Biocompatible structured materials and uses thereof

Abstract

A biocompatible structured material comprising a polymerized matrix and tetrapod-shaped ZnO microparticles (t-ZnO) and / or fragments thereof, wherein the t-ZnO microparticles have a core and arms, with an arm length of about 0.5 μm to about 100 μm, a core diameter of about 0.8 μm to about 5 μm, and a tip diameter of about 0.05 μm or less to the core diameter, the weight fraction of the t-ZnO microparticles and / or fragments thereof is about 20 to about 90 weight percent, and the t-ZnO microparticles and / or fragments thereof are incorporated into the polymerized matrix and / or partially protrude from the matrix on the surface of the biocompatible structured material.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to a biocompatible, anti-fibrotic structured material for implantable devices, in particular for drainage implants in glaucoma surgery. The present invention further relates to glaucoma drainage implants comprising said material, as well as their preparation and use. [Background technology]

[0002] Background of the Invention Glaucoma represents a group of disorders associated with optic nerve damage, usually caused by elevated intraocular pressure (IOP). Glaucoma results in a deterioration of visual field and ultimately permanent vision loss, as there are currently no treatments to reverse optic nerve damage. Glaucoma is the second leading cause of post-cataract blindness and the leading cause of irreversible blindness worldwide, posing a significant threat to public health and quality of life. The total number of glaucoma cases in people aged 40–80 years is estimated to increase from 76 million cases in 2020 to 111.8 million cases in 2040 due to the aging population.

[0003] The main risk factor for the development of glaucoma is elevated intraocular pressure, which occurs due to a slowdown in the removal of ocular fluid (aqueous humor). Depending on the appearance of the drainage pathway, glaucoma can be divided into open-angle glaucoma (OAG) and angle-closure glaucoma (ACG), with the first type being the most common. In this case, the angle between the iris and cornea is wide open, allowing aqueous humor to flow through its natural pathway around the lens and iris. However, if the drainage channels (trabecular meshwork and Schlemm's canal) become clogged, the outflow of aqueous humor is obstructed, leading to elevated IOP and subsequent degeneration of the optic nerve. Therefore, most treatments to prevent the progression of glaucoma focus on continuously lowering IOP. First-line treatments include noninvasive medical therapy (in the form of eye drops) and laser procedures, while invasive open surgeries such as trabeculectomy or tube shunt implantation are performed in more severe cases or when target IOP levels cannot be achieved by other means. However, these standard techniques have several drawbacks. The effectiveness of topical medications is limited by patient compliance with the medication regimen and intolerance due to side effects such as ocular surface irritation and allergies. Despite significant IOP reductions of up to 35.9%, the effectiveness of laser treatments has been found to decrease over time, requiring further medical therapy or surgical intervention after 5 years. Open surgery offers the highest efficiency in reducing IOP by nearly 50%, but has a postoperative complication rate of over 30% (e.g., hypotony, bleb leakage, or endophthalmitis) and a reoperation rate of approximately 20%.

[0004] In recent years, minimally invasive glaucoma surgery (MIGS) has emerged as an alternative, less invasive procedure for treating OAG. Although less effective at lowering IOP than conventional surgery, it remains a promising technique for patients with mild to moderate glaucoma and when medical or laser therapy has failed. In contrast to traditional open surgery, which requires a conjunctival incision, MIGS allows for the insertion of a micro-sized drainage stent through a small corneal incision using an injector, minimizing trauma to the target tissue and surgical and postoperative recovery time. Depending on their placement and outflow pathway, microstents used in MIGS can be classified as Schlemm's canal stents, suprachoroidal stents, and subconjunctival stents.

[0005] Regardless of placement, the primary challenge with MIGS devices is excessive wound healing (fibrotic scarring) and foreign body reaction processes as a response of vascularized tissue to injury and implantation, causing limited or complete obstruction of aqueous humor flow and resulting in increased IOP. Because the success of glaucoma filtration surgery is limited by postoperative encapsulation, the introduction of MIGS does not reduce postoperative fibrosis, with success rates of only 40–50% at 5 years after implantation of glaucoma drainage devices. To mitigate postoperative fibrosis, it is essential to influence the natural wound healing mechanism. To prevent excessive scarring, adjuvant antiproliferative drugs such as mitomycin C and 5-fluorouracil are used, similar to traditional open surgery. However, despite the assistance of these drugs, high rates of postoperative interventions, such as bleb puncture revisions and reoperations, have been reported. Similar to trabeculectomy, which has a long history of antifibrotic drug use, there is a potential for the development of thin, avascular filtering blebs and endophthalmitis. Furthermore, both antiproliferative substances can cause corneal epithelial toxicity. Therefore, reduction or elimination of anti-fibrotic drugs is desirable.

[0006] Inflammatory wound healing mechanisms, triggered by both the surgery and the introduced materials, are the primary determinants of the success or failure of MIGS. Newer devices made of glutaraldehyde-crosslinked porcine gelatin (XEN™) or polystyrene-b-isobutylene-b-styrene (Preserflo™) appear to reduce the fibrotic response, but these devices still require antifibrotic medication.

[0007] Therefore, there is a need for materials that can be used in implantable devices to avoid excessive wound healing processes and overcome one or more of the drawbacks of the prior art, particularly for the treatment of glaucoma in the setting of MIGS.

[0008] It is an object of the present invention to provide new materials for implantable devices to reduce or eliminate fibrotic and foreign body reaction processes, allowing for effective, long-term use of such devices with few side effects. Another object of the present invention is to provide a glaucoma drainage implant, particularly for MIGS, that can be implanted in the eye to alleviate excessive IOP and treat glaucoma, that overcomes at least to some extent the shortcomings of conventional glaucoma treatments, and that is easy and economical to manufacture. Summary of the Invention [Means for solving the problem]

[0009] Summary of the Invention According to the present invention, the objects are achieved by the main features of the claims. To these ends, the present invention provides a biocompatible structured material and an implantable device comprising such a biocompatible structured material.

[0010] According to a first aspect of the present invention, there is provided a biocompatible structured material comprising a polymeric matrix and tetrapod-shaped ZnO microparticles (t-ZnO) and / or fragments thereof incorporated within the polymeric matrix and / or partially protruding from the matrix on the surface of the biocompatible structured material.

[0011] Preferably, the polymeric matrix of the biocompatible structuring material comprises an elastomer such as a poly- and / or oligo-siloxane, more preferably polydimethylsiloxane (PDMS).

[0012] In one embodiment, a biocompatible structured material is provided, comprising a polymerized matrix having substantially interconnected tunnel-shaped pores, which can be obtained by partially or completely removing a substantially interconnected network structure of t-ZnO microparticles and / or fragments thereof from the polymerized matrix by acid hydrolysis.

[0013] In another aspect, the present invention provides an implantable device comprising a biocompatible structured material comprising a polymeric matrix and tetrapod-like t-ZnO microparticles and / or fragments thereof, and / or an implantable device comprising a polymeric matrix having substantially interconnected tunnel-shaped pores obtained by partially or totally removing the substantially interconnected network structure of t-ZnO microparticles and / or fragments thereof from the polymeric matrix.

[0014] In a preferred embodiment, the implantable device is a glaucoma drainage implant. Such a glaucoma drainage implant may have the shape of a substantially straight, flexible, elongated body having a circular or polygonal cross-section. The body of the glaucoma drainage implant may further comprise a lumen.

[0015] The present invention also provides methods for reducing intraocular pressure in the eye of a mammalian subject in need thereof by implanting one or more implantable devices according to the present invention into the eye. [Brief explanation of the drawings]

[0016] [Figure 1]Figure 1 shows scanning electron microscope (SEM) images of tetrapod-shaped ZnO microparticles (t-ZnO) according to the present invention. SEM micrographs of t-ZnO at different magnifications: 708x (A), 1440x (B), 350x (C), 1000x (D), and 5310x (E) show the unique morphological structure of the t-ZnO microparticles. The black lines in the graphs have lengths of 20 μm (A), 10 μm (B), 50 μm (C), 20 μm (D), and 2 μm (E).

[0017] [Figure 2] Figure 2 shows the absorption spectra of t-ZnO suspensions in HTF (human Tenon fibroblast) culture medium at different concentrations (B–D). A: Statistical analysis shows a significant increase in absorbance at 570 nm at t-ZnO concentrations of 100 μg / mL and 1000 μg / mL compared to untreated culture medium (p<0.05 and <0.001, one-way ANOVA, Dunn's multiple comparison test).

[0018] [Figure 3] Figure 3 shows the results of the MTT test to determine t-ZnO toxicity in HTF cultures. The half-maximal inhibitory concentration (IC50) was 9.4 μg / mL (range: 8.7–10.3 μg / mL).

[0019] [Figure 4] Figure 4 shows the effect of t-ZnO microparticles on HTF proliferation. (A) The control (medium only) shows high Ki67 expression (gray dots represent nuclei of proliferating HTFs). (B-F) Treatment with t-ZnO microparticles results in a decrease in KI67 expression in HTFs, indicating a decrease in cell proliferation. (G) Statistical analysis shows a significant decrease in HTF proliferation at concentrations of 8 μg / mL and 10 μg / mL of t-ZnO microparticles in the medium compared to the control (p<0.05 and <0.001, one-way ANOVA, Dunn's multiple comparison test).

[0020] [Figure 5]Figure 5 shows the effect of t-ZnO microparticles on HTF contractility (α-SMA expression). (A) Control HTFs (medium only) showed a strong fibrillar pattern of α-SMA-specific protein. (B-D) Treatment with t-ZnO microparticles resulted in a decrease in α-SMA expression in HTFs, indicating a decrease in cell contractility (A: 0 μg / mL, B: 5 μg / mL, C: 10 μg / mL, D: 20 μg / mL). (E) Statistical analysis shows a significant decrease in HTF contractility at a concentration of 20 μg / mL of t-ZnO microparticles in the medium compared to the control (p<0.001, one-way ANOVA, Dunn's multiple comparison test).

[0021] [Figure 6] Figure 6 shows the effect of t-ZnO microparticles on HTF transdifferentiation (p-SMAD expression). (A) Control HTFs (medium only) showed many p-SMAD-positive cells. (B-D) Treatment of HTFs with t-ZnO microparticles resulted in a decrease in p-SMAD expression, indicating a decrease in cell transdifferentiation. (A: 0 μg / mL, B: 2 μg / mL, C: 4 μg / mL, D: 6 μg / mL, E: 8 μg / mL, F: 10 μg / mL) (G) Statistical analysis shows a significant decrease in HTF transdifferentiation at concentrations of 8 μg / mL and 10 μg / mL of t-ZnO microparticles compared to the control (p<0.05, p<0.01, one-way ANOVA, Dunn's multiple comparison test).

[0022] [Figure 7]Figure 7 shows the wound healing rate after 24 and 48 hours of treatment with different concentrations of t-ZnO. (A) Wound gap area was calculated after 24 and 48 hours of treatment. The wound gaps of the untreated control (0 μg / mL) and the 1 μg / mL concentration were nearly closed by 48 hours. The 5 μg / mL concentration kept the wound gap open for 48 hours. The 10 μg / mL and 20 μg / mL concentrations resulted in an enlargement of the wound gap due to toxic effects. (B) The acellular wound area at 24 and 48 hours was compared relative to the initial wound area, which was doubled to account for cells lost at the wound margin. The decrease in proliferation rate after 48 hours of treatment with 10 μg / mL and 20 μg / mL t-ZnO may be explained by toxic effects.

[0023] [Figure 8-1] Figure 8 shows cytokine levels in HTFs 24 hours (AE) and 48 hours (FJ) after treatment with different concentrations of t-ZnO. PT = cytokine levels in HTFs before t-ZnO treatment. [Figure 8-2] Same as above. [Figure 8-3] Same as above. [Figure 8-4] Same as above. [Figure 8-5] Same as above.

[0024] [Figure 9] Figure 9A is a schematic diagram of a custom-made extrusion device for preparing drainage implants (stents). The polymer / t-ZnO mixture was loaded into the extrusion device, conveyed inside a cylinder, and extruded through a nozzle. Pressure was generated by a piston. Figure 9B shows a photograph of the ready-to-use drainage implant. Figure 9C shows the drainage implant after tensile testing. The drainage implant was fixed in a 3D-printed specimen holder, which was then attached to a tensile testing machine and cut in the middle before starting the tensile test. Figure 9D shows the specimen for in vitro testing. Drainage implants of the same material composition / variation were placed adjacent to each other on a glass slide with a thin PDMS coating.

[0025] [Figure 10] 10A is a schematic diagram of a drainage implant according to the present invention (Ldi = length of the drainage implant; dL = lumen diameter; da = outer diameter of the drainage implant). 1 and 2 represent examples of partially protruding t-ZnO microparticle arms. B is a schematic diagram of t-ZnO microparticles according to the present invention (Larm = arm length; dcore = core diameter; dtip = tip diameter). C is an SEM micrograph of a drainage implant according to the present invention showing a magnified view of the surface of the implant, where t-ZnO microparticles partially protruding from the polymerized matrix are visible.

[0026] [Figure 11] Figure 11 shows SEM micrographs of drainage implants containing different amounts of t-ZnO microparticles. Drainage implants fabricated using a 400 μm nozzle are shown at A 500x and B 3500x magnifications (top view) and C 500x and D 1500x magnifications (cross-section). Drainage implants fabricated using a 200 μm nozzle are shown at E 500x (top view) and F 1500x (cross-section). The black lines on the graphs have lengths of 100 μm (A), 10 μm (B), 100 μm (C), 20 μm (D), and 50 μm (E) and (F).

[0027] [Figure 12] Figure 12A is an SEM micrograph of a cross-section of a drainage implant with a lumen. B is an enlarged image of the indicated portion of A. C and D represent energy dispersive X-ray spectroscopy (EDX) analysis results showing the determined distribution of elements in the material cross-section of an implant according to the invention. Here, the presence of zinc (Zn; C) and silicon (Si; D) is shown to be related to the presence of t-ZnO particulates and [SiRO]n. SEM / EDX images were obtained using a Zeiss Ultra Plus (Carl Zeiss Microscopy GmbH, Jena, Germany) SEM equipped with an EDX unit (Oxford Instruments).

[0028] [Figure 13] Figure 13 is a graph showing the mechanical properties of the drainage implants obtained from the tensile tests. All results are expressed as the mean and standard deviation of five measurements for each material composition / variation tested.

[0029] [Figure 14] Figure 14 is a graph showing the cell viability of rat embryonic fibroblasts on drainage implants, correlated with roughness (Rz) and released Zn ion concentration. All results are expressed as the mean and standard deviation of triplicate samples. Statistical analysis shows a significant decrease in cell viability in implants containing 60% and 75% by weight (p<0.001, indicated by three asterisks) and etched implants (p<0.01, indicated by two asterisks) compared to the control.

[0030] [Figure 15] Figure 15 shows a photograph of a water droplet (stained with methylene blue) placed on a drainage implant containing 75 wt% t-ZnO. The combination of the hydrophobic PDMS matrix and the roughness created by the protruding t-ZnO particles makes the surface superhydrophobic, such that the water droplet remains approximately spherical.

[0031] [Figure 16] FIG. 16 shows the in vivo location of a drainage implant according to the present invention in the anterior chamber under the conjunctiva and 2-3 mm distally in a rabbit eye.

[0032] [Figure 17]17 shows the intraocular pressure (IOP) R / L ratio of rabbit eyes upon insertion of drainage implants according to the present invention. IOP was measured as the IOP ratio between the experimental right (R) eye and the control left (L) eye immediately before surgery (day 0) and on days 1, 3, 7, 10, and 14 after surgery. A: G1 implant with an outer diameter of 200 μm. B: G2 implant with a diameter of 400 μm. Statistically significant values ​​are marked with *.

[0033] [Figure 18] Figure 18 shows the IOP R / L ratio of rabbit eyes upon insertion of a drainage implant according to the present invention. IOP was measured as the IOP ratio between the experimental right (R) eye and the control left (L) eye immediately before surgery (day 0) and on postoperative days 1, 3, 7, 10, 14, 17, 21, 24, 28, 31, 35, 38, and 42. G3 implant with an outer diameter of 200 μm. Statistically significant values ​​are marked with an *.

[0034] [Figure 19] Figure 19 shows the IOP R / L ratio of rabbit eyes upon insertion of drainage implants according to the present invention. IOP was measured as the IOP ratio between the experimental right (R) eye and the control left (L) eye immediately before surgery (day 0) and on days 1, 3, 7, 10, 14, 17, 21, 24, 28, 31, 35, 38, and 42 after surgery. G4 implant with an outer diameter of 400 μm. Statistically significant values ​​are marked with *.

[0035] [Figure 20] Figure 20 shows a rabbit eye upon insertion of a drainage implant according to the present invention. Clinical examination of the inserted implant after 2 weeks (A) and 6 weeks (B) showed no toxic changes or inflammatory reactions in the eye.

[0036] [Figure 21]Figure 21 shows histological analysis of the implantation sites. AD: 2 weeks after drainage implant insertion, EH: 6 weeks after drainage implant insertion. Left column = hematoxylin and eosin staining; right column = Masson staining. DETAILED DESCRIPTION OF THE INVENTION

[0037] Detailed Description of the Invention ZnO is widely used in pharmaceuticals (e.g., as an antibacterial and UV-absorbing ingredient in creams) and is being actively investigated for use in various biomedical applications (e.g., cancer treatment, periodontal membranes, antibiofilm materials, and antiviral drugs). In these contexts, the shape and size of ZnO particles have been shown to influence their biological efficacy. It has been demonstrated that the incorporation of small amounts of tetrapod-shaped ZnO (t-ZnO) into 3D films supports eukaryotic cell growth and promotes bone formation, while increased t-ZnO concentrations can have cell-inhibitory effects. The cytotoxicity of t-ZnO microparticles has been found to be lower compared to ZnO nanoparticles due to their larger size (i.e., inability for cellular uptake) and therefore lower surface-to-volume ratio (i.e., lower surface reactivity).

[0038] t-ZnO microparticles, as shown in Figure 1 and described in more detail in the Examples section, represent a biocompatible material, both in its intact state and as fragments resulting from the disruption of one or more arms of the tetrapod-like structure, which, on the one hand, can inhibit cell proliferation and, on the other hand, do not cause unacceptable levels of cell or tissue damage. The dimensions of the t-ZnO microparticles (which can vary depending on synthesis parameters, e.g., temperature and duration, and / or growth technique), as well as their concentration and spatial distribution with respect to cellular material / tissue, as illustrated in Figures 3-8 and presented in the corresponding parts of the Examples section, crucially determine the biological properties of t-ZnO.

[0039] Combining t-ZnO microparticles with an inert support allows for the production of structured materials with a substantially defined amount and spatial distribution of t-ZnO. Such materials allow for the localized application of t-ZnO microparticles and the targeted control of their effects, for example, in biological tissues or organs. Furthermore, the overall structural characteristics of the resulting biocompatible structured material can further influence the behavior of biological tissues, resulting in desired anti-fibrotic properties.

[0040] Matrices containing t-ZnO microparticles have already been used, for example, as stain-resistant yarns (WO 2021228322 A1).

[0041] The present invention provides a biocompatible structured material comprising a polymerized matrix and t-ZnO microparticles and / or fragments thereof. The material of the present invention comprises t-ZnO microparticles having a core and arms with an arm length of about 0.5 μm to about 100 μm, a diameter at the core of about 0.8 μm to about 5 μm, and a diameter at the tip of about 0.05 μm to the maximum diameter at the core. The arms meet at the core of the particle. Tetrapod-shaped ZnO microparticles have tetrahedral angles between their arms. Fragments of such microparticles typically result from the breakage of one or more arms of the tetrapod-like structure. Preferably, the material comprises tetrapod-like microparticles and, optionally, fragments thereof, typically in smaller pieces.

[0042] Furthermore, the weight fraction of the t-ZnO microparticles and / or fragments thereof in the biocompatible structuring material is about 20 to about 90 weight percent, which may be, for example, 30 to 80 weight percent, 40 to 70 weight percent, or 50 to 60 weight percent.

[0043] In terms of spatial distribution, the t-ZnO microparticles and / or fragments thereof of the present invention are embedded in the polymerized matrix and / or partially protrude from the matrix on the surface of the biocompatible structured material. This is shown in Figures 10, 11, and 12 and described in more detail in the Examples section. The microparticles and / or fragments typically form a substantially interconnected network structure embedded in the matrix.

[0044] In the context of the present invention, "structured" means that the material is not homogeneous, but comprises, in addition to the matrix, specific ZnO particles and / or specific pores resulting from the removal of the ZnO particles. Typically, however, the t-ZnO particles and / or fragments thereof are uniformly distributed in the matrix throughout the material. This also applies to the implantable device of the present invention.

[0045] "Biocompatible" means that the material is suitable as an implant, as further demonstrated herein.

[0046] Preferably, throughout the present invention, the polymeric matrix of the biocompatible structuring material comprises an elastomer. Such elastomers are, for example, poly- and / or oligo-siloxanes [SiRO] n Or it may be a mixture thereof, preferably polydimethylsiloxane (PDMS).

[0047] The polymeric matrix of the biocompatible structuring material may comprise any biocompatible polymer, such as a synthetic polymer, a naturally occurring polymer, or a mixture thereof. The polymeric matrix of the biocompatible structuring material may also be a hydrogel.

[0048] Preferably, the elastic modulus of the material and implant of the present invention is, for example, poly- and / or oligo-siloxanes [SiRO] nAs found when using polymers, it is at least 0.4 MPa, more preferably at least 3 MPa, at least 10 MPa, or at least 15 MPa, for example 3-50 MPa, 3-21 MPa or 15-21 MPa.

[0049] In further embodiments, the biocompatible structured material of the present invention can be subjected to acid hydrolysis (e.g., using acetic acid or hydrochloric acid) to partially (e.g., 10-90%, 20-80%, 30-70%, or 40-60%, or about 50%) or completely remove the substantially interconnected network structure of t-ZnO microparticles or their fragments from the polymerized matrix (see the Examples section). The resulting biocompatible structured material (illustrated in FIG. 11) thus comprises a polymerized matrix with substantially interconnected tunnel-shaped pores, the majority of which form tetrahedral angles at the pore junctions. While greater than 50% is the majority, tetrahedral angles can also be formed by more than 60%, more than 70%, more than 80%, or even more than 90% of the junctions. In this embodiment, in other words, the matrix has interconnected tunnel-shaped pores with a three-dimensional configuration corresponding to an interconnected hollow tetrapod network. Such tunnel-shaped pores can have an average tunnel diameter of about 0.05 to about 5 μm and an average tunnel length of about 0.5 μm to about 100 μm. The tunnel length is determined between pore junctions that form tetrahedron angles. The tunnel density of the polymeric matrix preferably ranges from about 4 to about 65 volume percent. The matrix preferably includes an elastomer.

[0050] A microporous hydrogel comprising interconnected tunnel-shaped micropores having a three-dimensional configuration corresponding to an interconnected hollow tetrapod network suitable for reducing or eliminating motile cells from a solution or an object in contact with the solution is also disclosed in WO 2016 / 177872 A2.

[0051] Generally, additional biologically active molecules can be introduced into the biocompatible structuring material by forming the biocompatible structuring material in the presence of such biologically active molecules, by diffusing the biologically active molecules into the biocompatible structuring material, or by otherwise introducing the biologically active molecules into the biocompatible structuring material. Additionally or alternatively, the biocompatible structuring material of the present invention can also be coated with biologically active molecules.

[0052] Also provided herein are implantable devices comprising the biocompatible structuring materials of the present invention. The implantable devices may be orthopedic implants, dental implants, cardiovascular implants, neurological implants, neurovascular implants, gastrointestinal implants, muscle implants, or ocular implants. The implantable devices can be used to avoid, reduce, or eliminate fibrotic and foreign body reaction processes in tissues or organs upon implantation.

[0053] More specifically, the implantable device of the present invention may be a glaucoma drainage implant, which may have the shape of a substantially straight, flexible, elongated body having a substantially circular or polygonal cross-section.

[0054] In one embodiment, the glaucoma drainage implant of the present invention comprises a substantially straight, flexible, generally cylindrical body preferably having a length of about 5 to about 20 mm and an outer diameter preferably of about 0.1 to about 5 mm. Figures 10-12 show examples of such glaucoma drainage implants.

[0055] Further shapes of the glaucoma drainage implants of the present invention are possible, for example, as a substantially rectangular flexible body preferably having a length of about 5 to about 20 mm, a width of about 3 to about 10 mm, and a thickness of about 0.2 to about 0.5 mm.

[0056] The glaucoma drainage implants of the present invention may further comprise lumens within the body of the implant. Such lumens are substantially hollow channels extending along the length and connecting the ends of the body of the implant (as illustrated in FIGS. 10 and 12). The location and dimensions of such lumens may further influence the outflow of aqueous humor beyond the influence of the geometry of the glaucoma drainage implant itself.

[0057] Overall, the glaucoma drainage implants of the present invention are easy and economical to manufacture and sterilize by methods known in the art. Dimensionally stable yet sufficiently flexible implants of the present invention with desired dimensions and variable lengths can be manufactured in a single step, for example, by an extrusion process. An example of an extrusion device for preparing drainage implants is shown in Figure 9A. Furthermore, variable geometries and sizes can be achieved using other techniques known in the art (e.g., injection molding).

[0058] The present invention also provides a method for preparing an implantable device of the present invention, the method comprising: a) providing a homogeneously mixed composition comprising monomer components of a polymeric matrix and t-ZnO and / or its fragments; b) extruding the composition and polymerizing it; c) cutting the polymeric material to a desired length.

[0059] In principle, the manufacturing process for a glaucoma drainage implant according to the present invention may comprise the following steps: A homogeneously mixed polymer composition containing at-ZnO and / or its fragments is provided (depending on the proportion of t-ZnO, the mixture will be paste to powder-like). b. The polymer composition is incorporated into an extruder (eg, a piston extruder). c. The polymer composition is conveyed through a cylinder (if a piston extruder is used, the pressure to convey the mixture is generated by the piston). d. The polymer composition is extruded out of a molding nozzle. e. The semi-finished material (filamentary in the case of a cylindrical nozzle) may be suspended between two supports and dried, for example in an oven. f. After polymerization, cut the material to the desired length.

[0060] Although the inventors have surprisingly shown that glaucoma drainage implants comprising the compact, biocompatible structured material of the present invention provide IOP reduction in vivo, it may be advantageous to further modify the flow characteristics of the implant. Thus, in addition to the steps described above, one or both of the following steps may be performed in the manufacture of a glaucoma drainage implant according to the present invention for the purpose of modifying its flow characteristics and therefore its effect on IOP: g. Lumens can be created by masking partial areas during the extrusion process (e.g., using polymer fibers or metal wires) and then removing the masking material (e.g., by etching the wire or mechanical extraction), resulting in the formation of a substantially hollow channel extending along the length and connecting the ends of the implant's body. h. Additional hollow channels within the body of the implant can be created by partially or totally etching the t-ZnO particles with an acidic solution (e.g., acetic acid or hydrochloric acid). Depending on the initial t-ZnO content in the material and / or the etching parameters, narrow-mesh or wide-mesh framework structures can be obtained.

[0061] Variation in the amount of t-ZnO used in the biocompatible structured material of the present invention can be used to tailor the material's mechanical properties, such as elastic modulus. The relatively high weight fraction of t-ZnO (20-90 wt%) used in the biocompatible structured material of the present invention is advantageous for the rheological properties required for extrusion, as well as for the sliding of the implant in ocular insertion devices, and also facilitates fixation at the implant site due to the t-ZnO particles protruding from the polymerized matrix.

[0062] Implants of the present invention typically do not include fibers constructed from, for example, organic polymers.

[0063] Glaucoma drainage implants comprising the biocompatible structured materials of the present invention are particularly suitable for MIGS because they are easy to implant, readily conform to the shape of the implantation site, and ensure long-term positional stability. Once implanted, by helping to prevent or control fibrosis around the implantation site through reduced cell viability, thereby reducing or eliminating the encapsulation process, such glaucoma drainage implants provide controlled, long-term stable aqueous humor outflow for significant and durable reductions in IOP, thereby reducing surgical complications and extending the functional life of the implant in situ.

[0064] Through in vitro and in vivo studies, the inventors have demonstrated the biocompatibility (the implants were well tolerated, with no hypotension or clinical signs of inflammation or toxicity), successful cell proliferation and intraocular pressure reduction, and antifibrotic properties of the glaucoma drainage implants of the present invention. The results, shown in Figures 14 and 16-21 and in the Examples section below, demonstrate the significantly improved properties of such implants compared to the prior art.

[0065] Another aspect of the present invention further relates to a method for reducing intraocular pressure in the eye of a mammalian subject in need thereof, comprising implanting one or more glaucoma drainage implants according to the present invention into the eye. Such a method can be used to treat a subject with glaucoma. The method can include measuring the preoperative IOP of the subject's eye, implanting the glaucoma drainage implant(s) into the eye, and measuring the postoperative IOP to confirm treatment of the subject.

[0066] The present invention is further illustrated by the following examples and figures, which, however, should not be construed as limiting the scope of the invention in any way. [Example]

[0067] Example material and method 1.1 Preparation of tetrapod-shaped ZnO particles (t-ZnO) Medical-grade t-ZnO microparticles were fabricated at Phi-Stone AG (Kiel, Germany) using a simple, cost-effective, one-step approach described elsewhere (Paulowicz et al., 2018. Zinc Oxide Nanotetrapods with Four Different Arm Morphologies for Versatile Nanosensors. Sensors and Actuators B: Chemical 262:425-435). Medical-grade polydimethylsiloxane (PDMS) MED-6820 with a viscosity of 66 Pa*s (NuSil Technology LLC, Carpinteria, USA) was used as the matrix polymer and was provided by HumanOptics AG (Erlangen, Germany).

[0068] 1.2 t-ZnO in liquid culture, absorption spectrum At the beginning of each experiment, t-ZnO was dispersed in HTF culture medium at 1 mg / mL. One reproducible standard batch of t-ZnO served as a reference in all experiments and was used to establish the relationship between other samples. Because t-ZnO particles rapidly settle, the dispersion was vortexed and then serial dilutions (1–5000 μg / mL) were prepared in culture medium. The absorption spectra of the t-ZnO dispersions in HTF medium were evaluated at 570 nm using a microplate spectrophotometer (SpectraMax M4, Molecular Devices, Sunnyvale, USA). Concentrations of 0 μg / mL, 0.1 μg / mL, 1 μg / mL, 10 μg / mL, 100 μg / mL, and 1000 μg / mL were tested.

[0069] 1.3 Establishment of human Tenon's fibroblast (HTF) cultures Human Tenon's capsule samples were obtained from patients undergoing surgery at the University Eye Hospital in Lübeck, Germany. This study adhered to the principles of the Declaration of Helsinki regarding the use of human tissue, and informed consent was obtained from patients after explanation of the nature and potential consequences of the study. HTF cultures were generated as previously described (Tura et al., 2007. The Rho-Kinase Inhibitor H-1152P Suppresses the Wound-Healing Activities of Human Tenon's Capsule Fibroblasts In Vitro. Invest Ophthalmol Vis Sci. 48(5):2152). Briefly, tissues were cut into 1-2 mm cubes and maintained in HTF medium:DMEM / F-12 (1:1) supplemented with 10% heat-inactivated fetal calf serum (FCS, Invitrogen-Gibco Life Technologies, Karlsruhe, Germany), 2 mM L-glutamine, 100 U / mL penicillin, and 100 μg / mL streptomycin (Biochrom, Berlin, Germany) in 100 mm Petri dishes at 37°C in a humidified atmosphere of 5% CO. Fibroblasts migrating from these tissues were harvested approximately 3 weeks later by incubation with 0.05% trypsin and 0.02% EDTA (Invitrogen), centrifuged at 300 g for 8 min, and then separated into 75 cm cubes. 2 The cells were seeded in fresh culture medium in flasks. Cells between the third and ninth passages were used for the experiments.

[0070] 1.4 Cell viability after incubation with t-ZnO HTF was added to a 96-well plate at 5 × 10 3Cells were seeded at 6 cells / well (n=6) and grown to confluence for 36 h. t-ZnO stock solution was diluted with DMEM and added to the cell culture at different concentrations (0–15 μg / mL, 20–200 μg / mL, and 1000–5000 μg / mL). HTFs (passage 8) were initially grown for 36 h. The incubation time with t-ZnO was 48 h. An MTT assay was performed to assess the number of viable cells (see below), and absorbance at 570 nm was measured using a microplate reader (Tecan Group Ltd, Mennedorf, Switzerland). The standard error of the mean was calculated for three independent experiments.

[0071] 1.5 Ki67, α-SMA and pSMAD immunostaining HTFs were plated at 3 × 10 on either side of an Ibidi culture insert (Ibidi, Munich, Germany) for live cell analysis. 4Cells were seeded in triplicate at a density of 100 μM with a 500 μM separation between the two sides of the wells, and allowed to grow for 24 hours. Cells were treated with different concentrations of t-ZnO (0 μg / mL, 2 μg / mL, 4 μg / mL, 6 μg / mL, 8 μg / mL, and 10 μg / mL). Treatment was terminated 6 hours later, when a complete culture medium change was performed. After 48 hours, cells were fixed with 2% paraformaldehyde (PFA) followed by 4% PFA for 10 minutes. Immunostaining was performed using primary antibodies against Ki67 (1:300 dilution, MAB4190, Millipore, Hessen, Germany), alpha-smooth muscle actin (α-SMA) (1:100 dilution, Ab7817, Abcam, Cambridge, UK), or pSMAD 2 and 3 (1 μg / mL, ab65847, Abcam, Cambridge, UK), followed by Alexa 488-conjugated anti-rabbit antibodies (1:100 dilution in blocking buffer; Jackson Immuno-Research, Hamburg, Germany; Molecular Probes, Darmstadt, Germany, respectively) as previously described (Tura et al., 2007. The Rho-kinase inhibitor H-1152P suppresses the wound-healing activities of human tenon's capsule fibroblasts in vitro. Invest Ophthalmol Vis Sci. 48(5):2152). Nuclei were counterstained with DAPI (1 μg / mL in PBS) for 10 min. Stained HTFs were examined under an inverted microscope (Leica DMI 6000B, Wetzlar, Germany). Photographs were captured using a DFC290-compatible camera and appropriate software (Leica Application Suite LAS Software, Wetzlar, Germany).

[0072] 1.6 Quantification of immunoreactive cells Immunopositive cells were counted using ImageJ software. A grid was projected, then the image was initialized and the cell counter function was activated. The mean ± standard error of the mean of positive cells was calculated.

[0073] 1.7 Wound healing assay The effects of t-ZnO on primary cultures of HTFs were studied using a wound healing assay with cell inserts. HTFs were allowed to migrate freely after removal of the cell insert. Compared to wound scratch assays, this method provides reproducible wounds of fixed dimensions. To account for the poor solubility of t-ZnO microparticles, they were diluted in large quantities, repeatedly mixed in a vortex, and multiple experimental replicates were performed. While wound assays using insert plates do not accurately represent tissue responses after injury, they allow optimal conditions for understanding cell migration and proliferation. HTFs were placed in Ibidi culture inserts (Ibidi, Munich, Germany) at 3 × 10 cells per side for live cell analysis. 4 Cells were seeded at a density of 1000 μM with a 500 μM separation between each side of the well and grown for 24 hours. Cells were treated with different concentrations of t-ZnO (0 μg / mL, 1 μg / mL, 5 μg / mL, 10 μg / mL, and 20 μg / mL). Treatment was terminated after 6, 24, or 48 hours with a complete medium change.

[0074] Mosaic phase-contrast micrographs were captured using a Leica DMI 6000B microscope and Leica Application Suit LAS Software (Leica Mikrosysteme Vertrieb GmbH, Wetzlar, Germany). The use of automated mosaic image capture allows for a complete assessment of the wound gap and prevents missing or overlapping of specific areas. Images were imported into NIH ImageJ software, and the wound gap was calculated at 0, 24, and 48 hours. To account for cells lost at the wound edge, the unhealed area was compared to twice the wound gap area. The wound healing rate was calculated using the following formula:

number

[0075] 1.8 Culture supernatant samples After incubation with t-ZnO (1 μg / mL, 5 μg / mL, 10 μg / mL, and 20 μg / mL) for 24 or 48 hours, HTF culture supernatant samples were collected. A control group was incubated without t-ZnO. Samples were aliquoted in 50 μL volumes under sterile conditions, labeled, and stored at -80°C until further use.

[0076] 1.9 Immunoassays To evaluate the effect of t-ZnO on the inflammatory and wound-healing properties of HTFs, samples were examined for five cytokines: IL-1α, IL-1β, IL-6, platelet-derived growth factor (PDGF), and hepatocyte growth factor (HGF). For this purpose, a customized, fully quantitative multiplexed ELISA (Q-Plex™ Human Cytokine Array, Quansys Biosciences, Logan, UT, USA) was used, which functions as a sandwich immunoassay. Each of the five spots within each well contains a distinct capture antibody population. Cytokines in each sample bind to their distinct capture antibody spots and then bind to cytokine-specific horseradish peroxidase (HRP)-conjugated secondary antibodies. Samples were tested using a high-sensitivity protocol. Samples were diluted 1:2 and 1:5 in Quansys Human Sample Dilution Buffer (Quansys Biosciences, Logan, UT, USA). Diluted standards and samples were added to wells containing the 5-plex array and incubated for 1 h at room temperature on a plate shaker. The wells were then washed three times with wash buffer, and the detection mixture was added and incubated on a plate shaker at room temperature for 1 hour. The wells were washed three times, and then streptavidin-HRP was added for 15 minutes, followed by six washes and the addition of substrate for cytokine detection. To capture the biomarker concentrations in each sample, images of the plate were taken using a Quansys Q-view imager system (Quansys Biosciences, Logan, UT, USA).

[0077] 1.10 Scanning Electron Microscopy (SEM) Micrographs of the t-ZnO particles and stents were obtained using a Zeiss Ultra Plus SEM microscope equipped with a Gemini column (Carl Zeiss Microscopy GmbH, Jena, Germany) at an accelerating voltage of 5 kV. To prevent surface charging, the stents were sputtered with a gold conductive layer at 30 mA for 90 s using a BAL-TEC SCD 050 Sputter Coater (Bal-Tec AG, Pfäffikon, Switzerland) prior to SEM analysis.

[0078] 1.11 Statistics Statistical analysis was performed using GraphPad Prism 6 software for Windows (California, USA). Variable distributions were evaluated with a one-sample Kolmogorov-Smirnov test. One-way ANOVA, Kruskal-Wallis, Dunn's multiple comparison, two-way ANOVA, and Bonferroni post-hoc tests were used to evaluate in vitro experiments. A P value of less than 0.05 was considered statistically significant. A four-parameter logistic nonlinear regression model was used to estimate the half-maximal inhibitory concentration (IC50) (GraphPad Prism version 6.00 for Windows, GraphPad Software, San Diego, California, USA). All experiments were performed in triplicate.

[0079] 1.12 Preparation of drainage implants The drainage implants were prepared by extrusion using a custom-made device, as shown in Figure 9A. All components except the nozzle were made of stainless steel to withstand the high pressures during extrusion of the highly viscous polymer / particle mixture. Standard MK8 brass nozzles for 3D printers with inner diameters of 400 μm and 200 μm were used, and the drainage implants illustrated in Figure 9B were obtained.

[0080] A PDMS premix was prepared by manually mixing PDMS components A and B in a 1:1 ratio for at least 5 minutes. Next, t-ZnO microparticles were manually mixed into the PDMS premix until a homogeneous paste-like or powder-like mixture (depending on the t-ZnO concentration) was obtained. After extrusion, the drainage implants were suspended between two supports and dried overnight in an atmospheric oven at 85 °C. After curing, the drainage implants were cut into 1.5 cm lengths using a sharp blade. A minimum concentration of 45 wt% t-ZnO particles was required to maintain the cylindrical shape of the drainage implant after extrusion and during curing. Drainage implants with 45 wt%, 60 wt%, and 75 wt% t-ZnO were fabricated.

[0081] Etched drainage implants were prepared by acid hydrolysis, in which 75 wt% t-ZnO drainage implants were placed in a 60% acetic acid solution for 2 days. To accelerate the etching (acid hydrolysis) process, the solution with the drainage implants was placed on a heating plate at 50 °C. After etching, the drainage implants were thoroughly washed with ethanol and then water in an ultrasonic bath for 15 min.

[0082] The possibility of creating a lumen in the drainage implant was demonstrated by placing a copper wire with a diameter of 100 μm inside the nozzle during the extrusion process. After the drainage implant hardened, the wire was manually withdrawn.

[0083] 1.13 Surface characterization of drainage implants The surface morphology of the drainage implants was studied using a scanning electron microscope Zeiss Ultra Plus equipped with a Gemini column (Carl Zeiss Microscopy GmbH, Jena, Germany) at an accelerating voltage of 4 kV. To prevent surface charging, the drainage implants were sputtered with a conductive layer of gold at 30 mA for 90 s using a BAL-TEC SCD 050 Sputter Coater (Bal-Tec AG, Pfäffikon, Switzerland).

[0084] Surface roughness was evaluated at 50x magnification using a three-dimensional laser scanning confocal microscope VK-X (Keyence Corporation, Osaka, Japan) with a red semiconductor laser at a wavelength of 658 nm. Root-mean-square (RMS) roughness was determined by averaging the roughness values ​​along 61 horizontal lines spaced at 5-pixel intervals. For each material variation / composition, triplicate measurements were performed on drainage implants with a nominal diameter of 400 μm.

[0085] Surface wettability was assessed by placing a drop of methyl blue solution on closely spaced drainage implants and photographing them with a camera (Olympus TG-4, Olympus Corporation, Tokyo, Japan). Specific values ​​for the contact angle could not be determined for individual drainage implants due to their small size and uneven surfaces.

[0086] 1.14 Tensile Test To assess the mechanical properties of PDMS / t-ZnO drainage implants with different amounts of t-ZnO microparticles, tensile tests were performed using drainage implants with a nominal diameter of 400 μm without a lumen. To ensure accurate positioning of the drainage implant and avoid slippage or premature failure at the fastening hardware, the drainage implants were placed on a 3D-printed frame with external dimensions of 40 × 8 × 0.5 mm (L × W × D) and a central 10 × 5 mm (L × W) slot, similar to the tabs used for tensile testing of single carbon or glass fiber. To secure the drainage implants on the frame, double-sided Tesa tape (Tesa SE, Norderstedt, Germany) was first used to hold the drainage implants in place. Then, one-component moisture-curing silicone adhesive Elastosil E43 (Wacker Chemie AG, Munich, Germany) was applied to both ends of the drainage implant and allowed to cure overnight at room temperature. After the frame was attached to the tensile tester, both sides of the frame were carefully cut with scissors before the test began. Figure 9C shows the drainage implant after fracture at maximum load.

[0087] Tensile tests were performed using a BETA 5-5 / 6 × 10 tensile testing machine (Messphysik GmbH, Fürstenfeld, Germany) at a constant strain rate of 5 mm / min. A total of five drainage implants per material composition / variation were measured. Mechanical properties derived from the stress-strain curves were calculated using MATLAB® R2019b (MathWorks Inc., Natick, USA). The cross-sectional area of ​​the drainage implants for each material composition / variation was calculated using the corresponding average diameter obtained by SEM (three drainage implants were measured for each material composition / variation, and each drainage implant was measured at three different points).

[0088] 1.15 In vitro studies with drainage implants To increase the contact surface with cells, drainage implants (without lumens) with a nominal diameter of 400 μm were placed adjacent to each other on a 15 mm diameter glass slide (Figure 9D) and spin-coated with a thin layer of PDMS at 2500 rpm for 30 seconds (Specialty Coating Systems Inc., Indianapolis, Indiana). Three samples on the glass slide were fabricated for each material composition / variation. The samples were then placed in an atmospheric oven at 85 °C overnight to cure the PDMS and fix the drainage implants to the glass slide.

[0089] For in vitro experiments, samples were first placed in 24-well plates, disinfected overnight with 70% ethanol, and then washed several times with sterile phosphate-buffered saline (PBS). 30,000 rat embryonic fibroblasts per well were seeded directly onto the samples. Cell culture medium was Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (PAN-Biotech GmbH) and 1% penicillin / streptomycin (Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany) (PAN-Biotech GmbH, Aidenbach, Germany). A negative control (cells + culture medium) and a positive control (cells + culture medium + dimethyl sulfoxide (DMSO, Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany) were prepared simultaneously. Cells were grown to confluence for 48 h. Afterwards, the supernatant was removed for subsequent Zn ion release investigations. To access the number of viable cells after incubation on surfaces with and without t-ZnO, an MTT test was performed. 1 mL of MTT dye (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide; Sigma-Aldrich Chemie GmbH; 1 mg / mL) was added to each well and incubated for 3 h. After washing with PBS, the samples were transferred to a new 24-well plate, DMSO was added to each well, and the well plate was placed on a shaker for 5 min to solubilize the formed formazan crystals. The lysates were then transferred to a 96-well plate and analyzed using a plate reader (Epoch2, BioTek Absorbance was measured at 570 nm using a 3D NMR spectroscopy (Digital Instruments, Winooski, VT, USA). One-way ANOVA followed by Tukey's test was performed using Origin (OriginLab Corporation, Northampton, USA).

[0090] 1.16 Zn ion release measurement Free Zn ions (Zn 2+The concentration of Zn was assessed spectrophotometrically, and zincon monosodium salt (Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany) was used as an indicator for Zn by turning Zn ion-containing solutions blue at pH 9. The intensity of the blue color was measured at 620 nm using a plate reader (Tecan Group Ltd., Mennedorf, Switzerland). A set of samples with known Zn ion concentrations was used to obtain a calibration curve for determining the Zn ion concentration in cell culture medium samples.

[0091] 1.17 Animal testing All procedures followed the ARVO Statement for the Use of Animals in Ophthalmic Research and our institutional guidelines. This study was approved by the local committee for animal use at the University of Luebeck. All experiments were performed using female New Zealand White rabbits, 3–4 months old and weighing 1.5–2.5 kg. Animals were obtained from Charles River Laboratories (Sulzfeld, Germany) and allowed to acclimate for at least 1 week before the start of the experiment. Before surgery, all animals were examined to rule out ocular disease, and intraocular pressure was measured using an iCare® tonometer (Icare Finland Oy, Vantaa, Finland). Twelve rabbits were equally divided into four groups (G1–G4; Table 1). Each experimental group consisted of three animals. In the first set of experiments with a short follow-up of 2 weeks, animals (n = 6) in two different groups (G1–G2, n = 3 each) differed in the implanted device. A second set of experiments was conducted with the same two types of implants with a 6-week follow-up (G3-G4).

[0092] The drainage implants used in these experiments were composites of t-ZnO microparticles (75 wt%) and PDMS. The implants used in the experimental groups had different outer diameters (200 μm and 400 μm). To facilitate the insertion of the 200 μm-sized implants, we developed a disposable insertion device equipped with a grip, a 27-gauge slotted needle, and an unfolding slide. The 400 μm-sized implants could be easily implanted without the insertion device.

[0093] [Table 1]

[0094] 1.18 Surgical Procedures All rabbits (n = 12) underwent surgery on the right eye, and the left eye served as a control. Animals were intramuscularly injected with a ketamine-medetomidine mixture (35 mg / kg and 25 mg / kg, respectively). Additionally, all animals received local anesthesia (Conducaine eye drops). All surgeries were performed by the same surgeon and assistant using an operating microscope (Zeiss OPMI, Jena, Germany). A 90° limbal-based pericorneal incision was made in the conjunctiva 10 mm from the limbus in the superior temporal quadrant, and the subconjunctival space was incised anteriorly using Westcott scissors. Diathermy was not required. A scleral tunnel was created using a paracentesis starting 1.5 mm posterior to the limbus and directed toward the anterior chamber. A 200 μm drainage implant was preloaded into the insertion device. The preloaded insertion device was then advanced through the scleral tunnel. Once the implant was 2–3 mm into the anterior chamber, it was released from the insertion tool by retracting the needle. The distal tip was then placed under the conjunctiva (Figure 16). The conjunctiva was closed in an open position in three cases because the implant appeared exposed.

[0095] 1.19 Clinical Evaluation Clinical examinations were performed to evaluate the general appearance of the treated eyes, assess local toxicity and ocular intolerance, and measure IOP. IOP was measured using an iCare® tonometer (Icare, Finland Oy, Vantaa, Finland). IOP was recorded in both eyes before surgery as a baseline and on the designated days after surgery. To eliminate interindividual, cyclic, and anesthesia-related variations, IOP was compared between the experimental right eye and the left control eye. Measurements were performed in triplicate. The difference in measured IOP was expressed as the right-to-left (R / L) eye ratio. Preoperative R / L ratios ranged from 0.9 to 1.1. Success was defined by a 20% or greater difference in IOP, reflected as an IOP ratio of 0.8 or less. Weekly follow-ups were performed using a slit lamp (Keeler Ltd., Berkshire, UK). IOP was measured in both the operated and unoperated eyes without topical anesthesia immediately before surgery (day 0) in all groups, and on days 1, 3, 7, 10, and 14 after surgery in groups G1–G2, and on days 1, 3, 7, 10, 14, 17, 21, 24, 28, 31, 35, 38, and 42 after surgery in groups G3–G4. Animals were examined under general anesthesia on day 14 after surgery in groups G1–G2 and on day 42 in groups G3–G4. Statistical analysis of IOP values ​​was performed using SPSS 26 software (SPSS Inc., Chicago, USA). Postoperative IOP ratios were compared pairwise with preoperative values ​​using the Mann-Whitney U test for independent samples. A p ≤ 0.05 level was considered statistically significant.

[0096] 1.20 Histological evaluation On postoperative days 14 (G1-G2) and 42 (G3-G4), animals were euthanized under general anesthesia with pentobarbital (300 mg / kg body weight), and the eyes were enucleated along with the conjunctiva to preserve the bleb. The eyeballs were immediately fixed in 10% formaldehyde for at least 24 hours. The eyes were then examined, and a sagittal ring containing the relevant area was excised. The tissue samples were then dehydrated, embedded in paraffin, and 5-µm serial sections were cut, rehydrated, stained with hematoxylin and eosin and Masson's method, and coverslipped.

[0097] result 2.1 t-ZnO fine particles The arms of the t-ZnO particles are composed of alternating Zn 2+ and O 2- It exhibits a hexagonal wurtzite crystal structure oriented along the c-axis with stacking planes.

[0098] 2.1.1 Scanning Electron Microscopy (SEM) The t-ZnO particles have a tetrahedral shape with a bond angle of 109.5 μm between each other. The arm thickness of the t-ZnO particles varied from 0.05 μm to 5 μm. Their lengths ranged from 0.5 μm to 100 μm (Figure 1).

[0099] 2.1.2 t-ZnO absorption spectrum There was no significant difference in the absorption spectrum of t-ZnO in HTF medium at low concentrations (0–10 μg / mL). A significant increase in absorption was detected at higher concentrations of t-ZnO, 100 μg / mL and 1000 μg / mL (p<0.05 and <0.001, one-way ANOVA Dunn's multiple comparison test; Figure 2).

[0100] 2.2 t-ZnO drainage implant 2.2.1 Surface characterization Figure 11 shows the surface morphology of drainage implants with different amounts of t-ZnO microparticles fabricated using a 400 μm nozzle. Uniformly distributed protruding t-ZnO microparticles can be observed on the surface of the unetched drainage implant, and clear pores can be observed on the surface of the etched drainage implant. While single tetrapod-like arms are exposed from the surface of the drainage implants containing 45 wt% and 60 wt% t-ZnO, the surface morphology of the drainage implant with 75 wt% t-ZnO is completely modified by the particles. The diameter of the drainage implants (see Figures 11 and 12 for cross-sections of the drainage implants) was found to decrease as the concentration of t-ZnO particles decreased, which may be due to different viscosities during extrusion. The mean diameter values ​​reached 394.5 μm ± 0.4 μm, 374.8 μm ± 0.4 μm, and 333.4 μm ± 0.3 μm for drainage implants containing 75 wt%, 60 wt%, and 45 wt% t-ZnO, respectively. The etched drainage implants exhibited a minimum diameter of 325.3 μm ± 0.3 μm, due to shrinkage after removal of the t-ZnO particles. The feasibility of forming a lumen within the drainage implant by placing a metal wire inside the nozzle during extrusion is shown in Figure 12.

[0101] Given their low viscosity, liquid silicone rubber (LSR) is typically not suitable for extrusion molding. In this method, the addition of a large amount of t-ZnO particles to liquid PDMS increases the viscosity of the PDMS / t-ZnO mixture enough to retain its uncured cylindrical shape after extrusion. Furthermore, the high internal friction resulting from the very high viscosity prevents the particles from "filtering" under the pressure generated by the piston, i.e., agglomerating within the nozzle, thus preventing nozzle clogging and enabling uniform particle distribution throughout the drainage implant. Due to the flexible t-ZnO arms in the nanometer range, drainage implants with even smaller diameters of approximately 200 μm could be successfully fabricated with the same t-ZnO concentration (Figures 11E and 11F). Generally, a drainage implant with as small an outer diameter as possible is desirable to minimize trauma to the tissue. However, the external dimensions of the drainage implant are determined by its inner diameter, which must ensure sufficient flow rate, and the specific wall thickness to maintain the structural integrity of the drainage implant.Fluid-mechanical calculations have shown that the optimal diameters for drainage into the suprachoroidal space and the subconjunctival space are 53 μm and 40 μm, respectively.For example, the commercially available XEN® gel drainage implant has an inner diameter of 45 μm and an outer diameter of 150 μm (220 μm when hydrated).The technology and method of the present invention are suitable for the fabrication of drainage implants of similar dimensions.

[0102] 2.2.2 Mechanical properties Tensile testing revealed that the incorporation of t-ZnO significantly affected the mechanical properties of the drainage implants (Figure 13). The elastic modulus of the drainage implants containing 45 wt% t-ZnO was 3.26 MPa ± 0.48 MPa. Increasing the t-ZnO content to 60 wt% increased the elastic modulus by 6.5-fold (21.34 MPa ± 2.72 MPa). However, further increasing the t-ZnO content to 75 wt% decreased the elastic modulus to 15.09 MPa ± 2.97 MPa. Because high t-ZnO incorporation results in a nearly powder-like mixture, the decrease in elastic modulus may be due to air entrapment during extrusion. The same trend, although less pronounced, was observed for ultimate strength, although the elongation at break decreased with increasing amounts of incorporated t-ZnO. Etched drainage implants exhibited the lowest modulus of elasticity (0.42 MPa ± 0.07 MPa) and the highest elongation at break (232% ± 43%).

[0103] Drainage implants are inserted into target tissue through an injector and must provide sufficient rigidity to maintain the drainage implant structure and remain in situ for extended periods. At the same time, they should also be flexible enough to conform to the natural curvature of the eye. Mechanical flexibility has also been shown to reduce foreign body reactions to the implant. The flexibility of an implant can be modified by its elastic modulus, cross-sectional area, and length. In this study, drainage implants with the highest amounts of t-ZnO (60 wt% and 75 wt%) exhibited elastic modulus values ​​of approximately 15–20 MPa, which is higher than that of pure PDMS but lower than many drainage implants released for clinical use, with elastic moduli in the range of 104–105 MPa. Even though the addition of large amounts of t-ZnO significantly reduced the elongation to failure, drainage implants with 60 wt% and 75 wt% t-ZnO still exhibited ductile behavior, exhibiting elongation of approximately 30–50% before fracture.

[0104] 2.3 In vitro assays 2.3.1 Cytotoxicity of t-ZnO nanoparticles The cytotoxic potential of t-ZnO microparticles was first investigated in more detail using HTF cell cultures. A four-parameter logistic nonlinear regression model was used to estimate the IC50. Cell viability by MTT assay showed an IC50 of 9.4 μg / mL (range 8.7–10.3 μg / mL; Figure 3).

[0105] 2.3.2 Ki67, α-SMA, and pSMAD immunostaining Through Ki67 staining, a significant antiproliferative effect was observed after 6 hours of treatment with 8 μg / mL and 10 μg / mL t-ZnO compared to control cells (p<0.05 and <0.001, one-way ANOVA, Dunn's multiple comparison test; Figure 4). The number of α-SMA-positive cells, a marker of fibroblast contractility, was significantly reduced after treatment with 20 μg / mL t-ZnO compared to control (p<0.001, one-way ANOVA, Dunn's multiple comparison test; Figure 5). The number of pSMAD-positive cells, a marker for transdifferentiation, was significantly reduced after treatment with 8 μg / mL and 10 μg / mL t-ZnO compared to control (p<0.05, p<0.01, one-way ANOVA, Dunn's multiple comparison test; Figure 6).

[0106] 2.3.4 Wound healing assay Without treatment, fibroblasts covered the scratched area within 24 hours in the wound-healing assay we performed. Treatment with t-ZnO microparticles resulted in concentration- and time-dependent inhibition of HTF migration and proliferation. Both short-term (6 h) and long-term (24 and 48 h) treatment with t-ZnO dose-dependently inhibited cell growth and migration. Specifically, the presented experiments show that fibroblasts tolerated 6 h of treatment with t-ZnO at concentrations as high as 10 μg / mL without toxic effects (Figure 3), whereas prolonged exposure of cells, even at concentrations as low as 5 μg / mL, resulted in a significant decrease in cell number. Application of t-ZnO for 6 h was effective in impairing wound healing at a relatively high dose (10 μg / mL; data not shown). For long-term treatment, low doses (5 μg / mL for 48 h) significantly inhibited migration, but cytotoxicity became more evident at higher doses (10 μg / mL for 48 h, Figure 7). HTF migration was significantly reduced after t-ZnO treatment (10 μg / mL for 6 hours). This migration-inhibitory effect persisted for up to 48 hours after treatment was stopped and the medium was replaced, without any cytotoxicity (data not shown). A significant decrease in cell migration compared to control was observed after 24 and 48 hours of treatment with 5 μg / mL, 10 μg / mL, and 20 μg / mL t-ZnO (p<0.001, two-way ANOVA, Bonferroni post-hoc test; Figure 7). However, prolonged incubation with higher t-ZnO microparticle concentrations was associated with morphological changes in HTFs, ranging from loss of spindle shape, decreased cytoplasm, or cell death. Although t-ZnO microparticles were observed on the cell surface, they were also deeply integrated into the cell membrane. At a t-ZnO concentration of 20 μg / mL, cells acquired a rounded morphology accompanied by loss of cytoplasm (data not shown).

[0107] 2.3.5 Cytokine Production: Immunoassays IL-6 concentrations were significantly reduced in culture supernatants treated with 10 μg / mL and 20 μg / mL t-ZnO for 24 and 48 hours compared with pretreatment (p<0.001 and <0.05, respectively, Dunn's multiple comparison test; Figure 8). There were no significant differences in cytokine concentrations between 24 and 48 hours after t-ZnO treatment (data not shown).

[0108] 2.3.6 Cell viability assay using rat embryonic fibroblasts Figure 14 shows that exposure of cells to drainage implants containing different amounts of t-ZnO reduced cell viability in a concentration-dependent manner. Statistical analysis indicates a significant decrease in cell viability in drainage implants containing 60% and 75% by weight (p<0.001, indicated by three asterisks) and etched drainage implants (p<0.01, indicated by two asterisks) compared to the control. Drainage implants containing 45%, 60%, and 75% by weight of t-ZnO inhibited cell viability to 77% ± 9%, 57% ± 8%, and 43% ± 3%, respectively. The latter two concentrations were found to be significantly different from the control (p<0.001). Interestingly, at 66% ± 5%, cell viability in the etched drainage implant was also significantly lower compared to the control (p<0.01). In drainage implants containing different amounts of t-ZnO, the decrease in cell viability was found to be inversely correlated with roughness and Zn ion release.

[0109] In the literature, reported results regarding fibroblast responses to different surface topographies are inconsistent, which may be the result of different substrate materials, cell types, and roughness measurement techniques and definitions used. It should be noted that comparability of reported results and generalization based on average roughness values ​​is difficult because surfaces with different geometric shapes and sizes of roughness features may result in similar roughness values. Therefore, geometric parameters, lateral spacing, and distribution of roughness features may be more important than the average roughness value. Similarly, initial surface wettability is enhanced by the roughness factor, i.e., the ratio of effective surface area to projected surface area, rather than the average roughness value itself. Figure 15 shows the effect of roughness-induced superhydrophobicity, which was most pronounced for drainage implants containing 75 wt% t-ZnO. An undistorted water droplet resting on the surface of the drainage implant exhibits a high roughness factor, indicating that in some cases, the implant is wetted in a Cassie-Baxter state, where air is trapped between the roughness features. The generated roughness also reduces the contact area of ​​the soft silicone matrix with the syringe wall, facilitating the sliding of the drainage implant inside the syringe. Furthermore, the protruding t-ZnO particles may help to keep the implant in place after implantation.

[0110] In the case of t-ZnO-containing drainage implants, increased roughness also correlates with the amount of protruding t-ZnO particles. Direct contact between t-ZnO particles and human dermal fibroblasts (NHDFs) has previously been shown to have a much higher toxicity potential than indirect contact via Zn ions (Papavlassopoulos et al., 2014. Toxicity of functional nano-micro zinc oxide tetrapods: impact of cell culture conditions, cellular age, and material properties. PloS One. 9(1):e84983). Furthermore, we demonstrated the antifibrotic potential of t-ZnO by showing inhibition of HTF migration, proliferation, and transdifferentiation. It has been suggested that toxicity results from disruption of cell membranes by the tips of t-ZnO particles. Therefore, it is reasonable to expect that increasing the amount of protruding t-ZnO particles on the drainage implant surface will result in increased local contact with cells, enhancing the cell-inhibitory effect.

[0111] Nevertheless, ionic Zn, an essential trace element, the second most common metal in the body (after iron), and the most abundant in the mammalian retina, can exert toxic effects when present at high levels. Toxic effects were observed at concentrations of ZnO particles above 10 μg / mL. However, acute toxicity of ionic Zn from ZnO is typically associated with cellular uptake of ZnO particles, resulting in increased intracellular Zn ion concentrations and the intracellular generation of ROS, which is not the case when the t-ZnO-incorporated microparticles investigated in this study are used. After exposing mouse macrophages (Ana-1) to ZnO particle (<1 μm) suspensions and ZnCl2 supernatants, the half-maximal inhibitory concentrations (IC50s) of dissolved Zn ions at 24 h were determined to be approximately 10 μg / mL and 13 μg / mL, respectively (Song et al., 2010. Role of the Dissolved Zinc Ion and Reactive Oxygen Species in Cytotoxicity of ZnO Nanoparticles. Toxicology Letters 199(3):389-397). In this study, the highest detectable amount of dissolved Zn ions in the culture medium after 48 h was 2.55 ± 0.27 μg / mL for the glass slide sample, which was completely covered by a 75 wt% t-ZnO drainage implant (shown in Figure 9C). Therefore, the amount of Zn ions released from a single drainage implant is negligible. Nevertheless, at low distances, the released Zn ions may also contribute to the cell-inhibitory properties at the drainage implant surface as a secondary mechanism.

[0112] 2.4 In vivo assay in rabbit eyes 2.4.1 Intraocular pressure measurement Clinical success, defined as a 20% reduction in IOP ratio, was observed in G1 on days 3, 10, and 14. However, a statistically significant reduction in IOP ratio could not be achieved when compared pairwise with preoperative values ​​(Figure 17A). G2 had significantly lower IOP ratios on days 1 (p=0.046), 3 (p=0.043), 7 (p=0.046), and 10 (p=0.043) (Figure 17B).

[0113] Eyes in the long-term group G3 showed significantly lower IOP ratios up to 10 days after surgery (p=0.046 on days 1, 7, and 10, p=0.043 on day 3). Thereafter, the IOP ratios were higher and were indeed above 1 from days 21 to 31 (FIG. 18). Another long-term group, G4, showed significantly lower IOP ratios on days 1 (p=0.046) and 10 (p=0.05). Furthermore, clinical success was achieved on days 3, 7, 17, and 21. Thereafter, the IOP ratio increased with a maximum on day 38. During the final measurement, the IOP ratio was slightly below 1 (FIG. 19).

[0114] 2.4.2 Clinical biocompatibility After 2 and 6 weeks, slit-lamp examination of eyes with implants showed no inflammatory reaction in either the short- or long-term studies. The implants were well tolerated, with no hypotension or clinical signs of corneal toxicity (Figure 20). At the end of follow-up, all animals had a resting anterior chamber.

[0115] 2.4.3 Histological analysis Two weeks after insertion of the drainage implant, histological analysis revealed only a very mild cellular response: few cells were found on the duct wall, but the implant itself showed no cell colonization (Figure 21A-D). There were no signs of inflammation or toxic changes in sensitive structures such as the corneal endothelium or retina. In long-term experiments, after 6 weeks, few cells could be observed on the implant surface. Furthermore, more cells were found on the duct wall than after two weeks, and individual encapsulation was observed (Figure 21E-H). There was also no evidence of inflammation or toxic changes.

[0116] Consideration The biocompatibility, wound healing, encapsulation, and long-term success of drainage implants in glaucoma filtration surgery remain unresolved issues. Herein, a new biocompatible structured material for glaucoma filtration surgery, comprising a polymerized matrix and t-ZnO microparticles, is described.

[0117] We demonstrated that drainage implants with diameters of 200–400 μm can be fabricated by extrusion techniques by adding large amounts of t-ZnO microparticles (45 wt%–75 wt% t-ZnO) to liquid PDMS. Due to the high viscosity of the polymer / particle mixture, the drainage implants retain their cylindrical shape in the uncured state after extrusion. Depending on the amount of t-ZnO incorporated, the drainage implants exhibit elastic modulus values ​​ranging from 3.3 MPa ± 0.5 MPa to 21.3 MPa ± 2.7 MPa. The lumen of the drainage implant can be created by placing a metal wire inside the nozzle during extrusion and mechanically removing it after the curing process is complete. The addition of t-ZnO microparticles resulted in an increase in roughness (RMS) to 3.9 μm ± 0.4 μm, resulting in a superhydrophobic surface. This invention provides a relatively simple and straightforward method for fabricating drainage implants with promising biological and mechanical properties, with great potential for application in MIGS.

[0118] In vitro experiments revealed the ability of t-ZnO microparticles alone and in combination with a polymeric matrix to inhibit cell proliferation while avoiding toxic effects.

[0119] On the other hand, in vitro experiments using rat embryonic fibroblasts revealed that cell viability was significantly reduced to 57% ± 8% and 43% ± 3% for drainage implants containing 60% and 75% t-ZnO by weight, respectively. The cell-inhibitory properties may be due to the increased amount of protruding t-ZnO particles on the implant surface, which leads to increased local contact with cells and disruption of cell membranes. As a secondary mechanism, released Zn ions may also contribute to the cell-inhibitory properties in the immediate vicinity of the implant surface.

[0120] On the other hand, when HTFs were used, we demonstrated that experimental wounds closed much more slowly when preincubated with t-ZnO microparticles. t-ZnO microparticles effectively inhibited HTF proliferation, migration, and transdifferentiation. The antifibrotic and anti-inflammatory properties of t-ZnO were demonstrated by suppressing the expression of Ki67, α-SMA, and pSMAD, as well as reducing the synthesis of cytokines IL-6 and HGF. Expression of Ki67, SMA, and pSMAD was significantly downregulated in vitro after short-term treatment with t-ZnO for 6 hours, demonstrating the suppression of fibroblast proliferation, migration, and mesenchymal transition function. This potentially indicates a long-term antifibrotic effect without the need for repeated treatment.

[0121] Cell viability decreased only at higher t-ZnO dosages. The changes in cell morphology appeared to be related to the presence of t-ZnO microparticles on the cell surface. This may explain why surfaces displaying such t-ZnO microparticles resulted in lower HTF colonization of implants compared with matrix materials in the absence of t-ZnO. Direct contact with t-ZnO microparticles appears to be an absolute requirement for the inhibitory effect, since areas of the cell culture away from the structured material were well covered with cells. Therefore, it can be hypothesized that the inhibitory mechanism is primarily related to the morphology of the t-ZnO microparticles, which present an obstacle for cells that need to adhere before they can migrate and proliferate.

[0122] Therefore, short-term exposure of scleral flaps and conjunctiva to t-ZnO during glaucoma surgery may be an appropriate option for delivering high concentrations of t-ZnO. A sustained-release system or coated implants may be suitable for using low concentrations of t-ZnO microparticles to inhibit excessive wound healing. Long-term treatment with high concentrations of t-ZnO (10 μg / mL and 20 μg / mL) was associated with morphological changes in fibroblasts, such as loss of fibroblast spindle shape and decreased fibroblast cytoplasm. Given that cellular uptake of tetrapod-like particles can be eliminated (Papavlassopoulos et al., 2014. Toxicity of functional nano-micro zinc oxide tetrapods: impact of cell culture conditions, cellular age, and material properties. PloS one.9(1):e84983), the observed toxicity may be due to disruption of cell membranes by the tips of t-ZnO microparticles.

[0123] The antifibrotic effect of t-ZnO microparticles manifested itself as inhibition of HTF migration, proliferation, and transdifferentiation. Furthermore, the concentration of HGF in the culture supernatant samples was lower compared to the control before t-ZnO application (Figure 8). Because HGF stimulates cell proliferation, motility, morphogenesis, and angiogenesis, the reduction of HGF levels may be one of the mechanisms by which t-ZnO microparticles exert their antifibrotic effect.

[0124] Lower IL-6 concentrations in the culture supernatants with t-ZnO treatment indicate the anti-inflammatory effect of t-ZnO (Figure 8). IL-6 is a pleiotropic cytokine involved in the proliferation and differentiation of many cell types. t-ZnO treatment was able to suppress IL-6 production by HTFs even at concentrations as low as 1 μg / mL. This decrease in IL-6 may reflect the antiproliferative potential of t-ZnO but may also be related to its potential toxic effects at higher concentrations. The lower IL-6 concentration may also reflect a milder inflammatory response after treatment with t-ZnO compared with untreated controls.

[0125] Here, t-ZnO is proposed as a novel anti-scarring agent with the potential to contribute to effective wound control after glaucoma surgery. Generally, ZnO nanoparticles are one of the most widely used nanomaterials in biomedicine and have recently been described as selective killers of rapidly proliferating cells, while differentiated cells remain unaffected. Therefore, proliferating HTFs after glaucoma filtration surgery may also be targeted by ZnO nanoparticles. However, ZnO nanoparticles may also be cytotoxic to surrounding non-proliferating tissues, which could lead to conjunctival destruction and subsequent postoperative intraocular hypotension. To overcome these potential issues, we propose a tetrapod-like ZnO structure. t-ZnO microparticles have lower cytotoxic potential than spherical ZnO nanoparticles (Zarbin et al., 2010. Nanomedicine in ophthalmology: the new frontier. Am J Ophthalmol. 150(2):144-162.e2). Furthermore, they exert their cytotoxic effects through direct cell contact and, to a lesser extent, through free zinc ions, which may be useful for ensuring more localized antiproliferative effects and fewer side effects. The tetrapod-like structure of the t-ZnO microparticles used in this study consists of a zincblende-type ZnO core with four ZnO arms radiating from a wurtzite-type structure (Figure 1). This relatively large, biologically active structure prevents cellular uptake and preserves the specific properties of the tetrapod tips (Papavlassopoulos et al., 2014. Toxicity of functional nano-micro zinc oxide tetrapods: impact of cell culture conditions, cellular age, and material properties. PloS one.9(1):e84983).

[0126] Previous studies have demonstrated the antibacterial effect of ZnO nanoparticles against, for example, Staphylococcus aureus or Streptococcus agalactiae (Huang et al., 2008. Toxicological effect of ZnO nanoparticles based on bacteria. Langmuir 24(8):4140-4; Reddy et al., 2007. Selective toxicity of zinc oxide nanoparticles to prokaryotic and eukaryotic systems. Appl Phys Lett. 90(213902):2139021-3). Staphylococcus and Streptococcus species play the most important role in postoperative bleb infections and endophthalmitis. In this sense, t-ZnO microparticles may have a local antiproliferative effect, thus not only minimizing postoperative fibrosis but also reducing the risk of postoperative infection.

[0127] In conclusion, t-ZnO microparticles were shown to inhibit wound healing processes such as fibroblast proliferation, migration, transdifferentiation, and cytokine release. Thus, t-ZnO microparticles represent an innovative approach both for wound healing modulation in ocular surgery and as a material for ocular implants.

[0128] The drainage implant of the present invention reduced IOP in vivo for as long as two weeks. A limitation of this study is that the drainage implant of the present invention was not compared with other implants lacking microparticles. However, a previous study using the same model but a different implant demonstrated normal intraocular IOP levels within one week. In this study, a poly(styrene-b-isobutylene-b-styrene) (SIBS) drainage implant was compared with a silicone drainage implant, which had outer diameters of 250 ± 10 μm and 640 ± 15 μm, respectively. Furthermore, both the SIBS and silicone drainage implants had internal lumens of 65 ± 10 μm and 300 ± 10 μm, respectively (Acosta et al., 2006. A newly designed glaucoma drainage implant made of poly(styrene-b-isobutylene-b-styrene): biocompatibility and function in normal rabbit eyes. Arch Ophthalmol. 124(12):1742-1749). Nevertheless, their functional success, ie, reduction in IOP in the operated eye, was not as long-lasting as that of the drainage implant of the present invention.

[0129] The biocompatibility of the drainage implant of the present invention was very good: after 42 days, only individual encapsulations were observed, but a longer observation period is necessary to be able to make statements about long-term tolerance.

[0130] Here, a drainage implant design without a lumen was used. Drainage implants currently in clinical use, such as XEN™ or Preserflo™, have lumens. Implementing a lumen should improve aqueous humor outflow and further reduce IOP.

[0131] In summary, both in vitro and in vivo studies using the drainage implant of the present invention demonstrated functional and biocompatibility effects that were more favorable than those of comparable studies using commercially available devices. Nevertheless, further experiments, including long-term follow-up studies of at least several months, optimization of the implanted device and surgical implantation procedure, are necessary before clinical trials can begin.

Claims

1. A biocompatible structured material comprising a polymeric matrix and tetrapod-like ZnO particles (t-ZnO) and / or fragments thereof, a) the t-ZnO particles have a core and arms, with an arm length of about 0.5 μm to about 100 μm, a core diameter of about 0.8 μm to about 5 μm, and a tip diameter of about 0.05 μm to the core diameter or less; b) the weight fraction of the t-ZnO particulates and / or fragments thereof is about 20 to about 90 weight percent; c) A biocompatible structured material, wherein the t-ZnO particulates and / or fragments thereof are embedded in the polymeric matrix and / or partially protrude from the matrix on the surface of the biocompatible structured material.

2. The biocompatible structured material of claim 1 , wherein the polymeric matrix comprises an elastomer.

3. 3. The biocompatible structured material of claim 2, wherein the polymeric matrix comprises a poly- and / or oligo-siloxane, preferably polydimethylsiloxane (PDMS).

4. 4. The biocompatible structured material of claim 1, wherein the t-ZnO particulates and / or fragments thereof form a substantially interconnected network structure embedded in the polymeric matrix.

5. 5. The biocompatible structured material of any one of claims 1 to 4, wherein the t-ZnO particulates and / or fragments thereof are uniformly distributed in the matrix throughout the material.

6. 1. A biocompatible structured material comprising a polymeric matrix having substantially interconnected tunnel-shaped pores, a) a majority of the tunnel-shaped pores form tetrahedron corners at pore junctions; b) the tunnel-shaped pores have an average tunnel diameter of about 0.05 to about 5 μm; c) the tunnel-shaped pores have an average tunnel length of about 0.5 μm to about 100 μm; d) A biocompatible structured material, wherein said polymeric matrix has a tunnel density of from about 4 to about 65 volume percent.

7. 7. The biocompatible structured material of claim 6, wherein the biocompatible structured material is obtained by partially or completely removing the t-ZnO microparticles and / or fragments thereof from the polymeric matrix of the biocompatible structured material of any one of claims 1 to 5 by acid hydrolysis.

8. 8. An implantable device comprising the biocompatible structuring material of any one of claims 1 to 7, wherein the implantable device is an orthopedic implant, a dental implant, a cardiovascular implant, a neurological implant, a neurovascular implant, a gastrointestinal implant, a muscular implant, or an ocular implant.

9. 10. The implantable device of claim 8, wherein the implantable device is a glaucoma drainage implant having the shape of a substantially straight, flexible, elongated body having a substantially circular or polygonal cross section.

10. 10. The implantable device of claim 9, wherein the glaucoma drainage implant is comprised of a substantially straight, flexible, generally cylindrical body preferably having a length of about 5 to about 20 mm and an outer diameter preferably of about 0.1 to about 5 mm.

11. The implantable device of any one of claims 8 to 10, wherein the body of the implantable device further comprises a lumen.

12. A method for preparing an implantable device according to any one of claims 8 to 11, comprising the steps of: a) providing a homogeneously mixed composition comprising the monomer components of the polymeric matrix and t-ZnO and / or its fragments; b) extruding the composition and polymerizing it; c) cutting said polymeric material to a desired length.

13. 13. The method of claim 12, further comprising using a masking material selected from the group comprising polymer fibers and metal wires to mask a portion, e.g., a central region, during the extrusion process, and removing the masking after extrusion.

14. 14. The method of claim 12, further comprising partially or completely removing the t-ZnO particles with an acidic solution.

15. 12. A method for reducing intraocular pressure in the eye of a mammalian subject in need thereof, comprising implanting one or more implantable devices according to any one of claims 9 to 11 into the eye.

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