Currently, the development of antibiotic-resistant bacterial infections is a major problem, particularly in hospitals. Bacteria have the ability to quickly settle all surfaces and survive on them even for years. The patented hydrophobic carbon quantum dots (hCQDs) can serve as an innovative material in preventing nosocomial infections, generally the development of bacterial infections. These are cost-effective and time-saving nanomaterials that are biologically harmless and environmentally friendly. Furthermore, the material has controllable antibacterial activity, as it works on the principle of photodynamic therapy (PDT) and only an ordinary blue LED lamp is needed for activation. PDT is a non-invasive method commonly used in cosmetics and medicine. It consists of three components: light, oxygen, and a photosensitizer (in this case, hCQDs). After irradiation, the material produces oxygen radical - singlet oxygen - which causes oxidative stress in bacteria and disrupts their viable structures (cell wall, ribosomes, DNA, etc.). Another great advantage is their simple method for incorporation into polymer matrices. This way, stable antibacterial polymer composites can be prepared easily and quickly, which do not degrade and are suitable for modifying almost all surfaces. Examples are antibacterial windows, floors, and walls (not only) in hospitals, as well as antibacterial biomedical devices (urinary catheters, stents, etc.), but are also used in tissue engineering and dermatology (wound treatment and wart treatment) [1, 2, 3]. The efficiency of hCQDs can be improved by treatment in plasma generated by multi-hollow surface dielectric barrier discharge (MSDBD). MSDBD, as a combination of surface and volume DBD plasma, generates atmospheric plasma in an array of small holes penetrating ceramic plasma substrate . In such configuration, a working gas of nitrogen with admixture of pure oxygen and total flow rate of 2L/min flown through the holes. In the experiment the working gas of various concentrations of oxygen in nitrogen was bubbled through a toluene solution of hCQDs and subsequently flown through the holes of MSDBD with generated plasma at differend power input (40-50 W/cm3). This way, excess oxygen was added to the structure of hCQDs to form more reactive oxygen functional groups. Therefore, hCQDs produced an increased amount of singlet oxygen, which was measured by EPR spectroscopy and has the potential for an increased antibacterial effect against G+ and G- bacteria.