Composition and method for preparing biocompatible surfaces

Abstract

The invention provides methods and compositions for providing biocompatible surfaces to medical articles. In particular the invention provides biocompatible coatings with heparin activity. In some aspects, the biocompatible coatings of the invention are able to release a bioactive agent. The coatings can be formed using biostable or biodegradable polymeric material and photoreactive groups. The invention also provides methods for improving the quality of bioactive agent-containing coatings by performing pre-irradiation of biocompatible coating compositions.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of patent application Ser. No. 11 / 090,655, filed Mar. 25, 2005, now U.S. publication No. 2005 / 0244453A1 and entitled COMPOSITION AND METHOD FOR PREPARING BIOCOMPATIBLE SURFACES, which claims the benefit of U.S. Provisional Application No. 60 / 556,634, filed on Mar. 26, 2004, and entitled PROCESS AND SYSTEMS FOR BIOCOMPATIBLE SURFACES; U.S. Provisional Application No. 60 / 568,021, filed on May 3, 2004, and entitled COMPOSITION AND METHOD FOR PREPARING BIOCOMPATIBLE SURFACES; U.S. Provisional Application No. 60 / 640,602, filed on Dec. 31, 2004 and entitled COMPOSITION AND METHOD FOR PREPARING SURFACES WITH BIOCOMPATIBILITY; and U.S. Provisional Application No. 60 / 567,915, filed on May 3, 2004, and entitled DRUG RELEASE COATING WITH BLOOD COMPATIBLE POLYMERIC TOPCOAT, which Applications are incorporated herein by reference in their entirety.FIELD OF THE INVENTION [0002] The invention relates to preparation o...

AI Technical Summary

Benefits of technology

[0058] Another advantage of the present invention is that a biocompatible coating can be formed on the surface of a bioactive agent-releasing layer without significantly compromising the bioactive agent-releasing properties of the coating. For example, a coating with heparin activity can be formed on a medical article having a drug-releasing layer without significantly altering the drug releasing profile of the coating. Also, according to the invention, the presence of a bioactive agent-releasing layer does not compromise the formation or properties of a coated layer having biocompatible properties, such as heparin activity. Such results are seen because the present invention overcomes typical problems that can be encountered when multiple layers of coated materials are provided to a surface in order to provide a coating having more than one property. Therefore, in this regard, the properties of the inventive coatings described herein with regard to biocompatibility (e.g., heparin activity) and bioactive agent release are particularly surprising, as one would not expect that the biocompatible and drug-releasing properties would be maintained at levels that were achieved by preparation of these coatings not in combination. In other words, while it was expected that the combination of coated layers would lead to a decrease in the activity of each layer, this expectation, in fact, was not realized based on the results seen when bioactivity and drug release were tested on the inventive coatings described herein.

[0059] Yet another advantage of preferred embodiments of the invention is that it can provide methods for the preparation of biocompatible coating compositions that include polymeric materials which are typically difficult to combine and / or do not form a coated layer that has suitable activity or physical properties. Accordingly, the invention also provides methods for forming a coated layer on the surface of a medical article that includes combinations of these types of polymeric materials. The present invention overcomes problems, specifically, with preparing a coating composition that includes a hydrophilic biocompatible polymer and a hydrophobic polymeric material. The present invention not only overcomes challenges posed with the preparation of these coating compositions, but also challenges associated with forming a coating on the surface of an article, wherein the polymeric components are well dispersed (or mixed) in the coating and have properties that are reflected by the presence of both the hydrophilic biocompatible polymer and a hydrophobic polymeric material.

[0060] Yet another advantage of preferred embodiments of the invention is seen from results showing that the biocompatible bioactive-agent releasing coating has excellent durability. Test results demonstrate that the coating is durable and retains good biocompatible properties after the article has been subject to physical stresses. Such physical stresses may otherwise cause inferior (unacceptable) coatings to crack or delaminate from the surface of the device, thereby compromising the function of the coating by reducing, for example, biocompatible activity. Physical stresses can be encountered at one or more points during processes involving use of the article, including insertion of the article into the body.

[0061] Excellent biocompatible properties were also observed after the coated article was placed in a biochemical environment simulating the biochemical stresses that are encountered when the coated article is placed in vivo. It is generally desirable to form coatings that not degrade and that are not fouled by the presence of body fluids such as blood. Rather, it is desirable that the coatings display prolonged biocompatible activity in conjunction with the function of the device. Results of analysis of the inventive coatings described herein demonstrate that the coated articles are resistant to losing biocompatible properties even after the coated articles have been placed in conditions that simulate a physiological environment for an extended period of time.

[0062] Still yet another advantage of the invention is the ability to pre-treat components that are associated with the biocompatible coated layer, prior to disposing the biocompatible coating composition on an article having a bioactive agent coated layer. “Pre-treating” refers to applying a source of energy, such as actinic radiation (e.g., UV irradiation), that activates the photoreactive groups that are present in the biocompatible coating composition. These photoreactive groups are activated as a step in the process of forming the biocompatible layer, and generally serve to couple the polymeric agents that are present in this composition. While the step of applying a source of energy to the biocompatible composition can be performed before or after the composition is coated on the article, in many instances it is desirable to perform this step prior to disposing the composition. For example, a clear benefit of pre-treatment would be avoiding irradiating the article having a bioactive coated layer that includes a bioactive agent that is sensitive and, for example, can become inactive (for example, by degradation), upon exposure to this irradiation. Advantageously, the biocompatible coating composition that was pre-treated and disposed on an article having a bioactive agent-containing layer was able to form a layer having excellent biocompatible properties and that also provided an overall coating that demonstrated excellent bioactive agent release profiles. Therefore, this pre-treatment method preserves the quality of bioactive agents.

[0063] The invention will now be described in more detail.DETAILED DESCRIPTION

Problems solved by technology

However, the molecular weight, porosity of the polymer, a greater percentage of coating exposed on the medical device, and the thickness of the polymer coating can contribute to adverse reactions to the medical device.

The materials used for manufacture of medical devices are not inherently compatible with blood and its components, and the response of blood to a foreign material can be aggressive, resulting in surface induced thrombus (clot) formation.

This foreign body response can in turn impair or disable the function of the device and, most importantly, threaten patient health.

The preparation of biocompatible surfaces, however, can be challenging.

Materials that are used to form these coating may not be inherently compatible with each other, thereby making it difficult to form a coating that is both biocompatible and that has drug-releasing properties.

In addition, treatments that are used to form coatings can in some cases damage the bioactive agent and therefore reduce the overall effectiveness of the coated article.

Irradiation sources can be useful for activating components of a coating composition to form the coating, but can also lack the specificity and therefore cause degradation of the bioactive agent that is present in the coating.

Another problem relates to the release of bioactive agent, as some materials release the bioactive agent immediately upon contact with tissue; therefore the bioactive agent is not present for an amount of time sufficient to provide a beneficial effect.

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