WO2002026848A2

WO2002026848A2 - In-situ bonds

Info

Publication number: WO2002026848A2
Application number: PCT/US2001/030055
Authority: WO
Inventors: Paul J. Spacek
Original assignee: Praxis Llc
Priority date: 2000-09-29
Filing date: 2001-09-26
Publication date: 2002-04-04
Also published as: AU2001294727A1; EP1335690A4; WO2002026848A3; CA2423952A1; WO2002026848B1; JP2004525660A; US6524327B1; EP1335690A2

Abstract

The invention relates to an organic hydrogel bond for living tissue. The bond is comprised of living tissue pre-treated with hydrogen peroxide, body derived fluids, including at least one NCO-terminated hydrophilic urethane prepolymer, which is derived from an organic polyisocyanate, and oxyethylene-based diols, triols or polyols comprised essentially all of hydroxyl groups capped with polyisocyanate.

Description

In-Situ Bonds

Background of the Invention

Field of the Invention

This invention relates to synthetic surgical adhesives/sealants and

tissue bonds created by reacting the adhesive with living in-situ tissue. More

specifically, a unique tissue cross-linked polyurea-urethane bond is formed

by reaction of isocyanate capped ethylene oxide diols, triols or polyols with

activated living tissue.

Prior Art

Numerous urethane forming polyisocyanate reactions have been

published, not all of them teach use as a surgical adhesive. Those that do

teach use as a surgical adhesive do not teach the unique hydrogel/tissue bond

formed in the present invention.

US Pat. No. 4,994,542 (Matsuda et al) discloses a flexible surgical

adhesive comprised of a NCO-terminated hydrophilic urethane prepolymer

derived from a fluorine-containing polyisocyanate used alone or in

combination with an unsaturated cyano compound. The high reactivity of

fluorine-containing polyisocyanate capped urethane prepolymer with water

makes it unlikely that such adhesives bond directly with untreated tissue. The addition of cyano compounds further increases the intra-polymer

reactivity. These adhesives provide a mechanical bond by infiltrating

fissures in the tissue rather than bonding directly to the nitrogenous groups

of biological tissue. They consequently produce weaker bonds.

US Pat. No. 5,173,301 (Itoh et al) discloses a NCO-terminated

hydrophilic urethane prepolymer derived from an organic polyisocyanate

and a polyol component comprising a -polyester polyol derived from an

electron-attracting group capable of being easily hydrolyzed within a living

body. The present invention is not hydrolyzed in the body.

US Pat. No. 4,743,632 Marinovic) discloses a purified diisocyanate

polyetherurethane prepolymer and polymers prepared by mixing the

prepolymer with an organic filler to produce a space filling sealant. The

purified preparations teach that each mole of diisocyanate prepolymer is

substantially matched with one mole of a chain-extending compound. The

purification process ensures no excess of isocyanate, and therefore the

reaction proceeds slowly and only weakly bonds tissue.

US Pat. No. 5,266,608 (Katz et al) discloses a non-elastomeric

adhesive for bonding to calcified tissues. The present invention teaches an

elastomeric adhesive. US Pat. No. 4,804,691 (English et al) discloses an adhesive comprised

of a hydroxyl-terminated polyester reacted with 8 to 76 weight percent

excess aromatic diisocyanate. The polyester-base polymer is degraded by the

body.

US Pat. No. 5,922,809 (Bhat et al) discloses an adhesive comprised of

a polyisocyanate, polymers having isocyanate-reactive moieties, and a triol

dispersion. The triol dispersion is not taught in the present invention.

As can be seen, many polyurethane prepolymer compositions have

been patented. Some are strongly water reactive systems and tend to

crosslink internally rather than with tissue. The resulting mechanical bond

adheres to tissue, although it does not produce a chemical bond with cellular

constituents. These bonds are weaker than those derived in the present

invention, and are insufficient for general tissue adhesive use.

In addition, cure time is an important consideration in tissue adhesive

formulation. Optimal cure time is less than 1 minute. Although fluorine-

containing isocyanates are purported to be faster reacting, they still depend

on diffusion of water into the prepolymer to be activated. Pre-mixing the

prepolymer with water or providing a hygroscopic component to the

prepolymer has not been taught. Tissue activation and rapid water uptake into the prepolymer are essential to achieve fast cures that bond tissue

chemically.

Finally, an important feature of a surgical adhesive is

biocompatibility. Those adhesives that attain strong adhesive properties use

excess quantities of polyisocyanates. Unreacted polyisocyanates present

toxicity risks. The present invention teaches a reactive wash to eliminate

residual isocyanate activity. Additionally, a high oxyethylene content is

important to achieve a fully hydrated tissue bond that resists chronic protein

adsorption and denaturation. Continued protein denaturation can provoke a

chronic inflammatory response in the body.

Summary of the invention

It is an object of the present invention to provide a chemical bond to

living tissue that is biocompatible, elastomeric, and superior in strength.

It is another object of this invention to provide an adhesive

combination for surgery having shortened cure time.

It is another object of this invention to provide an adhesive

combination of lower toxicity to tissue.

The tissue bond of this invention is achieved by cross linking to living

tissue and reacting the activated tissue with a pre-mixed aqueous solution of a high molecular weight ethylene oxide polyol or diόl end-capped with an

organic polyisocyanate.

It is one primary object of this invention to provide a surgical

adhesive that is easily applied, cures quickly, and produces a strong tissue

bond. The preparations disclosed here are liquids and can be stored at

normal hospital room temperatures, and possess long shelf life.

It is a further object of this invention to provide a surgical adhesive

that forms a stable polyurethane tissue bond that is inactivated before wound

closure.

The invention thus comprises an organic hydrogel bond comprised of

living tissue pre-treated with hydrogen peroxide, body derived fluids, at least

one NCO-terminated hydrophilic urethane prepolymer, derived from an

organic polyisocyanate and oxyethylene-based diols, triols or polyols

comprised essentially all of hydroxyl groups capped with polyisocyanate.

Substantially all of the prepolymer units are aliphatic or aromatic

isocyanate-capped oxyethylene-based diols,, triols or polyols. The molecular

weight of the diols, triols or polyols prior to capping with polyisocyanate is

at least 3,000. The polyisocyanate may be a toluene diisocyanate. The

polyisocyanate may be isophorone diisocyanate. The polyisocyanate may be

a mixture of xylene diisocyanate and 6-chloro 2,4,5-trifluoro-l,3 phenylene diisocyanate. The polyisocyanate may be a mixture of xylene diisocyanate

and tetrafluoro- 1,3 -phenylene diisocyanate. The polyisocyanate may be a

mixture of diphenylmethane diisocyanate and 6-chloro 2,4,5-trifluoro-l,3

phenylene diisocyanate. The polyisocyanate may be a mixture of

diphenylmethane diisocyanate and tetrafluoro- 1,3 -phenylene diisocyanate.

The polyisocyanate may be paraphenylene diisocyanate. The diols, triols or

polyols are capped with polyisocyanate such that isocyanate-to-hydroxyl

group ratio is between 1.5 and 2.5. The isocyanate concentration in the

prepolymer units is preferably between 0.05 and 0.8 milliequivalents per

gram. The organic hydrogel bond may further comprise a surfactant to

control foam density. The organic hydrogel bond may further comprise

hydroxyethylcellulose. The organic hydrogel bond may further comprise

hydroxypropyl-cellulose .

The invention in a further descriptive embodiment preferably

comprises a tissue crosslinked hydrophilic hydrated bond prepared by

reacting together tissue, body derived fluids and a prepolymer in a

prepolymer-to-water ratio of 3:1 to 20: 1, the prepolymer prepared by:

selecting diols, triols or polyols, substantially all of which are oxyethylene-

based diols, triols or polyols having an average molecular weight of 3,000 to

about 15,000, and reacting the diols, triols or polyols with an aliphatic or aromatic polyisocyanate at an isocyanate-to-hydroxyl ratio of about 1.5 to

2.5 so that all of the hydroyl groups of the diols, triols or polyols are capped

with polyisocyanate and the resulting prepolymer has an isocyanate

concentration of no more than 0.8 milliequivalents per gram. Preferably

substantially all of the diols, triols or polyols selected in (a) are oxyethylene-

based. Preferably the diols, triols and polyols of step (a) are dissolved in an

organic solvent selected from acetonitrile or acetone. The hydrated bond

may further preferably comprise non-body derived water, ideally saline

solution containing 0.9% NaCl. The ratio of aliphatic or aromatic

polyisocyanate at an isocyanate-to-hydroxyl ratio may preferably be

between 3:1 to 20:1. The hydrogel bond may be preferably washed with a

polyfunctional diamine to end isocyanate reactivity. The hydrated bond

tissue is preferably pretreated with 3% hydrogen peroxide.

The invention in a further embodiment preferably comprises a

surgical adhesive for preparing a hydrophilic, biocompatible seal or bond

characterized by elasticity, and resistance to decomposition within the body,

said surgical adhesive comprising of a Part A including oxyethylene-based

diols, triols or polyols having an average molecular weight in excess of

3,000, the diols, triols or polyols having all of the hydroxyl groups capped

with an aromatic or aliphatic diisocyanate. The adhesive has an isocyanate concentration up to 0.8 meq/gm., and a Part B including a saline solution

containing 0.9% NaCl and 3% H202 wherein the Parts A and B are

premixed before tissue contact in Part A-to-Part B ratios of between 3 : 1 to

20:1 to create a surgical adhesive which creates a hemostatic tissue bond

within about 3 minutes. The adhesive invention includes a fluorine

containing diisocyanate, which is added to the Part A. The adhesive

invention includes a hygroscopic material, which is added to the Part A. A

surfactant is preferably added to the Part B. The adhesive invention also

includes a hygroscopic material, which is added to the Part A and a

surfactant, which is added to the Part B. The invention further includes a

Part C to be applied after tissue contact of the mixed Parts A and B, the Part

C comprised of a polyfunctional amine such as lysine to end isocyanate

reactivity. The adhesive invention also preferably includes a method to

enhance reactivity of the adhesive when added to tissue, comprising the step

of: heating the adhesive to between 65-80 degrees C before disposition on

the tissue. The penetrating ability of the adhesive may be enhanced by the

step of: mixing a acetonitrile solvent in part 2:1 to 1:10, adhesive to solvent

to the adhesive. The invention also comprises a method of establishing an organic

hydrogel bond at a situs of living tissue comprising the steps of: pre-treating

disparate portions of the living tissue with hydrogen peroxide, body derived

fluids, at least one NCO-terminated hydrophilic urethane prepolymer,

derived from an organic polyisocyanate, and oxyethylene-based diols, triols

or polyols comprised essentially all of hydroxyl groups capped with

polyisocyanate; and bonding the portions of the disparate living tissue

together.

Detailed Description of the Invention

The invention comprises a uniquely flexible, biocompatible, non-

biologic tissue bond that can be produced by crosslinking hydrated polymer

gels to nitrogenous components found in living tissue. The hydrated tissue

bond is formed by reacting polymeric monomer units with tissue, at least

55% of which are oxyethylene-based diols, triols or polyols with molecular

weight exceeding 10,000. The adhesive being comprised of hydroxyl groups

of diols, triols or polyols substantially all capped by polyisocyanate, where

non-polymerized polyisocyanate accounts for less than 4% (v/v) of the

adhesive. Amines in the tissue serve to polymerize tissue with the adhesive. Water mixed or acquired at the bond site generates additional amine through

reaction with polyisocyanate and serves to polymerize the bulk of the bond.

The diols, triols and polyols used in the tissue bond predominately or

exclusively are polyoxyalkylene diols, triols or polyols whose primary

building blocks are ethylene oxide monomer units. At least 55% of the units

should be ethylene oxide to achieve good tissue adhesion. This adhesive

system may contain proportions of propylene oxide (typically 25%) or

butylene oxide (typically 15%) units in the polyols. The copolymerization of

the allyl ether of M-PEG (or the corresponding "alkylene oxide" copolymer

of propylene oxide and ethylene oxide) with maleic anhydride produces a

series of comb-shaped, functional polymers that may be used. The anhydride

groups of these polymers are reactive toward nucleophilic groups such as

amino or hydroxyl, and thus it is possible to prepare protein-AO-MAL

adducts in which polymer covers significant portions of the protein surface

through multiple covalent linkages.

The isocyanate capped AO-MAL polymer forms polymer-protein

conjugates with enhanced stability toward heat, pH, are soluble and active in

aqueous and organic solvents, and have greatly reduced immunogeniocity in

vivo. Varying the propylene oxide/ethylene oxide ratio offers the possibility of tailoring polymer hydrophilicity since inclusion of propylene oxide

enhances hydrophobicity.

To obtain desirable adhesive viscosity and bond strength, high

molecular weight ethylene oxide-based diol and polyols are used to prepare

the adhesive. The diols, triols or polyols molecular weight prior to capping

with polyisocyanate should be at least 10,000 MW. Triols (trihydroxy

compounds) are suitable in the preparation of the polyols, and can serve as

precursors to preparation of the adhesive of this invention. There are many

suitable triols: triethanolamine, trimethylolpropane, trimethylolethane, and

glycerol. Alternatively, tetrols may be used. Triol- or tetrol-based polyols are

capped with polyfunctional isocyanate, preferably a diisocyanate.

Alternatively, diols may be used. High molecular weight polyethylene

glycols are satisfactory. Diols are to be end capped with diisocyanates in

addition with crosslinking compounds. Polyfunctional amines and

isocyanates are suitable as crosslinking agents. Mixtures of diols, triols and

polyols are also suitable.

The adhesive of this invention is formed by reacting the hydroxyl

groups of the diols, triols or polyols with polyisocyanates. The choice of the

polyisocyanate will depend on factors well known in the art, including precursor choice, cure time, and mechanical properties of the tissue bond

formed by reacting the adhesive with tissue.

The choice of precursor is not independent of the choice of

polyisocyanate. The choice must afford sufficient crosslinking to the tissue

so as not to compete detrimentally with internal crosslinking initiated with

the addition of water to the bond. This competition can be favorably biased

in favor of the tissue bonding reaction by heating the adhesive, reducing its

viscosity by addition of solvents, or adding macroscopic hygroscopic fillers.

The choice must also afford rapid bulk polymerization - typically less than

60 seconds. Reduction in bulk polymerization time can be accomplished by

heating the adhesive, pre-mixing the adhesive with water, or adding amines.

Aromatic polyisocyanates are preferred in the above embodiments

because they result in cure times substantially less than times obtained when

using aliphatic or cycloaliphatic polyisocyanates. However, aromatic

polyisocyanates result in bonds of higher toxicity. For this reason the

functionality of the polyisocyanates in the bond are quenched using lysine,

or similar amine.

Examples of suitable (listed in descending order of suitability)

polyfunctional isocyanates are found in the literature, and include the

following and commonly obtained mixtures of the following: 9,10-anthracene diisocyanate

1 ,4-anthracenediisocyanate

benzidine diisocyanate

4,4' -biphenylene diisocyanate

4-bromo-l ,3 -phenylene diisocyanate

4-chloro- 1 ,3 -phenylene diisocyanate

cumene-2,4-diisocyanate

Cyclohexylene- 1 ,2-diisocyanate

Cyclohexylene- 1 ,4-diisocyanate

1,4-cyclohexylene diisocyanate

1,10-decamethylene diisocyanate

3 ,3 ' dichloro-4,4 ' -biphenylene diisocyanate

4,4 ' diisocy anatodibenzyl

2,4-diisocyanatostilbene

2,6-diisocyanatobenzfuran

2,4-dimethyl- 1 ,3 -phenylene diisocyanate

5 ,6-dimethyl- 1 ,3 -phenylene diisocyanate

4, 6-dimethyl-l ,3 -phenylene diisocyanate

3,3 '-dimethyl-4,4 ' diisocyanatodiphenylmethane

2,6-dimethyl-4,4'-diisocyanatodiphenyl 3 ,3 ' -dimethoxy-4,4 ' -diisocy anatodiphenyl

2,4-diisocyantodiphenylether

4,4 ' -diisocyantodiphenylether

3,3 '-diphenyl-4,4'-biphenylene diisocyanate

4,4 ' -diphenylmethane diisocyanate

4-ethoxy- 1 ,3 -phenylene diisocyanate

Ethylene diisocyanate

Ethylidene diisocyanate

2, 5 -fluorenediisocyanate

1,6-hexamethylene diisocyanate

Isophorone diisocyanate

4-methoxy- 1 ,3 -phenylene diisocyanate

methylene dicyclohexyl diisocyanate

m-phenylene diisocyanate

1,5 -naphthalene diisocyanate

1,8-naphthalene diisocyanate

polymeric 4,4 '-diphenylmethane diisocyanate

p-phenylene diisocyanate

p,p ' ,p"-triphenylmethane triisocyanate

Propylene- 1 ,2-diisocyanate p-tetramethyl xylene diisocyanate

1 ,4-tetramethylene diisocyanate

2,4,6-toluene triisocyanate

trifunctional trimer (isocyanurate) of isophorone diisocyanate

trifunctional biuret of hexamethylene diisocyanate

trifunctional trimer (isocyanurate) of hexamethylene diisocyanate

Bulk curing of the tissue bond of this invention is achieved by using

stoichiometric amounts of reactants. The isocyanate-to-hydroxyl group ratio

should be as low as possible without inhibiting bonding function, typically 2

+/- 10%. Higher ratios achieve adequate bonds but result in excessive

amounts of monomer in the bond. The time period used to cap the polyol or

diol is dependent on the polyisocyanate used. Methods for polyisocyanate

are well known.

In forming the tissue bond, organic solvents are usefully present

during the polymerization with tissue to enable a greater tolerance of

excessive isocyanate that may disrupt hydrate polymer formation. Varying

the amount of solvent also varies the viscosity of the adhesive. The porosity

of the tissue bond can be increased by reducing the viscosity of the adhesive,

and conversely. Useful solvents are ethanol, acetonitrile and acetone. In certain cases a tissue bond of minimal cured mass is desirable. This

can be achieved by using large amounts of a volatile solvent, providing

practical working volumes and minimal cured mass.

Bulk curing is accomplished by the addition of a stoichiometric excess

of water or aqueous solution relative to the total available isocyanate groups.

If blood or saline solution is present in the field, excess liquid should be

removed by blotting away or through mixing into the adhesive. If liquid is

present in a volume exceeding that of the adhesive to be applied, liquid

should be removed from the site to prevent migration of the adhesive.

An adhesive-aqueous solution may be pre-mixed in ratios up to 1 : 1 to

initiate polymerization and curing. Alternatively, the adhesive may be coated

onto the site and coated with an amine to initiate bulk polymerization. Such

methods are useful in obtaining near instantaneous tackiness and fixation.

The adhesive-to-aqueous solution ratio should be 1 :1 to about 20:1,

preferably about 5:1 to about 10:1. When matching the modulus of tissue,

the adhesive-to-solution ratio should be 20:80. Bulk polymerization time,

bond strength and bond porosity increases in the preferred ratios when the

adhesive content increases.

Polymerization begins spontaneously upon contact with nitrogenous

tissue or urea formed by reaction with water. The urea is formed when isocyanate groups of the oligomers react with water. Surface treatments,

such as the use of hydrogen peroxide can increase the reactivity of tissue

surfaces. Alternatively, the tissue may be infused with a catalyst such as

lysine. Suitable infusion catalysts include primary and secondary polyamines

and polyfunctional isocyanates.

The cure time may be shortened by addition of chain terminating or

inactivation agents, which cause end-capping without chain extension. The

tissue bond is a polyurea-urethane.

When the object of the bond is to create a tissue seal, large

proportions of volatile solvent may be added to the adhesive to affect a thin

film coating.

The mechanical properties of the tissue bond described herein are

unique and offer advantages over fibrin or cyanoacrylate tissue

adhesive/sealant systems. In particular, the tissue bonds of this invention are

less prone to cause an inflammatory response due to their hydrated state.

Because the bond is hydrated, it is flexible offering longer bond life in

application where tissue is likely to move relative to the bond.

The uniqueness of the present invention is further enhanced by its

ability to form tissue bonds by incorporating liquids commonly found in the

operating field. The implantability of the bond of this invention relates to the bond's

ability to present a surface of water to adjacent tissue. When the bonds of

this invention are used in contact with water containing tissues, the ethylene

oxide segments of the bond attract and complex with water molecules.

Consequently, the surface presented to living cells is predominately a layer

of water. The protective layer of water renders the underlying synthetic

polymeric bond noninteractive with proteins. Consequently, the bond does

not remove or denature proteins from the environment in which it is

implanted.

It is known that aliphatic polyisocyanates are significantly less

carcinogenic than those of aromatic isocyanates. However, if the aromatic

polyisocyanates are used, careful washing for removal or reacting unreacted

isocyanates and related amine-containing by-products generally will be

sufficient to render the bond biocompatible.

In the preferred adhesive-to-aqueous solution ratios, the bond is

substantially less susceptible to water swelling. Volumetric expansion may

be 2-fold for bonds made with about a 1 :5 adhesive-to-water ratio.

The tissue bonds and bulk polymerization of this invention are

covalently extended and crosslinked and are not readily soluble or

degradable in aqueous environments under physiological conditions. The physical integrity of the bond is maintained when implanted, reducing or

eliminating problems with toxicity and contamination. Consequently, the

bonds of this invention provide tissue-joining strength over extended periods

with minimal loss of bond strength or integrity.

The examples that follow are given for illustrative purposes and are

not meant to limit the invention described herein.

Example I: Preparation of Adhesive A

Pluracol VIO™ (BASF, propylene oxide/ethylene oxide) is to be deionized

and dried. 2167.3 g deionized Pluracol VIO are to be mixed with 148.5 g

isophorone diisocyanate (IPDI) and 0.84 g Santonox R™ (Monsanto

Chemical Co.) and heated at 67 degrees C under dry nitrogen for 17 days, or

until isocyanate concentration reaches 0.4 meq/g. The appearance is clear,

with a viscosity of 78,000 cps at 22 oC and 1.1 g/ml at 22 oC and free IPDI

of approximately 1.5-3% (wt).

Example II: Preparation of Adhesive B

Pluracol V10™ (BASF, propylene oxide/ethylene oxide) is to be deionized

and dried. 2170 g deionized Pluracol V10 are to be mixed with 82.4 g IPDI,

150 ml butadione. The mixture is to be heated to 67 degrees C under dry

nitrogen until isocyanate concentration reaches 0.2 meq/g. Example III: Preparation of Adhesive C

AO-MAL20™ (Shearwater Polymers, Inc., copolymer of M-PEG Allyl

Ether and Maleic anhydride) is to be deionized and dried. 900 g deionized

TPEG 15000 are to be mixed with 45 g IPDI and 0.6 g Santonox R. To this

mixture 500 ml acetonitrile is to be added to obtain a liquid. The mixture is

to be heated to 72 degrees C under dry nitrogen until isocyanate

concentration reaches 0.13 meq/g.

Example IV: Preparation of Adhesive D

TPEG 10000™ (Union Carbide Corp., polyethylene glycol) is to be

deionized and dried. 1475 g deionized TPEG 10000 are to be mixed with

102.3 g IPDI and 0.79 g Santonox R. The reactants are to be dissolved in 87

ml acetonitrile. The mixture is to be heated to 72 degrees C under dry

nitrogen until isocyanate concentration reaches 0.43 meq/g.

Example V: Preparation of Adhesive E

BASF#46889 (polyethylene glycol) is to be deionized and dried. 567 g

deionized BASF#46889 are to be mixed with 59 g IPDI and 0.54 g Santonox

R. The reactants are to be dissolved in 572 ml acetonitrile. The mixture is to

be heated to 67 degrees C under dry nitrogen until isocyanate concentration

reaches 0.46 meq/g.

Example VI: Preparation of Adhesive F

TPEG10000™ (Union Carbide Corp., polyethylene glycol) is to be

deionized and dried. 475 g deionized TPEG 10000 are to be mixed with

102.3 g IPDI and 0.79 g Santonox R. The mixture is to be heated to 72

degrees C under dry nitrogen until isocyanate concentration reaches 0.46

meq/g. To this mixture 100 g of acetone are to be added to form a liquid at

room temperature.

Example VII: Preparation of Adhesive G

Polyethylene glycol (PEG) (12000 MW) is to be deionized and dried. 0.03

moles PEG are to be mixed with 0.15 moles trimethylolpropane and heated

to 60 degrees C. The heated mixture is to be combined, by stirring for one

hour, with 0.11 moles commercial isomer blend of xylene diisocyanate.

Stirring is to continue until the isocyanate concentration reaches an

asymptote of 0.39 meq/g. Example VIII: Preparation of Adhesive H

Polyethylene glycol (PEG) (28000 MW) is to be deionized and dried. 0.04

moles PEG are to be mixed with 0.2 moles trimethylolpropane and heated to

60 degrees C. The heated mixture is to be combined, by stirring for one

hour, with 0.1 moles commercial isomer blend of xylene diisocyanate.

Stirring is to continue until the isocyanate concentration reaches an

asymptote of 0.2 meq/g.

Example IX: Preparation of Adhesive I

An adhesive is to be formed by following Example I, substituting an

equivalent molar amount of commercial isomer blend of Toluene

diisocyanate for the IPDI. The isocyanate content is to reach 0.8 meq/g. The

appearance should be a light amber liquid of about 10,000 cps, containing

less than 3.5% free TDI.

Example X: Preparation of Tissue Bond A

Five grams of Adhesive A are to be mixed with 1 g water for about 1

minute. The pot time of such an adhesive mixture is about lhr. The mixture

is to be applied to living tissue. The crosslinked structure of tissue and

Adhesive A are Tissue Bond A. Example XI: Preparation of Tissue Bond F

Adhesive G is to be applied directly to a tissue surface and mixed at the site

with liquid present to reach a mixture of 1:5 water-to-adhesive. The cure

time is 30-60 seconds. The crosslinked structure of tissue and Adhesive G

are Tissue Bond F.

Example XII: Preparation of Tissue Bond C

Adhesive I is to be heated to 65-80 degrees C and applied directly to a tissue

surface. The cure time is 30 seconds. The crosslinked structure of tissue and

Adhesive I are Tissue Bond C.

Example XIII: Preparation of Tissue Bond D

The tissue surface is to be swabbed with 3% hydrogen peroxide until the

surface appears white. The treated surface is to be swabbed dry. Adhesive I

is to be heated to 65-80 degrees C and applied directly to a tissue surface.

Preferably the adhesive layer on the tissue measures less than 1 mm in

thickness. A second coat of saturated lysine solution is to be sprayed, but not

mixed on the site. Fixing power is achieved immediately. The crosslinked

structure of activated tissue, Adhesive I, and lysine are Tissue Bond D.

Example XIV: Preparation of Tissue Bond E

Example XIII if followed except Adhesive I is premixed with equal volumes

of acetonitrile and sprayed on the activated site. The crosslinked structure is adhesive immediately, but the acetonitrile is allowed to evaporate to create

Tissue Bond E, a thin sealing layer.

The principles, preferred embodiments and modes of operation of the

present invention have been described in the foregoing specification. The

invention that is intended to be protected herein, however, is not to be

construed as limited to the particular forms disclosed, since these are to be

regarded as illustrative rather than restrictive. Variations and changes may

be made by those skilled in the art without departing from the spirit of the

invention.

Claims

What is claimed is:

1. An organic hydrogel bond comprised of living tissue pre-treated with

hydrogen peroxide, body derived fluids, at least one NCO-terminated

hydrophilic urethane prepolymer, derived from an organic

polyisocyanate, and oxyethylene-based diols, triols or polyols comprised

essentially all of hydroxyl groups capped with polyisocyanate.

2. The hydrated, biocompatible tissue bond of claim 1 in which

substantially all of said prepolymer units are aliphatic or aromatic

isocyanate-capped oxyethylene-based diols, triols or polyols.

3. The organic hydrogel bond of claim 1 in which the molecular weight of

said diols, triols or polyols prior to capping with polyisocyanate is at least

3,000.

4. The organic hydrogel bond of claim 1 in which said polyisocyanate is a

toluene diisocyanate.

5. The organic hydrogel bond of claim 1 in which said polyisocyanate is

isophorone diisocyanate.

6. The organic hydrogel bond of claim 1 in which said polyisocyanate is a

mixture of xylene diisocyanate and 6-chloro 2,4,5-trifluoro-l,3 phenylene

diisocyanate.

7. The organic hydrogel bond of claim 1 in which said polyisocyanate is a

mixture of xylene diisocyanate and tetrafluoro- 1,3 -phenylene

diisocyanate.

8. The organic hydrogel bond of claim 1 in which said polyisocyanate is a

mixture of diphenylmethane diisocyanate and 6-chloro 2,4,5-trifluoro-l,3

phenylene diisocyanate.

9. The organic hydrogel bond of claim 1 in which said polyisocyanate is a

mixture of diphenylmethane diisocyanate and tetrafluoro- 1,3 -phenylene

diisocyanate.

10. The organic hydrogel bond of claim 1 in which said polyisocyanate is

para-phenylene diisocyanate.

11. The organic hydrogel bond of claim 1 in which the diols, triols or polyols

are capped with polyisocyanate such that isocyanate-to-hydroxyl group

ratio is between 1.5 and 2.5.

12. The organic hydrogel bond of claim 1 in which the isocyanate

concentration in the prepolymer units is between 0.05 and 0.8

milliequivalents per gram.

13. The organic hydrogel bond of claim 1 that further comprises a surfactant

to control foam density.

14. The organic hydrogel bond of claim 1 that further comprises

hydroxyethylcellulose.

15. The organic hydrogel bond of claim 12 that further comprises

hydroxyethylcellulose .

16. The organic hydrogel bond of claim 1 that further comprises

hydroxypropylcellulose .

17. The organic hydrogel bond of claim 12 that further comprises

hydroxypropylcellulose .

18. A tissue crosslinked hydrophilic hydrated bond prepared by reacting

together tissue, body derived fluids and a prepolymer in a prepolymer-to-

water ratio of 3 : 1 to 20: 1 , said prepolymer prepared by:

(a) selecting diols, triols or polyols, substantially all of which are

oxyethylene-based diols, triols or polyols having an average molecular

weight of 3,000 to about 15,000, and

(b) reacting said diols, triols or polyols with an aliphatic or aromatic

polyisocyanate at an isocyanate-to-hydroxyl ratio of about 1.5 to 2.5 so

that all of the hydroyl groups of said diols, triols or polyols are capped

with polyisocyanate and the resulting prepolymer has an isocyanate

concentration of no more than 0.8 milliequivalents per gram.

19. The hydrated bond of claim 18 in which substantially all of the diols,

triols or polyols selected in (a) are oxyethylene-based.

20. The hydrated bond of claim 18 in which said diols, triols and polyols of

step (a) are dissolved in an organic solvent selected from acetonitrile or

acetone.

21. The hydrated bond of claim 18 further comprising non-body derived

water, consisting of a saline solution containing 0.9%) NaCl.

22. The hydrated bond of claim 20 in which said ratio is between 3:1 to 20:1.

23. The hydrogel bond of claim 18 wherein said bond is washed with a

polyfunctional diamine to end isocyanate reactivity.

24. The hydrated bond of claim 18 in which the tissue is pretreated with 3%

hydrogen peroxide.

5. A surgical adhesive for preparing a hydrophilic, biocompatible seal or

bond characterized by elasticity, and resistance to decomposition within

the body, said surgical adhesive comprising of a Part A including

oxyethylene-based diols, triols or polyols having an average molecular

weight in excess of 3,000, said diols, triols or polyols having all of the

hydroxyl groups capped with an aromatic or aliphatic diisocyanate, and

said adhesive having an isocyanate concentration up to 0.8 meq/gm., and

a Part B including a saline solution containing 0.9% NaCl and 3% H202

wherein said Parts A and B are premixed before tissue contact in Part A-

to-Part B ratios of between 3:1 to 20:1 to create a surgical adhesive

which creates a hemostatic tissue bond within about 3 minutes.

26. The adhesive of claim 25 in which a fluorine containing diisocyanate is

added to said Part A.

27. The adhesive of claim 25 in which said part A includes a hygroscopic

material.

28. The adhesive of claim 25 in which said part B includes a surfactant.

29. The adhesive of claim 25 in which said Part B includes a hygroscopic

material and a surfactant.

30. The adhesive of claim 25 further including a Part C to be applied after

tissue contact of said mixed Parts A and B, said Part C comprised of a

polyfunctional amine consisting of lysine to end isocyanate reactivity.

31. The adhesive of claim 25, including a method to enhance reactivity of

said adhesive when added to tissue, including the step of:

heating said adhesive to between 65-80 degrees C before

disposition on said tissue.

32. The adhesive of claim 25, including a method to enhance penetrating

ability of said adhesive, including the step of:

mixing a acetonitrile solvent in part 2:1 to 1 :10, adhesive to solvent to

said adhesive.

3. A method of establishing an organic hydrogel bond at a situs of living

tissue comprising the steps of:

pre-treating disparate portions of said living tissue with hydrogen

peroxide, body derived fluids, at least one NCO-terminated hydrophilic

urethane prepolymer, derived from an organic polyisocyanate, and

oxyethylene-based diols, triols or polyols comprised essentially all of

hydroxyl groups capped with polyisocyanate; and

bonding said portions of said disparate living tissue together.