Devices with multiple surface functionality

Abstract

Phosphorus-based coatings having a plurality of phosphate moieties, a plurality of phosphonate moieties, or both, covalently bonded to an oxide surface of an implantable substrate exhibiting one or more of the following characteristics: (a) the surface phosphorus-containing group density of the coated regions of the substrate is at least about 0.1 nmol/cm²; (b) the phosphorus-based coating has a thickness of less than about 10 nm; or (c) the surface phosphorus-containing group density of the coated regions of the substrate is equal to or greater than the surface hydroxyl group density of the oxide surface of the substrate. Implantable devices embodying the coated substrates are also disclosed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application claims priority to U.S. Provisional Application No. 60 / 643,647 filed Jan. 13, 2005; U.S. Provisional Application No. 60 / 643,648 filed Jan. 13, 2005; U.S. Application No. 60 / 684,159 filed May 25, 2005; U.S. Application No. 60 / 699,498 filed Jul. 15, 2005; and, U.S. Application No. 60 / 707,525 filed Aug. 12, 2005, the entire contents of all of which are hereby incorporated by reference. [0002] This application is also a continuation-in-part of U.S. application Ser. No. 10 / 876,294, filed Jun. 23, 2004, which claims priority to U.S. Provisional Application No. 60 / 480,670, filed Jun. 23, 2003, which in turn is a continuation-in-part of U.S. application Ser. No. 10 / 405,557, filed Apr. 1, 2003, which claims priority to U.S. Provisional Application Nos. 60 / 369,236 and 60 / 369,237, both filed Apr. 1, 2002, which in turn is a continuation-in-part of U.S. application Ser. No. 10 / 179,743, filed Jun. 24, 2002, which claims prior...

AI Technical Summary

Benefits of technology

[0021] In one aspect, the present invention provides a medical device or an implantable device with one or more surface coatings covalently bonded to an oxide surface of one or more regions of the device to create different desirable surface properties on each region of the device surface. The coated medical device may be produced from an implantable substrate.

Problems solved by technology

For example, implant surfaces with long term exposure to blood may generate thrombus.

Inflammatory cells may also adhere to and proliferate on implant surfaces leading to increased inflammation and decreased healing rates.

When exposed to physiological conditions, the surface of a metal implant corrodes and leaches metal ions into the body.

Metal sensitivity may lead to implant rejection and require explantation.

Other metal ions, such as chromium, may have long term toxicity.

Infection presents a serious concern for implants.

Implantation or deployment of medical devices frequently causes injury at the site of deployment / implantation.

For example, balloon expandable stents injure the arterial wall when deployed resulting in inflammation that causes partial or complete restenosis of the artery.

Poor bonding with the interface between the metallic surface of the implant and the bone tissue leads to low mechanical strength of the bone-to-implant junction and the possibility of subsequent implant failure.

Currently, there is no effective way to obtain strong attachment of incipient bone with the implant material at the interface between the surfaces of the two materials in order to “stabilize” the implant.

The problem of interface synthesis is often approached from the prospective of high temperature methods, including using plasma or laser-induced coating techniques.

However, these methods engender problems of implant heating and surface coverage.

Therefore, control of surface stoichiometry can be problematic, and defects at the interface may translate into poor mechanical strength.

However, a practical limitation involving laser or plasma deposition is that it is hard to obtain comprehensive coverage on a titanium implant of complex 3-dimensional structure.

However, while solution-based procedures are inexpensive and give rise to materials resistant to dissolution by bodily fluids, adhesion of the hydroxyapatite to the implant metal is less strong than is observed when deposition is accomplished by plasma spraying techniques.

The deficiency of these solution approaches may lie in the nature of the native oxide surface of titanium materials.

But these phosphonic acid species fail to strongly adhere to the implant because they are not covalently bonded via heating.

In addition, Descouts does not disclose the preparation of different surface treatments on the same implant.

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