Antibacterial activity of 3D printed thermoplastic elastomers doped with carbon quantum dots for biomedical applications

3D printing provides a lot of varieties for the manufacturing of personalized biomedical devices. Incorporation of the nanoparticles with potential antibacterial activity to the printed materials is another added value. One example of such nanoparticles are hydrophobic carbon quantum dots (hCQDs), which are zero-dimensional redox-active materials with high chemical stability and low production costs. They produce singlet oxygen only when activated by a specific wavelength of visible blue light which allows for controlled antibacterial action and minimizes the chances of bacterial resistance emergence. We prepared and characterized polymer composites based on thermoplastic elastomers (TPE) doped with hCQDs (TPE/hCQDs). The composites were 3D printed using fused deposition modeling method. In the first set of samples, a filament of pure TPE was immersed in a solution of hCQDs (0.5 mg/mL), then 3D printed, and compared with unmodified TPE filament. The mechanical properties, swelling behavior, hardness, and thermal stability of TPE/hCQDs were compared with the pure TPE printed samples. The production of singlet oxygen was confirmed by the electron paramagnetic resonance method. The antibacterial activity of the samples was tested according to ISO 22196 against Staphylococcus aureus and Escherichia coli after one hour of exposure to blue light, which completely inhibited bacterial growth. Besides, the cytotoxicity of samples was evaluated by MTT assay, and no significant effect of the materials on cell viability was observed. 3D printed materials with antibacterial activity represent a perspective for the future, especially in the field of personalized medicine, as well as in products for other industries.