Methods and compositions for achieving hemostasis and stable blood clot formation

A method of preparing an acrylated chitosan composition comprising:

• (a) contacting a raw chitosan material with an aqueous organic acid solution to form a chitosan intermediate;
• (b) contacting the intermediate chitosan material with an α,β-unsaturated carboxylic acid to form an acrylated chitosan intermediate;
• and
• (c) purifying the acrylated chitosan intermediate thereby to produce the acrylated chitosan composition.

A method of preparing an acrylated chitosan composition comprising:

• (a) contacting a raw chitosan material with an acetic acid solution to form a chitosan intermediate, wherein the raw chitosan material has a PDI of from about 1.5 (Mw/Mn) to about 5.0 (Mw/Mn);
• (b) contacting the intermediate chitosan with acrylic acid to form an acrylated chitosan intermediate having a degree of substitution (DS) value of from about 25% to about 65%;
• and
• (c) purifying the acrylated chitosan intermediate thereby to produce the acrylated chitosan composition.

A hemostatic hydrogel composition containing oxidized dextran and acrylated chitosan, wherein the hydrogel composition comprises two or more of the following features:

• (i) a total amount of free aldehyde groups of from about 0.1 to about 0.7 moles aldehyde/mole oxidized dextran,
• (ii) the hemostatic hydrogel composition is formed from oxidized dextran and acrylated chitosan, wherein the ratio of primary aldehydes in the oxidized dextran to the amines in the acrylated chitosan is in the range from about 1.0 to about 2.0, and/or the ratio of total aldehydes in the oxidized dextran to amines in the acrylated chitosan is from about 1.5 to about 3.0,
• (iii) the ratio of Mw of the acrylated chitosan to the oxidized dextran is from about 2 to about 10, the ratio of Mn of the acrylated chitosan to the oxidized dextran is from about 4 to about 15, the ratio of Mz of the acrylated chitosan to the oxidized dextran is from about 2 to about 10, the ratio of PDI (Mw/Mn) of acrylated chitosan to oxidized dextran is from about 0.5 to about 0.8, and/or the ratio of PDI (Mz/Mw) of acrylated chitosan to oxidized dextran is from about 0.5 to about 1.0,
• (iv) upon formation of the hydrogel composition, the hydrogel composition comprises a bound water content of from about 65% w/w to about 95% w/w,
• (v) a three-dimensional porous structure comprising layers of substantially non-interconnected pores having (a) a pore size distribution from about 10 μm to about 850 μm in diameter, (b) a platelet adhesive surface, or a combination of (a) and (b),
• (vi) walls disposed between the substantially non-interconnected pores, the walls having a wall thickness of from 0.046 μm to 50 μm,
• (vii) a platelet adhesive surface so that, when in contact with blood, the hemostatic hydrogel composition permits platelets and/or red blood cells within the blood to adhere to platelet adhesive surface and promote blood clot formation at or within the hemostatic hydrogel composition,
• (viii) a platelet adhesive surface so that, when in contact with blood, the hemostatic hydrogel composition permits platelet and/or red blood cells within the blood to adhere to the platelet adhesive surface and not permit platelets and/or red blood cells from the blood to enter pores present in a first surface of the hemostatic hydrogel composition, pass through the hemostatic hydrogel composition, and then exit the hemostatic hydrogel composition via pores present in a second surface of the hemostatic hydrogel composition that opposes the first surface,
• (ix) at about 10 seconds after the formation of the hemostatic hydrogel composition, the hemostatic hydrogel composition has a burst strength of greater than 20 mmHg as determined using an ASTM F 2392-04 protocol,
• (x) at about 2 minutes after the formation of the hemostatic hydrogel composition, the hemostatic hydrogel composition has a burst strength of greater than about 35 mmHg as determined using an ASTM F 2392-04 protocol,
• (xi) at about 5 minutes after the formation of the hemostatic hydrogel composition, the hemostatic hydrogel composition has a burst strength of greater than about 70 mmHg as determined using an ASTM F 2392-04 protocol,
• (xii) an elastic modulus of from about 500 Pa to about 5000 Pa at from about 10 seconds to about 80 seconds after the formation of the hemostatic hydrogel composition,
• (xiii) a compression modulus of from about 3 kPa to about 250 kPa,
• (xiv) an average adhesion strength of from about 1.0 N to about 50.0 N, as determined using an ASTM F 2258-05 protocol,
• (xv) the volume of the hemostatic hydrogel composition, when formed, does not increase upon exposure to a physiological fluid or body fluid,
• (xvi) the volume of the hemostatic hydrogel composition shrinks by less than about 5% about 10 minutes after formation when exposed to a physiological fluid or body fluid,
• (xvii) the volume of the hemostatic hydrogel composition shrinks from about 5% to about 30% within about 2 hours after formation, from about 20% to about 60% within about 8 hours after formation, and from about 45% to about 70% within about 24 hours after formation, when exposed to a temperature of 37° C. and 75% relative humidity,
• (xviii) is substantially transparent when the hemostatic hydrogel composition has a thickness of 2 mm to 10 mm, and
• (xix) the hemostatic hydrogel composition optionally further comprises a therapeutic agent.

A hemostatic hydrogel composition comprising a gel produced by combining oxidized dextran with acrylated chitosan, wherein the hemostatic hydrogel composition comprises a plurality of crosslinked moieties of formula (IX)

• and comprises one or more of the following features:
• (i) the hemostatic hydrogel, when immersed in saline for about 4 hours, exhibits a mass reduction of from about 1% to about 5%,
• (ii) the hemostatic hydrogel, when immersed in saline for about 8 hours, exhibits a mass reduction of from about 6% to about 10%,
• (iii) the hemostatic hydrogel, when immersed in saline for about 24 hours, exhibits a mass reduction of from about 20% to about 25%,
• (iv) the hemostatic hydrogel, when exposed to a physiological fluid or body fluid for about 8 hours, exhibits an irreversible decrease in volume, and
• (v) the hemostatic hydrogel, at least 30 seconds after formation, takes at least 5 minutes to completely dissolve when exposed to a 5M hydroxylamine hydrochloride solution.