Introduction

Chitosan is a cationic carbohydrate polymer that is commercially derived from the deacetylation of chitin. Chitin exists in the shells of arthropods such as crabs, shrimps, and insects and can also be produced by fungi and bacteria.

In the last 20 years, chitosan fibre has become a popular material for wound dressing, mostly due to its hemostatic and bacteriostatic properties.

UMT’s chitosan wound dressing is composed of N-succinyl-chitosan fibre which has significantly enhanced hydrophilic and absorption performances over the standard chitosan fibres.

UMT’s chitosan wound dressing is a nonwoven sheet or ribbon made from chitosan fibres. The dressing absorbs exudates, management of minor bleeding and forms a cohesive gel to conform to the wound bed.

 

The chemistry of Chitosan

Chitosan is a polysaccharide composed of GlcN and GlcNAc linked with β-[1→4]-glycosidic linkages, where：

GlcN = D-Glucosamine = 2-Amino-2-deoxy-D-Glucopyranose

GlcNAc = N-Acetyl-D-glucosamine = 2-deoxy-2-acetamido-D-glucopyranose

UMT has developed a patented technology which turn the normally hydrophobic chitosan fibres into hydrophilic by a process of acylation. The chemical structure of the modified chitosan fibre is shown below:

The details of the acylation process can be found from the below granted patents:

GB2489541(B)

EP2695622 (B1)

CN102727925B

 

The process

Chitin, extracted from shells of cod crab, is made into chitosan by deacetylation. Through a wet-spinning process, chitosan is first dissolved in an acidic solution, then extruded into chitosan fibres. The fibres are then subject to a hydrophilizing chemical treatment to obtain acylated chitosan fibres.

Chitosan fibres are further processed into chitosan wound dressing through carding/needle punching, cutting and packaging.

This process can be illustrated by the diagram shown below.

 

How does Chitosan Dressing work?

Hemostatic Properties:

Due to the positive charge in the structure, chitosan can effectively adhere and aggregate red blood cells and platelets, activate the coagulation pathway through the activation of platelets, accelerate the synthesis of fibrin glue, stimulate vasoconstriction, and finally seal the micro vessels.

 

Hydrophilic properties:

The modified chitosan has a large number of hydrophilic carboxyl group introduced to the amino group, while can cause breaking of crystal structure of the original fibre, so that the carboxyl group in the molecular chain become free. Hydrogen bonds can therefore be established between hydrophilic groups and water to allow the dressing to absorb a large numbers of moisture.

 

The hydrophilic property of UMT’s chitosan wound dressing makes it more absorbent than other standard chitosan materials. Additionally it transforms into a cohesive hydrogel on absorption of aqueous solution such as wound exudates. The gel enables an intimate contact to the wound bed, provides an optimum moist environment to promote wound healings.

 

  Performance Data 

Absorbency: UMT’s acylated chitosan dressing is 20% more absorbent than other gelling dressings. The added absorbency helps to prevent the maceration of peripheral wound skin.

 

Wet Integrity: UMT’s chitosan dressing has greater wet strength than other gelling dressing, allowing one piece removal on dressing change.

 

Gelling: On absorbing the exudates, UMT’s chitosan turns into a cohesive gel which enable the dressing to form an intimate contact with the wound bed. This helps the provision of moist conditions to the healing process.

 

Bacteriostatic: The gelling and bacteriostatic properties helps the dressing to lock the bacteria in the dressing and to prevent infections.

 

Indications

The UMT Chitosan Wound Dressing is indicated for the management of moderate to heavily exuding chronic and acute wounds. The Chitosan Wound Dressings may be used to control minor bleeding in superficial wounds.

• Pressure sores

• Diabetic ulcers

• Leg ulcers

• Cavity wounds

• Donor sites and Graft sites

• Surgical wounds (e.g. post-operative, wounds left to heal by secondary intent)

• Skin abrasions and lacerations

• Superficial and partial thickness burns

• Trauma Wound

 

Clinical Data

Leg ulcer

An open multicenter comparative randomized clinical study on chitosan wound dressing has been completed to assess the safety and efficacy of the device. A total of 90 patients were enrolled into the study. The study has demonstrated that the UMT’s chitosan wound dressing, when compared to the control dressing, helped to reduce wound area and wound depth following 4 weeks of treatment ^{[Ref 1]}. 

 

The pictures below illustrate the progress made on a leg ulcer of a patient in the study ^{[Ref 2]}.

       

 

Diabetic foot ulcer

The following figure shows the healing process of diabetic foot ulcer after using chitosan dressing ^{[Ref 3]}.

          

 

Amputation

The following figure shows the healing process of toe amputation after using chitosan dressing ^{[Ref 3]}.

     

 

Skin-grafting

The following pictures illustrate the progress of abdominal skin grafting in patients in the study ^{[Ref 4]}.

          

 

[Ref 1]Xiaohui Mo et al, An open multicenter comparative randomized clinical study on chitosan, Wound Rep Reg (2015) 23, 518–524

 

[Ref 2]Clinical Study Data on file

 

[Ref 3]Angela Walker. Podiatry evaluation of a chitosan gelling fibre dressing in diabetic foot ulceration[J]. British journal of nursing, 2016, 25(12), S51-S58

 

[Ref 4]Mason S , Clarke C . A multicentred cohort evaluation of a chitosan gelling fibre dressing [J].British Journal of Nursing, 2015, 24(17), S868-876.