanostructures is less than the minimum size of bacteria associated with peri-implantitis. Therefore, in another embodiment of this disclosure, the average distance between two adjacent nanostructures, such as the average distance between the tips of two adjacent nanostructures, is between 10 nm and 300 nm. Furthermore, the height of the nanostructure, i.e., the distance from the surface plane perpendicular to the surface to the tip of the nanostructure, is preferably less than the size, such as the minimum size, of bacteria associated with peri-implantitis. Therefore, in another embodiment of the invention, the average height of the nanostructure is between 50 nm and 500 nm.

[0098] In another embodiment of this disclosure, the average aspect ratio of the nanostructure is between 0.14 and 50. As used herein, aspect ratio refers to the height of the nanostructure, such as the height from base to tip, divided by the width of the nanostructure, such as the base width of the nanostructure. The nanostructure can therefore be a high aspect ratio nanostructure. In another embodiment of this disclosure, the tip of the nanostructure has curvature, which can be described by the tip width. A tip width of less than 350 nm is preferred, for example, between 10 nm and 350 nm, preferably less than 350 nm, more preferably less than 100 nm, even more preferably less than 50 nm, even more preferably less than 30 nm, even more preferably less than 20 nm, still even more preferably less than 10 nm, and most preferably less than 7 nm. Surfaces containing nanostructures with lower tip widths are generally able to generate greater stress on bacteria, resulting in higher antibacterial properties. The aforementioned tip width is a result of the method disclosed in this invention. In another embodiment of this disclosure, the tip width of the nanostructure is less than 0.5 μm, more preferably less than 300 nm, even more preferably less than 200 nm, and even more preferably less than 100 nm, most preferably less than 50 nm. In many of the embodiments disclosed in this invention, the tip width is the same as the tip width. Therefore, a tip width smaller than the size of bacteria associated with peri-implantitis may be preferred. The nanostructure may be substantially vertical, i.e., perpendicular to the surface, or the nanostructure may have an average sidewall angle of less than 90°. In one embodiment of the invention, the sidewall angle is between 18° and 90°. The nanostructure can therefore be substantially conical, for example, extending from the surface of the implantable device.

[0099] Detailed description of the attached figures

[0100] The invention will now be described in more detail with reference to the accompanying drawings. The drawings are exemplary and intended to illustrate some features of the method disclosed in this invention for forming monolithic nanostructures on prosthetic devices, as well as some features of prosthetic devices including surfaces having monolithic nanostructures, and should not be construed as limiting the invention disclosed herein.

[0101] Figure 1An outline of a method for forming a monolithic nanostructure (9) is shown, wherein the nanostructure is formed by a method comprising: depositing (2) a metal film (3) on the surface of an implantable device (1), and subsequently transforming the metal film into an etch mask (5) containing nanoparticles (5) by heating (4). The surface (6) can then be etched by any isotropic and / or anisotropic etching method, such as dry etching or wet etching processes. The illustration shows a typical substantially anisotropic etching, in which columnar or conical nanostructures can be formed. It can be seen that the nanoparticles are also affected to some extent by the etching step and may therefore combine with isotropic directional etching to form conical nanostructures. The method may further include removing the etch mask (8) to form a monolithic nanostructure (9) on the surface of the implantable device. Removal of the etch mask may include immersing the surface in a suitable solution for removing nanoparticles from the nanostructure, such as aqua regia. The method is highly versatile because many properties of the final nanostructure can be tuned by, for example, the thickness of the metal film, the material of the metal film, the heating conditions, the etch solution, and the etching time. Therefore, monolithic nanostructures with desired properties can be formed, such as monolithic nanostructures for bone integration and bacterial prevention.

[0102] In specific embodiments of this disclosure, the method can be used to realize the surface of implantable devices including microstructures and nanostructures to improve osseointegration and antimicrobial properties. For example, the method can be repeated to form structures with different properties. In one specific example, the surface of the implant is initially treated according to the method of this disclosure to obtain a microstructure, and in a second step, the method is repeated under modified processing parameters to form a nanostructure, thereby realizing an implantable device including both microstructures and nanostructures to increase osseointegration and antimicrobial properties. Alternatively, the microstructure can be formed prior to forming the nanostructure using the method of this disclosure, according to methods known to those skilled in the art, such as those described in Jemat et al. Biomed Res Int. 2015;2015: 791725. For example, sandblasting or acid etching are common methods in dental implants today that can create microstructures on the surface to achieve better osseointegration. These known methods can be used to form microstructures prior to forming the nanostructures disclosed elsewhere herein. The surface of the implantable device can include microstructures, for example, formed by sandblasting and / or acid etching or any other method known to those skilled in the art for forming microstructures on the surface of an implantable device (e.g., a dental implant).

[0103] Figure 5 illustrates an exemplary conical monolithic nanostructure produced by chemical wet etching using a mixture of HF, H2O2, and H2O according to an embodiment of this disclosure. Figure 5AThis exhibits nanostructures with a higher aspect ratio. The average tip width is approximately 5 nm, the average base width is approximately 15-25 nm, and the height is approximately 50-75 nm. Therefore, the aspect ratio is between approximately 2 and 5. Figures 5B-5D Examples of nanostructures with low aspect ratios are shown. The tip width is approximately 3-5 nm, the base width is approximately 40-65 nm, and the height is approximately 40-60 nm. Therefore, the aspect ratio of these nanostructures is approximately 1.

[0104] Figure 6 A schematic diagram of a conical nanostructure is shown. It can be seen that the cone shape is defined by the tip width (8), the base width (9), the height (10), the distance between two adjacent nanostructures (11, i.e., the distance between the tips of two adjacent nanostructures), and the sidewall angle, which is defined by the angle between the sidewall and a plane perpendicular to the nanostructure (e.g., the base plane of the nanostructure), and can be obtained by taking the arctangent of the result of dividing the height of the nanostructure by half the base width. Similarly, the aspect ratio of the nanostructure is generally defined as the height of the nanostructure divided by the base width. Therefore, the tip width can be considered as a parameter defining the tip sharpness, where the tip width is defined as the width of the tip of the nanostructure.

[0105] Figure 6A schematic diagram of the etching of a target surface (78), such as the surface of an implantable device, according to an embodiment of this disclosure is shown. It can be seen that at least a portion of the surface has been covered by a mask (77). The structure formed by etching the implantable device depends on the etching rate of the mask and the etching rate of the target. Generally, an etching process with a lower etching rate of the mask material relative to the etching rate of the target material typically results in a process as shown in 71-73. Here, the mask material can be seen to remain almost intact, while the target material is etched to form deep trenches. The resulting nanostructure may be more columnar than conical, with vertical or nearly vertical sidewalls. In contrast, 74-75 show a process in which the mask (e.g., nanoparticles) is etched to a significantly greater extent than the target material. It can be seen that the mask material is etched away (here shown as isotropic etching, where the mask, such as the nanoparticles, becomes thinner and narrower). The smaller amount of mask material results in the exposure of a larger portion of the target surface, such as the surface of the implantable device, thus forming a nanostructure with sloping sidewalls. It is understood that the resulting sidewall angle depends on the relative etching rate between the mask material and the target material, particularly the rate of nanoparticle size reduction (i.e., the etching rate of the nanoparticles within the plane of the target material, such as the surface of an implantable device). In the horizontal direction (i.e., within the mask plane), the faster the mask material is etched away, the smaller the sidewall angle. Therefore, the etching process is advantageously configured such that the horizontal etching rate of the mask material is selected based on the vertical etching rate of the target material (i.e., the relative rate / ratio between the vertical etching of the target material and the horizontal etching of the mask material) to produce nanostructures with the desired sidewall angle, as well as other properties of the nanostructure, such as the height of the nanostructure according to the aforementioned process.

[0106] Examples of embodiments disclosed in this invention.

[0107] Example 1: Formation of monolithic nanostructures on titanium samples by wet etching and dry etching

[0108] Materials and methods

[0109] 1. Metal Thin Film Deposition

[0110] By using atomic layer deposition, at 1 A deposition rate of / s was used to deposit thin Au (gold) films with a thickness of approximately 5 nm onto multiple titanium samples.

[0111] 2. Rapid thermal annealing

[0112] The titanium sample was thermally annealed at 650°C for 3 minutes under vacuum. Then, gold nanoparticles were formed on the surface of the titanium sample and used as a mask pattern in the subsequent etching process.

[0113] 3. Dry etching or wet etching

[0114] 3.1 Dry Etching

[0115] Samples specified for dry etching are etched using inductively coupled plasma reactive ion etching (ICP-RIE) with a gas source mixture of CF4 / SF6.

[0116] 3.2 Wet Etching

[0117] Samples designated for wet etching are etched by immersion in a hydrofluoric acid (HF)-based solution. The samples are then rinsed clean after the wet etching process.

[0118] 4. Remove residual mask material.

[0119] After etching, the mask material is removed by immersion in an aqueous solution of nitric acid and hydrochloric acid.

[0120] result

[0121] The formed gold nanoparticles (after step 2) and the solid nanostructures formed without an etch mask (after step 4) were characterized by scanning electron microscopy.

[0122] Depending on the thickness of the formed metal film, the size of the nanoparticles can range from relatively small ( Figure 2A From relatively large nanoparticles () Figure 2C Adjustments will be made.

[0123] Figure 2B The average size (fitted diameter) of the nanoparticles shown is 42.2 nm, and the density is approximately 200 / μm. 2 .

[0124] Furthermore, scanning electron microscopy images of the monolithic nanostructures show cone-shaped nanostructures positioned in a largely random pattern on the sample surface. Figure 3 The average tip width is less than 10 nm, while the average diameter of the bottom of the nanostructure is approximately 80 nm. Meanwhile, the average height of the nanostructure is approximately 150 nm.

[0125] Wet etching nanostructures have ridge-like structures, such as... Figure 4A and 4B As shown. Figure 4A As shown, ridges are formed between substantially recessed indentations on the surface of the titanium sample. The isotropic nature of the wet etching process leads to variations in the size of the indentations, which in turn result in the nanostructures formed by the wet etching process.

[0126] Example 2: Formation and characterization of monolithic nanostructures by wet and dry etching

[0127] Materials and methods

[0128] 1. Metal Thin Film Deposition

[0129] By using electron beam deposition, at 1 A deposition rate of / s was used to deposit a thin Au (gold) metal film with a thickness of 5 nm onto the titanium sample.

[0130] 2. Rapid thermal annealing

[0131] The titanium sample was thermally annealed at 650°C for 3 minutes under vacuum. The resulting nanoparticles formed on the surface of the target substrate are shown in Figure 2D.

[0132] 3. Dry etching or wet etching

[0133] 3.1 Dry Etching

[0134] Half of the titanium sample was dry-etched, and the other half was wet-etched. The dry-etched sample was etched using an ICP-RIE machine under the following conditions: Cl2: 30 sccm, Ar: 2 sccm, pressure: 3 mTorr, coil power: 400W, board power: 100W, temperature: 20°C, etching time: 90 seconds. The resulting dry-etched nanostructures are shown below. Figure 3 As shown.

[0135] 3.2 Wet Etching

[0136] A portion of the sample was immersed in a buffered hydrofluoric acid (BHF) solution for 6 minutes, then rinsed with deionized water for 5 minutes and dried with an N2 gun. The etched nanostructures are as follows: Figure 4A As shown.

[0137] Another portion of the sample was immersed in an HF:H₂O₂:H₂O (2:1:10) solution for 4 minutes, then rinsed with deionized water for 5 minutes and dried with an N₂ torch. The etched nanostructures are as follows: Figure 5A As shown.

[0138] Another portion of the sample was immersed in an HF:H₂O₂:H₂O (2:1:10) solution for 3 minutes, then rinsed with deionized water for 5 minutes and dried with an N₂ torch. The etched nanostructures are as follows: Figure 5C As shown.

[0139] 4. Remove residual mask material.

[0140] Residual masking material in each sample was removed using an aqua regia solution (HCl:HNO3, 3:1 ratio). The samples were immersed in the aqua regia solution for 3 minutes, then rinsed with deionized water for 5 minutes and dried with an N2 gun.

[0141] Characterization and Results

[0142] The Au nanoparticles formed in step 2 were characterized using scanning electron microscopy (SEM). The measured average size (diameter) of the nanoparticles was 42.2 nm, and the nanoparticle density was 200 / μm. 2 The size and density of the nanoparticles depend on the thickness of the metal film deposited in step 1. A thicker metal film results in larger nanoparticle sizes and lower structural density. An exemplary SEM image of the formed gold nanoparticles is shown below. Figure 2A -D, and further quantified in the table below.

[0143]

[0144] Example 3: In vitro bacterial experiment

[0145] 1. Purpose and Principles

[0146] The aim of this study was to demonstrate whether titanium samples with surface nanostructures possess antibacterial properties. A titanium sample with a flat surface was used as a reference sample in the tests.

[0147] The concept involves introducing a biofilm onto the test unit and then comparing the microbial count on the treated test unit with that on a reference unit.

[0148] Test units with and without nanostructures were inoculated with bacterial suspensions. Samples containing nanostructures were wet-etched with buffered hydrofluoric acid (BHF) as described in Example 2. Figure 4A As shown. The microbial content was measured after storing the test unit in the inoculum at room temperature for 4 days. The test unit was rinsed with sterile water, and any remaining microorganisms were eluted in the MRD. The bacterial concentration in the MRD was measured, and finally, the test unit was wiped with a swab, and the bacterial content on the swab was measured.

[0149] 2. Procedure

[0150] 2.1 Sample

[0151] The surface area of ​​the titanium test unit is 1 x 1 cm. As mentioned, the test unit containing the nanostructure has been treated with wet etching in buffered hydrofluoric acid (BHF) according to Example 2, and is shown to be... Figure 4A middle.

[0152] 2.2 Inoculum

[0153] The test microorganism was Staphylococcus aureus ATCC 29523. The target inoculum level was approximately 10 μL / mL inoculum. 8 CFU.

[0154] The test organism was prepared according to standard procedures, including enrichment steps and purity and concentration controls.

[0155] 2.3 Equipment

[0156] Polycarbonate tubing, 99 x Ø16 mm, with screw cap, sterile.

[0157] TS / 5-42 dry swab with polyester tip, 10 mL neutralization buffer

[0158] sterile water

[0159] Maximum Recoverable Diluent (MRD)

[0160] Microbial growth medium: blood agar

[0161] 37°C incubator

[0162] 2.4 Methods and Culture Media

[0163] Total microbial count analysis on blood agar was performed using a plate-laying technique, with incubation at 37°C for 1 day, and all microorganisms were counted.

[0164] 2.5 Preparation, inoculation, and analysis of test units

[0165] The test unit was placed in a test tube containing 1 mL of inoculum and stored in an LAF workbench at ambient temperature for 4 days. The microbial content in the inoculum was analyzed.

[0166] The test unit was removed from the inoculum using sterile forceps and rinsed with 10 mL of sterile water to remove excess inoculum. It was then placed in a 9 mL sterile MRD and eluted by rotating at 500 rpm for 3 x 3 seconds. The microbial content in the MRD was analyzed.

[0167] The test unit was transferred from the MRD rinsing solution to a sterile culture dish using sterile forceps. Both sides of the test unit were thoroughly wiped, and the microbial content on the swab was analyzed.

[0168] 3. Results

[0169] like Figure 8 As shown, compared with the Ti sample (81) with a flat surface (4.3 log... 10 Compared to CFU / ml, the Ti sample (82) with a nanostructured surface showed a significantly reduced bacterial count (1.5 log CFU / ml). 10 (CFU / ml).

[0170] 4. Conclusion

[0171] In vitro bacterial assays showed that titanium with surface nanostructures has effective antibacterial properties compared to titanium with a flat surface.

[0172] project

[0173] 1. A method for forming monolithic nanostructures on implantable devices, the method comprising:

[0174] a. Depositing a metal film onto the surface of an implantable device;

[0175] b. The metal film is heated for a period of time, causing the metal film to transform into multiple discrete nanoparticles, which in turn form an etching mask on the surface of the implantable device.

[0176] c. Etching the implantable device such that the surface of the implantable device is etched through the etching mask, thereby forming a monolithic nanostructure on the surface of the implantable device; and

[0177] d. (Optional) Remove the etched mask.

[0178] 2. The method for forming a monolithic nanostructure according to claim 1, wherein the etching step is configured such that the surface of the implantable device and the nanoparticles are etched, for example, configured to form a tapered nanostructure.

[0179] 3. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the material of the implantable device is titanium, such as grade 4 or 5 titanium, titanium alloy, zirconium, or polyethylene, such as ultra-high molecular weight polyethylene (UHMWPE) or cross-linked polyethylene (XLPE).

[0180] 4. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the implantable device is a dental implant for providing support and stability for a dental prosthesis.

[0181] 5. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the implantable device is a hip joint prosthesis, a knee joint prosthesis, a trauma nail, a knee joint implant, a lag screw, a spinal cage, a glenoid implant, an ankle fusion implant, a foot / toe implant, a long bone osteotomy plate or bone implant, a sacroiliac joint implant, a skull plate or maxillofacial bone plate.

[0182] 6. A method for forming a monolithic nanostructure according to any one of the preceding items, wherein the nanostructure is configured to improve osseointegration of the implantable device and prevent bacterial growth.

[0183] 7. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the material of the metal film is selected from: gold, silver, aluminum, nickel, or combinations thereof.

[0184] 8. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the thickness of the metal film is 1 nm - 25 nm.

[0185] 9. A method for forming a monolithic nanostructure according to any one of the preceding items, wherein the metal film is deposited by thin film deposition, such as atomic layer deposition, electron beam deposition, or sputtering.

[0186] 10. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the heating step comprises, or consists of, rapid thermal annealing of the metal film.

[0187] 11. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the metal film is heated for at least 1 minute.

[0188] 12. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the metal film is heated to a temperature between 70°C and 900°C.

[0189] 13. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the heating step is carried out in an inert atmosphere, such as a nitrogen atmosphere.

[0190] 14. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the heating step is performed under conditions below atmospheric pressure, such as a vacuum.

[0191] 15. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the average density of the nanoparticles is 1 μm. -2 Up to 2000 μm -2 .

[0192] 16. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the average size, for example, diameter of the nanoparticles is between 10 nm and 350 nm.

[0193] 17. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the nanoparticles have a coefficient of variation such as size of less than 50%.

[0194] 18. A method for forming a monolithic nanostructure according to any one of the preceding items, wherein etching is performed by wet etching, for example by an etching solution.

[0195] 19. The method for forming a monolithic nanostructure according to Item 18, wherein the etching solution is a hydrofluoric acid (HF) solution, a hydrogen peroxide (H2O2) solution, or a mixture thereof.

[0196] 20. A method for forming a monolithic nanostructure according to any one of the preceding items, wherein etching is performed by dry etching, such as reactive ion etching (RIE), inductively coupled plasma reactive ion etching (ICP-RIE), and / or ion beam etching (IBE).

[0197] 21. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein etching is performed using a source gas composed of Cl2, Ar, CF4 / SF6 and O2 or a mixture thereof.

[0198] 22. A method for forming a monolithic nanostructure according to any one of the preceding items, wherein the etch mask is removed by immersion in a solution such as aqua regia.

[0199] 23. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the density of the nanostructure is 1 μm. -2 Up to 2000 μm -2 between.

[0200] 24. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the average height of the nanostructure is between 50 nm and 500 nm.

[0201] 25. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the average spacing between the nanostructures is between 10 nm and 300 nm.

[0202] 26. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the aspect ratio of the nanostructure is from 0.14 to 50.

[0203] 27. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the tip width of the nanostructure is between 10 nm and 350 nm.

[0204] 28. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the tip width of the nanostructure is less than 0.5 μm, more preferably less than 100 nm, even more preferably less than 50 nm, even more preferably less than 20 nm, still more preferably less than 10 nm, even more preferably less than 8 nm.

[0205] 29. The method for forming a monolithic nanostructure according to any one of the preceding items, wherein the sidewall angle of the nanostructure is between 18° and 90°.

[0206] 30. A method for forming a monolithic nanostructure according to any one of the preceding items, wherein the nanostructure is substantially conical and extends from the surface of the implantable device.

[0207] 31. The method of forming a monolithic nanostructure according to any one of the preceding items, wherein the nanostructure is provided as a plurality of ridges formed between substantially recessed indentations on the surface of the implantable device.

[0208] 32. An implantable device comprising a surface having a monolithic nanostructure formed from any of the foregoing items for bone integration and bacterial membrane prevention.

[0209] 33. An implantable device comprising a surface having a monolithic nanostructure for osseointegration and bacterial membrane prevention, wherein said nanostructure is:

[0210] a. Generally conical in shape, extending from the surface of the implantable device; or

[0211] b. It is essentially ridge-shaped, formed between several substantially recessed indentations on the surface.

[0212] 34. The implantable device according to claim 33, wherein the density of the monolithic nanostructure is 1 μm. -2 Up to 2000 μm -2 between.

[0213] 35. The implantable device according to any one of claims 33-34, wherein the average height of the nanostructure is between 30 nm and 500 nm, for example, between 50 nm and 500 nm.

[0214] 36. The implantable device according to any one of claims 33-35, wherein the recessed indentation is substantially hemispherical.

[0215] 37. The implantable device according to any one of claims 33-36, wherein the average radius of the recessed indentation is between 50 nm and 500 nm.

[0216] 38. The implantable device according to any one of claims 33-37, wherein the average spacing between nanostructures is 10-300 nm.

[0217] 39. The implantable device according to any one of claims 33-38, wherein the aspect ratio of said nanostructure is between 0.14 and 50.

[0218] 40. The implantable device according to any one of claims 33-39, wherein the tip width of the nanostructure is between 10 nm and 350 nm.

[0219] 41. The implantable device according to any one of claims 33-40, wherein the tip width of said nanostructure is less than 0.5 μm.

[0220] 42. The implantable device according to any one of claims 33-41, wherein the sidewall angle of said nanostructure is between 18° and 90°.

Claims

1. A method for forming a monolithic nanostructure on an implantable device, said nanostructure being configured for osseointegration and prevention of bacterial growth in said implantable device, the method comprising: a. Depositing a metal film onto the surface of an implantable device; b. The metal film is heated for a period of time, causing the metal film to transform into multiple discrete nanoparticles, which in turn form an etching mask on the surface of the implantable device. and c. The surface of the implantable device is etched using an etching mask to form a monolithic nanostructure on the surface of the implantable device, wherein the surface of the implantable device and the etching mask are etched simultaneously, and the sidewall angle of the nanostructure is between 18° and 85°. The nanostructure is conical and extends from the surface of the implantable device; or the nanostructure is provided as a plurality of ridges formed between recessed indentations on the surface of the implantable device.

2. The method for forming monolithic nanostructures according to claim 1, wherein, The surface of the implantable device is etched at an etch rate of 0.01 to 1 times that of the etch mask.

3. The method for forming a monolithic nanostructure according to claim 1 or 2, wherein, The metal film is heated to a temperature between 70°C and 900°C for at least 1 minute.

4. The method for forming a monolithic nanostructure according to claim 1 or 2, wherein, The average diameter of the nanoparticles is between 10 nm and 350 nm.

5. The method for forming a monolithic nanostructure according to claim 1 or 2, wherein, Etching is performed using wet etching.

6. The method for forming a monolithic nanostructure according to claim 1 or 2, wherein the method further comprises the step of removing the etch mask.

7. The method for forming a monolithic nanostructure according to claim 1 or 2, wherein, Etching is performed using dry etching.

8. The method for forming a monolithic nanostructure according to claim 1 or 2, wherein, The density of the nanostructure is 1 μm -2 Up to 2000 μm -2 between.

9. The method for forming a monolithic nanostructure according to claim 1 or 2, wherein, The average height of the nanostructure is between 10 nm and 500 nm.

10. The method for forming a monolithic nanostructure according to claim 1 or 2, wherein, The average spacing between the nanostructures is between 10 nm and 300 nm.

11. The method for forming a monolithic nanostructure according to claim 1 or 2, wherein, The tip width of the nanostructure is less than 0.5 μm.

12. The method for forming a monolithic nanostructure according to claim 1 or 2, wherein, The sidewall angle of the nanostructure is between 25° and 75°.

13. An implantable device comprising a surface having a monolithic nanostructure for osseointegration and bacterial membrane prevention, said nanostructure being formed by the method according to any one of claims 1-12. in, The nanostructure is tapered and extends from the surface of the implantable device, wherein the sidewall angle of the nanostructure is between 18° and 85°; or The nanostructure is ridge-shaped and is formed between several recessed indentations on the surface, wherein the sidewall angle of the nanostructure is between 18° and 85°.

14. The implantable device according to claim 13, wherein, The average spacing between the nanostructures is between 10 nm and 300 nm.

15. The implantable device according to claim 13 or 14, wherein, The aspect ratio of the nanostructure is between 0.14 and 50.

16. The implantable device according to claim 13 or 14, wherein, The average height of the nanostructure is between 10 nm and 500 nm.

17. The implantable device according to claim 13 or 14, wherein, The average size of the nanoparticles is between 10 nm and 350 nm.

18. The implantable device according to claim 13 or 14, wherein, The density of the nanostructure at the surface is 1 μm. -2 Up to 2000 μm -2 between.

19. The implantable device according to claim 13 or 14, wherein, The tip width of the nanostructure is less than 0.5 μm.

20. The implantable device according to claim 13 or 14, wherein, The base width of the nanostructure is less than 1 μm.

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