DETAILED DESCRIPTION OF THE INVENTIONPre-polymerThe pre-polymer according to the present invention comprises a polymeric unit of the general formula (-A-B-)n, wherein A represents a substituted or un-substituted ester, B represents a substituted or un-substituted acid or acid ester comprising at least two acid or acid ester functionalities; and n represents an integer greater than 1.
Component A may be derived from a polyol, such as a diol, triol, tetraol or greater. Suitable polyols include diols, such as alkane diols; triols, such as glycerol, trimethylolpropane, triethanolamine; tetraols, such as erythritol, pentaerythritol; and higher polyols, such as sorbitol. Unsaturated diols, such as tetradeca-2,12-diene-1,14-diol, or other diols including macromonomer diols such as, for example polyethylene oxide, and N-methyldiethanolamine (MDEA) can also be used. Preferably, the polyol is substituted or unsubstituted glycerol. Component B may be derived from a polyacid, such as a diacid or higher order acid. A wide variety of diacid, or higher order acids, can be used. Exemplary acids include, but are not limited to, glutaric acid (5 carbons), adipic acid (6 carbons), pimelic acid (7 carbons), sebacic acid (8 carbons), and azelaic acid (nine carbons). Exemplary long chain diacids include diacids having more than 10, more than 15, more than 20, and more than 25 carbon atoms. Non-aliphatic diacids can also be used. For example, versions of the above diacids having one or more double bonds can be used to produce polyol-diacid co-polymers. Preferably the diacid is substituted or unsubstituted sebacic acid.
Several substituents, such as amines, aldehydes, hydrazides, acrylates and aromatic groups, can be incorporated into the carbon chain. Exemplary aromatic diacids include terephthalic acid and carboxyphenoxy-propane. The diacids can also include substituents as well. For example, reactive groups like amine and hydroxyl can be used to increase the number of sites available for cross-linking. Amino acids and other biomolecules can be used to modify the biological properties. Aromatic groups, aliphatic groups, and halogen atoms can be used to modify the inter-chain interactions within the polymer.
The pre-polymer may further comprise a polyamide or polyurethane backbone. For example, polyamine (comprising two or more amino groups) may be used to react with polyacid together with polyol or after reacting with polyol. Exemplary poly(ester amide) includes those described in
Cheng, et al., Adv. Mater. 2011, 23, 1195-11100. In other examples, polyisocyanates (comprising two or more isocyanate groups) may be used to react with polyacid together with polyol or after reacting with polyol. Exemplary polyester urethanes include those described in
US2013231412.
The weight average molecular weight of the pre-polymer, measured by Gel Permeation Chromatography equipped with a refractive index, may be from about 1,000 Daltons to about 1,000,000 Daltons, from about 1,000 Daltons to about 1,000,000 Daltons, preferably from about 2,000 Daltons to about 500,000 Daltons, more preferably from about 2,000 Daltons to about 250,000 Daltons, most preferably from about 2,000 Daltons to about 100,000 Daltons. The weight average molecular weight may be less than about 100,000 Dalton, less than about 75,000 Daltons, less than about 50,000 Daltons, less than about 40,000 Daltons, less than about 30,000 Daltons, or less than about 20,000 Daltons. The weight average molecular weight may be from about 1000 Daltons to about 10,000 Daltons, from about 2000 Daltons to about 10,000 Daltons, from about 3000 Daltons to about 10,000 Daltons from about 5,000 Daltons to about 10,000 Daltons. Preferably, it is about 3000 Daltons.
The term "about" as used herein means within 10%, preferably within 8%, and more preferably within 5% of a given value or range. According to a specific embodiment, "about X" means X, when X refers to the value or range.
The pre-polymer may have a polydispersity, measured by Gel Permeation Chromatography equipped with a refractive index, below 20.0, more preferably below 10.0, more preferably below 5.0, and even more preferably below 2.5. Preferably, it is about 2.5.
The pre-polymer may have a melt viscosity at 80°C between 100 and 2000 cP, more preferably between 200 and 1000 cP and even more preferably between 300 and 500 cP.
The pre-polymer may have an acid number between 1 and 200 mg KOH/g of polymer, more preferably between 10 and 100 mg KOH/g of polymer, and even more preferably between 50 and 100 mg KOH/g of polymer. Preferably, it is about 80 mg KOH/g of polymer
The molar ratios of the polyol to the polyacid in the pre-polymer may be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 and 1:10. 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1. The molar ratios of polyol to the polyacid may also be 2:3, 3:2, 3:4, or 4:3. The polymer may also be the result of a mixture of two or more different ratios.
Activated Pre-polymerThe pre-polymer of the present invention is activated. It is activated by introducing functional groups that can react or be reacted to form crosslinks. The pre-polymer is activated by reacting one or more functional groups on the pre-polymer backbone with one or more functional groups that can react or be reacted to form crosslinks resulting in cured polymer. The activated pre-polymer is an acrylated pre-polymer or a vinylated pre-polymer.
Suitable functional groups to be activated on the pre-polymer backbone include hydroxy groups, carboxylic acid groups, amines, and combinations thereof, preferably hydroxy and/or carboxylic acid. The free hydroxyl or carboxylic acid groups on the pre-polymer can be activated by functionalizing the hydroxy groups with a moiety which can form a crosslink between polymer chains. The groups that are activated can be free hydroxyl or carboxylic acid groups on A and/or B moieties in the pre-polymer.
The free hydroxy or carboxylic groups can be functionalized with vinyl groups. Vinyl groups can be introduced by vinylation or acrylation. According to the present invention, vinyl groups contain the following structure -CR1=CR2R3 wherein R1, R2, R3 are independently from one another, selected in the group consisting of H, alkyl such as methyl, ethyl, aryl such as phenyl, substituted alkyl, substituted aryl, carboxylic acid, ester, amide, amine, urethane, ether, and carbonyl.
Preferably, the functional group is or contains an acrylate group. According to the present invention, acrylate groups are moieties containing substituted or unsubstituted acryloyl group. The acrylate may contain the following group: -C(=O)-CR1=CR2R3, wherein R1, R2, R3 are independently from one another, selected in the group consisting of H, alkyl such as methyl or ethyl, aryl such as phenyl, substituted alkyl, substituted aryl, carboxylic acid, ester , amide, amine, urethane , ether, and carbonyl.
Preferably, R1, R2 and R3 are H; or R1 is CH3, R2 and R3 are H; or R1 and R2 are H and R3 is CH3; or R1 and R2 are H and R3 is phenyl.
Vinyl groups can also be incorporated in the backbone of the pre-polymer using free carboxyl groups on the pre-polymer. For example, hydroxyethyl methacrylate can be incorporated through the COOH groups of the pre-polymer using carbonyl diimidazole activation chemistry.
The degree of activation can vary and can be from 0.2 to 0.9 mol/mol of polyacid or polyol, preferably from 0.3 to 0.8 mol/mol of polyacid or polyol and most preferably from 0.4 to 0.6 mol/mol of polyacid or polyol, such as 0.5 mol/mol of polyacid or polyol for achieving optimal bust performance properties at room temperature or elevated temperature up to 40 °C, preferably 37 °C. It is most preferred when the degree of activation is as described above and the reactive functional group is acrylate i.e. degree of acrylation as above.
The activated pre-polymer preferably has the general formula (I):wherein n and p each independently represent an integer equal or greater than 1, and wherein R2 in each individual unit represents hydrogen or a polymer chain or -C(=O)-CR3=CR4R5, wherein R3, R4, R5 are independently from one another, selected in the group consisting of H, alkyl such as methyl or ethyl, aryl such as phenyl, substituted alkyl, substituted aryl, carboxylic acid, ester , amide, amine, urethane , ether, and carbonyl.
Preferably, R3, R4 and R5 are H; or R3 is CH3, R4 and R5 are H; or R3 and R4 are H and R5 is CH3; or R3 and R4 are H and R5 is phenyl.
Preferably, p is an integer from 1-20, more preferably from 2-10, even more preferably from 4-10. It is most preferred when p=8.
The preferred pre-polymer has the following structure: wherein n represents an integer equal or greater than 1
The activated pre-polymer can be further reacted with one or more additional materials to modify the crosslinks between the polymer chains. For example, prior to or during curing/crosslinking, one or more hydrogel or other oligomeric or monomeric or polymeric precursors (e.g., precursors that may be modified to contain acrylate groups) such as poly(ethylene glycol), dextran, chitosan, hyaluronic acid, alginate, other acrylate based precursors including, for example, acrylic acid, butyl acrylate, 2-ethylhexyl acrylate, methyl acrylate, ethyl acrylate, acrylonitrile, n-butanol, methyl methacrylate, acrylic anhydride, methacrylic anhydride and TMPTA, trimethylol propane trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, ethylene glycol dimethacrylate. dipentaerythritol penta acrylate, Bis-GMA (Bis phenol A glycidal methacrylate) and TEGDMA (tri-ethylene, glycol dimethacrylate), sucrose acrylate; other thiol based precursors (monomeric or polymeric); other epoxy based precursors; and combinations thereof, can be reacted with the acrylated pre-polymer e.g. poly glycerol sebacate acrylate (PGSA).
The activated pre-polymer may be manufactured in the presence and/or mixed with a coloring agent. Preferred examples of coloring agents are the ones recommended by the FDA for use in medical devices, pharmaceutical products or cosmetics. Seehttp://www.fda.gov/ForIndustry/ColorAdditives/ColorAdditiveInventories/.
Active pre-polymer comprising grafted anhydridesThe anhydride compound of the composition according to the present invention may be generated from the activation of the pre-polymer, for example through the reaction of acryloyl chloride (AcCl) and free carboxylic acids. An example of such an anhydride has general formula (II):wherein p and n each individually represent an integer equal or greater than 1; wherein R6 and R6, in each individual unit are independent and can be a polymer chain or R6 and R6' in each individual unit are independent and can be -C(=O)-CR3=CR4R5, wherein R3, R4, R5 are independently from one another, selected from the group consisting of H, alkyl such as methyl or ethyl, aryl such as phenyl, substituted alkyl, substituted aryl, carboxylic acid, ester , amide, amine, urethane , ether, and carbonyl; or R6 and R6' in each individual unit are independent and can be alkyl, aryl, heterocycles, cycloalkyl, aromatic heterocycles, multicycloalkyl, ester, ether, halide, carboxylic acid, amino, alkylamino, dialkylamino, trialkylamino, amido, carbamoyl, thioether, thiol, alkoxy, or ureido groups.
Preferably, p is an integer from 1-20, more preferably from 2-10, even more preferably from 4-10. It is most preferred when p=8.
The preferred anhydride has the following structure: wherein OR6 or OR6' independently represent a polymer chain oror
During activation of the pre-polymer, both asymmetric and symmetric anhydride can be generated. It is preferred that there is a higher content of asymmetric anhydride than its symmetric counterpart.
An asymmetric anhydride (also referred as mixed anhydride) is a carboxylic acid anhydride that has the following general structural formula:wherein R1 and R2 are different, and R1 and R2 are selected in the group of hydrogen atoms, alkyl groups, aryl groups.
A symmetric anhydride is a carboxylic acid anhydride that has the following general structural formula: wherein R1 is selected in the group of hydrogen atoms, alkyl groups, aryl groups.
Preferably the molar ratio of the total grafted anhydride is above 0.02 mol/mol of polyacid, more preferably above 0.05 mol/mol of polyacid and even more preferably above 0.1 mol/mol of polyacid, as measured by nuclear magnetic resonance (NMR). This may also be the molar ratio of the total asymmetric grafted anhydride. Preferably the molar content of asymmetric anhydride is greater than 30% of the total dry anhydride content.
According to preferred embodiment, the asymmetric anhydride is stabilized to assure enhanced performance over time.
Hence, to improve the stability of the pre-polymer containing grafted anhydrides, unreacted nucleophilic groups may be partially or totally blocked or protected after pre-polymer activation. Examples of blocking or protection reactions are well known in the art. Hydroxyl protecting or blocking groups include acyl; cyclic or acyclic, branched or unbranched, substituted or unsubstituted alkyl; cyclic or acyclic, branched or unbranched, substituted or unsubstituted alkenyl; cyclic or acyclic, branched or unbranched, substituted or unsubstituted alkynyl; cyclic or acyclic, branched or unbranched, substituted or unsubstituted heteroalkyl; cyclic or acyclic, branched or unbranched, substituted or unsubstituted heteroalkenyl; or cyclic or acyclic, branched or unbranched, substituted or unsubstituted heteroalkynyl; substituted or unsubstituted aryl; or substituted or unsubstituted heteroaryl.
Preferably there are no free hydroxyl groups present on the pre-polymer. When there is low quantity free hydroxyls the content of total grafted anhydrides can be higher than 0.05 mol/mol of polyacid, as measured through NMR, and achieve enhanced stability as well as good adhesive and sealant properties.
Alternatively, in order to improve pre-polymer or composition stability, the methods of making and purifying the activated pre-polymer with grafted anhydrides should consider preferred conditions to avoid anhydride instability. For example, if the product is purified through water washings, conditions to allow a fast phase separation between organic and aqueous phase should be favored. For the present invention, phase separation during water washings can be improved by the use of salts solubilized in the aqueous phase. Examples of salts include but are not limited to, sodium chloride, sodium bicarbonate. In alternative, the salts produced during the reaction can be removed through filtration using an organic solvent such as ethyl acetate, n-methyl tetrahydrofuran, tetrahydrofuran.
Pre-polymer containing non-grafted anhydridesAdditionally or alternatively, the anhydride compound of the composition according to the present invention may also be mixed with the pre-polymer, preferably the activated pre-polymer. The non-grafted anhydride according to the present invention is not especially limited, examples including acrylic anhydride, methacrylic anhydride, 4-methacryloyloxyethyl trimellitate anhydride, succinic anhydride, maleic anhydride or any combination thereof. Preferably the anhydride comprises acrylic anhydride or methacrylic anhydride.
Preferably the amount of anhydride present in the composition is in the range of 1 to 10 wt%, by total weight of the composition. The presence of anhydride increases adhesive properties of the cured composition with a preferred range of 1 to 10 wt%, as measured by weighing, for providing optimal adhesive properties. Preferred content is between 3 and 6 wt%.
CuringThe composition according to the present invention can be a surgical composition and can be used as tissue sealants and/or adhesives. The composition has flow characteristics such that they can be applied to the desired area through a syringe or catheter but is sufficiently viscous to remain in place at the site of application without being washed away by bodily fluids, such as water and/or blood. Preferably, the viscosity of the composition is 500 cP to 100000 cP, more preferably 1000 to 50000 cP, even more preferably 2000 to 40000 cP and most preferably 2500 to 25000 cP. Viscosity analysis is performed using a Brookfield DV-II + Pro viscosimeter with a 2.2mL chamber and SC4-14 spindle, the speed during the analysis is varied from 5 to 80 rpm. The above mentioned viscosity is present in the relevant temperature range for medical application i.e. room temperature up to 40 °C, preferably 37 °C.
The composition is also sufficiently hydrophobic to resist washout by bodily fluids, such as blood. This facilitates delivery to the desired site as well as repositioning of devices implanted using the composition of the invention during minimally invasive surgery. Hydrophobicity is dependent on the chemical composition of the pre-polymer, including the hydrophobic nature of the polymer backbone(for example longer alkyl chains are more hydrophobic than shorter chains) and the degree of activation. Preferably there are no free hydroxyl groups on the pre-polymer of the uncured composition nor are there free hydroxyl groups present in the cured composition.
The pre-polymer of the present invention may already contain crosslinks before curing, but typically is not fully crosslinked as it is soluble in organic solvents such as dichloromethane or ethyl acetate. The composition of the invention may be incubated in bodily fluids, such as blood, prior to administration and curing, without a substantial decrease in adhesive strength when cured.
The composition of the invention is stable in bodily fluids, such as blood. More particularly, the composition of the invention does not spontaneously crosslink in bodily fluids absent the presence of an intentionally applied stimulus such as light, for example UV light, heat, or chemical initiator to initiate crosslinking.
The composition can be cured using a free radical initiated reaction, such as, for example, by photo-initiated polymerization, thermally-initiated polymerization, and redox initiated polymerization.
Preferably, the composition is irradiated with light, for example ultraviolet (UV) light in the presence of a photoinitiator to facilitate the reaction. Examples of suitable photoinitiators include, but are not limited to: 2-dimethoxy-2-phenyl-acetophenone, 2-hydroxy-1-[4-(hydroxyethoxy)phenyl]-2-methyl-1-propanone (Irgacure 2959), 1-hydroxycyclohexyl-1-phenyl ketone (Irgacure 184), 2-hydroxy-2-methyl-1-phenyl-1-propanone (Darocur 1173), 2-benzyl-2-(dimethylamino)-1-[4-morpholinyl) phenyl]-1-butanone (Irgacure 369), methylbenzoylformate (Darocur MBF), oxy-phenyl-acetic acid-2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester (Irgacure 754), 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (Irgacure 907), diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide (Darocur TPO), phosphine oxide, phenyl bis(2,4,6-trimethyl benzoyl) (Irgacure 819), and combinations thereof.
Preferably, the composition is irradiated with visible light (typically blue light or green light) in the presence of a photoinitiator to facilitate the reaction. Examples of photoinitiators for visible light include, but are not limited to, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, eosin Y disodium salt, N-Vinyl-2-Pyrrolidone (NVP) and triethanolamine, and camphorquinone.
In applications of the composition involvingin vivo photopolymerization and other medical applications, the use of cytocompatible photoinitiators is preferred and may be required by regulatory agencies. Photoinitiator Irgacure 2959 may be used which causes minimal cytotoxicity (cell death) over a broad range of mammalian cell types and species.
In order for the photopolymerization to occur, the composition (and the substrate to which is it applied, if applicable) is preferably sufficiently transparent to the light.
In applications when the composition is curedin vivo, the temperature at which curing occurs is preferably controlled as not damage the tissue on which the composition has been applied. Preferably, the composition is not heated above 45 °C during irradiation, more preferably not above 37 °C, and even more preferably not above 25 °C.
In addition to photochemical crosslinking, the composition can be cured thermally, by Mitsunobu-type reaction, by redox-pair initiated polymerization for example benzoyl peroxide, N,N,-dimethyl-p-toluidine, ammonium persulfate, or tetramethylenediamine (TEMED), and by a Michael-type addition reaction using a bifunctional sulfhydryl compound.
Upon polymerization, the pre-polymer forms a crosslinked network with improved adhesive properties and exhibits significant adhesive strength even in the presence of blood and other bodily fluids. The adhesive of the Invention obtained after curing is preferably sufficiently elastic to resist movement of the underlying tissue, for example contractions of the heart and blood vessels. The adhesive can provide a seal, preventing the leakage of fluids or gas. The adhesive is preferably biodegradable and biocompatible, causing minimal inflammatory response. The adhesive is preferably elastomeric.
Biodegradability can be evaluatedin vitro, such as in phosphate buffered saline (PBS) or in acidic or alkaline conditions. Biodegradability can also be evaluatedin vivo, such as in an animal, for example mice, rats, dogs, pigs or humans. The rate of degradation can be evaluated by measuring the loss of mass of the polymer over timein vitro orin vivo.
The cured composition, alone or coated on a patch or tissue exhibits a 90° pull off adhesive strength of at least 0.5 N/cm2, preferably at least 1 N/cm2 and even more preferably at least 2 N/cm2, for example 1.5N/cm2 to 2N/cm2, but preferably greater than 5 N/cm2, for example up to 6 N/cm2 or 7 N/cm2 or greater. Pull off adhesive strength refers to the adhesion value obtained by attaching an adhesive article or sample to wet tissue, such as epicardial surface of cardiac tissue, blood vessels, or the serosol side of porcine intestine tissue, immobilized on a flat substrate, such as a metallic stub. The 90° pull off adhesion test determines the greatest perpendicular force (in tension) that a surface area can bear before adhesive detachment.
According to preferred embodiment, the composition of the invention is cured in light and in presence of a photo initiator and the cured composition exhibits a 90° pull off adhesive strength of at least 0.5 N/cm2, preferably at least 1 N/cm2 and even more preferably at least 2 N/cm2, for example 1.5N/cm2 to 2N/cm2, but preferably greater than 5 N/cm2, for example up to 6 N/cm2 or 7 N/cm2 or greater.
The cured composition can also exhibit a burst pressure of greater than 100 mmHg, preferably in the range of 400 mmHg to 600 mmHg or greater, for example 400mmHg or 500mmHg. Burst pressure or strength refers to the pressure value obtained to burst an explanted porcine carotid arterial vessel which has an incision coated with the composition.
The composition of the present invention when cured in light and in the presence of a photo-initiator preferably has one or more of the following properties:
- i) 90° pull off strength greater than 1.5 N/cm2, preferably 2 to 7 N/cm2 or greater; and
- ii) burst performance of greater than 100 mmHg, preferably 400 to 500 mmHg or greater.
According to preferred embodiment, the composition of the invention is used as adhesive, i.e. is able after curing of binding strongly to a surface or binding one surface to another.
According to alternative embodiment, the composition of the invention is used as sealant, i.e.is able after curing of preventing leaking (e.g. fluid, gas) by forming a barrier or filling a void volume.
Besides adhesion and sealing of wet biological tissue, the composition can adhere to and seal a variety of hydrophilic or hydrophobic substrates, natural or synthetic, including polyethylene terephthalate, expanded polyethylene terephthalate, polyester, polypropylene, silicones, polyurethanes, acrylics, fixed tissue (e.g. pericardium), ceramics or any combinations thereof.
Method of ManufactureThe method for manufacturing the composition of the present invention comprises:
- i) polycondensation of a first component comprising two or more functionalities of the general formula -OR, where R of each group is independently hydrogen or alkyl; and a second component comprising two or more acid ester functionalities;
- ii) activation of the pre-polymer made by step i);
- iii) formation or addition of an anhydride compound; optionally
- iv) blocking free hydroxyl groups; and/or optionally
- v) purification of the activated pre-polymer made by steps ii) and/or iii) and/or iv).
The said first component may be a polyol, such as a diol, triol, tetraol or greater. Suitable polyols include diols, such as alkane diols; triols, such as glycerol, trimethylolpropane, triethanolamine; tetraols, such as erythritol, pentaerythritol; and higher polyols, such as sorbitol. Unsaturated diols, such as tetradeca-2,12-diene-1,14-diol, or other diols including macromonomer diols such as polyethylene oxide, and N-methyldiethanolamine (MDEA) can also be used. Preferably, the polyol is substituted or unsubstituted glycerol.
The said second component may be a polyacid, such as a diacid or higher order acid. A wide variety of diacid, or higher order acids, can be used. Exemplary acids include, but are not limited to, glutaric acid (5 carbons), adipic acid (6 carbons), pimelic acid (7 carbons), sebacic acid (8 carbons), and azelaic acid (nine carbons). Exemplary long chain diacids include diacids having more than 10, more than 15, more than 20, and more than 25 carbon atoms. Non-aliphatic diacids can also be used. For example, versions of the above diacids having one or more double bonds can be used to produce polyol-diacid co-polymers.
Exemplary aromatic diacids include terephthalic acid and carboxyphenoxy-propane. The diacids can also include substituents as well, for example amine and hydroxyl substituents.
Preferably the diacid is substituted or unsubstituted sebacic acid.
The said first and second component are added together in a first component: second component molar ratio range of 0.5:1 to 1.5:1, preferably 0.9:1.1 and most preferred 1:1. Where the first component is glycerol and the second component is sebacic acid and added in a 1:1 molar ratio, there are three hydroxyl groups on glycerol for two carboxyl groups on the sebacic acid. Therefore the extra hydroxyl group on glycerol is used during the activation step.
The conditions for step i) are not especially limited but may include a temperature range of 100 to 140°C, preferably 120 to 130°C, an inert atmosphere, preferably comprising nitrogen, and under vacuum.
The activating agent of step ii) is preferably an acrylating agent which comprises an acrylate group which are moieties containing substituted or unsubstituted acryloyl group. The acrylate may contain the following group: -C(=O)-CR1=CR2R3, wherein R1, R2, R3 are independently from one another, selected in the group consisting of H, alkyl such as methyl or ethyl), aryl such as phenyl, substituted alkyl, substituted aryl, carboxylic acid, ester , amide, amine, urethane , ether, and carbonyl.
Preferably, R1, R2 and R3 are H; or R1 is CH3, R2 and R3 are H; or R1 and R2 are H and R3 is CH3; or R1 and R2 are H and R3 is phenyl.
Most preferably, the acrylating agent is acryloyl chloride.
Steps i) to iv) can be carried out in the presence of one or more solvents or catalysts, examples including dichloromethane (DCM), ethyl acetate (EtOAc) dimethylaminopyridine (DMAP), and triethylamine (TEA) or any combination thereof.
The purification step v) is carried out to ensure that any solvents and un-reacted products are removed from the pre-polymer made by step iii) and iv). This purification step can comprise filtration and/or water washing. For the present invention, it has been shown that phase separation during water washings can be improved by the use of salts solubilized in the aqueous phase (e.g. from about 50 to about 500 g/L salt aqueous solution, preferably about 300g/L salt, for example sodium chloride, aqueous solution). It is thus most preferred when the water washing is salted water washing. Examples of salts include but are not limited to, sodium chloride, sodium bicarbonate. According to a preferred alternative embodiment, the salts produced during said reaction can be removed through salt precipitation using an organic solvent such as ethyl acetate, n-methyl tetrahydrofuran, tetrahydrofuran followed by purification. Purification through filtration after salt precipitation for example in presence of ethyl acetate might not able to reduce enough the salt content in composition of the invention therefore, an additional salted water wash (e.g. with 200g/L sodium chloride in water) can be performed.
The inventors have shown that an increased amount of anhydrides and purification with salted water wash, particularly NaCl, demonstrates a synergistic effect of unexpectedly high adhesion, good sealant properties such as burst performance, as well as enhanced stability. This is also demonstrated when filtration is used followed by salted water wash.
The purification step may also preferably be followed by one or more, more preferably all of the following steps including addition of free radical inhibitor, for example butylated hydroxytoluene (BHT), monomethylether-hydroquinone (MEHQ), phenylbutyl-nitrone (PBN), and/or photoinitiator, for example Irgacure 2959 or diphenyl-trimethyl-phosphine oxide (TPO), solvent evaporation and/or extraction, preferably through supercritical CO2 to assure efficient solvent and impurities removal without interfering with the activation of the pre-polymer.
Special embodiment A : Manufacture of composition with grafted anhydrides (formation of anhydrides during activation step with acrylating agent)During the acrylation process, anhydrides can be formed resulting from the reaction of the acrylated monomer with any carboxylic acid groups (step iii)).To enhance the stability of the anhydride groups, hydroxyl blockage or protection may be performed (step iv)). Techniques known in the art can be applied. Preferably, the hydroxyls are blocked through acylation using a compound such as ethanoyl chloride.
As indicated above, to improve stability of the pre-polymer containing grafted anhydrides, unreacted nucleophilic groups may be partially or totally blocked or protected after pre-polymer activation. Examples of blocking or protection reactions are well known in the art. Hydroxyl protecting or blocking groups include acyl; cyclic or acyclic, branched or unbranched, substituted or unsubstituted alkyl; cyclic or acyclic, branched or unbranched, substituted or unsubstituted alkenyl; cyclic or acyclic, branched or unbranched, substituted or unsubstituted alkynyl; cyclic or acyclic, branched or unbranched, substituted or unsubstituted heteroalkyl; cyclic or acyclic, branched or unbranched, substituted or unsubstituted heteroalkenyl; or cyclic or acyclic, branched or unbranched, substituted or unsubstituted heteroalkynyl; substituted or unsubstituted aryl; or substituted or unsubstituted heteroaryl.
Similarly, in order to improve pre-polymer or composition stability, the methods of making and purifying the activated pre-polymer with grafted anhydrides should consider preferred conditions to avoid anhydride instability. For example, if the product is purified through water washings, as mentioned above.
Special embodiment B : Manufacture of composition with non-grafted anhydrides (addition of anhydrides)Additionally or alternatively, anhydrides are added after activation of the pre-polymer, preferably after purification step v) and followed by mixing. The anhydride used according to the present invention is not especially limited, examples including methacrylic anhydride, acrylic anhydride, 4-methacryloyloxyethyl trimellitate anhydride, succinic anhydride, maleic anhydride and any combination thereof. Preferably the anhydride comprises methacrylic anhydride or acrylic anhydride.
Preferably the amount of anhydride added in the composition is in the range of 1 to 1 0wt%, by total weight of the composition. The presence of anhydride increases adhesive properties with a preferred range of 3 to 6 wt% for providing optimal adhesive properties.
The anhydride may be mixed in situ with the pre-polymer and immediately applied to the targeted substrate, for example using a double barrel syringe. The anhydride may also be mixed in the pre-polymer and then stored; in this scenario, and to increase the stability of the formulation in the presence of anhydride functional groups, hydroxyl groups may be blocked in the activated pre-polymer.
Residual levels of grafted anhydrides may also be present, preferably at a level below 0.05 mol/mol of polyacid. The content of anhydride content can be controlled by ethanol capping or using any other nucleophilic substitution reaction. Suitable reagents include alcohols, amines or sulfhydryl compounds. The addition of ethanol is preferably at a temperature in the range of 30 to 50 °C, for example 40 °C. The duration of the ethanol capping step is conducted preferably during 10 and 40 hours, more preferably during 24 hours. The volumetric ratio of polymer solution to ethanol is in the range of 20:1, more preferably in the range of 10:1 and even more preferably in the rage of 5:1.
The formation of grafted anhydrides may also be prevented through blockage of any free carboxylic acid groups prior to activation.
Methods of UsingThe composition can be applied directly to the desired site, such as by application with syringe or a catheter, through a spreading tip, by spraying or using a brush. The composition preferably is sufficiently non-viscous as to be injectable through a syringe needle having a gauge of 14 to 20, preferably 14 to 18 but sufficiently viscous to remain in place at the site of administration with minimum washout. The composition can be mixed before application or during application with a photoinitiator, stabilizer, therapeutic, prophylactic, and/or diagnostic agent, and/or one or more excipients.
The materials can be used directly, i.e., applied directly to the site to be adhered or sealed. Alternatively, the materials can be applied to a device, such as a patch or tape, to adhere the patch to the desired site. Conventional patch, patch materials or graft materials, natural or synthetic, known in the art can be used. Patches for use with major blood vessels, cardiac tissue, and/or hard to treat wounds (e.g., diabetic ulcers) are known in the art. Biocompatible, biodegradable surgical tape can be used, for example, to stop bleeding during surgery. Since the tape is biodegradable, it does not need to be removed before the surgeon sutures the wound closed. Examples of other suitable materials include polyethylene terephthalate, expanded polyethylene terephthalate, polyester, polypropylene, silicones, polyurethanes, acrylics, fixed tissue (e.g. pericardium), ceramics or any combinations thereof.
The thickness of the composition or adhesive layer can be varied depending on the application and site of administration. The thickness of the coatings can be at least about 50 microns, 60 microns, 70, microns, 74 microns, 75 microns, 80 microns, 100 microns, 125 microns, 150 microns, 175 microns, 200 microns, 225 microns, 250 microns, 275 microns, 300 microns, 325 microns, 350 microns, 375 microns, 400 microns, 425 microns, 450 microns, 475 microns, 500 microns, 525 microns, 550 microns, 575 microns, 600 microns, 625 microns, 650 microns, 675 microns, 700 microns, or 725 microns.
The adhesive and sealing properties of the activated pre-polymer can be induced through different approaches. The preferred approach is through a light stimulus in the presence of a photoinitiator. Other potential stimuli include heat in the presence of suitable initiators known in the art, or the use of reactive chemicals that can induce the network polymerization as disclosed above.
The adhesive strength may be improved by subjecting the composition to preload during curing. This may be particularly useful for those embodiments involving a patch where the prepolymer is coated on a patch and then applied to a tissue. The preload applied in the coated patch during curing can vary provided it results in an improvement in adhesive strength. The preload force applied to the patch may be from about 0.5 N to about 10 N, preferably from about 1 N to about 8 N, more preferably from about 2 N to about 8 N, most preferably from about 3 N to about 7 N. The application of preload may help the adhesive penetrate into the tissue.
UsesA. Tissue adhesion and sealingThe composition according to the invention may be used for adhering or sealing targeted surfaces including tissue, graft material such as PTFE-based graft, or any combination thereof. The method for adhering or sealing targeted surfaces comprises applying the composition to the surface and curing the composition.
Unlike conventional tissue adhesives that spontaneously activate during application or in the presence of water, or adhesives that are hydrophilic and thus are subject to washout prior to curing, the composition according to the invention can be applied to wet substrates without activation or displacement. The composition can also be applied to dry substrates.
The composition may also be used for adhering tissue to the surface of a medical device. The composition can be used in medical devices, either as part or all of a device or to adhere a device to tissue. The method for adhering tissue to the surface of a medical device comprises applying the composition to the surface of the tissue and/or medical device and curing the composition. The composition can also be used to join tissue, including one or more tissuein vivo.
Surgical adhesives comprising the composition according to the invention can also be used. Examples of applications include to stop bleeding, for example, due to a wound or trauma or during surgery such as after suturing a graft to a vessel or after vascular access in endovascular procedures. The adhesive does not need to be removed before the surgeon sutures the wound closed since it will degrade over time. Other types of wounds that can be treated include, but are not limited to, wounds that leak, wounds that are hard to close or that fail to heal properly through normal physiologic mechanisms. The application can be performed both inside or outside the body, for human or veterinary use.
The composition according to the invention can also be fabricated into a biodegradable stent. The stent can increase the diameter of a blood vessel to increase flow through the vessel, but since the stent is biodegradable, the blood vessel can increase in diameter with a reduced risk of thrombosis or covering the stent with scar tissue, which can re-narrow the blood vessel. The composition can cover an outer surface of a stent to help adhere the stent to a vessel wall in a manner that is less damaging to the tissue than an uncovered stent or avoid its displacement inside the body. Similarly, the composition can cover the surface of any devices which are in contact with tissue to provide a suitable interface that can be adhesive to tissue.
The composition according to the present invention can be used in a variety of other applications where an adhesive or sealant is required. These include, but are not limited to, air leaks following a lung resection; to reduce the time for surgical procedures; to seal dura; to ease laparoscopic procedures; as a degradable skin adhesive; as a hernia matrix to prevent or to reduce the need for stables or tacks; to prevent blood loss; to manipulate organs or tissues during surgical procedures; to secure corneal transplants in place; to patch a heart to deliver drugs and/or to reduce dilation of the heart after myocardial infarction; to attach another material to a tissue; to augment sutures or staples; to distribute forces across tissue; to prevent leaks; as a barrier membrane on the skin to prevent evaporation of water from burnt skin; as a patch for delivery of anti-scar or antimicrobial medication; to attached devices to tissue; to attach devices to mucus membrane as a tape to secure devices within an oral cavity, such as to hold dentures and oral appliances; as a tape to anchor soft tissue to bone; and, preventing the formation of holes in tissue, enhancing/augmenting mechanical properties of tissues, etc.
B. Delivery of bioactive moleculesThe composition according to the invention described may also contain one or more pharmaceutical, therapeutic, prophylactic, and/or diagnostic agents that are released during the time period that the material functions as a sealant/adhesive. The agent may be a small molecule agent, for example having molecular weight less than 2000, 1500, 1000, 750, or 500 Da, a biomolecule, for example peptide, protein, enzyme, nucleic acid, polysaccharide, growth factors, cell adhesion sequences such as RGD sequences or integrins, extracellular matrix components, or combinations thereof. Exemplary classes of small molecule agents include, but are not limited to, anti-inflammatories, analgesics, antimicrobial agents, and combinations thereof. Exemplary growth factors include, without limitation, TGF-β, acidic fibroblast growth factor, basic fibroblast growth factor, epidermal growth factor, IGF-I and II, vascular endothelial-derived growth factor, bone morphogenetic proteins, platelet-derived growth factor, heparin-binding growth factor, hematopoietic growth factor, peptide growth factor, or nucleic acids. Exemplary extracellular matrix components include, but are not limited to, collagen, fibronectin, laminin, elastin and combinations thereof. Proteoglycans and glycosaminoglycans can also be covalently or non-covalently associate with the composition of the present invention.
Functional groups on the pre-polymer that were not activated may be used to covalently attach one or more agents, such as small molecule agents and/or biomolecules. Alternatively, the one or more agents can be physically entrapped within the cured composition by curing the composition in the presence of the agent.
C. Tissue supportThe materials can be used to create tissue supports by forming shaped articles within the body to serve a mechanical function. The shaped articles may be produced by a variety of fabrication techniques know in the art, including 3D printing. Such articles may exert functions such as holding two tissues together or positioning the tissue in a specific position inside or outside the body.
The tissue can be coated with a layer of the materials, for example the lumen of a tissue such as a blood vessel to prevent restenosis, reclosure or vasospasm after vascular intervention.
The composition may also contain one or more types of cells, such as connective tissue cells, organ cells, muscle cells, nerve cells, and combinations thereof. Optionally, the material is seeded with one or more of tenocytes, fibroblasts, ligament cells, endothelial cells, lung cells, epithelial cells, smooth muscle cells, cardiac muscle cells, skeletal muscle cells, islet cells, nerve cells, hepatocytes, kidney cells, bladder cells, urothelial cells, chondrocytes, and bone-forming cells. The combination of cells with the material may be used to support tissue repair and regeneration.
D. Anti-adhesion barriersThe materials herein described can be applied to reduce or prevent the formation of adhesions after surgical procedures. For example, to prevent adhesion of brain tissue to the skull after brain surgery or implantation of devices or to prevent peritoneal adhesion
E. Other applicationsThe compositions can also be used to coat tools, such as surgical instruments, for example forceps or retractors, to enhance the ability of the tools to manipulate objects. The materials can also be used herein can also be used in industrial applications where it is useful to have a degradable adhesive that is biocompatible, for example to reduce potential toxicity of the degradation products, such as marine applications, for example in underwater use or attaching to the surface of boats. The materials can be also used to produce shaped objects by a variety of techniques known in the art, including 3D printing. The shaped object may have micro or nanoscale resolution.
The present invention will now be illustrated by reference to the following examples.