Antimicrobial polymeric surfaces

Abstract

Bactericidal compositions are disclosed that comprise a polymeric compound immobilized on a material. Medical devices are also disclosed which comprise such a bactericidal composition. Methods are disclosed for covalently derivatizing the surfaces of common materials with an antibacterial polycation, e.g., poly(vinyl-N-pyridinium bromide); the first step of the methods involves coating the surface with a nanolayer of silica. Various commercial synthetic polymers derivatized in this manner are bactericidal, i.e., they kill on contact up to 99% of deposited Gram-positive and Gram-negative bacteria, whether deposited through air or water.

Description

RELATED APPLICATIONS [0001] This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 60 / 285,883, filed Apr. 23, 2001; U.S. Provisional Patent Application Ser. No. 60 / 340,078, filed Dec. 10, 2001; and U.S. Provisional Patent Application Ser. No. 60 / 368,495, filed Mar. 29, 2002.GOVERNMENT SUPPORT [0002] This invention was made with support provided by the National Institutes of Health (Grant No. GM26698) and the National Science Foundation (Grant No. DMR-9400334); therefore, the government has certain rights in the invention.BACKGROUND OF THE INVENTION [0003] Due to the ever-growing demand for healthy living, there is a keen interest in materials capable of killing harmful microorganisms. Such materials could be used to coat surfaces of common objects touched by people in everyday lives, e.g., door knobs, children toys, computer keyboards, telephones, etc., to render them antiseptic and thus unable to transmit bacterial infections. Since ordinary...

AI Technical Summary

Benefits of technology

[0019] One aspect of the present invention is directed to antimicrobial surfaces comprised of covalently attached amphipathic compounds. In certain embodiments, a surface of the present invention acts to eliminate airborne biologics on contact. In certain embodiments, a surface of the present invention acts to eliminate waterborne biologics on contact. In certain embodiments, a surface of the present invention acts to prevent the formation of biofilms.

Problems solved by technology

Although these strategies have been verified in aqueous solutions containing bacteria, they would not be expected to be effective against airborne bacteria in the absence of a liquid medium; this is especially true for release-based materials, which are also liable to become impotent when the leaching antibacterial agent is exhausted.

Infection is a frequent complication of many invasive surgical, therapeutic and diagnostic procedures.

For procedures involving implantable medical devices, avoiding infection can be particularly problematic because bacteria can develop into biofilms, which protect the microbes from clearing by the subject's immune system.

As these infections are difficult to treat with antibiotics, removal of the device is often necessitated, which is traumatic to the patient and increases the medical cost.

Antibiotics typically treat the infection caused by the planktonic organisms, but fail to kill those sessile organisms protected in the biofilm.

Antibodies and host immune defenses are ineffective in killing the organisms in the biofilm, even though these organisms have elicited the antibody and related immune response.

This phenomenon can also give rise to local inflammation around implanted medical devices and bone resorption with loosening of orthopedic and dental implants.

Many patients in a hospital setting have compromised immune systems, rendering them more vulnerable to invasive infections once a biofilm community has become established.

Patients requiring implantable medical devices may likewise have compromised immune systems, whether on a short-term or long-term basis.

A poorly functioning immune system puts the host at greater risk for initial formation of a contaminated biofilm around a medical device and for the invasion of planktonic organisms into the surrounding tissues and the system.

Once the planktonic organisms mount a full-scale infection, the immunocompromised host will be less likely to contain and control it, with potentially lethal results.

Protected from antibiotic treatment and host defenses, the microorganisms in a biofilm typically cause recurrent infections and low-grade local symptoms.

If the material being removed is essential for health, a similar article may need to be replaced in the same location; the replacement article will be especially prone to infection because of the residual microorganisms in the area.

Biofilms adversely affect medical systems and other systems essential to public health such as water supplies and food production facilities.

Despite these technologies, contamination of medical devices and invasive infection therefrom continues to be a problem.

The presence of these organisms can result in infection of hospitalized patients and medical personnel.

Even barrier materials, such as gloves, aprons and shields, can spread infection to the wearer or to others in the medical environment.

Certain biocidal agents, in quantities sufficient to interfere with biofilms, also can damage host tissues.

As a further problem, it is possible that materials added to the surfaces of implantable devices to inhibit contamination and biofilm formation may be thrombogenic.

For example, it has been shown that contact with metal, glass, plastic or other similar surfaces can induce blood to clot.

However, there are few known products in the medical arsenal whose antimicrobial effects are combined with antithrombogenic effects.

In these settings, clot formation can obstruct the flow of blood through the conduit and can furthermore break off pieces called emboli that are carried downstream, potentially blocking circulation to distant tissues or organs.

Water cooling towers for air conditioners are well-known to pose public health risks from biofilm formation, as episodic outbreaks of infections like Legionnaires' Disease attest.

Turbulent fluid flow over the surface does not provide protection: biofilms can form in conduits where flowing water or other fluids pass, with the effects of altering flow characteristics and passing planktonic organisms downstream.

Industrial fluid processing operations have experienced mechanical blockages, impedance of heat transfer processes, and biodeterioration of fluid-based industrial products, all attributable to biofilms.

Biofilms are a constant problem in food processing environments.

Meat processing and packing facilities are in like manner susceptible to biofilm formation.

Controlling biofilms and microorganism contamination in food processing is hampered by the additional need that the agent used not affect the taste, texture or aesthetics of the product.

Images