AU2020102595A4

AU2020102595A4 - Novel osteoconductive material composition and coating thereof.

Info

Publication number: AU2020102595A4
Application number: AU2020102595A
Authority: AU
Inventors: Lekshmi Gangadhar; Renuka Devi Pothuraju; Teja Putti venkata Siva; Siva Sankar Sana; Abhishek Nalluri
Original assignee: Sana Siva Sankar Dr; Gangadhar Lekshmi Dr; Pothuraju Renuka Devi Miss
Current assignee: Sana Siva Sankar Dr; Gangadhar Lekshmi Dr; Pothuraju Renuka Devi Miss
Priority date: 2020-10-05
Filing date: 2020-10-05
Publication date: 2020-11-26
Anticipated expiration: 2028-10-05

Abstract

The disclosed osteocondcutive material composition 1 is tailored to intensify the regeneration process. The grafts developed by the composition mentioned in the claims has proven to demonstrate expedited healing by promoting blood vessel in growth and bone formation phenomena. The proposed composition is applied over the implants 2 for accelerated regeneration and improved bio compatibility with the body fluids and tissues. Few bio-metals which were prone to corrosion and degradation are made to fit the needs by applying an coating 1, developed by the proposed material composition. The method and parameters of such is disclosed wherein a plasma spray technique is used in this invention. ......................... 1 -2 FIG. 1. FIG. 2. FIG. 3.

Description

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FIG. 1.

FIG. 2.

FIG. 3.

AUSTRALIA Patents Act 1990

COMPLETE SPECIFICATION INNOVATION PATENT

Novel osteoconductive material composition and coating thereof.

The following statement is a full description of this invention, including the best method of performing it known to us:

Novel osteoconductive material composition and coating thereof TECHNICAL FIELD

The present disclosure relates to a osteoconductive material composition and a coating produced therefore.

DEFINITION

In the present specification and claims the term "comprising" shall be understood to have a broad meaning similar to the term "including" and will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the term "comprising" such as "comprise" and "comprises".

BACKGROUND

Bone implants design and integration into the human and animal life forms is often a baffling and daunting phenomenon.

With rise in global population and accidents, there is a great need to accelerate the bone and tissue healing and regeneration processes. During the times of injury or other events, the implants are produced based on the targeted bone dimensions of the individuals.

Introducing a foreign element in living bodies must be meticulously engineered due to its critical aftereffects. The materials for scaffolds for human body implants should possess properties such as biological compatibility, corrosion resistance and should support tissue growth.

Ease of manufacturing, osteoconduction supportive and comparable bone stiffness has made metals as a promising implant material. However, on the contrary, most of the approved metals for biomedical applications have shown degradation due to corrosion when prolonged exposure to body fluids.

There are many metals based bio-compatible materials that were widely used in the biomedical fields such metals include Nickel- Ni; Titanium-Ti and few grades of stainless steels materials. Addressing the issue of the corrosion inhibition and promoting tissue regeneration phenomena are crucial.

The material design for improved tissue regeneration and coating of such on the implants are disclosed in the resent invention.

SUMMARY

To improve healing of injuries and bones fractures,metal based biomaterials are widely used. These metals often results in corrosion and degradation when exposed to body fluids for prolonged periods. Moreover,due to the structural differences between metallic implants and human bones, the healing time is more than expected in most cases.

The most powerful features of bone implant materials are corrosion resistance, biocompatibility, wear resistance, bone stiffness match, and enhanced bone growth. There are numerous materials and deposition techniques developed for biomedical applications especially in the areas of orthopedic and bone grafting.

To improve bone- implant interactions, a tailored coating material composition is required for enhanced osteointegration phenomena and should be an ideal coating material on the bone implants. The deposition of coatings such as hydroxyapatite Ca 1 O(PO4 )e (OH) 2 ) (HA), polycaprolactone (PCL), di-calcium phosphate CaHPO 4.2H 2 0 (CA) and oxides such as TiO 2 , A1 203 have been significantly researched.

In the present invention, an optimized coating composition constitutes a mixture of HA and CA; the coatings greatly improves specific bone in-growth and supports osteointegration. The most widely researched deposition techniques include sol-gel, electrodeposition & electrochemical coatings, thermal spray techniques such as high-velocity oxy-fuel-based deposition, plasma spraying.

Above all, suspension plasma spraying technique is selected for the present invention disclose. this method is opted for obtaining high surface area which promotes tissue regrowth and bone healing as well as good adhesion strength at the implant interface.

The in-lab synthesized powders or commercial grade powders are procured according to the need. Later, subjected to ball milling and the ball milled powder was sieved to remove coarse grained particles. About 8 g of the fine powder was mixed with 1 g of sodium hexametaphophate.

In the subsequent step, the stated mixture is ultrasonicated for 5 min to get a stable suspension for suspension plasma spraying. The nozzle diameter of spray gun is 0.8mm.

As disclosed in the above statement, the adhesion strength is promoted by customizing the coat layer with by adding fractions of titanium dioxide in the range 3 to 5.5%. a range of particle sizes are used to optimize implant bond strength.

For the second pass, the plasma plume is fed with the mixture of HA and CA.

One major factor for promoting healing and better interaction with other tissues is by improving the surface area of the coat layer. Nevertheless, a trade-of between surface area and adhesion strength has to be engineered for biomedical applications.

The Suspension precursor plasma spraying of hydroxyapatite HA and CA novel composition on the the interface biomedical implants. Defined proportions are disclosed in the claims.

Example 1:

In one experimental case study, the suspension of 62.5% of (HP, Caio(PO4) (OH) 2 ), and 44% of (CaHPO 4.2H 20) along with 3.5% of nano titania powder for first pass and 82% of (HP, Caio(PO4)e (OH) 2 ), and 18% of (CaHPO 4 .2H20) for second pass.

Example 2:

In another experiment, suspension of 76% of (HP, CaO(PO 4 )e (OH) 2 ), and 19.5% of (CaHPO4.2H 20) along with 4.5% of nano titania powder for first pass and 86% of (HP, Ca1O(PO 4 )e (OH) 2 ), and 14% of (CaHPO 4.2H 20) for second pass.

The plasma operating parameter and feed rates are also optimized after series of experiments.

The suspension precursor is made to flow through the spray gun of standard 0.8mm nozzle diameter.The spray is be operated at different powers and feed rates along with carrier gases.

During suspension from the spray gun enters the plasma plume and gets carried by the feed gas.The particles gets melted and traverses with high speed and hits the target and bonds to the Ti-6Al-4V and Stainless steel implants.

Several experiments were carried out with changes in processing parameters.

Example 1:

Suspension is plasma sprayed at distance of 80mm at a feed rate of 35 ml/min operated at power range of 28KW for the first pass and the feed rate is increased to 30 KW during the second pass at constant distance and carriers gases.

Example 2:

The suspension is prepared with greater loading capacity of 9 g of the fine HA and CA powders mixed with 1 g of sodium hexametaphophate. In the volume fractions as mentioned in the materials composition example 2. The feed rate is reduced to 30ml/min keeping the other variables same as above stated example. This is ideal for first pass as it results in dense and thick layer.

BRIEF DESCRIPTION OF DRAWINGS

The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings, in which:

Fig 1 schematic illustration of the osteocondcutive coating layer on the substrate(biomedical implant)

Fig 2. illustrates the balled milled powder of the disclosed mixture composition by scanning electron microscopy at 0.2pm magnification.

Fig 3. illustrates a coated layer onto medical implants by scanning electron microscopy at 10pm magnification.

DETAILED DESCRIPTION

In fig 1. the coat layer 1 is a two component layer on the implant 2 the during first pass a composite mixture of HA and CA along with titanium dioxide. Whereas the second pass constitutes HA and CA exclusively.

The illustration as in fig1 the coat layer 1 need not be necessarily be a mixture of CA and HA it can also be a single elemental composition material either HA or CA respectively.

The substrate or base element 2 in fig 1. can be any metallic bio-material and need not be confined to metallic materials. The most commonly used implant materials are considered which include Titanium; nickel and few grades bio-compatible of stainless steels.

The Fig2. is an scanning electron microscopy image of the ball milled powder samples of the comprising of the base elements as stated for coat layer. The powder are thoroughly mixed in planetary ball milling. This step during processing is also used to reduce the particle size of the powder.

As in Fig3. which depicts the surface image of the coat layer on the implant produced by scanning electron microscopy. It is evident that the coat layer thus obtained is rough and porous.

Claims

The claims defining the invention are as follows:

1. The material composition for biomedical implants, and the coating route along with its operating parameters are claimed in the present invention. The materials composition includes a mixture with various weight fractions which are bio-compatible and osteoconduction supportive in nature. Furthermore, it also catalyzes tissue growth. The disclosed composition is also effective as a coating layer on the metal based biomedical implants for hindering corrosion when exposed to body fluids.

2. The material as stated in claim 1, is a mixture which constitutes, 58% to 86% of (HP, Calo(PO4)6 (OH) 2 ), and 32% to 45% of (CaHPO 4 .2H 20) along with 3 to 5.5% of nano titania powder.

3. The material as claimed in claim 2, are materials in powder form and shows a uni-modal particle size distribution, whereas its claimed to the size regime from 1.5nm to 10pm.

4. The coating mentioned in the claim 1, is developed over the implant via suspension precursor plasma spraying. The coat produced shown a porous network framework architecture which is facilitates body fluid interaction.Two pass model is used for deposition, first pass is used to make a dense layer for better adhesion strength and second pass to improve porosity. As mentioned above, in first pass titania powder as claimed in claim 2 is used.

5. The operating parameters of the coating method as stated in claim 4, are as follows; for first pass: plasma plume is operated at 30KW power, 500 A current with spray distance of 85mm, suspension feed rate of 30 ml/min in Ar and H 2 gas environments at 50 and 8 nlpm. In case of second pass: plasma is operated at same environments as first pass and flow rates while other operating parameters are operated at deviation of ±8% to the first pass.

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FIG. 1.

FIG. 2.

10μm

FIG. 3.