# US 5,702,818 A · Biocompatability of solid surfaces

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- Number: US 5,702,818 A
- Document ID: US5702818A
- Status: Granted
- Kind: A
- Application number: 08/430,001
- Filed: 1995-04-27
- Granted: 1997-12-30
- Earliest claimed: 1993-01-19
- Assignees: Medtronic, Inc.
- Inventors: Patrick T. Cahalan; Michel Verhoeven; Marc Hendriks; Linda Cahalan
- Web page: https://patentgrep.com/patent/US5702818A

## CPC

- A61L 33/0041: {characterised by the choice of an antithrombatic agent other than heparin (heparinoïd A61L33/08; polypeptides A61L33/12)}
- A61L 33/0005: {Use of materials characterised by their function or physical properties}
- A61L 33/0029: {using an intermediate layer of polymer}
- Y10T 428/31: Surface property or characteristic of web, sheet or block
- Y10T 428/31504: Composite [nonstructural laminate]
- Y10T 428/31562: Next to polyamide [nylon, etc.]
- Y10T 428/31721: Of polyimide
- Y10T 428/31946: Next to second aldehyde or ketone condensation product
- A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An improved spacer material for improving the biocompatibility of a biomaterial and a method for making it in which a polyalkylimine is covalently attached to an aminated substrate and combined with a crosslinking agent which is at least difunctional in aldehyde groups. The polyalkylimine can be for example, polyethyleneimine and the crosslinking agent can be, for example, glutaraldehyde. Preferably, the crosslinking agent is applied in dilute solution and at a pH suitable to accomplish light crosslinking of the polyalkylimine and also provide aldehyde linkages at the interface between the biomolecule and the spacer.

## Claims

### Claim 1

A medical device having a biocompatible surface comprising:
(a) a solid surface;
(b) a first layer comprising a graft polymer of acrylamide covalently attached to the solid surface, said graft polymer including carboxylic acid groups pendant to acrylamide moieties of the graft polymer;
(c) a second layer comprising a crosslinked polyalkylimine covalently bonded to the first layer by attachment to the pendant carboxylic acid groups of the first layer; and
(d) a biomolecule covalently bonded to the second layer.

### Claim 2 (depends on 1)

A medical device according to claim 1 wherein the covalent attachment between first layer and second layer includes a linking molecule covalently bonded at a first end to a carboxylic acid group of the first layer and covalently bonded to the second layer.

### Claim 3 (depends on 2)

A medical device according to claim 2 wherein the linking molecule is a carbodiimde.

### Claim 4 (depends on 1)

A medical device according to claim 1 wherein the polyalkylimine is polyethyleneimine.

### Claim 5 (depends on 1)

A medical device according to claim 1 wherein the polyalkylimine is crosslinked by a crosslinking agent which is at least difunctional in aldehyde groups.

### Claim 6 (depends on 1)

A medical device according to claim 1 wherein the biomolecule is a cellular adhesive molecule.

### Claim 7 (depends on 1)

A medical device according to claim 1 wherein the biocompatible surface is the biocompatable surface of a blood oxygenator.

### Claim 8 (depends on 1)

A medical device according to claim 1 wherein the biocompatable surface is the biocompatible surface of a catheter.

### Claim 9 (depends on 1)

A medical device according to claim 1 wherein the biocompatable surface is the biocompatible surface of a vascular graft.