YY/T 1477.4-2017 English PDF (YYT1477.4-2017)

The in vitro wound model presented in this Part of YY/T 1477 is used to evaluate and compare the potential adhesion properties of wound dressings in vitro. This Part is applicable to the evaluation of the adhesion between the wound contact layer of the dressing and the wound.

YY/T 1477.4-2017
YY
PHARMACEUTICAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 11.120.20
C 48
Standard test models for primary wound dressing
performance evaluation - Part 4. In vitro wound model
for adhesion properties evaluation of dressings
ISSUED ON. FEBRUARY 28, 2017
IMPLEMENTED ON. JANUARY 1, 2018
Issued by. China Food and Drug Administration
Table of Contents
Foreword ... 3
Introduction ... 4
1 Scope ... 5
2 Terms and definitions ... 5
3 Summary... 5
4 Model construction ... 5
5 Model application ... 6
Appendix A (Informative) An example of a test using the wound model to
evaluate the potential adhesion of dressings ... 8
Appendix B (Informative) An example of a test using the wound model to
evaluate the performance between dressings ... 11
References ... 13
Standard test models for primary wound dressing
performance evaluation - Part 4. In vitro wound model
for adhesion properties evaluation of dressings
1 Scope
The in vitro wound model presented in this Part of YY/T 1477 is used to evaluate and compare the potential adhesion properties of wound dressings in vitro. This Part is applicable to the evaluation of the adhesion between the wound contact layer of the dressing and the wound.
2 Terms and definitions
The following terms and definitions are applicable to this document.
2.1 Wound model
A fibrin clot which simulates a wound, to evaluate the potential adhesion properties of the dressing to the wound.
3 Summary
This model is a unique in vitro quantitative model developed based on the adhesion properties of wound dressings to fibrin clots. The water-soluble fibrinogen is coagulated with thrombin into a water-insoluble fibrin, and further solidified into a fibrin clot. An adhesion is provided by the protein clot, and the wound is simulated with a biological matrix and applied between two dressings. By measuring the peel force required to peel the dressing material from the fibrin clot, the potential adhesion of the wound dressing is evaluated. 4 Model construction
4.1 Test devices
Test devices include.
a) 6-well cell culture plate (or other equivalent devices);
b) Constant temperature-humidity chamber;
c) Drying oven;
d) Precision balance with an accuracy of 0.001 g.
4.2 Preparation of wound model (fibrin clot)
4.2.1 Reagents
Reagents include.
a) Bovine serum albumin (BSA) phosphate buffer solution (c=10 mg/mL). 1.0 g of bovine serum albumin (BSA) is dissolved in 100 mL of phosphate
buffered saline (PBS);
b) Fibrinogen (source. cattle). commercially available;
c) Thrombin. USE an appropriate amount of 9 g/L sodium chloride solution to dissolve, so that the concentration is about 300 units/mL.
4.2.2 Fibrin clot preparation
TAKE 3 g of fibrinogen; ADD it to bovine serum albumin (BSA) phosphate buffer solution [4.2.1a)], so that the fibrinogen concentration is 30 mg/mL. Then, TAKE 10 mL of the solution and ADD to a 6-well cell culture plate; and ADD 1 mL of thrombin to each well, and quickly MIX it well. The mixture is placed at (37±2)°C for 1 h, and then cooled at room temperature for 1 h, to form and solidify a fibrin clot.
Note. When fibrinogen is dissolved in the cold season or fibrinogen is just removed from the cryogenic storage and at a lower temperature, special attention shall be paid to raising the temperature of fibrinogen and dissolving solution to 30 °C ~ 37 °C, and then dissolution is performed. Too low temperature tends to cause dissolution difficulties and protein denaturation.
5 Model application
The type of dressing is different, the intended use is different, and the potential adhesion is also quite different. Obviously, it is unreasonable to use the same evaluation method (including test methods and test parameters) to evaluate the potential adhesion of different dressings. Therefore, users of this Standard shall, according to the material, intended use, and potential adhesion, etc. of the dressing, design a suitable evaluation method, to obtain a reasonable
evaluation result.
1 - Briquetting block;
2 - Dressing sample A;
3 - Wound model (fibrin clot);
4 - Dressing sample B.
Note. If 0° without support [SEE Figure A.2a)] is used for the test, dressing sample A and dressing sample B shall be in the form of opposite placement. This figure shows the form of placement in the same direction.
Figure A.1 -- Illustration for the combination method of test dressings, wound model, and briquetting block
TAKE the combination of the dressings and the wound model out from the
constant temperature-humidity chamber; PLACE in a drying oven to dry for 3 h ~ 4 h at (37±2)°C; TAKE out, and PLACE it to cool to room temperature. The combination of the dressings and the wound model, according to one of the methods shown in Figure A.2, is mounted on the clamps of the tensile tester, so that the upper and lower clamps respectively hold two pieces of the test dressing. The initial spacing of the two clamps is approximately 50 mm. STRETCH at a rate of 100 mm/min, until one of the dressings is completely peeled off from the wound model (fibrin clot). The way the sample is supported during the test, that is, at different angles to the tensile direction, will result in different test results. The different sample holding methods are given in Figure A.2. It is recommended that the same sample support be used consistently in a test series and documented.
The peel force corresponding to the clamp displacement during the stretching process is recorded.
 The drying time can be adjusted appropriately according to the type of dressing. It shall dry the outer surface of the dressing.
 The user can, according to the type of dressing, the expected peel force, etc., select an appropriate method.