**4. Conclusions**

We have shown that specific functionalization of polysiloxanes may increase their antiadhesive properties against a range of prokaryotic and eukaryotic microorganisms of different cell organization and cell wall structures, while not decreasing the inherent hydrophobic nature of silicone materials. Polysiloxanes bearing 2-(carboxymethylthioethyl)-, 2-(*n*-propylamidomethylthioethyl)- and 2-(mercaptoethylamidomethylthioethyl)- side groups have shown good antimicrobial and antibiofilm activity towards selected strains of bacteria (*A. hydrophila*, *S. aureus*, *E. coli*), fungi (*A. pullulans*) and algae (*C. vulgaris*). The results obtained for model thin-coating samples are promising for application of the studied polymers incorporated as structural units in more complicated macromolecular systems, e.g., crosslinked silicone rubber or gels.

This research is in line with current trends and developments for antimicrobial materials. The antimicrobial and antiadhesive polymers not only play a critical role in cell biology, but they are a powerful tool in many applications, where the control of microbial adhesion is necessary. However, it is worth paying attention to the mechanisms of antimicrobial action of modified compounds, effects of their lasting action on microbial cells and whether the long-term use of such antimicrobial materials is not associated with the risk of increasing cell resistance to the biocides used.

**Author Contributions:** Conceptualization, A.K.; formal analysis, M.N.; investigation, M.N., A.R. and D.K.; writing—original draft preparation, A.K., D.K.; writing—review and editing, A.K., M.N.; supervision, A.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data presented in this study are available on request.

**Acknowledgments:** The studies were carried out within statutory funds of Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences and Department of Environmental Biotechnology, Faculty of Biotechnology and Food Sciences, Lodz University of Technology.

**Conflicts of Interest:** The authors declare no conflict of interest.

**Sample Availability:** Samples of the compounds are available from the authors only for scientific collaboration.
