Introduction:
Chronic wounds, including diabetic foot ulcers, require proper diagnostics. Proper wound care must be supported by proper diagnostic procedures, one of which is the diagnosis of biomarkers that accelerate and inhibit wound healing, consistent for wound analysis. Many researchers have stated the importance of gelatinase, collagenase and matrix metalloprotease (MMP) levels and their role in wound healing. A balance between vascular endothelial growth factor (VEGF), inflammatory cytokines, MMPs and tissue matrix metalloprotease inhibitors (TIMPs) is indispensable in the wound healing process. Previous test results showed Whatmann had the ability to carry out cytokines and proteases in diabetic foot ulcer (DFU). The purpose of this study was to compare the sampling technique with the cotton swab technique and use Whatman cellulose paper as a preliminary study. The biomarkers taken were VEGF, interleukin 6 (IL-6), MMP-9 and TIMP-1 as representatives of growth factors, markers of inflammation and protease enzymes. The aim of the study was to determine the standard for taking commonly used media practicality for the extraction of growth factor (GF) and protein from the wound surface.

Material and methods:
Six DFU subjects were included in this study, and divided into two groups based on the method of topical extraction: the cotton group and the Whatman paper group. The swab method is to use a cotton swab on the center of the wound and rotate it about 3 times until the cotton swab is wet. The Whatman method involves sticking Whatman paper to the wound surface, applying light pressure and leaving it for 15 min. Cotton swabs and Whatman paper were placed in Eppendorf tubes with 1.5 cm3 of NaCl and processed by making lysates in an integrated laboratory. Furthermore, cotton swabs and Whatman paper containing wound fluid in the Eppendorf tube were centrifuged immediately at 10,000 rpm for 3 min at room temperature. The resulting cell-free supernatant was subjected to analysis by the ELISA method. VEGF, interleukin-6 and MMP-9 and TIMP-1 proteins were calculated by statistic analysis. Descriptive statistics were used to present the variable location and type of injury. Quantitative variables are summarized as mean with standard deviation (SD). The relationship between levels of biomarkers obtained from concurrently collected wound fluids (cotton swab and Whatman) was assessed using an independent t test analysis using SPSS 2015 software, version 20.0

Results:
There was a significant difference in material collection from cotton swabs compared to the material collection method with Whatman paper for MMP-9 protein (p = 0.028) and TIMP-1 (p = 0.030). Meanwhile, for VEGF and IL-6, there were no insignificant differences between the two methods of taking the material on the diabetic foot ulcers surface.

Conclusions:
Diagnostic wound fluid in diabetic foot ulcers using a non-pressure wound swab (Levine technique) can be considered for the collection of wound fluid from diabetic foot ulcers for ELISA examination as a guideline for further treatment.