Design of a sensory polymer for the detection of Zn(II) for the diagnosis of chronic wounds

Introduction

Wound repair is a complex process formed for various phases (formation of fibrin clot or inflammatory response, among others). Metalloproteases (MMP) are enzymes that play a relevant role in this process since their functions are; regulate inflammation and degrade the extracellular matrix (ECM). This degradation allows the beginning of the cellular migration process and the formation of a new ECM.

Moreover, new studies show that an increase in enzyme activity of MMP could cause a chronic wound. Therefore, the control and knowledge of their enzyme activity have a great interest since it can help diagnose and treat this type of wounds [1].

On the other hand, Zn(II) is present as a structural and catalytic component of MMP, so the concentration of this ion could be correlated with the activity of MMP, and finally, this activity is correlated with the state of chronic wounds [2].

Hence, this study is based on the following objectives: (1) Chronic wound evaluation by medical personnel, (2) determination of Zn(II) in chronic wound through ICP-MS as a reference method, and (3) determination of Zn(II) in chronic wounds with an alternative, simpler, and more direct method.

The first two objectives will confirm the relationship between Zn(II) concentration and chronic wound severity, and the third objective is the main line of our study. It is oriented to developing an alternative method for Zn(II) detection “by the easy way”, using fluorimetric sensory polymers.

The last objective will be carried out through polymer science, specifically with polymer sensors. This kind of materials has obtained good results with simple procedures; thus, we proposed an inexpensive and rapid sensory material, which causes a change of fluorescent that can be measured both visually (naked eye) and smartphone boosted.

Our sensory motif is based on the quinoline family that is usually used to detect Zn(II) as we have seen in previous studies of the group.[2] Moreover, this method is cheap, simple, and the measurements can be easily carried out by unskilled personnel.

Polymer synthesis

The material was prepared by radical copolymerization of the different monomers: Vinylpyrrolidone (VP), methyl methacrylate (MMA), and the sensory monomer previously described (2). The radical polymerization was carried out in a silanized glass mould (100 μm thick) in an oxygen-free atmosphere at 60ºC overnight to obtain the polymeric film.

Results and Discussion

Preparation of biological samples from chronic wounds

Different kinds of samples (swab, wound bed, edge, capsular tissue, and bone) were obtained from chronic wounds of patients at Burgos University Hospital (HUBU). Each sample was then boiled in a pH 4.66 buffer solution for 10 min (20ml of buffer per gram of sample). Finally, the samples were cold filtered.

Conclusions

We have designed a new sensory material for the determination of Zn(II) in biological samples, that could be correlated with the enzyme activity of MMP and therefore, with the state of chronic wounds.

We have obtained the sensory material related to objective 3, and we are working on the study of chronic wound samples containing zinc, namely, objectives 1 & 2.

References

1. Xue, M., Le, N. T. V., & Jackson, C. J. (2006). Targeting matrix metalloproteases to improve cutaneous wound healing. In Expert Opinion on Therapeutic Targets (Vol. 10, Issue 1, pp. 143–155).
2. Adjepong, D., Jahangir, S., & Malik, B. H. (2020). The Effect of Zinc on Post-neurosurgical Wound Healing: A Review. Cureus, 12(1), 1–7.

3. Guembe-García, M., Vallejos, S., Carreira-Barral, I., Ibeas, S., García, F. C., Santaolalla-García, V., Moradillo-Renuncio, N., & García, J. M. (2020). Zn(II) detection in biological samples with a smart sensory polymer. Reactive and Functional Polymers, 154 (2020).