ANTIMICROBIAL FIBER COMPRISING SILVER, FABRIC AND WOUND DRESSING COMPRISING THE ANTIMICROBIAL FIBER, AND METHODS FOR MANUFACTURING THE FIBER, THE FABRIC, AND THE WOUND DRESSING

Abstract

A wound dressing, including fibers containing silver ions. The fibers are manufactured by dissolving silver nitrate into a polymer solution in the substantial absence of light, and then extruding the obtained solution into fibers by wet spinning process. The silver content of the wound dressing is between 0.01-10% by weight, and preferably 0.1-7% by weight.

Claims

1. A wound dressing, comprising fibers, the fibers comprising silver ions; wherein the content of the silver ions in the fiber is between 0.01-10% by weight.

2. The wound dressing of claim 1, wherein the fiber further comprises chitosan fibers or alginate fibers.

3. The wound dressing of claim 2, wherein the alginate fibers are high guluronic alginate fiber, high mannuronic alginate fiber, or a mixture thereof.

4. The wound dressing of claim 2, wherein the alginate fibers are: calcium alginate fibers or calcium and sodium alginate fiber.

5. The wound dressing of claim 2, wherein the chitosan fiber has a degree of deacetylation of at least 80%.

6. The wound dressing of claim 2, wherein the chitosan fibers are carboxymethylated or acylated chitosan fibers.

7. The wound dressing of claim 1, wherein the fibers have a linear density of 1-5 dtex and a fiber length of 5-125 mm.

8. The wound dressing of claim 1, wherein the silver dressing is a needle punched nonwoven fabric having dressing wet strengths in machine direction (MD) and in cross machine direction (CD) of 0.3 N/cm or above and 0.4 N/cm or above, respectively.

9. A method of manufacturing the wound dressing of claim 1, the method comprising: a) dissolving silver nitrate in water in the substantial absence of light thereby yielding a silver nitrate solution; b) adding a polymer to the silver nitrate solution in the substantial absence of light thereby yielding a polymer solution comprising silver ions, wherein a ratio of the weight of silver ions to the dry weight of the polymer is 0.01-10%, and the polymer is chitosan or alginate; c) extruding the polymer solution comprising silver ions into fibers comprising silver ions through a wet spinning process; d) fabricating the fibers comprising silver ions into a nonwoven fabric through needle punching process or chemical bonding process; and e) cutting, packing, and sterilizing the nonwoven fabric to obtain the wound dressing.

10. The method of claim 9, wherein sodium hypochlorite is added to the silver nitrate solution between step a) and step b) in the substantial absence of light, and the weight ratio of the sodium hypochlorite to the polymer is between 0.005% and 2%.

11. The method of claim 9, wherein sodium chloride is added to the silver nitrate solution between step a) and step b) in the substantial absence of light, and the weight ratio of the sodium chloride to the polymer is between 0.001% and 11.0%.

12. A method of manufacturing the wound dressing of claim 1, the method comprising: a) dissolving a first portion of a polymer in water in the substantial absence of light thereby yielding a solution, wherein the solution has a viscosity of between 200-1000 cps, and the polymer is chitosan or alginate; b) dissolving silver nitrate in the solution of a) in the substantial absence of light thereby yielding a mixture, and after stirring the mixture for 20-90 mins in the substantial absence of light, adding a second portion of the polymer to the mixture in the substantial absence of light, thereby yielding a polymer solution comprising silver ions; c) degassing the polymer solution comprising silver ions in the substantial absence of light; d) extruding the polymer solution comprising silver ions into fibers comprising silver ions through a wet spinning process; e) fabricating the fibers comprising silver ions into a nonwoven fabric through needle punching process or chemical bonding process; and f) cutting, packing, and sterilizing the nonwoven fabric to obtain the wet-spun fibrous silver wound dressing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1 is a photograph of zone of inhibition of the dressing containing 0.5 wt. % silver for Staphylococcus aureus after 1 day;

[0040] FIG. 2 is a photograph of zone of inhibition of the dressing containing 0.5 wt. % silver for Staphylococcus aureus after 5 days;

[0041] FIG. 3 is a photograph of zone of inhibition of the dressing containing 0.5 wt. % silver for Staphylococcus aureus after 7 days;

[0042] FIG. 4 is a photograph of zone of inhibition of the dressing containing 1 wt. % silver for Escherichia coli after 1 day;

[0043] FIG. 5 is a photograph of zone of inhibition of the dressing containing 1 wt. % silver for Escherichia coli after 5 days;

[0044] FIG. 6 is a photograph of zone of inhibition of the dressing containing 1 wt. % silver for Escherichia coli after 7 days;

[0045] FIG. 7 is a photograph of zone of inhibition of the dressing containing 10 wt. % silver for Bacillus subtilis after 1 day;

[0046] FIG. 8 is a photograph of zone of inhibition of the dressing containing 10 wt. % silver for Bacillus subtilis after 7 days;

[0047] FIG. 9 is a photograph of zone of inhibition of the dressing containing 0.05 wt. % silver for Staphylococcus aureus after 1 day;

[0048] FIG. 10 is a photograph of zone of inhibition of the dressing containing 0.05 wt. % silver for Staphylococcus aureus after 7 days;

[0049] FIG. 11 is a photograph of zone of inhibition of the dressing containing 0.01 wt. % silver for Staphylococcus aureus after 1 day;

[0050] FIG. 12 is a photograph of zone of inhibition of the dressing containing 0.01 wt. % silver for Staphylococcus aureus after 7 days; and

[0051] FIG. 13 shows a silver releasing profile of the dressing made from Example 1 in 10 ml of simulated wound exudate.

DETAILED DESCRIPTION

[0052] This invention is further illustrated through the following examples and figures.

[0053] In the following examples, the operations of preparing, mixing, and degassing the polymer and silver nitrate solutions were conducted in a vessel with a cover, such as a stainless-steel tank, in the substantial absence of light.

[0054] The calculation for mixing and components weights is summarized as follows:

[0055] When the dry weight of sodium alginate powder is 6 kg and the moisture content of the material is 11%, the weight of sodium alginate at ambient conditions is 6 kg(1-11%)=6.74 kg. When preparing a polymer solution of sodium alginate at 5% solid content, the quantity of water needed for the mixing is 6 kg5%95%=114 kg.

[0056] The silver content in silver nitrate is 60%. To make silver alginate fibers with 0.5% silver content, the weight of silver in 6 kg of sodium alginate powder is calculated as: 6 kg0.5%=0.03 kg, which requires 0.03 kg60%=0.05 kg of silver nitrate.

Example 1

[0057] The manufacturing method for antimicrobial fibers and wound dressing containing 0.5% by weight silver:

[0058] To make 6 kg of silver alginate fibers with 0.5% silver content, it needed 50 g of silver nitrate, 6.74 kg of sodium alginate, and 114 L of water.

[0059] 114 L of water was added to a mixing vessel.

[0060] 50 g of silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water, and then while the mixer was kept running, 1 kg of sodium alginate powder was added to the solution. After that, the mixer was kept running and the mixture of undissolved alginate and silver nitrate was checked to ensure that the viscosity reach the pre-stated ideal level.

[0061] The remaining sodium alginate was added to the solution while the mixer was kept running.

[0062] After the sodium alginate was completely dispersed, the solution was kept still for 24 hours in a sealed stainless-steel vessel for natural degassing. Because of the high viscosity of the polymer solution, the silver ion was evenly distributed in the alginate polymer solution.

[0063] After the degassing was completed, the polymer solution was ready to be extruded to calcium silver alginate fiber through a standard wet-spinning process. Typically, silver-containing sodium alginate solution was pumped through a spinneret into a coagulating bath to convert the sodium alginate to calcium alginate fiber, followed with stretching bath, washing, drying, crimping, and cutting.

[0064] This process yielded white or off-white fibers with 0.5 wt. % silver content.

[0065] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for packaging. The dressing was irradiated by 25-40 kGy of gamma ray.

[0066] The silver alginate dressing with 0.5% silver content was obtained.

Example 2

[0067] The dressing from Example 1 was cut into 22 cm, wetted, and then placed into a petri dish that was covered evenly with Staphylococcus aureus. The petri dish was placed into a 37 C. incubator for 7 days, and the growth of the microorganic was observed. When the silver ions were released from the dressing, the microorganisms surrounding the dressing sample were killed, creating a visible zone of inhibition. The larger the zone is, the better the antimicrobial property the dressing has. FIG. 1 displays a zone of inhibition of the dressing containing 0.5 wt. % silver for Staphylococcus aureus after 1 day; FIG. 2 displays a zone of inhibition of the dressing containing 0.5 wt. % silver for Staphylococcus aureus after 5 days; FIG. 3 displays a zone of inhibition of the dressing containing 0.5 wt. % silver for Staphylococcus aureus after 7 days. It can be seen that the dressing with 0.5% silver content still has a good antimicrobial function after 7 days.

Example 3

[0068] The manufacturing method for antimicrobial fibers and wound dressing containing 1% by weight silver:

[0069] To make 6 kg of silver alginate fibers with 1% silver content, it needed 100 g of silver nitrate, 6.74 kg of sodium alginate, and 114 L of water.

[0070] 114 L of water was added to a mixing vessel.

[0071] 100 g of silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water, and then while the mixer was kept running, 1 kg of sodium alginate powder was added to the solution. After that, the mixer was kept running, and the mixture of undissolved alginate and silver nitrate was checked to ensure that the viscosity reach the pre-stated ideal level.

[0072] The remaining sodium alginate was added to the solution while the mixer was kept running.

[0073] After the sodium alginate was completely dispersed, the solution was kept still for 24 hours for natural degassing. Because of the high viscosity of the polymer solution, the silver ion was evenly distributed in the alginate polymer solution.

[0074] After the degassing was completed, the polymer solution was ready to be extruded to calcium silver alginate fiber through a standard wet-spinning process. Typically, the silver-containing sodium alginate solution was pumped through a spinneret into a coagulating bath to convert the sodium alginate to calcium alginate fiber, followed with stretching bath, washing, drying, crimping, and cutting.

[0075] This process yielded white or off-white fibers with 1 wt. % silver content.

[0076] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0077] The silver alginate dressing with 1% silver content was obtained.

Example 4

[0078] The dressing from Example 3 was cut into 22 cm, wetted, and placed into a petri dish that was covered evenly with Escherichia coli. The petri dish was placed into a 37 C. incubator for 7 days, and the growth of the microorganic was observed. When the silver ions were released from the dressing, the microorganisms surrounding the dressing sample were killed, creating a visible zone of inhibition. FIG. 4 displays a zone of inhibition of the dressing containing 1 wt. % silver for Escherichia coli after 1 day; FIG. 5 displays a zone of inhibition of the dressing containing 1 wt. % silver for Escherichia coli after 5 days; FIG. 6 displays a zone of inhibition of the dressing containing 1 wt. % silver for Escherichia coli after 7 days. It can be seen that the dressing with 1% silver content has a good antimicrobial function after 7 days.

Example 5

[0079] The manufacturing method for antimicrobial fibers and wound dressing containing 10% by weight silver:

[0080] To make 6 kg of silver alginate fibers with 10% silver content, it needed 1000 g of silver nitrate, 6.74 kg of sodium alginate, and 114 L of water.

[0081] 114 L of water was added to a mixing vessel.

[0082] 1000 g of silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water, and then while the mixer was kept running, 1 kg of sodium alginate powder was added to the solution. After that, the mixer was kept running, and the mixture of undissolved alginate and silver nitrate was checked to ensure that the viscosity reach the ideal level to prevent re-grouping of the silver material.

[0083] The remaining sodium alginate was added to the solution while the mixer was kept running.

[0084] After the sodium alginate was completely dispersed, the solution was kept still for 24 hours for natural degassing. Because of the high viscosity of the polymer solution, the silver ion was kept suspended and evenly distributed in the alginate polymer solution.

[0085] After the degassing was completed, the polymer solution was ready to be extruded to calcium silver alginate fiber through a standard wet-spinning process. Typically, the silver-containing sodium alginate solution was pumped through a spinneret into a coagulating bath to convert the sodium alginate to calcium alginate fiber, followed with stretching bath, washing, drying, crimping, and cutting.

[0086] This process yielded white or off-white fibers with 10 wt. % silver content.

[0087] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0088] The silver alginate dressing with 10% silver content was obtained.

Example 6

[0089] The dressing from Example 5 was cut into 22 cm, wetted, and then placed into a petri dish that was covered evenly with Staphylococcus aureus. The petri dish was placed into a 37 C. incubator for 7 days, and the growth of the microorganic was observed. When the silver ions were released from the dressing, the microorganisms surrounding the dressing sample were killed, creating a visible zone of inhibition. FIG. 7 displays a zone of inhibition for Staphylococcus aureus after 1 day; FIG. 8 displays a zone of inhibition after 5 days; FIG. 9 displays a zone of inhibition after 7 days. It can be seen that the dressing produces an excellent zone of inhibition in 7 days.

Example 7

[0090] The manufacturing method for antimicrobial fibers and wound dressing containing 0.05% by weight silver:

[0091] To make 6 kg of silver alginate fibers with 0.05% silver content, it needed 5 g of silver nitrate, 6.74 kg of sodium alginate and 114 L of water.

[0092] 114 L of water was added to a mixing vessel.

[0093] 5 g of silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water.

[0094] 6.74 kg of sodium alginate was added to the solution.

[0095] After the sodium alginate was completely dispersed, the solution was kept still for 24 hours for natural degassing. Because of the high viscosity of the polymer solution, the silver ion was evenly distributed in the alginate polymer solution.

[0096] After the degassing was completed, the polymer solution was ready to be extruded to calcium silver alginate fiber through a standard wet-spinning process.

[0097] This process yielded white or off-white fibers with 0.05% (by weight) silver content.

[0098] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0099] The silver alginate dressing with 0.05% silver content was obtained.

Example 8

[0100] The dressing from Example 7 was cut into 22 cm, wetted, and then placed into a petri dish that was covered evenly with Staphylococcus aureus. The petri dish was placed into a 37 C. incubator for 7 days, and the growth of the microorganic was observed. When the silver ions were released from the dressing, the microorganisms surrounding the dressing sample were killed, creating a visible zone of inhibition. FIG. 9 displays a zone of inhibition of dressing with 0.05% silver for Staphylococcus aureus after 1 day; FIG. 10 displays a zone of inhibition after 7 days. These indicate that the dressing with 0.05% of silver still has a good antimicrobial property.

Example 9

[0101] The manufacturing method for antimicrobial fibers and wound dressing containing 0.01% by weight silver:

[0102] To make 6 kg of silver alginate fibers with 0.01% silver content, it needed 1 g of silver nitrate, 6.74 kg of sodium alginate and 114 L of water.

[0103] 114 L of water was added to the mixing vessel.

[0104] All of the silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water.4. All of the sodium alginate was added to the solution.

[0105] After the sodium alginate was completely dispersed, the solution was kept still for 24 hours for natural degassing. Because of the high viscosity of the polymer solution, the silver ion was evenly distributed in the alginate polymer solution.

[0106] After the degassing was completed, the polymer solution was ready to be extruded to calcium silver alginate fiber through a standard wet-spinning process.

[0107] This process yielded white or off-white fibers with 0.01% (by weight) silver content.

[0108] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0109] The silver alginate dressing with 0.01% silver content was obtained.

Example 10

[0110] The dressing from Example 9 was cut into 22 cm, wetted, and placed into a petri dish that was covered evenly with Staphylococcus aureus. The petri dish was placed into a 37 C. incubator for 7 days, and the growth of the microorganic was observed. When the silver ions are released from dressing, the microorganisms surrounding the dressing sample were killed, creating a visible zone of inhibition. FIG. 11 displays a zone of inhibition of dressing with 0.01% silver content for Staphylococcus aureus after 1 day; FIG. 12 displays a zone of inhibition after 7 days. These figures indicate that the dressing with 0.01% of silver still has some antimicrobial property.

Example 11

[0111] The manufacturing method for antimicrobial chitosan fibers and chitosan wound dressing containing 1.1% by weight silver:

[0112] Target silver content was 1.1%, quantity of chitosan powder or flakes was 200 g, the moisture content of the chitosan was 10% by weight. At 5 wt. % solid content, 3420 ml of 2 wt. % acetic acid solution was needed. The dry weight of the chitosan powder was 180 g.

[0113] To make 180 g of chitosan fiber with target silver content of 1.1%, 3.3 g of silver nitrate was required.

[0114] All of the silver nitrate was added to a small container that had been pre-charged with the required amount of acetic acid solution. The mixer was started to dissolve the silver nitrate.

[0115] 30 g of chitosan powder was added to the acetic acid solution prepared in the above step.

[0116] When the chitosan powder was fully dissolved and the solution reached the ideal viscosity, the remaining powder was added.

[0117] When all the chitosan was fully mixed into the solution, the mixer was removed, and the solution was kept still for 24 hours for natural degassing.

[0118] After the degassing was completed, the polymer solution was ready to be extruded into silver chitosan fiber through a standard wet-spinning process. Typically, silver-containing chitosan solution was pumped through a spinneret into a bath of 5 wt. % sodium hydrate solution to convert the chitosan solution into filaments, followed with stretching bath, washing, drying, crimping, and cutting.

[0119] This process yielded white or creamy colored fibers with 1.1% (by weight) silver content.

[0120] The silver fibers were converted into nonwoven felt on standard textile machine, and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0121] The silver chitosan dressing with 1.1% silver content was obtained.

Example 12

[0122] The manufacturing method for antimicrobial fibers and wound dressing containing silver chloride:

[0123] 114 L of water was added to the mixing vessel.

[0124] 5 g of silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water. 1.72 g of sodium chloride was added to the solution while the mixer was kept running. The weight of sodium chloride was at a molar ratio of 1:1 to silver nitrate. This converted the silver nitrate to silver chloride. Another 1 kg of sodium alginate was added to the mix while the mixer was kept running.

[0125] The remaining 5.74 kg of sodium alginate was added to the solution while the mixer was on.

[0126] After the sodium alginate was completely dispersed, the solution was kept still for 24 hours for natural degassing. Because of the high viscosity of the polymer solution, the silver chloride was evenly mixed with the alginate polymer solution without aggregation of silver chloride.

[0127] After the degassing was completed, the polymer solution was ready to be extruded into silver alginate fiber through a standard wet-spinning process, i.e. metering pump, coagulant bath, stretching, washing, drying, crimping, and cutting.

[0128] This process yielded white or off-white silver alginate fibers with 0.05% (by weight) silver content.

[0129] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0130] The silver alginate dressing with 0.05% silver content was obtained.

Example 13

[0131] The manufacturing method for antimicrobial fibers and wound dressing containing silver hypochlorite:

[0132] 114 L of water was added to the mixing vessel.

[0133] 5 g of silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water. 2.19 g of sodium hypochlorite was added to the solution while the mixer was kept running. The weight of sodium hypochlorite was at a molar ratio of 1:1 to silver nitrate. This converted the silver nitrate into silver hypochlorite. Another 1 kg of sodium alginate was added to the mix while the mixer was kept running.

[0134] The remaining 5.74 kg of sodium alginate was added to the solution while the mixer was on.

[0135] After the sodium alginate was completely dispersed, the solution was kept still for 24 hours for natural degassing. Because of the high viscosity of the polymer solution, the silver hypochlorite was evenly mixed with the alginate polymer solution without aggregation of silver chloride.

[0136] After the degassing was completed, the polymer solution was ready to be extruded into silver alginate fibers through a standard wet-spinning process, i.e. metering pump, coagulant bath, stretching, washing, drying, crimping, and cutting.

[0137] This process yielded white or off-white silver alginate fibers with 0.05% (by weight) silver content.

[0138] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0139] The silver alginate dressing with 0.05% silver content was obtained.

Example 14

[0140] The manufacturing method for antimicrobial fibers and wound dressing containing silver chloride:

[0141] 114 L of water was added to the mixing vessel.

[0142] 100 g of silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water. 34.4 g of sodium chloride was added to the solution while mixer was kept running. The amount of sodium chloride added was at a molar ratio of 1:1 to silver nitrate. This converted the silver nitrate to silver chloride. Another 1 kg of sodium alginate was added to the mix while the mixer was kept running.

[0143] The remaining 5.74 kg of sodium alginate was added to the solution while the mixer was on.

[0144] After the sodium alginate was completely dispersed, the solution was left still for 24 hours for natural degassing. Because of the high viscosity of the polymer solution, the silver chloride was evenly mixed with the alginate polymer solution without aggregation.

[0145] After the degassing was completed, the polymer solution was ready to be extruded into silver alginate fiber through a standard wet-spinning process, i.e. metering pump, coagulant bath, stretching, washing, drying, crimping, and cutting.

[0146] This process yielded white or off-white silver alginate fibers with 1.0% (by weight) silver content.

[0147] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0148] The silver alginate dressing with 1.0% silver content was obtained.

Example 15

[0149] The manufacturing method for antimicrobial fibers and wound dressing containing silver hypochlorite:

[0150] 114 L of water was added to the mixing vessel.

[0151] 100 g of silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water. 43.8 g of sodium hypochlorite was added to the solution while the mixer was kept running. The amount of sodium hypochlorite was at a molar ratio of 1:1 to silver nitrate. This converted the silver nitrate into silver hypochlorite. Another 1 kg of sodium alginate was added to the mix while the mixer was kept running.

[0152] The remaining 5.74 kg of sodium alginate was added to the solution while the mixer was on.

[0153] After the sodium alginate was completely dispersed, the solution was left still for 24 hours for natural degassing. Because of the high viscosity of the polymer solution, the silver hypochlorite was evenly mixed with the alginate polymer solution without aggregation.

[0154] After the degassing was completed, the polymer solution was ready to be extruded into silver alginate fibers through a standard wet-spinning process, i.e. metering pump, coagulant bath, stretching, washing, drying, crimping, and cutting.

[0155] This process yielded white or off-white silver alginate fibers with 1% (by weight) silver content.

[0156] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0157] The silver alginate dressing with 1% silver content was obtained.

Example 16

[0158] The manufacturing method for antimicrobial fibers and wound dressing containing silver chloride:

[0159] 114 L of water was added to the mixing vessel.

[0160] 1000 g of silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water. 344 g of sodium chloride was added to the solution while the mixer was kept running. The amount of sodium chloride added was at a molar ratio of 1:1 to silver nitrate. This converted the silver nitrate to silver chloride. Another 1 kg of sodium alginate was added to the mix while the mixer was kept running.

[0161] The remaining 5.74 kg of sodium alginate was added to the solution while the mixer was on.

[0162] After the sodium alginate was completely dispersed, the solution was left still for 24 hours for natural degassing. Because of the high viscosity of the polymer solution, the silver chloride was evenly mixed with the alginate polymer solution without aggregation.

[0163] After the degassing was completed, the polymer solution was ready to be extruded into silver alginate fiber through a standard wet-spinning process, i.e. metering pump, coagulant bath, stretching, washing, drying, crimping, and cutting.

[0164] This process yielded white or off-white silver alginate fibers with 10% (by weight) silver content.

[0165] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0166] The silver alginate dressing with 10% silver content was obtained.

Example 17

[0167] The manufacturing method for antimicrobial fibers and wound dressing containing silver hypochlorite:

[0168] 114 L of water was added to the mixing vessel.

[0169] 1000 g of silver nitrate was added to the mixing vessel. The mixer was started to fully dissolve and mix the silver nitrate in the water. 438 g of sodium hypochlorite was added to the solution while the mixer was kept running. The amount of sodium hypochlorite was at a molar ratio of 1:1 to silver nitrate. This converted the silver nitrate into silver hypochlorite. Another 1 kg of sodium alginate was added to the mix while the mixer was kept running.

[0170] The remaining 5.74 kg of sodium alginate was added to the solution while the mixer was on.

[0171] After the sodium alginate was completely dispersed, the solution was left still for 24 hours for natural degassing. Because of the high viscosity of the polymer solution, the silver hypochlorite was evenly mixed with the alginate polymer solution without aggregation.

[0172] After the degassing was completed, the polymer solution was ready to be extruded into silver alginate fibers through a standard wet-spinning process, i.e. metering pump, coagulant bath, stretching, washing, drying, crimping, and cutting.

[0173] This process yielded white or off-white silver alginate fibers with 10% (by weight) silver content.

[0174] The silver fibers were converted into nonwoven felt and cut into 1010 cm pads for package. The dressing was irradiated by 25-40 kGy of gamma ray.

[0175] The silver alginate dressing with 10% silver content was obtained.

Example 18

[0176] Determination of silver release:

[0177] In order to establish the silver release profile of the silver-containing antimicrobial wound dressing, the silver dressing from Example 1 was cut into 2.52.5 cm and placed into 10 ml of simulated wound fluid. The sample was incubated in a water bath at 37 C. and was kept shaking at 60-80 rpm for 7 days. The silver ions were released into the wound fluid and the amount of the silver in the solution was tested at the time points of 24 hrs, 72 hrs and 168 hrs. The following Table 1 gives the amount of silver released into 10 ml of simulated wound exudates at the relevant time points. It can be seen that the silver release increases with the time, with the maximum silver release of 38.4 ppm at the time point of 168 hrs.

TABLE-US-00001 TABLE 1 Silver release in 10 ml of simulated wound exudate Silver Time release (hrs) (ppm) 24 20.3 72 36.1 168 38.4