Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Peptide containing doai
Reexamination Certificate
1999-04-29
2004-07-06
Tate, Christopher (Department: 1654)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Peptide containing doai
C514S002600, C530S300000
Reexamination Certificate
active
06759388
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention provides comblike surfactant polymers that are useful for changing the surface properties of synthetic biomaterials, particularly implantable biomaterials.
The use of synthetic biomaterials to sustain, augment, or completely replace diseased human organs has increased tremendously over the past thirty years. Synthetic biomaterials are used in synthetic implants such as vascular grafts, heart valves, and ventricular assist devices that have cardiovascular applications. Synthetic biomaterials are also used in extracorporeal systems and a wide range of invasive treatment and diagnostic systems. Unfortunately, existing biomaterials suffer from well-known problems associated with surface-induced thrombosis or clot formation, such as thrombotic occlusion and thromboemboli, and infection.
There have been several attempts to create nonthrombogenic surfaces on synthetic implants thereby increasing the blood-biocompatibility of implants. Early attempts included precoating the implants with proteins not involved in thrombosis, such as albumin, to mask the thrombogenic surface of the implant. However, such implants lose their nonthrombogenic properties within a short time. Attempts have been made to mask the thrombogenic surface by coating gelatin onto implants such as ventricular assist devices. While the gelatin coating reduced the thrombus formation, it did not adhere to the implant and it did not prevent thromboemboli and infection.
Attempts have been made to render implants nonthrombogenic by coating the surface of the implant with polyethylene oxide to mask the thrombogenic surface of the implant. At times this treatment reduced protein adsorption and thrombogenesis However, the coupling of polyethylene oxide to the surface of the implant involves complex chemical immobilization procedures. Moreover, the coated implants do not consistently exhibit protein resistance because of the lack of control over the density of immobilized polyethylene oxide.
There have been many attempts to prepare nonthrombogenic surfaces by attaching heparin to biomaterials. However, each method requires complex immobilization procedures such that the implant surface be first modified by attachment of a coupling molecule before heparin can be attached. For example, the positively charged coupling agent tridodecylmethylammonium chloride (TDMAC) is coated onto an implant, which provides a positively charged surface and allows heparin which has a high negative charge density, to be attached. However, the heparin slowly dissociates from the surface, to expose the positively charged TDMAC surface, which is particularly thrombogenic. Thus, the TDMAC heparin coated implant is successful only for short term implants such as catheters.
Despite these considerable research efforts, synthetic biomaterials and medical devices made from such biomaterials still suffer well-known problems associated with surface-induced thrombosis and infection. Accordingly, it is desirable to have new materials that can be used to coat biomaterials and to change their surface properties. Materials that are useful for preventing undesirable adhesions, such as proteins, or promoting desirable adhesions, such as endothelial cells are especially desirable.
SUMMARY OF THE INVENTION
In accordance with the present invention, novel, comblike, surfactant polymers which are useful for changing the surface properties of biomaterials are provided. Such surfactant polymers comprise a polymeric backbone of repeating monomeric units having functional groups for coupling with side chains, a plurality of hydrophobic side chains linked to said backbone via the functional groups, and a plurality of hydrophilic side chains linked to said backbone via the functional groups. The hydrophobic side chains comprise an alkyl group (CH
3
(CH
2
—)
n
) comprising from about 2 to 18 methylene groups. The alkyl groups are linked to the polymeric backbone through ester linkages, secondary amine linkages, or, preferably, amide linkages. The hydrophilic side chain is selected from the group consisting of: a neutral oligosaccharide, which, preferably, has weight average molecular weight of less than 7000; a charged oligosaccharide, preferably a negatively charged oligosaccharide having a weight average molecular weight of less than 10,000; an oligopeptide of from about 3 to about 30 amino acid residues, said oligopeptide having an amino acid sequence which interacts with protein receptors on the surface of cells; and combinations thereof. A preferred amino acid sequence which is known to interact with molecules on the surface of cells is arginine (R), glycine (G), and aspartic acid (D). The hydrophilic side chains are linked to the polymeric backbone through ester linkages, secondary amine linkages, or, preferably, amide linkages. It has been shown that effective surface modification of biomaterials can be accomplished using the surfactant polymers of the present invention without any requirements for surface coupling chemistries.
The present invention also provides an implantable, biomaterial having a comblike surfactant polymer of the present invention coated on a hydrophobic surface thereof.
REFERENCES:
patent: 5741852 (1998-04-01), Marchant
patent: 5897955 (1999-04-01), Drumheller
Qiu, “Novel oligosaccharide surfactant polymers derived from poly(vinylamine) with pendant dextran and hexanoyl groups” 1998, Macromolecules, vol. 31, pp. 165-171.*
Marchant, “Biosynthetic surfactants: novel biomimetic surface modifications for biomedical deposit resistance” 1997, American Chemical Society Conference.*
“Biomimetic engineering of non-adhesive glycocalyx-like surfaces using oligosaccharide surfactant polymers” by Holland, et al.Nature,vol. 392, Apr. 23, 1998, pp. 799-801.
Marchant Roger E.
Qiu Yongxing
Ruegsegger Mark A.
Zhang Tianhong
Benesch Friedlander Coplan & Aronoff LLP
Nanomimetics, Inc.
Tate Christopher
Teller Roy
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